,transcriber's ,notes3 ,underscores 80 before and after a word or phrase indicate italics in the original text4 ,equal signs 80 before and after a word or phrase indicate bold in the original text4 ,small capitals have been converted to ,,solid capitals4 ,illustrations have been moved so they do not break up paragraphs4 ,typographical and punctuation errors have been silently corrected4 ,,steel3 ,a ,,manual ,,for ,,steel-,,users4 ,,by ,,william ,,metcalf4 ,,first ,,edition4 ,,first ,,thousand4 ,,new ,,york3 ,,john ,,wiley ,,sons4 ,,london3 ,,chapman ,,hall1 ,,limited4 #ahif4 ,copyright1 #ahif1 ,,by ,,william ,,metcalf4 ,,robert ,,drummond1 ,,electrotyper ,,and ,,printer1 ,,new ,,york4 ,,introduction4 ,twenty-seven years of active practice in the manufacture of steel brought the author in daily contact with questions involving the manipulation of steel1 its properties1 and the results of any operations to which it was subjected4 ,blacksmiths1 edge-tool makers1 die-makers1 machine-builders1 and engineers were continually asking questions whose answers involved study and experiment4 ,during these years the ,bessemer and the open-hearth processes were developed from infancy to their present enormous stature2 and the shadows of these young giants1 ever menacing to the expensive and fragile crucible1 kept one in a constant state of watching1 anxiety1 and more study4 ,the literature of steel has grown with the art2 its books are no longer to be counted on the fingers1 they are to be weighed in tons4 ,then why write another8 ,because there seems to be one little gap4 ,metallurgists and scientists have worked and are still working2 they have given to the world much information for which the world should be thankful4 ,engineers have experimented and tested1 as they never did before1 and thousands of tables and results are recorded1 providing coming engineers with a mine of invaluable wealth4 ,steel-workers and temperers have written much that is of great practical value4 ,still the questions come1 and they are almost always those involving an intimate acquaintance with the properties of steel1 which is only to be gained by contact with both manufacturers and users4 ,in this little manual the effort is made to fill this gap and to give to all steel-users a systematic1 condensed statement of facts that could not be obtained otherwise1 except by travelling through miles of literature1 and possibly not then4 ,there are no tables1 and no exact data2 such would be merely a re-compilation of work already done by abler minds4 ,it is a record of experiences1 and so it may seem to be dogmatic2 the author believes its statements to be true--they are true as far as his knowledge goes2 others can verify them by trial4 ,if the statements made prove to be of value to others1 then the author will feel that he has done well to record them2 if not1 there is probably nothing said that is likely to result in any harm4 ,,contents4 ,,chapter ,i4 ,,page ,,general ,,description ,,of ,,steel1 ,,and ,,methods ,,of ,,manufacture4--,cemented or ,converted ,steel4 ,blister1 ,german1 ,shear1 ,double-shear4 ,crucible-steel1 ,bessemer1 ,open-hearth #a ,,chapter ,,ii4 ,,applications ,,and ,,uses ,,of ,,the ,,different ,,kinds ,,of ,,steel4--,crucible1 ,open-hearth1 ,bessemer #ad ,,chapter ,,iii4 ,,alloy ,,steels ,,and ,,their ,,uses4--,self-hardening1 ,manganese1 ,nickel1 ,silicon1 ,aluminum #bg ,,chapter ,,iv4 ,,carbon4--,general ,properties and ,uses4 ,modes of ,introducing ,it in ,steel4 ,carbon ,tempers1 ,how ,determined4 ,the ,carbon-line4 ,effects of ,carbon1 in ,low ,steel1 in ,high ,steel4 ,importance of ,attention to ,composition #cg ,,chapter ,v4 ,,general ,,properties ,,of ,,steel4--,four ,conditions3 ,solid1 ,plastic1 ,granular1 ,liquid4 ,effects of ,heat4 ,size of ,grain4 ,recalescence1 ,magnetism4 ,effects of ,cooling1 ,hardening1 ,softening1 ,checking4 ,effects of ,forging or ,rolling1 ,hot or ,cold4 ,condensing1 ,hammer-refining1 ,bursting4 ,ranges of ,tenacity1 etc4 ,natural ,bar1 ,annealed ,bar1 ,hardened ,bar1 etc4 #eb ,,chapter ,,vi4 ,,heating4--,for ,forging2 ,hardening2 ,overheating2 ,burning2 ,restoring2 ,welding #gg ,,chapter ,,vii4 ,,annealing #hd ,,chapter ,,viii4 ,,hardening ,,and ,,tempering4--,size of ,grain2 ,refining at ,recalescence2 ,specific-gravity ,tests2 ,temper ,colors2 ,how to ,break ,work2 a ,word for the ,workman #if ,,chapter ,,ix4 ,,effects ,,of ,,grinding4--,glaze1 ,skin1 ,decarbonized ,skin1 ,cracked ,surfaces1 ,pickling #abh ,,chapter ,x4 ,,impurities ,,and ,,their ,,effects4--,cold-short4 ,red-short1 ,hot-short1 ,irregularities1 ,segregation1 ,oxides1 etc41 ,wild ,heats1 ,porosity4 ,removing ,last ,fractions of ,hurtful ,elements4 ,andrews ,broken ,rail and ,propeller-shaft #abi ,,chapter ,,xi4 ,,theories ,,of ,,hardening4--,combined1 ,graphitic1 ,dissolved1 ,cement1 ,hardening and ,non-hardening ,carbon4 ,carbides4 ,allotropic ,forms of ,iron 1 1 etc4 ,iron as an ,igneous ,rock or as a ,liquid #adf ,,chapter ,,xii4 ,,inspection4--,ingots1 ,bars1 ,finished ,work4 ,tempers and ,soundness of ,ingots4 ,seams1 ,pipes1 ,laps1 ,burns1 ,stars #aea ,,chapter ,,xiii4 ,,specifications4--,physical1 ,chemical1 and of ,soundness and ,freedom from ,scratches1 ,sharp ,re-entrant ,angles1 etc4 #aed ,,chapter ,,xiv4 ,,humbugs #afa ,,chapter ,,xv4 ,,conclusions #afd ,,glossary4 ,,definitions ,,of ,,shop ,,terms ,,used #afg ,,steel3 ,a ,,manual ,,for ,,steel ,,users4 ,i4 ,,general ,,description ,,of ,,steel ,,and ,,of ,,modes ,,of ,,its ,,manufacture4 ,steel may be grouped under four general heads1 each receiving its name from the mode of its manufacture2 the general properties of the different kinds are the same1 modified to some extent by the differences in the operations of making them2 these differences are so slight1 however1 that after having mentioned them the discussion of various qualities and properties in the following pages will be general1 and the facts given will apply to all kinds of steel1 exceptions being pointed out when they occur4 ,the first general division of steel is cemented or converted steel1 known to the trade as blister-steel1 ,german1 shear1 and double-shear steel4 ,this is probably the oldest of all known kinds of steel1 as there is no record of the beginning of its manufacture4 ,this steel is based upon the fact that when iron not saturated with carbon is packed in carbon1 with all air excluded1 and subjected to a high temperature1--any temperature above a low red heat1--carbon will be absorbed by the iron converting it into steel1 the steel being harder or milder1 containing more or less carbon1 determined by the temperature and the time of contact4 ,experience and careful experiment have shown that at a bright orange heat carbon will penetrate iron at the rate of about one eighth of an inch in twenty-four hours4 ,this applies to complete saturation1 above #ajj carbon2 liquid steel will absorb carbon with great rapidity1 becoming saturated in a few minutes1 if enough carbon be added to cause saturation4 ,,manufacture ,,of ,,blister-,,steel4 ,bars of wrought iron are packed in layers1 each bar surrounded by charcoal1 and the whole hermetically sealed in a fire-brick vessel luted on top with clay2 heat is then applied until the whole is brought up to a bright orange color1 and this heat is maintained as evenly as possible until the whole mass of iron is penetrated by carbon2 usually bars about three quarters of an inch thick are used1 and the heat is required to be maintained for three days1 the carbon1 entering from both sides1 requiring three days to travel three eighths of an inch to the centre of the bar4 ,if the furnace be running hot1 the conversion may be complete in two days1 or less4 ,the furnace is then cooled and the bars are removed2 they are found to be covered with numerous blisters1 giving the steel its name4 ,the bars of tough wrought iron are found to be converted into highly crystalline1 brittle steel4 ,when blister-steel is heated and rolled directly into finished bars1 it is known commercially as ,,german ,,steel4 ,when blister-steel is heated to a high heat1 welded under a hammer1 and then finished under a hammer either at the same heat or after a slight re-heating1 it is known as ,,shear-,,steel1 or ,,single-,,shear4 ,when single-shear steel is broken into shorter lengths1 piled1 heated to a welding-heat and hammered1 and then hammered to a finish either at that heat or after a slight re-heating1 it is known as ,,double-,,shear ,,steel4 ,seebohm gives another definition of single-shear1 and double-shear2 probably both are correct1 being different shop designations4 ,until within the last century the above steels were the only kinds known in commerce4 ,there was a little steel made in ,india by a melting process1 known as ,wootz4 ,it amounted to nothing in the commerce of the world1 and is mentioned because it is the oldest of known melting processes4 ,although converted steel is so old1 and so few years ago was the only available kind of steel in the world1 nothing more need be said of it here1 as it has been almost superseded by cast steel1 superior in quality and cheaper in cost1 except in crucible-steel4 ,inquiring readers will find in ,percy1 and many other works1 such full and detailed accounts of the manufacture of these steels that it would be a waste of space and time to reprint them here1 as they are of no more commercial importance4 ,in the last century ,daniel ,huntsman1 of ,england1 a maker of clocks1 found great difficulty in getting reliable1 durable1 and uniform springs to run his clocks4 ,it occurred to him that he might produce a better and more uniform article by fusing blister-steel in a crucible4 ,he tried the experiment1 and after the usual troubles of a pioneer he succeeded1 and produced the article he required4 ,this founded and established the great ,crucible-cast-steel industry1 whose benefits to the arts are almost incalculable2 and none of the great inventions of the latter half of this nineteenth century have produced anything equal in quality to the finer grades of crucible-steel4 ,,crucible-,,cast ,,steel is the second of the four general kinds of steel mentioned in the beginning of this chapter4 ,although ,huntsman succeeded so well that he is clearly entitled to the credit of having invented the crucible process1 he met with many difficulties1 from porosity of his ingots mainly2 this trouble was corrected largely by ,heath by the use of black oxide of manganese4 ,heath attempted to keep his process secret1 but it was stolen from him1 and he spent the rest of a troubled life in trying to get some compensation from the pilferers of his process4 ,an interesting and pathetic account of his troubles will be found in ,percy4 ,heath's invention was not complete1 and it was finished by the elder ,mushet1 who introduced in addition to the oxide of manganese a small quantity of ferro-manganese1 an alloy of iron and manganese2 and it was now possible1 with care and skill1 to make a quality of steel which for uniformity1 strength1 and general utility has never been equalled4 ,crucible-steel was produced then by charging into a crucible broken blister-steel1 a small quantity of oxide of manganese1 and of ferro-manganese1 or ,spiegel-eisen1 covering the crucible with a cap1 and melting the contents in a coke-furnace1 a simple furnace where the crucible was placed on a stand of refractory material1 surrounded by coke1 and fired until melted thoroughly4 ,the first crucibles used1 and those still used largely in ,sheffield1 were made of fire-clay2 a better1 larger1 and more durable crucible1 used in the ,united ,states exclusively1 and in ,europe to some extent1 is made of plumbago1 cemented by enough of fire-clay to make it strong and tough4 ,as the demands for steel increased and varied it was found that the carbon could be varied by mixing wrought iron and blister-bar1 and so a great variety of tempers was produced1 from steel containing not more than #j4aj of carbon up to steel containing #a4ej to #b of carbon1 and even higher in special cases4 ,it was soon found that the amount of carbon in steel could be determined by examining the fractures of cold ingots2 the fracture due to a certain quantity of carbon is so distinct and so unchanging for that quantity that1 once known1 it cannot be mistaken for any other4 ,the ingot is so sensitive to the quantity of carbon present that differences of 4#je may be observed1 and in everyday practice the skilled inspector will select fifteen different tempers of ingots in steels ranging from about #ej carbon to #aej carbon1 the mean difference in carbon from one temper to another being only 4#jg4 ,and this is no guess-work2--no chemical color determination will approach it in accuracy1 and such work can only be checked by careful analysis by combustion4 ,this is the steel-maker's greatest stronghold1 as it is possible by this means for a careful1 skilful man to furnish to a consumer1 year after year1 hundreds or thousands of tons of steel1 not one piece of which shall vary in carbon more than 4#je above or below the mean for that temper4 ,the word 8temper0 used here refers to the quantity of carbon contained in the steel1 it is the steel-maker's word2 the question1 8,what temper is it80 answered1 ,no4 #c1 ,no4 #f1 or any other designation1 means a fixed1 definite quantity of carbon4 ,when a steel-user hardens a piece of steel1 and then lets down the temper by gentle heating1 and he is asked1 8,what temper is it80 he will answer straw1 light brown1 brown1 pigeon-wing1 light blue1 or blue1 as the case may be1 and he means a fixed1 definite degree of softening of the hardened steel4 ,it is an unfortunate multiple meaning of a very common word1 yet the uses have become so fixed that it seems to be impossible to change them1 although they sometimes cause serious confusion4 ,the quantity of carbon contained in steel1 and indeed of all ingredients1 as a rule1 is designated in one hundredths of one per cent2 thus ten 74#aj7 carbon means ten one hundredths of one per cent2 nineteen 74#ai7 carbon means nineteen one hundredths of one per cent2 one hundred and thirty-five 7#a4ce7 carbon means one hundred and thirty-five one hundredths of one per cent1 and so on4 ,so also for contents of silicon1 sulphur1 phosphorus1 manganese and other usual ingredients4 ,this enumeration will be used in this work1 and care will be taken to use the word 8temper0 in such a way as not to cause confusion4 ,it has been stated that crucible-cast steel is made from ten carbon up to two hundred carbon1 and that its content of carbon can be determined by the eye1 from fifty carbon upwards1 by examining the fracture of the ingots4 ,the limitation from fifty carbon upwards is not intended to mean that ingots containing less than fifty carbon have no distinctive structures due to the quantity of carbon2 they have such distinctive structures1 and the difficulty in observing them is merely physical4 ,ingots containing fifty carbon are so tough that they can only be fractured by being nicked with a set deeply1 and then broken off2 below about fifty carbon the ingots are so tough that it is almost impossible to break open a large enough fracture to enable the inspector to determine accurately the quantity of carbon present2 therefore it is usual in these milder steels1 when accuracy is required1 to resort to quick color analyses to determine the quantity of carbon present4 ,color analyses below fifty carbon may be fairly accurate1 above fifty carbon they are worthless4 ,as the properties and reliability of crucible-steel became better known the demand increased1 and the requirements varied and were met by skilful manufacturers1 until1 by the year #ahfj1 ingots were produced weighing many tons by pouring the contents of many crucibles into one mould2 in this way the more urgent demands were met1 but the material was very expensive and the risks in manufacturing were great4 ,about this time1 stimulated by the desire of enlightened governments to increase their powers of destruction in war by the use of heavy guns of greater power than could be obtained by the use of cast iron1 and for heavier ship-armor to be used in defence1 ,mr4 ,bessemer1 of ,england1 now ,sir ,henry ,bessemer1 reasoned that if melted cast iron was reduced to wrought iron by puddling1 or boiling1 by the mere oxidation1 or burning out1 of the excess of carbon and silicon from the cast iron1 that the same cast iron might be reduced to steel in large masses by blowing air through a molten mass in a close vessel1 retaining enough heat to keep the mass molten so that the resulting steel could be poured into ingots as large as might be desired4 ,at about the same time1 or a little earlier1 ,mr4 ,kelly1 of the ,united ,states1 devised and patented the same method4 ,both of these gentlemen demonstrated the potencies of their invention1 and neither brought it to a successful issue4 ,to persistent and intelligent iron-masters of ,sweden must be given the credit of bringing the process of ,bessemer to a commercial success1 and so they gave to the world pneumatic or ,bessemer steel1 the latter name holding1 properly1 as a just tribute to the inventor1 and this inaugurated the third general division3 ,,bessemer ,,steel4 ,bessemer steel is made by pouring into a bottle-shaped vessel lined with refractory material a mass of molten cast iron1 and then blowing air through the iron until the carbon and silicon are burned out4 ,the gases and flame resulting escape from the mouth of the vessel4 ,the combustion of carbon and silicon produce a temperature sufficient to keep the mass thoroughly melted1 so that the steel may be poured into moulds making ingots of any desired size4 ,in the beginning1 and for many years1 the lining of the vessel was of silicious or acid material1 and it was found that all of the phosphorus and sulphur contained in the cast iron remained in the resulting steel1 so that it was necessary to have no more of these elements in the cast iron than was allowable in the steel4 ,the higher limit for phosphorus was fixed at ten points 74#aj71 and that is the recognized limit the world over4 ,when ,bessemer pig is quoted1 or sold and bought1 it means always a cast iron containing not more than ten phosphorus4 ,in regard to sulphur1 it was found that if too much were present the material would be red-short1 so that it could not be worked conveniently in the rolls or under the hammer1 and that when the amount of sulphur present was not enough to produce red-shortness it was not sufficient to hurt the steel4 ,as red-short material is costly and troublesome to the manufacturer1 it was not found necessary to fix any limit for sulphur1 because the makers could be depended upon to keep it within working limits4 ,later investigations prove this to be a fallacy1 as much as ten or even more sulphur has been found in broken rails and shafts1 the steel having made workable by a percentage of manganese4 7,see the results of ,andrews's investigation given in ,chap4 ,x47 ,during the operation of blowing ,bessemer steel the flame issuing from the vessel is indicative of the elimination of the elements1 and it is found that while the combustion is partially simultaneous the silicon is all removed before the carbon1 and the characteristic white flame towards the end of the blow is known as the carbon flame2 when the carbon is burned out1 this flame drops suddenly and the operator knows that the blow is completed4 ,any subsequent blowing would result in burning iron only4 ,during the blow the steel is charged heavily with oxygen1 and if this were left in the steel it would be rotten1 red-short1 and worthless4 ,this oxygen is removed largely by the addition of a predetermined quantity of ferro-manganese1 usually melted previously and then poured into the steel4 ,the manganese takes up the greater part of the oxygen1 leaving the steel free from red-shortness and easily worked4 ,the fact that the phosphorus of the iron remained in the steel notwithstanding the active combustion and high temperature led to the dictum that at high temperatures phosphorus could not be eliminated from iron4 ,this conclusion was credited because in some of the so-called direct processes of making iron where the temperature was never high enough to melt steel all1 or nearly all1 of the phosphorus was removed from the iron4 ,for many years steel-makers the world over worked upon this basis1 and devoted themselves to procuring for their work iron containing not more than ten 74#aj7 phosphorus1 now universally known and quoted as ,bessemer iron4 ,two young ,english chemists1 ,sidney ,gilchrist ,thomas and ,percy ,c4 ,gilchrist1 being careful thinkers1 concluded that the question was one of chemistry and not one of temperature2 accordingly they set to work to obtain a basic lining for the vessel and to produce a basic slag from the blow which should retain in it the phosphorus of the iron4 ,after the usual routine of experiment1 and against the doubtings of the experienced1 they succeeded1 and produced a steel practically free from phosphorus4 ,for the practical working of their process it was found better1 or necessary1 to use iron low in silicon and high in phosphorus1 using the phosphorus as a fuel to produce the high temperature that is necessary instead of the silicon of the acid process4 ,in the acid process it is found necessary to have high silicon--two percent or more--to produce the temperature necessary to keep the steel liquid2 in the ,thomas-,gilchrist process phosphorus takes the place of silicon for this purpose4 ,in this way the basic ,bessemer process was worked out and became prominent4 ,the basic ,bessemer process is of great value to ,england and to the continent of ,europe by enabling manufacturers to use their native ores1 which are usually too high in phosphorus for the acid process1 so that before this invention nearly all of the ores for making ,bessemer steel were imported from ,sweden1 ,spain1 and ,africa4 ,the basic process has found little development in the ,united ,states1 because the great abundance of pure ore keeps the acid process the cheaper1 except in one or two special localities4 ,where the basic process is profitable in the ,united ,states1 it is worked successfully4 ,at about the time that ,bessemer made his invention ,william ,siemens1 afterward ,sir ,william1 invented the well-known regenerative gas-furnace4 ,a ,frenchman named ,martin utilized this furnace to melt steel in bulk in the hearth of the furnace1 developing what was known for some years as ,siemens-,martin steel1 or open-hearth steel2 the latter name has prevailed1 and open-hearth steel is the fourth of the general kinds of steel mentioned in the beginning of this chapter4 ,at first open-hearth steel was made upon a specially prepared sand bottom1 by first melting a bath of cast iron and then adding wrought iron to the bath until by the additions of wrought iron and the action of the flame the carbon and silicon of the cast iron were reduced until the whole became a mass of molten steel4 ,sometimes iron ore is used instead of wrought iron as the reducing agent2 this is called the pig and ore process4 ,now in general practice wrought iron1 steel scrap1 and iron ore are used1 sometimes alone and sometimes together1 as economy or special requirements make it convenient4 ,it was found as in the ,bessemer1 so in the open-hearth1 the sulphur and the phosphorus of the charge remained in the steel1 making it necessary to see that in the charge there was no more of these elements than the steel would bear4 ,this is known now as the acid open-hearth process4 ,after the success of the basic ,bessemer process was assured the same principle was tried in the open-hearth2 a basic bottom of dolomite or of magnesite was substituted for the acid sand bottom1 and care was taken to secure a basic slag in the bath4 ,success was greater than in the ,bessemer2 phosphorus was eliminated and a better article in every way was made by this process1 now used extensively over the whole civilized world4 ,this is the basic open-hearth process4 ,neither the basic ,bessemer process nor the basic open-hearth removed sulphur1 so that this element must still be kept low in the original charge1 until some way shall be found for its sure and economical elimination4 ,the four general divisions1 then1 are3 ,converted or ,cemented ,steel4 ,crucible-cast ,steel4 ,bessemer ,acid ,basic ,cast ,steel4 ,open-hearth ,acid ,basic ,cast ,steel4 ,little or nothing more will be said of the first kind1 as it has been so thoroughly superseded by the cast steels4 ,after a statement of the most patent applications and uses of the different cast steels the discussions which follow will apply to all1 because practically they are all governed by the same general laws4 ,,ii4 ,,applications ,,and ,,uses ,,of ,,the ,,different ,,kinds ,,of ,,steel4 ,where exact uniformity of composition is not a necessity1 and where welding is required1 cemented or converted steel may be preferred to cast steel1 because the converted bar retains the occluded layers of slag which give to wrought iron its peculiar welding properties1 and for this reason blister- or shear-steel may be welded more easily and surely than cast steel4 ,for tires1 composite dies1 and many compound articles this steel will do very well1 and it may be worked with good results by almost any smith of ordinary skill2 however1 owing to the more uniform structure and the greater durability of the cast steels1 they have1 even for these purposes1 almost entirely displaced the more easily worked1 but less durable1 cemented steels4 ,,crucible-,,cast ,,steel4 ,for all purposes crucible-steel has proved to be superior to all others2 it is well known to all experienced and observing workers in steel that1 given an equal composition1 crucible is stronger and more reliable in every way than any of the other kinds of steel4 ,this may read like a mere dictum1 and it might be asked properly1 ,what are the proofs8 ,the proofs are wanting for two reasons3 first1 because crucible-steel is so expensive that except for gun parts1 armor1 and such uses where expense could be ignored1 crucible-steel never came into extensive use for structural purposes2 second1 that while thousands upon thousands of tests of the cheaper steels are recorded and available to engineers very few of such tests have been made on crucible-steel1 simply because it has not been used for structural purposes4 ,on the other hand1 intelligent makers of crucible-steel have for self-preservation made careful study of the relative properties of the different steels in order that they might know what to expect from the cheaper processes4 ,in this way they have surrendered boiler-steel1 spring-steel1 machinery-steel1 battering-tool steel1 cheap die-steel1 and many smaller applications2 not because they could not produce a better article1 but because the cheaper steels met the requirements of consumers satisfactorily1 and therefore they could not be expected to pay a higher price for an article whose superiority was not a necessity in their requirements4 ,still this stated superiority is proven best by the fact that many careful consumers who have special reasons for studying durability as against first cost adhere to the higher priced crucible-steel for such uses as1 for instance1 parts of mining- and quarrying-drills1 high-speed spindles1 in cotton-mills1 and in expensive lathes and machines of that kind4 ,this sort of testimony should be more conclusive than that of interested steel-makers1 because these men pay their own money for the higher priced material1 and because men who are most careful of the quality of their produce and of their reputation are the most clear-headed and most sensible men of their class2 they have the best business and the greatest success4 ,such men are not fools2 they may be depended upon to try everything of promise with the greatest care1 and to use only that thing which pays them best4 ,in fact such men do use the cheaper steels freely wherever they can do so safely4 ,a good car-spring1 carriage-spring1 or wagon-spring is made from ,bessemer or open-hearth steel1 a spring that will wear out the car or carriage2 it would be stupid then to buy more expensive steel for such purposes1 for even if crucible-steel would wear out two cars or two wagons the owner never expects to take the springs out of an old wagon to put them under a new one4 ,on the other hand1 the watch-spring maker or the clock-spring maker will find a great advantage in using the very best crucible-steel that can be made4 ,a sledge1 a maul1 or a hammer can be made of such excellent quality from properly selected ,bessemer or open-hearth steel that it would be foolish for makers of such tools to continue to buy crucible-steel1 even though they knew it to be superior1 for lower first cost in such cases outweighs superiority that cannot be shown for a number of years4 ,locomotive-boilers1 crank-pins1 slide-rods1 connecting-rods1 and springs can be made of such good quality of ,bessemer or open-hearth steel that1 like the 8one-horse shay10 the whole machine will wear out at the same time practically1 and that a good long time2 there would be no reason in this case for using crucible-steel for one or more of these parts1 although twenty-five years ago it was by means of crucible-steel that engineers learned to use steel for these purposes4 ,a good cam for an ordinary machine1 such as a shear or punch1 may be made of ,bessemer or open-hearth steel where greater strength and endurance are required than can be had in cast iron2 on the other hand1 makers of cams for delicately adjusted high-speed machines where intricacy and accuracy are necessary will touch nothing but the very best crucible-steel of fine-tool quality for their work4 ,it is of no use to suggest the greater cheapness of the other steels2 they have tried them thoroughly1 and they know that in their case the highest priced is the cheapest4 ,this superiority of crucible-steel has been doubted1 because the claim appeared to rest solely upon the statements of steel-makers1 and not to have any scientific basis2 there is1 however1 a scientific basis for the fact4 ,given three samples of steel of say the following composition3 ,crucible4 ,open-hearth4 ,bessemer4 ,carbon #a4jj #a4jj #a4jj ,silicon 4#aj 4#aj 4#aj ,phosphorus 4#je 4#je 4#je ,sulphur 4#jb 4#jb 4#jb ,copper1 arsenic1 etc4 traces ,why should there be any difference in the strength of the three8 ,in mere tensile strength in an untempered bar the difference might not be very great1 although all experienced persons would expect the crucible to show the highest2 but it is not necessary to make the claim1 because we have not enough tests of crucible-steel to enable us to establish a mean1 and one or two tests are insufficient to establish a rule in any case4 ,there have been made1 however1 hundreds of tests of hardened and tempered samples by the most expert persons1 with one invariable result3 the crucible-steel is incomparably finer and stronger than the others1 and the open-hearth is almost invariably stronger and finer than the ,bessemer4 ,unfortunately for the argument these tests cannot be recorded so as to be intelligible to the non-expert1 because we cannot tabulate the result of the touch of the expert hand or the observation of the experienced eye4 ,for a time it was popular to call these differences mysteries1 and so let them pass2 this1 however1 was not satisfactory1 and the question was studied carefully for the physical reasons which must exist4 ,much thought led to the conclusion that the reason lay with the three elements oxygen1 nitrogen1 and hydrogen2 they are known to exist in greater or less quantity in all iron and steel4 ,it is known that the presence of oxygen beyond certain small limits produces red-shortness and general weakness2 it is probably a much more hurtful element than phosphorus or sulphur1 but no quantitative method for its determination has been worked out2 there is an effort now being made to develop a simple and expeditious oxygen determination1 and it is to be hoped that it will be successful4 ,in the crucible no more oxygen1 hydrogen1 or nitrogen can get into the steel than is contained in the material charged and in the atmosphere of the crucible1 or than may penetrate the walls of the crucible during melting4 ,in the open hearth the process is an oxidizing one1 and besides the charge is swept continuously by hot flames containing all of these elements4 ,in the ,bessemer process the conditions are worse still1 as these elements are all blown through the whole mass of the steel4 ,we know the effect of oxygen and how to eliminate it practically4 ,percy gives the effects of nitrogen as causing hardness and extreme brittleness1 and giving to iron or steel a brassy lustre4 ,such a brassy lustre may be seen frequently in open-hearth or ,bessemer steel1 and occasionally in crucible-steel4 ,when seen in crucible-steel it is known to be due to the fact that the cap of the crucible became displaced1 exposing the contents to the direct action of the flame4 ,of the effect of hydrogen we know less2 there is no reason apparent why it may not be as potent as the others4 ,ammonia in sufficient quantity to be detected by the nose has often been observed in open-hearth and ,bessemer steel4 ,to settle the nitrogen question ,prof4 ,john ,w4 ,langley developed some years ago a very delicate and accurate process for the determination of nitrogen even in minute quantities2 the process was tedious and expensive1 so that it was not adapted for daily use2 it involved the careful elimination of nitrogen from all of the reagents to be used1 requiring several days' work1 in each case to prepare for only a few nitrogen determinations4 ,by this process it was found1 in every one of many trials1 that crucible-steel contained the least amount of nitrogen1 open-hearth steel the next greater quantity1 and ,bessemer steel the greatest amount4 ,he found no exceptions to this4 ,for many years great efforts had been made both in ,europe and in the ,united ,states to make by the ,bessemer or the open-hearth process a cheap melting-product to be used in the crucible instead of the expensive irons which so far have proved to be necessary to give the best results4 ,there appeared to be no difficulty in making a material as pure chemically1 or purer1 than the most famous irons in the world1 and this material was urged upon the crucible-steel makers4 ,careful tests of such material failed to produce the required article2 in fact it was demonstrated over and over again that an inferior wrought iron would produce a stronger steel than this very pure steel melting-material1 and crucible-steel makers were compelled to adhere to the more costly irons to produce their finer grades4 ,prof4 ,langley determined the nitrogen in a given quantity of open-hearth and ,bessemer steel2 this same material was then melted in a crucible1 and it was found that the resulting ingots contained nearly as much nitrogen as the original charge4 ,the quantity was reduced slightly2 still this steel contained more nitrogen than any other sample of crucible-steel that he had tested4 ,the physical test of this trial steel showed the usual weakness of the ,bessemer or open-hearth steel1 as compared to crucible-steel4 ,the next step was to try to get rid of nitrogen by the use of some affinity1 as oxygen is removed by manganese4 ,boron and titanium seemed to be the most feasible elements2 boron appeared to offer less chance of success1 and titanium was selected4 ,a ferro-titanium containing six per cent of titanium was imported from ,europe at some expense4 ,as the most careful and exacting analyses of this material failed to reveal a trace of titanium1 it was not used4 ,after many futile efforts ,langley succeeded1 by means of electric heat1 in reducing rutile and producing a small quantity of an alloy of iron and titanium4 ,a trial of this alloy1 although not conclusive1 led to the belief that such an alloy could be used successfully to eliminate nitrogen2 but as its cost1 about two dollars a pound1 was prohibitory of any commercial use1 the subject was not pursued farther4 ,although we know these elements only as gases1 there is no reason to suppose that their atoms may not be as potent1 when added to steel1 as atoms of carbon1 silicon1 phosphorus1 or any other substance4 ,such are the facts for crucible-steel as far as they are known2 it is vastly more expensive than any other kind of steel1 yet for the present it holds its own unique and valuable place in the arts4 ,for all tools requiring a fine edge for cutting purposes1 such as lathe-tools1 drills1 taps1 reamers1 milling-cutters1 axes1 razors1 pocket-knives1 needles1 graving-tools1 etc42 for fine dies where sharp outline and great endurance are required2 for fine springs and fine machinery parts and fine files and saws1 and for a hundred similar uses1 crucible-cast steel still stands pre-eminent1 and must remain so until some genius shall remove from the cheaper steels the elements that unfit them for these purposes4 ,as stated before1 crucible-steel is divided into fifteen or more different tempers1 ranging in carbon from 4#ej to #a4ej4 ,each of these tempers has its specific uses1 and a few will be pointed out in a general way4 4#ej to 4#fj carbon is best adapted for hot work and for battering-tools4 4#fj to 4#gj carbon for hot work1 battering-tools1 and tools of dull edge4 4#gj to 4#hj carbon for battering-tools1 cold-sets1 and some forms of reamers and taps4 4#hj to 4#ij carbon for cold-sets1 hand-chisels1 drills1 taps1 reamers1 and dies4 4#ij to #a4jj carbon for chisels1 drills1 dies1 axes1 knives1 and many similar purposes4 #a4jj to #a4aj carbon for axes1 hatchets1 knives1 large lathe-tools1 and many kinds of dies and drills if care be used in tempering them4 #a4aj to #a4ej carbon for lathe-tools1 graving-tools1 scribers1 scrapers1 little drills1 and many similar purposes4 ,the best all-around tool-steel is found between 4#ij and #a4aj carbon2 steel that can be adapted safely and successfully to more uses than any other temper4 ,at somewhere from 4#ij to #a4jj carbon1 iron appears to be saturated with carbon1 giving the highest efficiency in tools and the highest results in the testing-machine except for compressive strains4 ,more will be said upon this point in treating of the carbon-line4 ,much more could be said about the uses for the different tempers of steel2 it would be easy to write out in great detail the exact carbon which experience has shown to be best adapted to any one of hundreds of different uses1 but it would only be confusing and misleading to a great many people4 ,it is within the experience of every steel-maker that men are just as variable as steel1 and the successful steel-maker must familiarize himself with the personal equations of his patrons4 ,one man on the sunny side of a street may be making an excellent kind of tool from a certain grade and temper of steel1 and be perfectly happy and prosperous in its use4 ,his competitor on the shady side of the street may fail in trying to use the same steel for the same purpose and condemn it utterly4 ,the know it all agent will condemn the latter man with an intimation that his ears are too long1 and so lose his trade4 ,the tactful agent will supply him with steel a temper higher or a temper lower1 until he hits upon the right one1 and so will retain both men on his list2 and both men will turn out equally good products4 ,few men know their own personal equations1 and the best way for a steel-user to do is to tell the steel-maker what he wants to accomplish1 and put upon him the responsibility of selecting the best temper4 ,it costs no more to make and to provide one temper than another2 therefore the one inducement of the steel-maker is to give his patron that which is best adapted to his use4 ,this plan puts all of the responsibility upon the steel-maker1 just where it ought to be1 because he should know more about the adaptability of his steel than any other person4 ,,bessemer ,,steel4 ,bessemer steel is probably the cheapest of all grades of steel2 that is to say1 it can be made so rapidly1 so continuously1 and in such enormous quantities that a greater output per dollar invested can be made than by either of the other processes4 ,again1 the work is controlled and operated by machinery to a much greater extent than in the other processes2 therefore the cost of labor per ton of product both for skilled and unskilled labor is less than in the crucible or the open-hearth method4 ,this being the case1 it might be inferred that the result would be the eventual driving out of all other steels by this1 the cheapest4 ,this would be the inevitable result if ,bessemer steel were as well adapted to all purposes as either of the other kinds of steel2 there are limitations which prevent this4 ,the source of heat in the ,bessemer process is in the combustion of the elements of the charge1 there is no extraneous source of heat2 therefore1 if the heat be too cold1 there is no way to remedy it unless it be by the addition of ferro-silicon and more blowing2 if it be too hot1 it may be allowed to stand a few minutes to cool4 ,still in either case the remedy is somewhat doubtful4 ,this limitation must not be taken as being fatal to good work1 for in skilful hands such cases are rare1 and the product is generally fully up to the standard of good work4 ,as there is no known sure way of stopping the blow at a given point in the operation to produce a steel of required carbon1 it is usual to blow clear down1 that is1 to burn out all of the carbon practically and then to re-carbonize by the addition of spiegel-eisen or ferro-manganese4 ,it is necessary1 also1 to add the manganese in one of these forms to remove the oxygen introduced during the blow2 this must be done quickly1 and all accomplished before the metal becomes too cold for pouring into ingots4 ,so little time for reactions is available that it is doubtful if the material is ever quite as homogeneous as it can be made by either of the other processes4 ,notwithstanding these limitations1 which are not mentioned to throw doubt upon the process1 but merely to inform readers fully so as to enable them to judge rightly as to what may be expected1 enormous quantities of good1 reliable ,bessemer steel are made to meet many requirements4 ,for good1 serviceable1 cheap rails ,bessemer steel stands pre-eminent1 and if it found no other use it would be difficult to overestimate the benefit to the world of this one great success4 ,bessemer steel is used largely for a great number of purposes1 ,bessemer billets being now as regular an article of commerce as pig iron4 ,for wire for all ordinary purposes2 for skelp to be worked into butt-welded and lap-welded tubing2 for wire nails1 shafting1 machinery-steel1 tank-plates1 and for many other uses1 ,bessemer steel has absorbed the markets almost entirely4 ,for common cutlery1 files1 shovels1 picks1 battering-tools1 and many such uses it contests the market with open-hearth steel2 and while many engineers now specify that their structural shapes1 plates1 beams1 angles1 etc41 must be of open-hearth steel1 there are many eminent engineers who see no need for this discrimination1 they being satisfied that if their requirements are met the process by which they are met is a matter of indifference4 ,,open-,,hearth ,,steel4 ,as in the ,bessemer process1 so in the open-hearth1 carbon and silicon are burned out1 phosphorus is removed on the basic hearth1 and the sulphur of the charge remains in the steel4 ,during the operation oxygen and nitrogen are absorbed by the steel1 although not quite so largely as in the ,bessemer process1 so that practically the chemical limitations are the same in each4 ,the open-hearth reductions are much slower than in the ,bessemer1 each heat requiring from five to eight hours for its completion2 the furnace must be operated by a skilled man of good judgment1 so that more time and more skilled labor per ton of product are required than in the ,bessemer1 and the making of an equal quality as cheaply in the open hearth is problematical4 ,the open hearth has extraneous sources of heat at the command and under the control of the operator1 and there need be no cold heats1 and no too hot heats4 ,the time for reactions is much longer1 and for this reason they ought to be more complete1 and they are so in good hands2 yet it is a fact that1 as the operation is a quiet one compared to the ,bessemer1 and not nearly so powerful and energetic1 a careless or unskilful operator may produce in the open hearth an uneven result that is quite as bad as anything that can be brought out of a ,bessemer converter4 ,the process that eliminates the human factor has not yet been invented4 ,for fine boiler-plates1 armor-plates1 and gun parts open-hearth steel has won its place as completely as has the crucible for fine-tool steel or the ,bessemer for rails4 ,for all intermediate products there is a continued race and keen competition1 so that it is impossible to draw any hard and fast line between the products of the three processes where they approach each other2 the only clear distinctions are at the other extremes4 ,owing to the power to hold and manipulate a heat in the open-hearth it is safe to say that it is superior to the ,bessemer in the manufacture of steel castings2 and owing to its much greater cheapness it is difficult for the crucible to compete with it at all in this branch of manufacture4 ,in conclusion of this chapter it is safe to say that in good hands these processes are all good1 and each has its own special function to perform4 ,,iii4 ,,alloy ,,steels ,,and ,,their ,,uses4 ,in addition to the four general kinds of steel treated of in the last chapter there are a number of steels in the market which contain other metals1 and which may be termed properly alloy steels1 to distinguish them from carbon steel1 or the regular steels of world-wide use which depend upon the quantity of carbon present for their properties4 ,the most generally known of the alloy steels is the so-called ,self-hardening steel4 ,self-hardening steel is so called because when it is heated to the right temperature1--about a medium orange color1--and is then allowed to cool in the air1 it becomes very hard4 ,this steel is so easily strained that it is impossible1 as a rule1 to quench it in water without cracking it4 ,it may be quenched in a blast of air without cracking1 and so be made much harder than if it be allowed to cool more slowly in a quiet atmosphere4 ,if it be quenched in oil or water1 it will become excessively hard1 much harder than when quenched in air1 and it will almost invariably be cracked1 or if it be not cracked it will be so excessively brittle as to be of little use4 ,self-hardened steel is so hard in what may be called its natural condition1 that is1 in ordinary bars1 that it cannot be machined1 drilled1 planed1 or turned in a lathe4 ,by keeping it in an annealing-furnace at about bright orange heat for about twenty-four to thirty-six hours1 and then covering it with hot sand or ashes in the furnace1 and allowing about the same time for it to cool1 it may be annealed pretty thoroughly so that it may be machined readily4 ,when annealed in this way and formed into cutters of irregular shape1 or dies1 it has been found so far not to be economical or well adapted to such work1 so that up to the present time annealing is more of a scientific than a useful fact4 ,self-hardened steel has the useful property of retaining its hardness when heated almost to redness2 therefore it may be used as a lathe or similar cutter upon hard work1 such as cutting cast iron and other metals1 at a much higher speed than is possible with ordinary steel1 which would be softened by the heat generated by the high speed4 ,this property makes self-hardened steel very useful and economical for many purposes4 ,self-hardened steel is an alloy of iron1 carbon1 tungsten1 and manganese1 and some brands contain chromium in addition to these1 and it is claimed1 and probably truly1 that the chromium improves the quality of the steel4 ,it was supposed for a long time that tungsten was the hardener that gave to self-hardened steel its peculiar properties4 ,by means of an open hearth1 steel was produced containing about #c tungsten and little carbon and manganese4 ,this steel worked like any mild steel1 except that it was hot-short and difficult to forge4 ,it was not hard and had no hardening properties2 that is1 it did not harden in the ordinary sense when quenched in water4 ,the addition of carbon to this steel1 keeping the manganese low1 produced a steel very difficult to work1 which would harden like ordinary steel when quenched1 and which had no self-hardening properties whatever4 ,the addition of #b to #c of manganese to this steel produced self-hardening steel having the usual properties4 ,manganese1 then1 is the metal that gives the self-hardening property1 and this might have been anticipated by considering the properties of ,hadfield's manganese steel1 which1 when it contains above #g manganese1 cannot be annealed so that it can be machined or drawn into wire4 ,from this it might be inferred that tungsten is not a necessary constituent of self-hardened steel2 that it performs an important function will be shown presently4 ,tests of the iron-tungsten alloy low in carbon gave only a small increase in strength above ordinary low cast steel containing little carbon2 it was difficult and troublesome to work1 and more expensive than the common steels1 so that its production presented no advantages4 ,when carbonized1 it was fine-grained and could be made exceedingly hard2 it was brittle1 and compared to very ordinary cast steel comparatively worthless4 ,in self-hardened steel tungsten is the mordant that holds the carbon in solution and enables the steel to retain its hardness at comparatively high temperatures4 ,that it does hold the carbon in solution may be proved in a moment by a beautiful test1 first observed by ,prof4 ,john ,w4 ,langley4 ,when a piece of carbon steel is pressed against a rapidly running emery wheel1 there is given off a shower of brilliant sparks which flash out in innumerable white1 tiny stars of great beauty2 it is accepted that this brilliancy is due to the explosive combustion of particles of carbon4 ,when a steel containing as much as three per cent of tungsten is pressed against the wheel1 the entire absence of these brilliant flashes is at once noticeable1 and if there be an occasional little flash it only serves to emphasize the absence of the myriads4 ,instead there is an emission of a comparatively small number of dull particles1 and there is clinging to the wheel closely a heavy band of a deep1 rich red color4 ,this red streak is distinctive of the presence of tungsten4 ,by testing various pieces it was soon observed that different quantities of tungsten gave different sizes of red streaks2 as tungsten decreased the width of the band diminished and the number and brilliancy of carbon sparks increased4 ,as little as 4#aj tungsten will show a fine red line amidst a brilliant display of sparks1 and it soon became possible to determine so closely by the streak the quantity of tungsten present that the ordinary analyses for tungsten became unnecessary1 except in occasional important cases where analysis was used merely to confirm the testimony of the wheel4 ,self-hardening steel1 then1 is a steel which1 owing to the presence of manganese and tungsten1 hardens when quenched in quiet air1 and which retains its hardness almost up to a red heat4 ,it may be forged between the temperatures from orange to bright orange2 it cannot be worked safely outside of this range4 ,the more quickly it is quenched the harder it will be2 and it may be annealed so that it can be machined readily4 ,therefore it is not self-hardening2 it simply has all of the properties of carbon steel modified profoundly by tungsten and manganese4 ,if a piece of this steel will not harden sufficiently by cooling in the air quietly1 that difficulty may be remedied by cooling it in an air-blast2 if quenching in an air-blast will not give sufficient hardness1 the steel had better be rejected1 for quenching in oil or water means almost certain destruction4 ,as stated before1 the range of temperature in which self-hardened steel can be forged safely is much smaller than for a high-carbon steel2 it is harder at this heat than carbon steel and not so plastic1 so that it requires more care and more heats in working it to tool-shapes4 ,this steel is so sensitive that it often occurs in redressing it that it will crumble at a heat that was all right in the first working4 ,this difficulty may be remedied by first cutting off the shattered part with a sharp tool1--it must be cut hot1--then heating the piece up to nearly a lemon color1 heating it through without soaking it in the fire1 and then allowing it to cool slowly in a warm1 dry place4 ,after this treatment the steel may be heated and worked as at first4 ,this treatment does not anneal the steel soft1 because the heat is not continued long enough1 and the cooling is not sufficiently slow2 it does relieve the strains in the steel1 so that it is plastic and malleable4 ,this treatment is good in any high steel which has become refractory from previous working4 ,self-hardened steel is not as strong in the hardened condition as good high-carbon steel2 it has not been used successfully for cutting chilled cast iron1 for instance4 ,if made hard enough to cut a chill1 it is so brittle that the cutting-edge will crumble instead of cutting2 if the temper be let down enough to stop the crumbling1 the steel will be softer than the chill1 and the edge will curl up instead of cutting4 ,owing to the retention of hardness at a higher temperature than carbon steel will bear this steel is capable of doing a great amount of work at high speed1 so that for much lathe-work it is cheap at almost any price4 ,owing to its brittle1 friable nature its use is limited to the simpler forms of tools1 and to a narrower range of work than is possible with carbon steel4 ,,chrome ,,steel4 ,an alloy of chromium with carbon steel has been before the public for many years1 and greater claims have been made for it than experience seems to justify4 ,chrome steel is fine-grained and very hard in the hardened state1 and it will do a large amount of work at the first dressing2 upon redressing it deteriorates much more rapidly than carbon steel and becomes inferior2 it is believed that this is due to a rapid oxidation of the chromium4 ,it is claimed for it that it will endure much higher heats without injury than carbon steels of the same temper4 ,intending purchasers will do well to satisfy themselves upon these points before investing too heavily4 ,,silicon ,,steel4 ,steel containing two to three per cent of silicon was put upon the markets1 and great claims were made for it4 ,it is exceedingly fine-grained and hardens very hard2 it is brittle1 much more liable to crack in hardening than ordinary steel1 and it is not nearly so strong as carbon steel4 ,it is made cheaply enough as far as melting goes1 but it may not be melted dead1 and therefore sound1 because long-continued high heat will destroy it2 therefore the ingots are more honeycombed than well-melted carbon steel ingots4 ,the steel will not bear what is known as a welding-heat in steel-working2 it is hot-short2 for this reason the bars are more seamy than is usual in carbon steel4 ,added to this the hot-shortness makes it so difficult to work that the labor cost is high4 ,altogether1 then1 silicon steel is expensive1 and it presents no extra good qualities in compensation4 ,,manganese ,,steel4 ,the glassy hardness1 brittleness1 and friability of ferro-manganese and of spiegel-eisen are well known2 these are products of the blast-furnace1 and the manganese ranges all the way from say #aj up to #hj4 ,steel containing from #a to #c of manganese is about as brittle and almost as unworkable as spiegel-eisen1 and a fair deduction would be that manganese above very small limits will not form any useful alloy with iron4 ,many a general law of nature has been based upon much more meagre data and has been announced with a great flourish of trumpets2 such discoveries are usually heard of no more after the first blare has died away4 ,r4 ,a4 ,hadfield1 of ,sheffield1 ,england1 is an inquirer who wants to know1 and who is willing to travel the whole road in order to find out4 ,hadfield discovered that an alloy of iron and manganese containing from #g to #bj of manganese was a compound possessing many remarkable properties4 ,this alloy is now known as manganese steel4 ,manganese steel is both hard and tough to a degree not found in any other metal or alloy4 ,it is so hard and strong that it cannot be machined with the best of tools made of the finest steel4 ,castings made of it may be battered into all sorts of shapes as completely as if they were made of the mildest dead-soft steel2 still they are too hard to be machined4 ,the ordinary hardening process toughens this steel instead of hardening it to brittleness4 ,this steel is non-magnetic1 and this property alone would give it exceedingly great value if the steel could only be worked into the required shapes4 ,up to this time all attempts to anneal this steel have failed1 and this persistent hardness is the best proof that manganese is the real hardener in self-hardened steel4 ,so far carbon and manganese have not been separated in this steel or in any other4 ,persistent attempts have been made to produce manganese steel low in carbon1 but all have been failures1 because any operation that burned out the carbon took the manganese with it4 ,the hope was that a non-magnetic alloy might be produced that would be soft enough to work4 ,this may yet be accomplished1 and if it should be another great step in the arts will have been taken4 ,hard1 tough1 strong1 non-magnetic--what great things may not come out of this when it has been worked out finally8 ,since this was written carbonless manganese has been produced which is claimed to contain #ih of manganese and no carbon1 but at present it is sold at #a per pound4 ,if it can be produced more cheaply1 it may lead to a workable non-magnetic alloy of iron and manganese which may prove to be of great value to electricians and to watchmakers4 ,the uses of manganese steel are large and growing1 and it must be regarded as having an established and a prominent place4 ,it has been stated that in self-hardened steel and in manganese steel manganese is the hardener2 it should be borne in mind that carbon is always present1 that it is the one great hardener1 but its hardening property in the absence of manganese depends directly upon rapidity of cooling4 ,by rapid cooling steel containing carbon is made harder than glass1 and by slow cooling it may be made softer and more ductile than ordinary wrought iron4 ,self-hardened steel may be annealed so that it can be machined1 but it is by no means as soft and ductile as well-annealed carbon steel4 ,manganese steel has not been annealed at all2 it cannot be annealed by any of the well-known annealing processes2 some new way of doing it must be discovered4 ,therefore it is proper to say that the peculiar hardening properties of these two steels are due to manganese4 ,,nickel ,,steel4 ,the addition of a few per cent of nickel to mild steel adds greatly to its strength--so much so that nickel steel is now world-renowned as used in armor-plate for navy vessels1 and for great guns4 ,recent reports from the ordnance bureaus indicate that it will also be of great use in the barrels of small arms1 by means of which they may be made lighter1 and still of sufficient strength4 ,nickel is so expensive and it adds so much to the cost of steel that its use for ordinary structural purposes1 bridges1 etc41 has not been found to be economical4 ,some years ago careful experiments were made with nickel alloy in a fine grade of high-carbon tool-steel to find out whether such steel would be improved as much as are the mild steels4 ,in such case the expense would not count1 for if the best steel can be made better there are many users who would gladly pay a higher price for a better service4 ,the results were not encouraging4 ,the high-carbon nickel steel was not as strong as the same quality of steel without nickel2 the mixture seemed to be imperfect1 containing little dark specks1 supposed to be carbon thrown into the graphitic state4 ,the steel did not refine as well and was not as strong as the carbon steel4 ,all of this applies to high-carbon tool-steel1 hardened and tempered2 no tests were made of the steel unhardened1 for they would have been of no practical use4 ,,aluminum ,,steel4 ,when a heat of steel is boiling violently1 is wild1 and unfit to be poured1 the addition of a minute quantity of aluminum will have the effect of quieting it quickly4 ,half an ounce to an ounce of aluminum to a ton of steel will be enough usually1 and for this purpose aluminum has become useful to steel-makers4 ,if a little too much aluminum be added1 the ingots will pipe from end to end2 therefore the use of aluminum is restricted to small quantities4 ,experiments have shown that a considerable percentage of aluminum adds no good properties to steel2 therefore aluminum steel so called may be treated later under a different heading4 ,,iv4 ,,carbon4 ,of all of the abundant elements of nature carbon is presented in the greatest variety of forms1 and admits of the greatest number of useful applications4 ,in the form of the diamond it is the hardest of substances1 and is the base used in determining the comparative hardness of all others4 ,in the form of graphite it is soft and smooth1 and is one of the best and most durable of lubricants4 ,in the form of soot it is probably the softest of solids4 ,in the form of coal it is the one great and abundant fuel of the world1 while as graphite again it is one of the best of refractory materials4 ,hard1 soft1 highly combustible1 almost infusible1 refractory1 it lends itself to the greatest variety of useful applications4 ,to the iron- and steel-maker or worker it is simply indispensable2 as charcoal or coke it is the fuel of the smelter2 as gas1 either carbon monoxide or as a hydrocarbon1 it is the cheapest and most manageable fuel for melting and for all operations requiring heat4 ,as graphite1 plumbago1 mixed with a little fire-clay as a binder1 it is the best material for crucibles in which to melt metals2 as soot it forms the best coating for moulds into which metals are to be cast4 ,durable beyond almost any other substance1 it would make the very best paint for metal structures if there were any known way to make it adhere4 ,,carbon ,,in ,,iron4 ,carbon may be introduced into iron in any quantity from a few hundredths of one per cent as usually found in wrought iron1 and in what is known as dead-soft steel1 up to about four per cent as found in cast iron4 ,by the addition of manganese as high as six or seven per cent of carbon has been introduced into iron4 ,carbon does not form a true alloy with iron1 neither does it form any stable chemical compound4 ,its condition in iron seems to be as variable as it is in nature1 and sometimes it has been supposed to be as capricious as it is variable4 ,it is hoped that the reader of these pages will find that there is no caprice about it1 that its action is governed by as sure laws as any in nature1 and that certain results may be predicated upon any treatment to which it is subjected4 ,the theories of its actions are as numerous and variable as are the actions themselves1 and they will be treated in a separate chapter1 this chapter being confined to a statement of known facts4 ,as stated in ,chap4 ,i1 carbon may be introduced into iron by heating carbon and iron in contact when air is excluded2 and1 conversely1 carbon is burned out of cast iron by the ,bessemer and open-hearth processes to reduce the cast iron to cast steel4 ,in the crucible any quantity of carbon may be obtained in steel by melting a mixture of high blister-steel and wrought iron1 or cast iron and wrought iron1 or by charging with wrought iron the necessary quantity of coke or charcoal4 ,when using plumbago crucibles1 the iron takes up some carbon from the crucible2 also the spiegel-eisen or ferro-manganese used adds some carbon2 and for these two sources of carbon the melter allows when he decides upon the quantity of charcoal needed4 ,results from crucible-melting are not strictly uniform2 even if every charge were weighed in a chemical balance accurately the product would not be uniform1 because one crucible gives off more carbon than another2 in one crucible a little more charcoal may be burned and escape as gas than in another2 and most variable of all1 unless the charcoal has been dried thoroughly1 is the quantity of moisture in the charcoal4 ,one charge of charcoal may be dry1 and the next may contain as much as twenty-five per cent of moisture2 obviously equal weights in such a case would not give equal quantities of carbon to the steel4 ,in crucible steel this is no disadvantage2 a skilful mixer will get from #ge to #ij of his ingots of the desired temper2 the other ingots will all be in demand for other uses1 and as he can separate them all with absolute certainty by ocular inspection1 as described before1 he labors under no fear of bad results4 ,in the ,bessemer process it is usual to burn out all of the carbon and then to add the required amount in the spiegel2 for structural steels and for rails this method is satisfactory4 ,for high steel--from fifty to a hundred or more carbon--the spiegel method does not answer so well1 because it increases the quantity of manganese to too great an amount2 higher carbon is then sometimes put in by the addition of a given quantity of pure pig iron previously melted1 or by putting coke in the ladle1 but this is very uncertain on account of the tendency of the coke to float1 and be dissipated as a gas instead of entering the steel4 ,the ,darby method is to place in the way of the stream of steel as it is poured from the vessel to the ladle a refractory-lined1 funnel-shaped vessel filled with finely divided1 but not powdered1 coke4 ,as the stream rushes through the coke it absorbs carbon with great rapidity1 and it is asserted that the currents and eddies formed in the ladle by the rush of the stream cause an even distribution of carbon4 ,that carbon will be taken up in this way is certain2 that a required amount1 evenly distributed1 can be obtained is not so certain4 ,in the acid open-hearth as in the ,bessemer process for milder steels it is usual to burn the carbon out almost entirely1 and then to add the desired amount with the spiegel4 ,higher carbon may be obtained by the addition of pure pig iron1 or by using carbon bricks pasted together with tar and weighted with iron turnings2 these bricks may be pushed under the surface in different parts of the bath1 and in this way the carbon can be distributed pretty evenly4 ,in good practice now the melt is stopped at the carbon desired with great success1 thus saving time and expense4 ,in the basic open-hearth the melter1 by the use of a little care and good judgment1 stops his melt at the required carbon1 and so avoids any additional operations1 unless his charge is excessively high in phosphorus and his steel is to be very low in the same2 in that case he may have to melt clear down and re-carbonize4 ,steel of #acj carbon with phosphorus 4#je may be made on the basic hearth from a charge containing #aj to #ab phosphorus without melting below #acj carbon4 ,if high-carbon ,bessemer steel is not uniform1 it is not to be wondered at1 but as a matter of fact it is usually found to be fairly uniform1 sufficiently so to work well4 ,if open-hearth steel of high carbon is not uniform1 it is clearly because the maker would not take a little trouble to have it so4 ,assuming that for convenience cast steel is graded for carbon content by even tens1 and that the different tempers are separated half-way between the tens1 we have3 ,carbon4 4#aj including from 4#je to 4#ae 4#bj 8 8 4#af 8 4#be 4#cj 8 8 4#bf 8 4#ce 4#dj 8 8 4#cf 8 4#de 4#ej 8 8 4#df 8 4#ee 4#fj 8 8 4#ef 8 4#fe 4#gj 8 8 4#ff 8 4#ge 4#hj 8 8 4#gf 8 4#he 4#ij 8 8 4#hf 8 4#ie #a4jj 8 8 4#if 8 #a4je #a4aj 8 8 #a4jf 8 #a4ae #a4bj 8 8 #a4af 8 #a4be #a4cj 8 8 #a4bf 8 #a4ce #a4dj 8 8 #a4cf 8 #a4de #a4ej 8 8 #a4df 8 #a4ee ,this covers the usual commercial range from what is known as dead-soft steel up to a high1 lathe-temper steel4 ,higher steels are used sometimes1 even up to #bbe carbon1 but they are so exceptional that it is not worth while to continue the list above #aej4 ,this list allows a variation of 4#je carbon above and below the datum of each temper2 some margin must be had of course1 and this is sufficient in the hands of a careful steel-maker2 it is found in practice to be satisfactory to the user4 ,even in the highest lathe-steel where the strains from hardening are the greatest1 because the change in volume due to a degree of temperature is the greatest1 a variation of three or four points above and below the mean does not make enough difference in the results to throw a skilful temperer off from his desired conditions4 ,on the other hand1 a difference of a full temper will throw the most skilful worker off from the track1 and so that much variation is not allowable4 ,for instance1 if a man be working #acj carbon1 and he should receive a lot of steel of #abj carbon1 he would get his work too soft in following his regular methods2 then if he doubted himself1 as he would be apt to do1 and raised his heat to correct his supposed aberration1 he would get his work too hard1 coarse-grained1 and brittle2 if he tried to correct this by drawing to a lower temper color1 his tools would be too soft4 ,again1 if he received a lot of steel of #adj carbon and proceeded in his regular way1 he would get a lot of cracked tools4 ,so that in either case the result would be confusion4 ,it is probable that in almost any case either #abj or #adj carbon would make a thoroughly good tool if the temperer knew what he was working with and adapted his heats to the carbon4 ,but he does not know of the variation1 and even if he did he would say1 very rightly1 that he did not propose to make daily changes in his methods to suit the convenience or the carelessness of the steel-maker4 ,it must not be understood1 however1 that this narrow range for each temper limits the capacity of the steel2 it merely gives the limit for regular easy working4 ,to illustrate3 ,a good lathe-tool may be made of #ajj-;carbon steel1 and of #aej carbon2 but no worker could use these tempers indiscriminately1 nor even alternately1 although he knew which was which1 because he could not change all of his heats say every five minutes and turn out satisfactory work4 ,a spring of given size1 and to carry a given load1 may be made equally good of #fj-;carbon steel or of #adj carbon1 and such work is done frequently in shops that are attached to steel-works2 but the spring-maker must be told beforehand what he is to work with1 and he must be given enough of one kind of steel to make say a day's work1 so that he can go along regularly4 ,the springs will be good1 but the one containing #adj carbon will have the highest elasticity and the most life1 although both will have the same modulus of elasticity4 ,the spring-maker who buys his steel will not submit to any such variations1 and he ought not to be asked to do it1 because one temper of steel costs no more than another1 and the selecting out and separating the tempers is only a matter of a little care4 ,is it practicable to keep steel uniform in carbon within such narrow limits8 ,in crucible-steel practice it is very easy to do so4 ,all ingots of #fj carbon upwards up to four or four and one half inches square may be broken completely off at the top1 and then the clean fracture will indicate the quantity of carbon invariably1 and after the ingot has been glanced at and marked properly it is as easy to put it on its proper pile as to put it on any other4 ,in a good light a competent inspector will mark thirty or forty ingots per minute and do it correctly2 it is as easy to the trained eye as it is to read a printed page4 ,this inspection is so important that it should never be neglected4 ,it is not costly1 much less than a dollar a ton4 ,with larger ingots only a piece can be broken off from the edge1 but if the topper does his work properly1 enough can be taken off to show the temper clearly4 ,large ingots containing the contents of a number of crucibles are liable to unevenness of temper from having uneven mixtures in the pots and from bad teeming into the moulds2 this can be detected usually in the ingot inspection1 and if not it can be found later during another inspection4 ,such variations are often called segregations4 ,this question of segregation will be discussed in a future chapter4 ,in the ,bessemer and the open-hearth practice ocular inspection of ingots to determine carbon is not used4 ,enough examinations have been made to show that the fractures1 although differing from those of crucible-steel1 are quite as characteristic1 and ocular inspection could be used4 ,the ingots are large usually and to handle and top them would be expensive2 but the heats are also large1--from five tons up to thirty tons in one heat1--and as they are supposed to be homogeneous1 one chemical carbon analysis is enough for each heat4 ,below #ej carbon a quick color analysis is accurate enough2 above #ej carbon combustion should be used1 for in high carbons the color test in the best hands is only the wildest guess-work4 ,the ten-point range of carbon is far more difficult to attain in high-carbon open-hearth practice than in the crucible4 ,in one case where the limit fixed in a specification was #ij to #aaj carbon1 two full tempers1 one of the most skilful and successful concerns in the world failed to meet the specification in twenty-ton and thirty-ton furnaces4 ,it was supposed at first that the trouble came from using different heats1 and large lots of billets were sent out with the heat number stamped on each billet4 ,the same variations were found in every heat1 the carbon ranging from #hj to #abj4 ,the specification was met without any trouble in five-ton furnace4 ,this illustration should not lead to the conclusion that practically uniform steel cannot be obtained2 there is little doubt that if the #cj-ton heats had been stirred thoroughly in the furnace the required limits would have been obtained4 ,neither is it to be understood that the same variation would occur in mild steel under #cj carbon4 ,a call for #bj carbon would not result in steel ranging from below #aj to above #cj1--such a result would show gross carelessness on the part of the melter1--the variation would go by percentage2 thus the variation in the high steel is from #ae below to #ae above the mean of #ajj1 or even as much as #bj4 ,if #bj-;carbon steel be required1 a variation of #bj would give a range from #af to #bd carbon1 or well within the limits of one temper4 ,this matter will be considered farther under the head of ,segregation4 ,the appropriate applications of the different tempers of steel have been stated in a general way1 with the advice that for all tool purposes it is better to leave the selection of the temper to the steel-maker2 also in structural work it may prove to be better to leave the question of temper1 or carbon content1 to the steel-maker1 who should know how to meet any specification that is within the capacity of steel4 ,on the other hand1 every engineer should know what is attainable1 and an effort to give this information in more definite form will be made in later chapters4 ,a general view will now be taken of what may be called the carbon-line4 ,illustration ,let the horizontal line represent iron1 the inclined line iron plus carbon1 and the verticals physical properties4 ,we do not know the physical properties of pure iron4 ,assuming them to be uniform1 let the vertical at 4#je represent the tensile1 torsional1 transverse1 or compressional strength of steel of #e carbon2 then for every increment of carbon up to #ij to #ajj there will be an increase of strength to resist any of these strains1 increasing in such regular amounts as to make the resulting carbon-line practically straight1 as shown in the sketch4 ,above #ajj carbon these resistances will all decrease1 except resistance to compression4 ,so far as it is known1 compressive strength increases slightly with the carbon1 until cast iron is fairly reached2 then the presence of silicon1 and the fact that we are dealing with a casting instead of forged or rolled metal1 causes a rapid fall in all resistances until the strength is below that of #e carbon steel4 ,with increase of carbon there is a reduction of ductility1 so that the extension of length and reduction of area decrease as the strength increases4 ,in every case the engineer must decide how little ductility he can do with safely in securing the ultimate strength or the elastic limit he may require4 ,the highest strength and the greatest ductility cannot be had together2 they are inverse functions one of the other4 ,if the exact resistances due to carbon were known along the whole line1 it would be of great value to give them here but nearly all of the thousands of tests published are influenced by the quantities of silicon1 phosphorus1 sulphur1 manganese1 or oxides present1 and an effort to determine the effects of the carbon-line exactly would be hazardous4 ,kirkaldy's tests of ,fagerota steel1 published in #ahgf1 furnish a valuable guide in this direction4 ,webster's experiments on the effects of the different elements1 phosphorus1 manganese1 etc41 are interesting and valuable1 but he has not yet tested a complete carbon-line with no other variables4 ,it has been stated time and again by experienced steel-makers that the best steel1 the most reliable under all circumstances1 is that which comes nearest to pure iron and carbon4 ,some intelligent steel-makers1 and engineers cast doubts upon this statement1 and assert that because phosphorus up to a certain limit1 or manganese1 or silicon1 or in fact it may be said almost any element1 added to dead-soft steel will give an increase of strength1 therefore the presence of one or more of these elements is not only not harmful1 but beneficial4 ,as a matter of fact1 however1 every one of these elements is harmful1 either in producing cold-shortness1 or red-shortness1 or brittleness1 and not one of them will add any good quality to steel that may not be obtained better by the use of carbon4 ,given a uniform minimum content of these impurities1 the carbon-line may be depended upon to furnish any desirable quality that is obtainable in steel2 and it is certain1 always sure1 that that steel which is the nearest to pure carbon and iron will endure the most punishment with the least harm4 ,that is to say1 that such a steel when overheated a little1 or overworked1 or subjected to any of the irregularities that are inevitable in shop practice1 will suffer less permanent harm than a steel of equal strength where there is less carbon and the additional strength is given by any other known substance4 ,it is difficult to show this from testing-machine data1 indeed it is doubtful if any such data exist1 but experience in the steel-works1 in the bridge- and machine-shops1 and in the field proves it to be true4 ,for further discussion of this question see ,chap4 ,x4 ,the effects of a small difference in phosphorus or in silicon contents are shown plainly and unmistakably in high-carbon steel1 and not so plainly in low-carbon steel2 but as there is no known hard and fast line that divides low steel1 medium steel1 and high steel1 so there is no marked difference in their properties4 ,the same rules hold all along the line1 the same laws govern all of the way through4 ,there is no set of properties peculiar to low steel and another set peculiar to high steel2 the same laws govern all1 and differences are those of degree and not of law4 ,given three samples of steel of the following compositions3 ,no4 #a4 ,no4 #b4 ,no4 #c4 ,silicon 4#jb 4#bj 4#jb ,phosphorus 4#ja 4#ja 4#jb ,sulphur 4#jje 4#jje 4#jje ,manganese 4#ajj 4#ajj 4#ajj ,carbon #a4ajj #a4ajj #a4ajj ,a skilful worker1 not knowing the composition of any1 will pick them out invariably by tempering them and testing them with a hand-hammer and by inspecting the fractures4 ,he will pronounce ,no4 #a to be the best and the strongest in every way2 ,no4 #b to be not quite as strong as ,no4 #a1 and more liable to crack from a little variation in heat2 ,no4 #c to be not so strong as ,no4 #a1 and that it will not come quite as fine as either of the others1 and1 like ,no4 #b1 it will not stand as much variation in heat as ,no4 #a4 ,give a ton of each to a skilful axe-maker1 from which he will make one thousand axes of each1 and he will be sure to report ,no4 #a all right2 ,no4 #b good steel1 more loss from cracked axes than in ,no4 #a4 ,no4 #c good steel1 some inclination to crack2 it will not refine as well as ,no4 #a and is not as strong4 ,this is no guess-work1 nor is it a fancy case2 it is simple fact1 borne out by long experience4 ,give a skilful die-maker one hundred blocks of each to be made into dies4 ,he will not break one of ,no4 #a in hardening them2 he will probably break five to ten of ,no4 #b2 and if he breaks none of ,no4 #c--;a doubtful case--he will find in use that ,no4 #a will do from twice to twenty times as much work as either of the others4 ,if he is making expensive dies1--many dies cost hundreds of dollars each for the engraving1--he will think ,no4 #a cheap at #be cents a pound1 and either of the others dear at #ae cents a pound4 ,in such steel1 then1 the absence of a few points of silicon1 or of a point or two of phosphorus1 is worth easily #aj cents a pound4 ,now let the carbon in these three steels be reduced to #aj1 making them the mildest structural steel4 ,the differences to be found in the testing-machine in tensile strength1 elastic limit1 extension1 and reduction of area will be almost or altogether nothing2 in forging1 flanging1 punching1 etc41 under ordinary conditions differences would not be observable2 therefore there would be no practical difference in value4 ,but let the silicon be raised to #cj or the phosphorus to #aj1--the ,bessemer limit1--or let both be raised together1 and both the testing-machine and shop practice would show a marked difference4 ,this shows that in the absence of carbon the action of these elements is sluggish as compared to their effects in the presence of high carbon1 or in the low-carbon steels their effects are not so observable4 ,that their influence is there1 there can be no doubt1 but if it be not enough to endanger the material it is not worth while to take it into account4 ,is it safe and wise1 then1 for steel-users to ignore composition8 ,users of tool-steel may do so safely1 because the smallest variations will manifest themselves so unmistakably that they give immediate warning1 and the steel-maker must keep his product up to a rigid standard of excellence or lose his character and his trade4 ,many of the ablest users of structural steel take a similar ground1 and say1 ,we have nothing to do with method or composition if the material meets our tests4 ,it is believed that if these men knew how easy it is for a skilful worker to doctor temporarily an off heat by a little manipulation1 and how dangerous the same may become by a little off practice in the field1 they would be convinced that some limits should be put upon composition1 especially if they could realize that a reasonable specification would add nothing to cost1 as competition would take care of that4 ,the reader is referred again to ,chap4 ,x on impurities4 ,v4 ,,general ,,properties ,,of ,,steel4 ,steel is very sensitive to heat4 ,in general it may be stated that1 starting with cold steel1 every degree of heat added causes a change in size and in structure1 until the limit is reached where disintegration begins4 ,the changes are not continuous2 there are one or two breaks in the line1 notably at the point where we have what is called recalescence2 this is a marked phenomenon and it will be considered later4 ,the effects of heat are permanent1 so that it is a fact that every variation of temperature which is marked enough to be visible to the naked eye will leave a structure1 due to that variation1 when the steel is cold1 which will be observable by the naked eye1 and such structure1 when not influenced by external force1 such as by hammering or rolling1 is as invariable and certain as is the structure of an ingot due to the quantity of carbon present4 ,this property furnishes what may be called the steel-maker's and the steel-user's thermometer4 ,by its means the steel-maker can discover every irregularity in heating that may have been perpetrated by the operatives2 so also the steel-user can decide whether the steel furnished him has been heated and worked uniformly and properly1 and later he can tell whether those who have shaped this steel to its final forms have done their work properly4 ,a thorough knowledge of this property is essential to a steel-maker2 until he possesses it he is not fit to conduct his business4 ,it is of great importance to the steel-user1 and every engineer should try to acquire a knowledge of it in order that he may not be fooled by the carelessness or rascality of those who have preceded him4 ,the steel-maker acquires this knowledge by daily contact with the facts2 the engineer does not have it forced upon him in this way1 but he should seek opportunities of observation1 which will be abundant in his earlier practice when he is sent upon inspection duty4 ,like the structure of ingots1 this heat-structure cannot be illustrated on paper1 and an attempt to do so would be misleading2 attempts at description will be made in the hope that by their means the engineer will have a pretty good idea what to look for1 and to know when his suspicions should be aroused4 ,in addition to the ocular observations mentioned it has been shown by specific-gravity determinations1 and by delicate electrical tests through small ranges of temperature1 that steel is as truly thermometrical as mercury4 ,steel passes through or into four general conditions due to heat4 ,first1 in the cold state1 it is a crystalline solid of no uniform structure1 for its structure is influenced by every element that enters into it1 and by every irregularity of heat to which it has been subjected4 ,good steel may be described as having a bluish-gray color1 uniform grain as seen by the naked eye1 and little lustre4 ,but it should have some lustre and a silky appearance4 ,when it is right1 a steel-worker will say it is 8sappy10 and that name1 absurd as it may sound when applied to a metal1 really expresses an appearance1 and implies an excellence that it would be hard to find a better word for4 ,if the structure be dull and sandy-looking1 the steel-worker will say it is 8dry10 and that term is as suggestive and appropriate as the word 8sappy40 ,if the fracture be granular with bright1 flashing lustre1 the steel-worker will say it is 8fiery10 and again his term is expressive and proper4 ,it is perfectly safe to say that steel of a 8sappy0 appearance is good steel2 but in order to know what it is it must be learned by observation1 it cannot be described in exact terms4 ,it is equally certain that a 8dry0 fracture indicates a mean steel1 a steel inherently mean1--too much phosphorus1 or silicon1 or oxides1 or all combined1--and such a steel is incurable4 ,a 8fiery0 fracture indicates too much heat4 ,it may be found in the best steel and in the poorest2 it may be corrected by simply heating to a proper temperature4 ,it shows that some one needs to be reprimanded for careless work4 ,if now an inquirer will take a piece of good steel of 8sappy0 fracture1 and of 8dry0 steel of dull1 sandy fracture of the same carbon1 and will heat them say first to dark orange1 then to bright orange1 dark lemon1 and so on1 and examine the fractures after each heating1 he will find a 8fiery0 fracture in the 8dry0 steel at a heat much below that which is necessary to make the 8sappy0 steel 8fiery40 ,this is one proof that good steel will endure more punishment than poor steel4 ,cold steel is not plastic in the common acceptance of the word2 strictly speaking it has some plasticity1 as shown in the extension noted in pulling it2 this is its measure of ductility4 ,also it may be drawn cold to fine wire of only a few thousandths of an inch in diameter1 and it has been rolled cold to one five thousandth of an inch thick4 ,but this work must be done with great care2 the steel soon becomes brittle1 and a little overdrawing or overrolling will crush the grain and ruin the steel2 therefore the work must be done a little at a time1 and be followed by a careful annealing4 ,to reduce a ,no4 #e wire rod to 4#jje inch diameter will require with high steel suitable for hair-springs about fourteen annealings4 ,a skilful hammerman will take a piece of mild cold steel1 and by means of light1 rapid blows he will heat it up to a bright lemon heat without fracturing it2 then he will have it thoroughly plastic and malleable4 ,this has no practical commercial value2 it is a beautiful scientific experiment exhibiting high manual skill1 and showing that there is no hard and fast line between non-plasticity and plasticity4 ,the first condition1 then1 is cold steel1 not plastic1 not malleable4 ,when steel is heated1 it begins to show color at about #gjj to #hjj ,f42 the first color is known as dark cherry red1 or1 better1 orange red3 above this color it turns to a distinct1 rather dark1 or medium orange color2 this is the heat of recalescence1 a good forging-heat1 and the best annealing- and quenching-heat4 ,at this heat and above it good steel is truly plastic and malleable2 a roller or hammerman will say1 8,it works like wax10 and so it does4 ,this is the second or plastic condition4 ,heated above this plastic condition to a bright lemon in high steel1 or to a creamy1 almost scintillating1 heat in mild steel1 steel will go to pieces under the hammer or in the rolls2 the workman will probably say it is burned1 but it is not burned necessarily2 it is simply heated up to the third or granular condition2 it is the beginning of disintegration and the end of plasticity4 ,this granular condition is important in several ways4 ,it is made use of in ,sweden1 and has been demonstrated in the ,united ,states1 to determine the quantity of carbon in steel4 ,an intelligent blacksmith is given a set of rods of predetermined carbon1 ranging from #ajj carbon to zero1 or through any range that may be necessary2 each rod is marked to indicate its carbon4 ,he takes the rods one by one and heats them until they scintillate1 well up into the granular condition1 then lays them on his anvil and hammers them1 observing carefully the color at which each one becomes plastic as it cools slowly4 ,after a little practice he is given rods that are not marked1 and by treating them in the same way he will give them their proper numbers1 rarely missing the carbon by as much as #aj points1 or one temper4 ,it is a beautiful and useful illustration of the effect of carbon4 ,the rule is1 the higher the carbon the lower the granulating-point2 or1 as is well known1 high steel will melt at a lower temperature than low steel4 ,this shows that every temper of steel has its disintegration temperature where it passes from plastic to granular1 as fixed as its fusion-point or its point of recalescence4 ,steel passes from the granular condition to the liquid or fourth form4 ,there is little of interest in the liquid condition of steel to any but the steel-maker2 what there is to be said will be mentioned later4 ,steel in cooling from the liquid passes through the granular and the plastic conditions to the cold state4 ,the granular form is of special interest to the steel-maker for the reason that in this condition the steel has more of adhesion than cohesion2 it will stick to anything it touches1 and so cannot be made to flow4 ,this is the cause of 8bears10 8stickers10 and many of the troubles of the melter4 ,therefore steel must be put into the moulds while it is still molten1 and moulds should be well smoked or lime-washed to prevent stickers4 ,this condition is of great interest to engineers1 because the failure to roll or shape molten steel by pouring it directly between the rolls is doubtless due to this adhesive1 non-cohesive condition4 ,to produce sheets1 bars1 and all sorts of shapes from molten steel direct1 without the expense of making1 handling1 and re-heating ingots1 is an enticing idea which has occupied the minds and efforts of many able mechanics and engineers4 ,if steel passed directly from the liquid to the plastic condition as glass does1 hammers and rolls would soon be replaced by dies at a great saving of cost and labor4 ,it is no wonder that such a desirable end has led to many persistent and costly efforts1 but until some way can be devised to eliminate this granular form in cooling it would seem that all such efforts must end in failure4 ,as steel cools down through the plastic condition the cooling is not continuous2 there are two or three points where it is arrested for a time1 and at one notable point the cooling is not only arrested1 but after a few moments of stop the operation is reversed1 the steel becomes visibly hotter1 and then the cooling goes on regularly2 there may be other slight pauses1 but they are of little importance compared to this one1 which is known as the point of recalescence4 ,there are many theories of the cause of this recalescence2 the ablest scientists are still working at it2 and until some definite conclusion is reached it is not worth while to write pages of discussion which may be found fully stated and illustrated over and over again in the various technical journals1 and transactions of different engineering societies4 ,there are some properties of steel of great interest which seem to cluster around this recalescence-point2 they will be noted as they are reached4 ,we have seen that there is a marked1 definite structure of the grain of ingots due to every quantity of carbon1 and also that there is a fixed limit of malleability for every quantity of carbon4 ,it is known also that the recalescence-point shifts slightly with a change of carbon1 and that it is much more marked and brighter in high-carbon steel than in low4 ,there are no other sure indications of the quantity of carbon present4 ,as soon as an ingot is heated up to orange color1 or the recalescent-point1 it loses its distinctive structure and its fracture no longer furnishes a sure guide4 ,if three ingots of say1 #bj1 #hj1 and #abj carbon respectively be heated to orange and then cooled slowly1 their fractures will be so different as to enable an expert to place them properly in their order of carbon1 and to classify them as mild1 hard1 and harder2 beyond that he could not go2 if he attempted to give them their temper numbers1 he would be likely to miss by four or five numbers either way1 and a correct mark would be only a lucky guess4 ,hammering and rolling heated steel affect the grain or structure profoundly2 a high steel may be worked so that the grain will look mild1 and a mild steel may be so worked that the grain will look hard4 ,it is common to see a bar of steel with a fine grain at one end and a coarse grain at the other1 and this state of things often frightens a consumer1 who imagines that he has received a very irregular1 uneven article1 and he is as often astonished when it is shown to him that at the same proper heat the two ends will refine and harden equally well1 and be exactly alike4 ,in such a bar one end has been finished a little hotter than the other1 and the grain is due to the heat in each case4 ,this uneven heating may have been incidental or careless2 with skilful workers it is rare4 ,one end might have been finished so cold as to crush the grain1 and the other end so hot as to cause incipient disintegration1 but a competent inspector would discover either condition at once and reject the bar4 ,there is1 then1 a specific structure due to temperature2 it is modified by carbon and by treatment under the hammer or in the rolls4 ,if a bar of steel be heated up to the highest plastic limit1 just so that it will not fall to pieces1 and then cooled slowly without disturbance1 and a fracture be taken1 it will be found to be coarse and with an exceedingly brilliant lustre4 ,now let it be heated again to a bright lemon color1 but still plastic1 and cooled as before2 it will be found to be coarse1 with bright lustre1 but neither so coarse nor so bright as the first piece4 ,then let it be treated in this way to lemon color1 light orange1 medium orange1 dark orange1 and orange red2 as the heats go down the grain will be finer and the lustre will be less1 until at about medium orange the lustre will be absent4 ,if any number of bars of even composition be heated in this way1 the fractures will all be alike for each temperature4 ,if a series of bars of the different full tempers1 about seven in all1 be treated in this way1 the structures due to a given temperature will all be similar1 but there will be no two exactly alike1 because high steel is much more profoundly affected by heat than low steel4 ,seven tempers are mentioned here1 because that is the number of full tempers in common use4 ,steel is graded out into fifteen tempers ordinarily by the interpolation of half numbers2 this is easy and sure in the ingot inspection4 ,in the above experiment the differences due to carbon are not quite so delicate1 and the work is hampered in the heating by the personal equation1 so that the use of seven full tempers is refinement enough4 ,there is a difference due to every separable quantity of carbon1 which could be shown if all of the operations of the experiment were exact4 ,if when a bar is broken cold the fracture is uneven1 with coarse grain in one part and fine grain in another1 it shows that there has been uneven heating4 ,if one side has large grain and the other side is fine1 the bar has been a great deal hotter on the side having coarse grain than on the other3 the heater has let the bar lie in the furnace with one side exposed to a hot flame and the other protected from the flame in some way2 he has neglected to turn the bar over and heat it evenly4 ,if the outside of the bar is fine and the centre is coarse1 the bar has been very hot all through and has been finished by light blows of the hammer or by light passes in the rolls2 it has been worked superficially and not thoroughly4 ,if the outside of the bar is coarse and the centre is fine1 the steel has been heated on the surface too hot and too quickly2 it has not had time to get hot through1 and it has had too little work in the finishing4 ,if the grain is dark1 with the appearance of a rather heavy india-ink tint1 the steel has been finished too cold1 and it will be found to be brittle4 ,if the grain is very dark1 especially about the middle1 looking almost black1 then it has been finished altogether too cold3 the grain is disintegrated1 and the bar is fit only for the scrap heap4 ,a bar of this kind containing enough carbon to harden will harden thoroughly1 and often appear to be sound and fine1 but it is not sound and will not do good work2 if it be brought up to a proper heat and forged to a point1 it will almost certainly burst1 showing that the integrity of the steel has been destroyed4 ,if a bar1 or plate1 or beam shows cracks on the surface or at the corners1 with rough1 torn surfaces1 the steel has either been superficially burned or it is red-short4 ,in either case it should be rejected1 for the cracks1 although small1 will provide starting-points for ultimate fractures1 whether it be tool-steel that is to be hardened1 or structural steel that is to be strained without hardening4 ,if the steel is to be machined1 so that all of the cracks can be cut out1 then in machinery-steel the removal of these surface defects might leave the finished piece sufficiently sound and good4 ,if1 however the steel is to be hardened1 and the defects should be due to red-shortness1 the piece would almost certainly break in the hardening2 and if it were not red-short1 then unless the cracks were cut away entirely1 if the least trace of the crack is there1 although it may not be visible1 that trace will be sufficient to start a crack when the piece is hardened4 ,,effects ,,of ,,cooling4 ,increase of heat causes increase of softness up to the liquid condition4 ,decrease of heat--cooling--increases hardness up to the hardness of glass4 ,as an invariable rule the rate of cooling fixes the degree of hardness to be had in the cold piece within the limits of obtainable hardness or softness4 ,slow cooling retains softness1 so that when annealing is to be done the slower the cooling the better4 ,cooling is always a hardening process1 but when it is carried on slowly more softness1 will be retained than when the cooling is quick4 ,rapid cooling produces hardness1 and the more nearly instantaneous it is the greater the hardness will be4 ,this property of hardening is of such extreme importance that it will be treated fully in a separate chapter4 ,there is an apparent exception to this rule shown in the operation called water-annealing4 ,it is common1 when work is hurried1 to heat a piece of steel carefully and uniformly up to the first color1 that is1 until it just begins to show color1 and then to quench it in water4 ,this is called water-annealing2 and many believe that because a piece so treated is left softer than it was before treatment1 the water-cooling had something to do with it4 ,the fact is that hammering and rolling are hardening processes4 ,when the increment of heat due to the work is less than the decrement of heat due to radiation1 the compacting of the grain increases hardness4 ,this process leaves the piece harder than does the quenching in water-annealing2 the decrease in hardness due to water-annealing is the difference between the effects of the two operations4 ,let two pieces of the same bar be heated exactly the same for water-annealing2 let one be quenched in water1 and the other be allowed to cool in the air in a dry place4 ,then the superior softness of the air-cooled piece will show that the so-called water-annealing furnishes no exception to the rule4 ,there is one extremely important matter connected with cooling that should be noted carefully4 ,it is a common practice among steel-workers when they get a part of a piece of steel too hot to partially quench that part1 and then go on with their heating2 or if they are in a hurry to get out a big day's work1 or if the weather is hot1 and a pile of red-hot bars is uncomfortable1 to dash water over the pile and hurry the cooling4 ,this practice means checks in the steel1 hundreds of them4 ,illustration ,a bar breaks and has this appearance4 ,the dark spot is the check2 it did not show in the bar1 no inspector could see it1 but it broke the bar4 ,any one can prove this to his own satisfaction in a few minutes4 ,take a bar of convenient size1 about one inch by one eighth2 heat it carefully to an even medium orange color and quench it completely2 then snip it with a hand-hammer over the edge of an anvil1 snipping away until satisfied that it is sound steel4 ,there are no checks4 ,now beat a similar length of the same bar in the same way1 and pass it through the stream from the bosh-pipe1 or submerge it for a moment in the bosh1 not long enough to produce more than the slightest trace of a change in the color2 then put it back in the fire and bring it gently to the uniform color used before1 and quench it completely4 ,now when it is snipped over the anvil it will show numerous checks1 dozens of them4 ,in this experiment the complete submersion for a moment may not produce checks at every trial1 because the complete submersion permits practically uniform cooling1 which if continued to complete cooling would be simply the ordinary hardening process4 ,still it will produce checks in the majority of cases1 indicating that starting the changes1 strains1 or whatever they are of the quenching process and then stopping them suddenly while the steel is in the plastic condition does cause disintegration1 so that the operation is dangerous and should not be tolerated4 ,passing the hot steel through a stream of water or dashing water over it must cause different rates of cooling1 and necessarily produce local strains resulting in checks4 ,these latter ways of injuring1 therefore1 rarely fail to produce the ruinous checks4 ,if this positive destruction is produced in this way1 in steel containing enough carbon to harden it is clear that similar1 although not so pronounced1 results will be produced in the mildest steels when they are treated in the same manner4 ,the rule1 then1 should be3 ,never allow water to come in contact with hot steel1 and never allow hot steel to be laid down upon a damp floor4 ,even the spray from water which is run upon roll-necks may cause these checks in steel that is passing through the rolls1 so that it is better to put up a guard to deflect such water away from the body of the roll4 ,a hammerman may sweep a bar with a damp broom to cause the vapor to explode with violence when the hammer comes down1 and so tear away all rough scale and produce a beautiful finish4 ,a careful1 skilful man may be permitted to do this1 but as surely as he gets his broom too wet1 so that drops of water will fall on the steel and whirl around in the spheroidal condition1 just so surely will he check the steel4 ,the best way is to have the broom not wet enough to drip1 and then to strike it up against the top die when it is ready to descend2 sufficient moisture will be caught upon the die to cause a loud explosion when it strikes the hot steel2 it is a violent explosion and will drive off every particle of detachable scale1 leaving as beautiful a surface as that which is peculiar to ,russia sheet iron4 ,it is common in rolling tires to run jets of water over the tire to break up the scale and produce a clean surface4 ,tire-makers assert that experience shows that the water does no harm4 ,there are two reasons for this if it be true3 first1 the steel is of medium carbon and more inert than high steel1 and it has been hammered and compacted before rolling2 second1 the tires are usually turned1 and this would cut away any little checks that might occur on the surface4 ,the magnetic properties of steel are well known4 ,soft steel1 like soft wrought iron1 cannot be magnetized permanently2 higher carbon steel will retain magnetism a long time1 and hardened steel will retain it still longer4 ,hardened-steel magnets are the most permanent4 ,the permanency and the efficiency of a magnet increase with the quantity of carbon up to about #he carbon2 steel of higher carbon than this will not make magnets of so good permanency4 ,the efficiency of a magnet of #he carbon is increased largely by the addition of a little tungsten2 a little less than 4#je is sufficient4 ,it has been shown that tungsten has the property of retaining the hardness of steel up to a relatively high temperature2 this additional power of retaining magnetism may indicate a close relation between the conditions set up by magnetism and by hardening4 ,it has been stated that maximum physical properties1 except as to compression1 are found at from #ij to #ajj carbon2 now we find maximum magnetic properties in the same region4 ,prof4 ,arnold has found by microscopic tests the same point of saturation2 he fixes it at #hi carbon and deduces from it an unstable carbide of ,fe,c4 ,the magnetic maximum was found by magnet-makers by actual use in large numbers of magnets4 ,prof4 ,j4 ,w4 ,langley found the same maximum in a series of careful and delicate experiments undertaken to determine the best composition and the best treatment for the production of permanent magnets4 ,magnetism is affected by temperature1 and it is found that steel becomes non-magnetic at or about the point of recalescence4 ,this is important to electricians1 as it marks the limit of temperature that is available to them4 ,it is of interest to the scientists1 as it is another indication of the importance of the changes that take place at this temperature4 ,later1 recalescence will be found to be an equally important point to the steel-worker1 especially to the temperer4 ,it has been stated that if a bar of steel be heated to any visible temperature and then be cooled without disturbance there will be a resulting grain or structure that is due to the highest temperature to which the bar was subjected4 ,as a rule the highest temperature leaves a grain that appears to the eye to be the largest1 or coarsest1 whether the microscope shows it to be composed of larger crystals or not4 ,let the following squares represent the apparent sizes of the grains3 ,illustration #a4 ,the natural bar1 untreated4 #b4 ,grain due to dark orange or orange red4 #c4 8 8 8 medium orange4 #d4 8 8 8 bright orange4 #e4 8 8 8 dark lemon4 #f4 8 8 8 medium lemon4 #g4 8 8 8 bright lemon4 #h4 8 8 8 very bright lemon1 or creamy4 ,these designations are used because steel in cooling down1 or in heating up1 runs through a series of yellow tints1 not reds4 ,it is common to see the expression 8glowing white0 applied to steel that is not even melted1 when as a matter of fact melted wrought iron is not quite white4 ,an occasional heat of steel may be seen that could fairly be called white1 and then the melter knows that it is altogether too hot1 and that he must cool the steel or make bad ingots4 8,glowing white10 like 8cherry red10 will do for ordinary talk1 but not for accurate description1 although 8cherry red0 comes nearer to describing the dying color than 8glowing white0 comes to describing the highest heat4 ,an arc light may be 8glowing white10 and sunlight is 8glowing white10 and when either light falls upon melted steel it shows how far the steel is from being 8glowing white40 ,referring to the squares3 ,if a bar that has been heated to ,no4 #h be re-heated to ,no4 #b and be kept at that color a few minutes to allow the steel to arrange itself1 in other words1 to provide for lag1 and then be cooled1 it will be found to have grain ,no4 #b4 ,sometimes in performing this experiment the fracture will be interspersed with brilliant spots as if it were set with gems2 this shows that not quite enough time was allowed for lag4 ,another trial with a little more time will bring it to a complete ,no4 #b fracture4 ,if now it be heated to ,no4 #d1 or #e1 or #f in the same way1 it will be found to have when cold the grain due to ,no4 #d1 or #e1 or #f temperature4 ,this may be repeated any number of times1 and the changes may be rung on all of the numbers1 until the disintegrating effect of numerous heatings begins to destroy the steel4 ,this property of registering temperature1 this steel thermometer1 is of great value1 and it will be referred to frequently4 ,,effects ,,of ,,mechanical ,,work4 ,when an ingot is heated and then hammered1 rolled1 or pressed hot1 its density will be increased1 as well as its strength when cold under all strains4 ,if it be hammered carefully1 with heavy blows at first1 and with lighter and quicker blows at the last1 the grain will become very close and fine2 it is called 8hammer-refined40 ,when down to the so-called cherry red1 orange red1 great care is needed1 and when black begins to show through the red much caution must be used2 any heavy blows will crush the grain and produce the dark or black color mentioned before4 ,fine-tool makers attach great importance to this hammer-refining2 some of the most expert will not have a rolled bar if a well-hammered one can be had4 ,at first thought this would seem to be a mere notion1 but the testimony in favor of hammering is so universal among those who know their business that it would seem as if it must be based upon some reason4 ,if it have any scientific basis of fact1 it is that the shocks or vibrations of the hammer keep the carbon in more intimate union with the iron1 whether it be combination or solution1 than either rolling or pressing will do4 ,after considering the phenomena of hardening1 tempering1 annealing1 etc41 it may be concluded that there is something in this4 ,it is easy to laugh at and to deride shop prejudices1 and there are enough of them that deserve ridicule2 again1 there are some that will not down1 and they compel the scientist to hunt for explanations4 ,but after all1 ridicule is dangerous2 it is possible that a careful comparison of some of the laws laid down by the highest scientists would tend to excite the risibles4 ,if the hand-worker sometimes flounders in the mud1 the scientist is sometimes enveloped and groping in mist4 ,hot-rolling produces results similar to those of hot-hammering2 it makes the grain finer1 increases density1 and adds to the strength4 ,the same precautions are needed in rolling as in hammering4 ,heavy passes with rapid reduction may be used to advantage while the steel is hot and thoroughly plastic2 as the heat falls the passes should be lighter to avoid crushing the grain4 ,overrolling1 like too much hammering1 may be more injurious than too little work2 a coarse1 irregular structure due to too little work may be rectified and made fine and even by annealing1 while if the grain be crushed by overwork the damage cannot be cured by annealing2 the annealed grain may appear to be all right1 but on testing1 the strength will be found impaired4 ,by care and light passes steel may be rolled safely down to a black heat and be made elastic and springy4 ,it is common to roll spring-steel in this way so that it may be formed into a spring and have all of the properties of a tempered spring without going through the operations of hardening and tempering4 ,this is often desirable for spring-makers1 as it saves them considerable expense2 but it is hazardous work1 because it is so difficult to heat every piece exactly to the same temperature1 and secure every time the same number of passes and the same pressure in each4 ,the best roller will get some pieces too hard and brittle1 and some too soft and ductile4 ,a careful steel-maker will shun such work4 ,cold-hammering1 cold-rolling1 and cold-drawing reduce specific-gravity and increase tensile1 transverse1 compressive1 and torsional strength4 ,they increase hardness and brittleness1 reducing ductility4 ,the hardness due to cold-working is different from that due to hot-work or quenching2 the latter operations produce great elasticity as well as hardness4 ,the hardness due to cold-working might be described as harshness2 the steel is not truly springy2 of course it will bend farther without permanent set than an annealed piece1 but it never has the true spring elasticity4 ,if it be worked far enough to be really springy1 it will bear the same relation to a hot-worked spring that a piece of cross-grained1 brashy oak bears to a piece of well-seasoned1 straight-grained hickory4 ,the hammering of round sections between flat dies tends to burst the bars in the centre2 great care must be used to avoid this1 and the most skilful and careful hammermen will often turn out bursted bars4 ,the bursts do not show on the surface2 the bars are true to size1 round1 smooth1 and sound on the outside4 ,the safest plan is to hammer in a ,v-die1 or in rounded swedges4 ,radial rolling will produce the same results1 and it is on this principle that the celebrated ,mansmann tubes are made4 ,the explanation seems to be simple1 as the following exaggerated sketches will show3 ,illustration ,no4 #a has been struck2 it is then turned up to position ,no4 #b and knocked into shape ,no4 #c4 ,the rapid hammering of a bar1 turning it a little at a time1 must burst it if the blows are heavy enough to deform the whole section4 ,heavy radial rolling produces the same results4 ,the concluding pages of this chapter will be devoted to a few examples showing by tests the effects of heat and work upon specific-gravity1 tensile strength1 elasticity1 and ductility2 they are not to be taken as fixing exact limits in any case2 they are given merely to illustrate the truth of the general properties stated1 and to show the wide ranges of strength that are attainable by varying carbon and work4 ,,table ,i4 ---------------------------------------- --------------------- ,character ,ingot ,numbers4 of ---------------------------------------- - ,steel4 #a #b #c #d #e #f ---------------------------------------- ---------------- ,carbon 4#cjb 4#dij 4#ebi 4#fdi 4#hja 4#hda ,silicon 4#jai 4#jcd 4#jdc 4#jci 4#jbi 4#jci ,phosphorus 4#jdg 4#jje 4#jdg 4#jcj 4#jce 4#jbd ,sulphur 4#jah 4#jaf 4#jah 4#jab 4#jaf 4#jaj ,sp4 gr4 ingots4 #g4hee #g4hcf #g4hda #g4hbi #g4hch #g4hbd ,sp4 gr4 bars1 burned1 #a #g4hah #g4gia #g4ghi #b #g4had #g4haa #g4ghd #c #g4hbc #g4hcj #g4ghj #d #g4hbf #g4hdi #g4hjh #e #g4hha #g4hjf #g4hab cold1 #f #g4hdd #g4hbd #g4hbi ,diff4 #f-a 4#jbe 4#jcd 4#jdj ,mean diff4 of carbon 4#jga ---------------------------------------- ---------------- #g #h #i #aj #aa #ab ---------------------------------------- ---------------- ,carbon 4#hfg 4#hga 4#iee #a4jje #a4jeh #a4jgi ,silicon 4#jeg 4#jec 4#jei 4#jhh 4#abj 4#jci ,phosphorus 4#jad 4#jbd 4#jgj 4#jcd 4#jfd 4#jdd ,sulphur 4#jah 4#jab 4#jaf 4#jab 4#jjf 4#jjd ,sp4 gr4 ingots4 #g4hai #g4hah #g4hac #g4hjg #g4hjh #g4hje ,sp4 gr4 bars1 burned1 #a #g4geb #g4gdd #g4fij #b #g4gee #g4gdi #g4gda #c #g4geh #g4gee #g4gfi #d #g4ggc #g4ghi #g4gih #e #g4gij #g4hab #g4haa cold1 #f #g4hbe #g4hbf #g4hbe ,diff4 #f-a 4#jgc 4#jhb 4#ace ,mean diff4 of carbon ---------------------------------------- ---------------- ,the twelve ingots treated here were first selected by ocular inspection for carbons2 the carbons were then determined by combustion analyses4 ,it will be seen that the inspection was correct1 and that the mean difference in carbon between consecutive numbers is 4#jjg4 ,between ,nos4 #g and #h there is a difference of only 4#jjd2 when the analyst discovered this1 he asked for a reinspection1 not giving any reason for his request4 ,the inspectors made new fractures1 examined the ingots carefully in good light1 and reported that they erred the first time1 that both ingots belonged in the same temper number1 but that if there were any difference ,no4 #h was the harder4 ,it is not claimed that a difference of 4#jjd is really observable4 ,the contents of silicon1 phosphorus1 and sulphur show clearly that the controlling element is carbon4 ,this experiment has been repeated a number of times1 and always with the same result1 showing that there is no uncertainty in this method of separating tempers4 ,parts of these ingots were reduced to -inch round bars4 ,the specific gravities of the ingots were taken1 showing generally a reduction of sp4 gr4 for an increase of carbon4 ,no4 #c and #e are anomalous2 an explanation of this could doubtless have been found if a careful investigation had been made1 but there was no re-examination4 ,the sp4 gr4 ,no4 #f are of the -inch bars as they came from the rolls2 they are all heavier than the ingots except ,no4 #d1 and they are of nearly uniform sp4 gr42 this is due doubtless to the fact that the higher carbon steels are so much harder than the low-carbon steels that it required much more work to reduce them to the bars1 and as hot-working increases density1 the densities of the higher carbons were increased more than those of the lower4 ,the bars were nicked six times at intervals of about -inch and then heated so that the ends were scintillating1 ready to pass into the granular condition1 and the heat was so regulated as to have each piece less hot than the piece next nearer to the end1 the last piece1 ,no4 #f1 being black and as nearly cold as possible4 ,it is manifest that this operation is subject to the error of accidentally getting ,no4 #b1 for instance1 hotter than ,no4 #a1 and so on1 so that perfect regularity is not to be expected2 to obtain a true rule of expansion it would be necessary to make hundreds of such experiments and use the mean of all4 ,it will be noticed that ,no4 #d is abnormal in the ingot series1 and that the ,no4 #f piece of ,no4 #d is abnormal in being lighter than the ingot2 probably this ,no4 #f of ,no4 #d was hot when it was intended to be cold4 ,also ,no4 #b of ingot ,no4 #c is lighter than its ,no4 #a1 showing another irregularity in heating4 ,taking the whole list of ,no4 #a pieces1 they are all lighter than their respective ,no4 #f pieces2 the differences of sp4 gr4 #f-a are progressive1 being only 4#jbe for the ,no4 #c ingot and 4#ace for the ,no4 #ab ingot4 ,this shows clearly that expansion due to a given difference in temperature is much greater in high steel than in low steel4 ,this clears away the mystery of the so-called treachery of high steel1 its tendency to crack when hardened4 ,there is no treachery about it2 it is very sensitive to temperature1 and it must be treated accordingly4 ,a few examples will now be given to show the changes of tensile strength1 ductility1 etc41 that may be had by differences of carbon1 and by differences of treatment1 annealing1 hardening1 and tempering4 ,,table ,,ii4 ---------------------------------------- ----------------------- ,character of ,steel4 ,o4 ,h4 ,crucible ,o4 ,h4 ,o4 ,h4 ,o4 ,h4 ,sheet ---------------------------------------- ----------------------- ,carbon 4#ji to 4#ab 4#dce 4#ej 4#fj 4#gj ,silicon 4#jjh 4#jad 4#jbe ,phosphorus 4#jjg 4#jej 4#jaf ,sulphur 4#jbf 4#jbh 4#jbh ,manganese 4#jee 4#bjd 4#cbe ,tensile strength1 lbs4 per sq4 in4 #dfhjj #gcadb #hdbbj #a #jhhjj #aagdjj ,elastic limit #cjijj #fcefj #gaejj #fiihj ,elongation in #b in #a #be #ad4e #aa4e in4 #da in4 #db ,reduction of area #ge4he #fb4c #bi4ia #ac4ee #h4ei silky ,fracture cup ---------------------------------------- ----------------------- ---------------------------------------- --------------------- ,crucible ,crucible ,crucible ,crucible ,character of ,eye-bar1 ,eye-bar1 ,eye-bar1 -in4 ,steel4 #b #a4 #b #a4 #b #a4 ,drawn ,wire4 ---------------------------------------- --------------------- ,carbon 4#if #a4ce #a4dj #a4ae ,silicon 4#aef 4#jb ,phosphorus 4#jjh 4#jb ,sulphur 4#jae trace ,manganese 4#bd 4#cj ,tensile strength1 lbs4 per sq4 in4 #abdhjj #ajjgcc #aaggaj #adaejj ,elastic limit #fejjj #hejgh #fihej #ibdbj ,elongation #d4ge 4#e #g4bh at #b #b4he in #b ,reduction of area #ac4jc #b4db broke in neck broke broke slight in head in ,fracture flaw1 close grip fine grain grain ---------------------------------------- --------------------- ,o4 ,h4 is the abbreviation for open hearth4 ,second column is mean of #bd analyses and #bd tests of boiler-sheets4 ,,table ,,iii4 ---------------------------------------- ------------------------ ,tensile ,elastic ,elongation4 ,reduc- ,cold-drawn ,wire1 ,strength1,limit1 ----------- tion of -inch ,diam4 lbs4 per lbs4 per,in #c ,per ,area1 sq4 in4 sq4 in4 in4 cent4 per ct4 ---------------------------------------- ----------------------- ,cold-drawn1 broke in grip #ada1ejj #ib1djj 4#jf #b4jj #b4db ,same bar drawn black #ach4djj #aad1gjj 4#ah #f4jj #ab4de 8 8 annealed #ih1daj #fh1aaj 4#cj #aj4jj #aa4fi 8 8 hardened and then drawn black #bdh1gjj #aeb1hjj 4#be #h4cc #ai4g ---------------------------------------- ----------------------- ,analysis of this bar is given in ,table ,,ii in the last column4 ,a test of -inch wire to show effect of cold-drawing1 tempering1 annealing1 and hardening and tempering4 ,four pieces were cut from the same bar4 ,it is probable that the first piece would have given a little higher tensile if it had not broken in the grip2 it was clamped too tight4 ,the second piece was heated until it passed through all of the temper colors and turned black1 technically called 8drawing black10 or drawing out all of the temper4 ,it is not quite annealing2 the idea was to find the effect of temper-drawing upon a cold-hardened drawn wire4 ,the effect of this operation was to lower the ultimate and raise the elastic strength1 increasing also the ductility4 ,the third piece was heated carefully to the recalescence-point1 and cooled slowly1 thus annealing it completely1 and giving the normal strength of a bar of this composition4 ,the fourth piece was heated to recalescence and quenched1 hardening and refining it thoroughly2 it was then tempered through all of the colors until it turned black2 the result shows the enormous potencies there are in the hardening and tempering operations4 ,the cases given in ,table ,,ii were selected indiscriminately1 so as to show better the effect of carbon1 as we here have tests of ordinary test-bars1 boiler-sheet1 small eye-bars1 and drawn wire4 ,the #if-;carbon eye-bar and the #aae-;carbon -inch wire are the nearest to the #ajj-;carbon saturation limit mentioned before1 and they show the highest strength4 ,the #if-;carbon eye-bar had a slight flaw in the fracture1 which doubtless caused it to break below its real strength4 ,the #ace-;carbon eye-bar broke in the head in a way to indicate that there was some local strain there1 due to forging4 ,these examples are not given as establishing any general law2 they are illustrations of what all experience shows to be the fact1 that the strength of steel is affected profoundly by the quantity of carbon present1 and also by heat and by mechanical work4 ,from #df1hjj lbs4 to #bdh1gjj lbs4 tensile strength per square inch is an enormous range1 and these figures probably represent pretty closely the ultimate limits at present attainable4 ,an inspection of the analyses makes it clear that the other elements present in addition to carbon were not there in sufficient quantity or variety to have had much effect upon the results4 ,,vi4 ,,heating ,,for ,,forging2 ,,for ,,hardening2 ,,for ,,welding4 ,,burning1 ,,overheating1 ,,restoring4 ,from what has been said already about the effects of heat it follows without further argument that heating is one of the most important1 or perhaps more properly the most important of all1 of the operations to which steel has to be subjected4 ,the first and vital thing to be borne in mind is that all heating should be uniform throughout the mass4 ,it has been shown that heat affects the grain1 the structure1 as surely as it moves the mercury-column1 and such being the case it is plain that as perfect uniformity as it is possible to attain is the first essential for all heating1 no matter what the ultimate object may be4 ,in heating for forging the limit lies between the point of recalescence1 the beginning of true plasticity1 and the granular condition1 the end of plasticity2 these temperatures lie between dark or medium orange for all steels and medium or light lemon on the upper limit1 depending on the carbon content1 or lower if it be an alloy steel4 ,if there is much work to be done upon a piece of steel1 it is well to heat at first to as high a temperature as is safe1 and then to forge or work heavily at the higher heat1 reducing the blows or passes as the piece is reduced and the temperature falls4 ,although this high heating will raise the grain of the steel1 the heavy working will bring it back to a fine1 compact structure4 ,if little work is to be done1 then it is better to heat as low as may be safe1 and allow the work to be done without letting the heat down below orange red1 so that the steel may not be crushed in the grain4 ,below orange red1 the so called 8dark cherry10 steel should not be forged1 except that in forging for fine tools it is well to give many light and rapid blows until black begins to show in order to hammer-refine it2 this must be done with extreme care so as not to crush the steel and cause cracking in the subsequent hardening1 or crumbling in the hardened tool4 ,,heating ,,for ,,hardening4 ,when a piece of steel is to be hardened by quenching in water or any quick-cooling medium1 it should be heated with great care to the exact temperature to produce the required hardness4 ,after forging1 no piece of steel should be quenched without first being heated uniformly to the proper temperature4 ,ede in his book recommends quenching immediately after forging in some cases4 ,the so-called ,harvey patent recommends cooling from a high heat down to the required heat and then quenching4 ,both practices are bad4 ,in the ,ede case this is believed to be the only bad piece of advice in his very valuable book--in every other respect the most practical and useful book upon the manipulation of steel known to the author4 ,the reason for objecting to the quenching after forging without re-heating is that forging always sets up uneven strains in the mass2 the flow is easier from the sides than from the middle of the piece1 and therefore the amount of work done upon one part is greater than upon another2 also it is impossible to hammer or press a piece of steel with exact uniformity throughout1 so that it follows that after forging there is never exact uniformity of texture or temperature1 and such uniformity is the one essential thing to insure good and even hardening4 ,the practice of allowing a highly heated piece to cool down to a given color and then quenching is objectionable1 because it produces a coarse and brittle grain due to the higher heat4 ,referring to the illustration on page #fg of the squares representing grains due to different temperatures3 ,assume that square ,no4 #c represents the heat at which quenching is to take place1 and ,no4 #f is the heat to which the piece has been subjected2 then the piece when it has cooled to ,no4 #c will not have the grain due to ,no4 #c heat3 it will have a larger1 coarser grain that formed as the piece cooled from ,no4 #f4 ,if now it be quenched1 it will have only the hardness due to ,no4 #c1 with a much coarser and more brittle grain than ,no4 #c heat should give4 ,the way to manage such a case is to let the piece cool completely and assume the ,no4 #f grain2 then re-heat carefully to exactly ,no4 #c and no hotter2 keep the piece at that heat for a few minutes1 or moments1 according to its size1 to allow for lag2 then it will have the finer grain due to ,no4 #c heat1 and when quenched it will be as hard as under the other method1 and it will be much finer and stronger4 ,the same rule applies to any two temperatures4 ,as an expression of exactness as to evenness of heat1 it may be said that the piece should be as uniform in color as if it had been dipped into a pot of paint4 ,when such uniformity is attained1 a break from quenching is rare1 unless the piece has been shamefully overheated so that the strains of quenching are greater than the tenacity of the steel4 ,,heating ,,for ,,welding4 ,when an ingot is to be forged or rolled1 it is well to take the highest heat possible--that immediately below the heat of granulation4 ,such a heat may be taken safely by keeping the steel covered with a surface flux to protect it from the flame4 ,ordinary red clay1 dried and powdered1 is an excellent flux for the purpose1 and the cheapest known4 ,melted and powdered borax is the best of known fluxes1 but it is so expensive that1 as a rule1 it is used only on the finest tool-steel1 or on some of the alloy steels where the highest heat possible is not above a bright orange color1 or hardly so high4 ,a good flux1 intermediate in cost between common red clay and powdered borax1 is an earth or mineral barite1 or heavy spar4 ,this material fuses more readily than red clay and not quite so easily as borax4 ,it forms a good protective covering on the steel1 and it is nearly or quite as efficient as borax4 ,the object in heating so high is to make the steel as soft and plastic as it may be1 so that the subsequent working will close up all porosity as far as possible4 ,nearly all ingots have in them a greater or less number of cavities1 commonly called blow-holes1 that are caused by the separation of occluded gases during cooling4 ,if such porosities are not oxidized on the surface they will disappear under heavy working at a high heat4 ,it is probable that under the compression of the work the gases are redisseminated in the mass and the walls of the cavities are reunited4 ,if there be the slightest oxidation of the surface of a cavity the walls will not reunite3 there will be left in the mass a little flat film of oxide which will prevent the union4 ,in mild steels used for machinery or structural purposes these little films may do no harm1 the factor of safety being sufficient to more than cover any weakening effect4 ,in tool-steel that is to be hardened such little films are almost certain to cause fracture4 ,dies as large as twelve inches square and six to eight inches thick1 having been heated and quenched with the greatest care1 have split fairly in two1 and have revealed in the fracture a little film no larger than half an inch in diameter and of inappreciable thickness4 ,at the same time the perfectly uniform grain and hardness showed that the highest skill had been used4 ,this is only one illustration of the fact that every break in the continuity of the grain in steel forms a starting-point for fracture under heavy stress4 ,from what has been said it is plain that to weld two pieces of steel together is a difficult matter2 still it can be done if great care be used4 ,in general it is better to avoid such welding except in cases of necessity4 ,the welding of steel tubing1 and the electric welding of rails1 frogs1 switches1 etc41 is done on a large scale and satisfactorily1 so that it will not do to say that steel cannot be welded4 ,it can be welded or pasted together1 and it is a good operation to avoid in all high steel4 ,in case steel is to be hardened a weld will reveal itself almost certainly4 ,,burning ,,in ,,heating4 ,when a piece of steel breaks and shows a coarse1 fiery fracture1 it is common to say that it is burned4 ,this is not necessarily the case4 ,there are several degrees in the effects of heat4 ,the first is the raising of the grain2 the second1 in high steel1 is the decarbonizing or burning out of carbon from the surface in1 the depth of the decarbonizing depending upon time and temperature2 the third is oxidizing1 or actual burning in the common acceptance of the term4 ,all of these operations go on to a slight extent every time a piece of steel is heated1 but when the heating is done carefully there is only a small film of steel that is decarbonized and oxidized1 and this film flies off when the piece is quenched for hardening4 ,when the steel is forged or rolled this skin will be united firmly to the steel1 and it will be thinner or thicker1 according to the number of heatings and the time of exposure to the fire4 ,in tool-making this skin must always be removed4 ,many an expensive tool is made perfectly worthless by not having this skin all removed1 owing usually to mistaken economy4 ,the steel is expensive1 and the tool-maker does not wish to cut it up into worthless chips4 ,when a tool costing1 say1 twenty-five dollars is made useless by failure to cut away twenty-five cents' worth of useless skin1 the economy of such an operation requires no discussion4 ,it is impossible to forge a piece of steel without producing such a skin1 and it is well known that decarbonized iron will not harden4 ,ordinarily a cut of _/ of an inch should remove such a skin on straight rolled or hammered bars4 ,in the case of a shaped forging where many re-heatings have been required the forgeman will have done good work if the cutting away of of an inch will present a good surface3 tool-makers should consider this and allow for it4 ,on the other hand1 if a tool-maker finds that the removal of of an inch from a bar1 or of an inch from a forging will not yield him a good1 hard surface1 he should hold the steel-maker responsible for bad work4 ,actual burning reveals itself in rough tears1 and cracks at the surface and corners of the piece4 ,such a piece should go to the scrap heap4 ,overheated steel of coarse1 fiery grain has been injured1 and not necessarily destroyed4 ,such a piece may be restored to any fineness of grain by heating to the right temperature--medium orange for the best grain--keeping it at that heat for1 say1 one minute for a little piece1 and five to ten or fifteen minutes for a large piece4 ,the heat should penetrate the whole mass1 and it should not be allowed to run above the given color in any part1 not even for a moment4 ,it should then be allowed to cool in a dry place1 without disturbance4 ,the grain will now be fine and uniform1 and the steel may be worked in the ordinary way4 ,this simple operation is all that is necessary to restore to a fine grain any piece of steel that has been overheated1 provided that the piece has not been actually burned nor ruptured4 ,,vii4 ,,annealing4 ,it has been shown that the grain or structure of steel is profoundly affected by heat1 so that any difference of heat-color that is visible to the naked eye will cause a difference of grain that is also visible to the naked eye4 ,specific-gravity tests and delicate magnetic tests have proved that for every variation in grain there is a difference of specific-gravity1 which means1 of course1 a difference in volume2 from this it is clear that if in any one piece of steel there exists a variety of grain due to uneven heating1 there must necessarily be in the mass internal destructive strains4 ,these strains become manifest when a piece of unevenly heated steel cracks in hardening2 in this case the strains are greater than the tenacity of the steel4 ,it is well known1 also1 that all working of steel1 such as forging or rolling1 has a hardening effect1 so that ordinary bars or forgings cannot be machined readily in the condition in which they are left by these operations4 ,if there were no remedy for these conditions of internal stress and initial hardness1 the general use of steel would be very difficult1 and its application would be limited seriously4 ,fortunately1 there are three properties of steel which furnish an easy and efficient remedy4 ,first1 the fact that steel will assume by mere heating a grain or structure due to any temperature1 no matter what its previous structure may have been1 makes it a simple matter to remove practically all irregularities of grain and stress1 by heating the mass to a perfectly uniform color and allowing it to cool uniformly4 ,second1 as heating is a softening process always1 the mere heating of any piece of steel will soften it1 and the amount of this softness that can be retained when the piece is cold is a direct function of the length of time of cooling1 so that by sufficiently slow cooling any steel can be left reasonably soft4 ,this does not apply to ,hadfield's manganese steel1 which cannot be made soft when cold by any of the known processes of annealing4 ,third1 by reference to the specific-gravity table ,no4 ,i1 ,chap4 ,v1 it will be seen that the change in volume due to differences of temperature is much less in mild steel than in high steel4 ,this fact does not rest upon the evidence of this table alone2 it is a fact of common knowledge to all steel-makers that mild steel is much more inert than high steel2 therefore differences of heat and working that produce serious results in high steel are hardly appreciable in mild steel4 ,as a rule all structural steels are comparatively mild1 therefore they are generally in a fit condition for use when they leave the rolls or forge4 ,in cases of special forging1 where one part is heated and another is left cold1 as in the forging of the heads of eye-bars1 it would seem to be wiser to anneal such pieces to remove the area of strain that must exist between the unheated parts and those that were heated and forged4 ,the operation of removing strains and hardness by careful1 uniform heating and slow cooling is known as annealing4 ,annealing should not be confused with tempering4 ,tempering is the partial softening of hardened steel1 to remove some of the exceeding brittleness of hardened steel1 and so to make it strong and highly elastic while it is still very hard4 ,annealing is the complete softening of a piece of steel2 that is to say1 as a rule1 the obtaining of the utmost softness that is possible2 or in any case to have the steel softer than any tempering would leave it4 ,annealing1 and tempering are frequently used synonymously4 ,such misuse of terms in speaking of technical matters leads to confusion of ideas and misunderstandings4 ,as a rule1 the best heat to use for annealing is that which gives a medium orange color2 it is a good heat to quench from2 it is a little above the heat of recalescence1 about #fee ,cent4 ,this heat is that which gives the finest grain to steel when it is hardened1 and is known as the refining heat4 ,as steel is thoroughly plastic and soft at this heat1 and as it yields the best and strongest grain when cooled from this heat1 it is clear that there is nothing to be gained by heating any higher for annealing4 ,in annealing1 the steel should be brought up to the right color1 medium orange1 and left at that heat until it is hot through1 care being taken that the heat does not run any higher in any part of the piece4 ,if the corners or edges or any part be allowed to run up to bright orange1 or to medium or bright lemon1 as is often done1 then there is bad work2 the result will be uneven grain and internal strains4 ,when steel is to be hardened afterwards1 there may be no harm in heating up to an even lemon color2 but where is the use in applying this excess of heat merely to make a coarse grain1 when the lower1 medium orange color will give just as good softness and a much better grain8 ,the time necessary for good annealing depends upon the size of the piece2 a wire may be brought up to the right heat in five minutes or less1 and heated through in another minute2 then it should be removed from the fire1 as every additional moment of heating will only injure the steel4 ,a block six or eight inches cube may require three to five hours to bring it up to the color and have it heated through1 and sufficient time should be given2 but as soon as it is hot through it should be removed from the fire4 ,a six-inch block may be brought up to a medium orange color in twenty minutes or less in a hot furnace1 and then if it be kept in such a furnace until it is hot all through1 the surface and edges will almost certainly be brought to a bright lemon color1 with bad results4 ,to do good annealing a piece should never be hotter in one part than in another1 and no part should be hotter than necessary1 usually the medium orange color4 ,annealing1 then1 is a slow process comparatively1 and sufficient time should be allowed4 ,there are many ways of annealing steel1 and generally the plan used is well adapted to the result desired2 it is necessary1 however1 to consider the end aimed at and to adopt means to accomplish it1 because a plan that is excellent in one case may be entirely inefficient in another4 ,probably the greatest amount of annealing is done in the manufacture of wire1 where many tons must be annealed daily4 ,for annealing wire sunken cylindrical pits built of fire-bricks are used usually2 the coils of wire are piled up in the cylinders1 which are then covered tightly1 and heat is applied through flues surrounding the cylinders1 so that no flame comes in contact with the steel4 ,for all ordinary uses this method of annealing wire is quick1 economical1 and satisfactory4 ,the wire comes out with a heavy scale of oxide on the surface2 this is pickled off in hot acid1 and the steel should then be washed in limewater1 then in clean water1 and finally dried4 ,if it be desired to make drill-wire for drills1 punches1 graving-tools1 etc41 this plan will not answer1 because under the removable scale there is left a thin film of decarbonized iron which cannot be pickled off without ruining the steel1 and which will not harden4 ,it is plain that this soft surface must be ruinous to steel intended for cutting-tools1 for it prevents the extreme edge from hardening--the very place that must be hard if cutting is to be done4 ,tools for drills1 lathe-tools1 reamers1 punches1 etc41 are usually annealed in iron boxes1 filled in the spaces between the tools with charcoal2 the box is then looted and heated in a furnace adapted to the work4 ,this is a satisfactory method generally1 because the tools are either ground or turned after annealing1 removing any decarbonized film that may be found2 the charcoal usually takes up all of the oxygen and prevents the formation of heavy scale and decarbonized surfaces1 but it does not do so entirely1 and so for annealing drill-wire this plan is not satisfactory4 ,it is a common practice in annealing in this way to continue the heating for many hours1 sometimes as many as thirty-six hours1 in the mistaken notion that long-continued heating produces greater softness1 and some people adhere to this plan in spite of remonstrances1 because they find that pieces so annealed will turn as easily as soft cast iron4 ,this last statement is true2 the pieces may be turned in a lathe or cut in any way as easily as soft cast iron1 for the reason that that is exactly what they are practically4 ,when steel is made properly1 the carbon is nearly all in a condition of complete solution2 it is in the very best condition to harden well and to be enduring4 ,when steel is heated above the recalescence-point into the plastic condition1 the carbon at once begins to separate out of solution and into what is known as the graphitic condition4 ,if it be kept hot long enough1 the carbon will practically all take the graphitic form1 and then the steel will not harden properly1 and it will not hold its temper4 ,to illustrate3 ,let a piece of #ij-;carbon steel be hardened and drawn to a light brown temper2 it will be found to be almost file hard1 very strong1 and capable of holding a fine1 keen edge for a long time4 ,next let a part of the same bar be buried in charcoal in a box and be closed up air-tight1 then let it be heated to a medium orange1 no hotter1 and be kept at that heat for twelve hours1 a common practice1 and then cooled slowly4 ,this piece will be easily cut1 and it will harden very hard1 but when drawn to the same light brown as the other tool a file will cut it easily2 it will not hold its edge1 and it will not do good work4 ,clearly in this case time and money have been spent merely in spoiling good material4 ,there is nothing to be gained1 and there is everything to be lost1 in long-continued heating of any piece of steel for any purpose4 ,when it is hot enough1 and hot through1 get it away from the fire as quickly as possible4 ,this method of box-annealing is not satisfactory when applied to drill-wire1 or to long thin strands intended for clock-springs1 watch-springs1 etc4 ,the coils or strands do not come out even2 they will be harder in one part than in another2 they will not take an even temper4 ,when hardened and tempered1 some parts will be found to be just right1 and others will have a soft surface1 or will not hold a good temper4 ,the reason of this seems to be a want of uniformity in the conditions3 the charcoal does not take up all of the oxygen before the steel is hot enough to be attacked1 and so a decarbonized surface is formed in some parts2 or it may be that some of the carbon dioxide which is formed comes in contact with the surface of the steel and takes another equivalent of carbon from it4 ,whatever the reaction may be1 the fact is that much soft surface is formed4 ,this soft surface may not be more than 4#jja of an inch thick1 but that is enough to ruin a watch-spring or a fine drill4 ,again1 it seems to be impossible to heat such boxes evenly2 it is manifest that it must take a considerable length of time to heat a mass of charcoal up to the required temperature1 and if the whole be not so heated some of the steel will not be heated sufficiently2 this will show itself in the subsequent drawing of the wire or rolling of the strands4 ,on the other hand1 if the whole mass be brought up to the required heat1 some of the steel will have come up to the heat quickly1 and will then have been subjected to that heat during the balance of the operation1 and in this way the carbon will be thrown out of solution partly4 ,this is proven by the fact that strands made in this way and hardened and tempered by the continuous process will be hard and soft at regular intervals1 showing that one side of the coil has been subjected to too much heat4 ,this trouble is overcome by open annealing1 which will be described presently4 ,when steel is heated in an open furnace1 there is always a scale of oxide formed on the surface2 this scale1 being hard1 and of the nature of sand or of sandstone1 grinds away the edges of cutting-tools1 so that1 although the steel underneath may be soft and in good cutting condition1 this gritty surface is very objectionable4 ,this trouble is overcome by annealing in closed vessels2 when charcoal is used1 the difficulties just mentioned in connection with wire- and strand-annealing operate to some extent1 although not so seriously1 because the steel is to be machined1 removing the surface4 ,the ,jones method of annealing in an atmosphere of gas is a complete cure for these troubles4 ,jones uses ordinary gas-pipes or welded tubes of sizes to suit the class of work4 ,one end of the tube is welded up solid2 the other end is reinforced by a band upon which a screw-thread is cut2 a cap is made to screw on this end when the tube is charged4 ,a gas-pipe of about -inch diameter is screwed into the solid end1 and a hole of _/- to -inch diameter is drilled in the cap4 ,when the tube is charged and the cap is screwed on1 a hose connected with a gas-main is attached to the piece of gas-pipe in the solid end of the tube2 the gas-pipe is long enough to project out of the end of the furnace a foot or so through a slot made in the end of the furnace for that purpose4 ,the gas is now turned on and a flame is held near the hole in the cap until the escaping gas ignites2 this shows that the air is driven out and replaced by gas4 ,the pipe is now rolled into the furnace and the door is closed1 the gas continuing to flow through the pipe4 ,by keeping the pipe down to a proper annealing-heat it is manifest that the steel will not be any hotter than the pipe4 ,by heating the pipe evenly by rolling it over occasionally the steel will be heated evenly4 ,a little experience will teach the operator how long it takes to heat through a given size of pipe and its contents1 so that he need not expose his steel to heat any longer than necessary4 ,there is not a great quantity of gas consumed in the operation1 because the expanding gas in the tube makes a back pressure1 the vent in the cap being small4 ,this seems to be the perfection of annealing4 ,a tube containing a bushel or more of bright1 polished tacks will deliver them all perfectly bright and as ductile as lead1 showing that there is no oxidation whatever4 ,experiments with drill-rods1 with the use of natural gas1 have shown that they can be annealed in this way1 leaving the surface perfectly bright1 and thoroughly hard when quenched4 ,this ,jones process is patented4 ,although the ,jones process is so perfect1 and necessary for bright surfaces1 its detail is not necessary when a tarnished surface is not objectionable4 ,the charcoal difficulty can be overcome also4 ,let a pipe be made like a ,jones pipe without a hole in the cap or a gas-pipe in the end4 ,to charge it first throw a handful of resin into the bottom of the pipe1 then put in the steel1 then another handful of resin near the open end1 and screw on the cap4 ,the cap is a loose fit4 ,now roll the whole into the furnace2 the resin will be volatilized at once1 fill the pipe with carbon or hydrocarbon gases1 and unite with the air long before the steel is hot enough to be attacked4 ,the gas will cause an outward pressure1 and may be seen burning as it leaks through the joint at the cap4 ,this prevents air from coming in contact with the steel4 ,this method is as efficient as the ,jones plan as far as perfect heating and easy management are concerned4 ,it reduces the scale on the surfaces of the pieces1 leaving them a dark gray color and covered with fine carbon or soot4 ,for annealing blocks or bars it is handier and cheaper than the ,jones plan1 but it will not do for polished surfaces4 ,this method is not patented4 ,,open ,,annealing4 ,open annealing1 or annealing without boxes or pipes1 is practised wherever there are comparatively few pieces to anneal and where a regular annealing-plant would not pay1 or in a specially arranged annealing-furnace where drill-wire1 clock-spring steel1 etc41 are to be annealed4 ,for ordinary work a blacksmith has near his fire a box of dry lime or of powdered charcoal4 ,he brings his piece up to the right heat and buries it in the box1 where it may cool slowly4 ,in annealing in this way it is well not to use blast1 because it is liable to force all edges up to too high a heat and to make a very heavy scale all over the surface4 ,with a little common-sense and by the use of a little care this way of annealing is admirable4 ,it is a common practice where there is a furnace in use in daytime and allowed to go cold at night to charge the furnace in the evening1 after the fire is drawn1 with steel to be annealed1 close the doors and damper1 and leave the whole until morning4 ,the furnace does not look too hot when it is closed up1 but no one knows how hot it will make the steel by radiation3 the steel is almost always made too hot1 it is kept hot too long1 and so converted into cast iron1 and there is an excessively heavy scale on it4 ,many thousands of dollars worth of good steel are ruined annually in this way1 and it is in every way about the worst method of annealing that was ever devised4 ,to anneal wire or thin strands in an open furnace the furnace should be built with vertical walls about two feet high and then arched to a half circle4 ,the inports for flame should be vertical and open into the furnace at the top of the vertical wall2 the outports for the gases of combustion should be vertical and at the same level as the inports and on the opposite side of the furnace from the inports4 ,these outflues may be carried under the floor of the furnace to keep it hot4 ,the bottom of the door should be at the level of the ports to keep indraught air away from the steel4 ,the annealing-pot is then the whole size of the furnace--two feet deep--and closed all around4 ,the draught should be regulated so that the flame will pass around the roof1 or so nearly so as to never touch the steel1 not even in momentary eddies4 ,in such a furnace clock-spring wire not more than 4#ja inch in diameter1 or clock-spring strands not more than 4#jjf to 4#jjh inch thick and several hundred feet long1 may be annealed perfectly4 ,the steel is scaled of course1 but the operation is so quick and so complete that there is no decarbonized surface under the scale4 ,this plan is better than the ,jones method or any closed method1 because the big boxes necessary to hold the strands or coils cannot be heated up without in some parts overheating the steel2 all of which is avoided in the open furnace1 because by means of peep-holes the operator can see what he is about1 and after a little practice he can anneal large quantities of steel uniformly and efficiently4 ,,viii4 ,,hardening ,,and ,,tempering4 ,for nearly all structural and machinery purposes steel is used in the condition in which it comes from the rolls or the forge2 in exceptional cases it is annealed1 and in some cases such as for wire in cables or for bearings in machinery1 it is hardened and tempered4 ,for all uses for tools steel must be hardened1 or hardened and tempered4 ,the operations of hardening and tempering1 including the necessary heating1 are the most important1 the most delicate1 and the most difficult of all of the manipulations to which steel is subjected2 these operations form an art in themselves where skill1 care1 good judgment1 and experience are required to produce reliable and satisfactory results4 ,it is a common idea that all that is necessary is to heat a piece of steel1 quench it in water1 brine1 or some pet nostrum1 and then warm it to a certain color2 these are indeed the only operations that are necessary1 but the way in which they are done are all-important4 ,an experienced steel-maker is often amazed at the confidence with which an ignorant person will put a valuable tool in the fire1 rush the heat up to some bright color1 or half a dozen colors at once1 and souse it into the cooling-bath without regard to consequences4 ,that such work does not always result in disastrous fractures shows that steel does possess marvellous strength to resist even the worst disregard of rules and facts4 ,on the other hand1 the beautiful work upon the most delicate and difficult shapes that is done by one skilled in the art cannot but excite the surprise and admiration of the onlooker who is familiar with the physics of steel1 and who can appreciate the delicacy of handling required in the operation4 ,there are a few simple laws to observe and rules to follow which will lead to success2 they will be stated in this chapter as clearly as may be1 in the hope of giving the reader a good starting-point and a plain path to follow2 but he who would become an expert can do so only by travelling the road carefully step by step4 ,the hair-spring of a watch1 or a little pinion or pivot1 so small that it can only be seen through a magnifying-glass1 the exquisitely engraved die costing hundreds or thousands of dollars1 and the huge armor-plate weighing many tons1 must all be hardened and tempered under precisely the same laws and in exactly the same way2 the only difference is in the means of getting at it in each case4 ,referring now to properties mentioned in the previous chapters1 we have first to heat the piece to the right temperature and then to cool it in the quickest possible way in order to secure the greatest hardness and the best grain4 ,in doing this we subject the steel to the greatest shocks or strains1 and great care must be used4 ,the importance of uniformity in heating for forging and for annealing has been stated1 and it has been shown how an error in this may be rectified by another and a more careful heating2 when it comes to hardening1 this uniformity must be insisted upon and emphasized1 for as a rule an error here has no remedy4 ,there may be cases of bad work that do not cause actual fracture that can be remedied by re-heating and hardening1 but these are rare1 because even if incurable fracture does not occur the error is not discovered until the piece has been put to work and its failure develops the errors of the temperer4 ,if the error is one of merely too low heat1 not producing thorough hardening1 it will generally be discovered by the operator1 who will then try again and possibly succeed2 but if the error be of uneven heat1 or too much heat1 the probabilities are that it will not be discovered until the piece fails in work1 when it will be too late to apply any remedy4 ,referring to ,table ,i1 ,chap4 ,v1 treating of specific gravities1 it is clear that all steel possesses different specific gravities1 due to differences of temperature1 and that these differences of specific gravity increase as the carbon content increases2 it follows that if a piece of steel be heated unevenly1 internal strains must be set up in the mass1 and it is certain that if steel be quenched in this condition violent strains will be set up1 even to the causing of fractures4 ,the theory of this action1 as of all hardening1 is involved in discussion which will be considered later2 in this chapter the facts will be dealt with4 ,when a piece of steel is heated1 no matter how unevenly or to what temperature below actual granulation1 and is allowed to cool slowly and without disturbance1 it will not break or crack under the operation4 ,if a piece be heated as unevenly as1 say1 medium orange in one part and medium lemon in another1 and is then quenched1 it will be almost certain to crack if it contains enough carbon to harden at all in the common acceptance of the term1 that is to say1 file hard or having carbon #dj or higher4 ,this fact is too well known to be open to discussion2 therefore the quenching of hot steel1 the operation of hardening1 does set up violent strains in steel1 no matter what the true theory of hardening may be4 ,referring to ,chap4 ,v1 to the series of squares representing the apparent sizes of grain due to different temperatures1 similar results follow from hardening1 with the exceptions that the different structures are far more plainly marked1 and the squares should be arranged a little differently2 they are shown as continuously larger in ,chap4 ,v1 from the grain of the cold bar up to the highest temperature2 this is true if a bar has been rolled or hammered properly into a fine condition of grain4 ,of course if a bar be finished at1 say1 medium orange it will have a grain due to that heat--,no4 #c in the series of squares4 ,then if it be heated to dark orange and cooled from that heat it will take on a grain corresponding to square ,no4 #b1 and ,no4 #a square will be eliminated4 ,the series of squares to represent hardened grain will be as follows3 ,illustration ,the heat colors being the same as before1 viz43 #a4 ,the natural bar--untreated4 #b4 ,quenched at dark orange or orange red4 #c4 8 8 medium orange--refined4 #d4 8 8 bright orange4 #e4 8 8 dark lemon4 #f4 8 8 medium lemon4 #g4 8 8 bright lemon4 #h4 8 8 very bright lemon or creamy4 ,heats #f1 #g1 #h will almost invariably produce cracks although the pieces be evenly heated4 ,illustration ,illustration ,these squares do not represent absolute structures with marked divisions2 they are only the steps on an incline1 like the temper numbers in the carbon series2 thus1 the carbon-line is continuous1 but the temper divisions represent steps up the incline4 ,so with the series of squares1 the changes of grain or structure are continuous1 as represented by the doubly inclined line2 the squares being only the steps to indicate easily observed divisions4 ,the minuteness of the changes is illustrated by the fact that in a piece heated continuously from creamy to dark orange and quenched1 differences of grain have been observed unmistakably on opposite sides of pieces broken off not more than inch thick4 ,in practice the differences due to the colors given in the list above are as plain and surely marked as are the differences in the structure of ingots due to the different temper carbons already described4 ,in this hardened series each carbon temper gives its own peculiar grain2 in low steel1 say #dj carbon compared to #a4jj carbon or higher1 ,no4 #c will be larger and ,no4 #h will be smaller in the low temper than in the high--another illustration of the fact that low steel is more inert to the action of heat than high steel4 ,all grades and all tempers go through the same changes1 but they are more marked in the high than in the low steel4 ,the grain of hardened steel is affected by the presence of silicon1 phosphorus1 and manganese1 and doubtless by any other ingredients1 these three being the most common4 ,it is in the grain of hardened steel that the conditions described in ,chap4 ,v as 8sappy10 8dry10 and 8fiery0 are the most easily and frequently observed1 although the same conditions obtain in unhardened steel in a manner that is useful to an observing steel-user4 ,but it is in this hardened condition that the excellences or defects of steel are brought out and emphasized4 ,when a piece of steel is heated continuously from 8creamy10 or scintillating1 down to black1 or unheated1 and is then quenched1 the grain will be found to be coarsest1 hardest1 and most brittle at the hottest end1 and with the brightest lustre1 even to brilliancy1 and to become finer down to a certain point1 noted as ,no4 #c in the series of squares1 or at a heat which shows about a medium orange color2 here the grain becomes exceedingly fine1 and here the steel is found to be the strongest and to be without lustre4 ,below this heat the grain appears coarser and the steel is less hard1 until the grain and condition of the unheated part are reached4 ,this fine condition1 known as the refined condition1 is very remarkable4 ,it is the condition to be aimed at in all hardening operations1 with one or two exceptions which will be noted1 because in this state steel is at its best2 it is strongest then1 and it would seem to be clear without argument that the finest grain and the strongest will hold the best at a fine cutting-edge1 and will do the most work with the least wear1 although a coarser grain may be a little harder1 the coarser and more brittle condition of the latter more than counterbalancing its superior hardness4 ,the advantages of this refined condition are so great that it is found to be well to harden and refine mild-steel dies1 and battering- and cutting-tools that are to be used for hot work1 although the heat will draw out all of the temper in the first few minutes1 because the superior strength of the fine grain will enable the tool to do twice to twenty times more work than an unhardened tool4 ,the refining-heat1 like most other properties1 varies with the carbon2 the medium orange given is the proper heat for normal tool-steel of from about #ij to #aaj carbon4 ,steel of #aej carbon will refine at about a dark orange1 and steel of #ej to #fj carbon will require about a bright orange to refine it4 ,this range is small1 but it must be observed and worked to if the best results are desired4 ,a color-blind person can never learn to harden steel properly4 ,in studying this phenomenon of refining1 the conclusion was reached that it occurred at or immediately above the temperature that broke up the crystalline condition of cold steel and brought it fairly into the second1 the plastic condition4 ,farther observation led to the conclusion that the coarser grain and greater hardness caused by higher heats were due to the gradual change from plastic toward granular condition that takes place as the heat increases4 ,later investigations have given no reason for changing these conclusions4 ,when the phenomenon of recalescence was observed and investigated by ,osmond and others1 different theories were advanced in explanation4 ,langley concluded that if recalescence occurred at the change from a plastic to a crystalline condition1 then the heat absorbed and again set free during such changes would account for the visible phenomenon of recalescence4 ,again1 if it should prove that recalescence occurred at the refining point1 the conjunction of these phenomena would indicate strongly1 first1 that refining does occur at the point where this change of structure is complete in the reverse order1 from crystalline to plastic2 and second1 the first being true1 recalescence would be explained as stated1 as indicating the inevitable absorption and emission of heat due to such a change4 ,langley fitted up an electric apparatus for heating steel1 in a box so placed that the light was practically uniform1 that is1 so that bright sunlight1 or a cloudy sky1 or passing clouds would not affect seriously the observation of heat-colors4 ,pieces of steel were heated far above recalescence1 up to bright lemon1 and then allowed to cool slowly2 in this way recalescence was shown clearly4 ,it was found to occur at the refining heat in every case1 shifting for different carbons just as the refining heat shifts4 ,immediately under the pieces being observed was a vessel of water into which the pieces could be dropped and quenched4 ,after observing the heating and cooling until the eye was well trained1 pieces were quenched at different heats and the results were noted4 ,it was found that in the ascending heats no great hardness was produced until the recalescence heat was reached or passed slightly2 and in the descending heat excessive hardening occurred at a little below the recalescent heat1 although no such hardening occurred at that color during ascending heats4 ,this apparent anomaly is due simply to lag4 ,if1 in ascending1 the piece be held for a few moments at the recalescent point1 no increase being allowed1 and then it be quenched1 it will harden thoroughly and be refined4 ,if1 in descending1 the cooling be arrested at a little below the recalescence for a few moments1 neither increase nor decrease being allowed1 and then the piece be quenched1 it will not harden any better than if it be quenched immediately upon reaching the same heat in ascending4 ,time must be allowed for the changes to take place1 and lag must be provided for4 ,these experiments show that refining and recalescence take place at the same temperature4 ,,as ,,to ,,hardness4 ,prof4 ,j4 ,w4 ,langley showed by sp4 gr4 determinations that steel quenched from #bab ,f4 in water at #fj ,f4 showed the hardening effect of such quenching1 the difference of temperature being only #aeb ,f4 ,prof4 ,s4 ,p4 ,langley1 of the ,smithsonian1 proved the same to be true by delicate electrical tests1 and these again were confirmed by ,prof4 ,j4 ,w4 ,langley in the laboratory of the ,case ,school of ,sciences4 ,a piece of refined steel will rarely be hard enough to scratch glass4 ,a piece of steel quenched from creamy heat will almost always scratch glass4 ,the maximum hardness is produced by the highest heat1 or when temperature minus cold is a maximum2 the least hardness is found by quenching at the lowest heat above the cooling medium1 or when temperature minus cold is a minimum--the time required to quench being a minimum in both cases4 ,what occurs between these limits8 ,is the curve of hardness a straight line1 or an irregular line8 ,let a piece of steel be heated as uniformly as possible from a creamy heat at one end to black at the other1 and then be quenched4 ,now take a newly broken hard file and draw its sharp corner gently and firmly over the piece1 beginning at the black-heated end4 ,the file will take hold1 and as it is drawn along it will be felt that the piece becomes slightly harder as the file advances1 until suddenly it will slip1 and no amount of pressure will make it take hold above that point4 ,the piece has become suddenly file hard4 ,next try the same thing with a diamond2 the diamond will cut easily until the point is reached where the file slipped1 then there will be found a great increase of hardness4 ,from this point to the end of the piece it is observed readily by the action of the diamond that there is a gradual increase of hardness from the hump to the end of the piece to the creamy-heated end4 ,attempts were made to measure this curve of hardness by putting a load on the diamond and dragging it over the piece2 but no diamond obtainable would bear a load heavy enough to produce a groove that could be measured accurately by micrometer4 ,an examination of such a groove1 through a strong magnifying-glass revealed the conditions plainly2 the groove of hardness may be illustrated on an exaggerated scale2 thus3 ,illustration ,the next question was1 ,where does this hump occur1 and what is the cause of it8 ,careful observation showed that it occurred at the point of recalescence1 at the refining-point4 ,this word point must not be taken as space without dimension in this connection2 it is used in the common sense of at or adjacent to a given place4 ,there is of course a small allowable range of temperature above any given exact point of recalescence1 such as #fee ,c4 or #abaa ,f4 ,by superimposing ,langley's curves of cooling and of hardening 7see ,trans4 ,am4 ,soc4 ,civ4 ,eng41 ,vol4 ,,xxvii1 p4 #djc71 the relation between recalescence and the hardening-hump is obvious4 ,illustration ,it is safe to say that experience proves that the refined condition is the best for all cutting-tools of every shape and form4 ,it seems to be obvious2 the steel is then in its strongest condition1 and when the grain is finest1 the crystals the smallest1 a fine edge should be the most enduring1 because there is a more intimate contact between the particles4 ,that a steel will refine well1 and be strong in that condition is the steel-maker's final test of quality4 ,no steel-maker who has a proper regard for the character of his product will accept raw material upon mere analysis2 analysis is of the utmost importance1 for material for steel-making must be of a quality that will produce a certain quality of steel1 or the result will be an inferior product4 ,this applies to acid ,bessemer and open-hearth1 and to crucible-steel especially2 the basic processes admit of a reduction of phosphorus not obtainable in the others4 ,in making fine-tool steel a bad charge in the pot inevitably means a bad piece of steel4 ,it may happen also that an iron of apparently good analysis will not produce a really fine steel2 then there must be a search for unusual elements1 such as copper1 arsenic1 antimony1 etc41 or for dirt1 left in the iron by careless working4 ,the refining-test then is as necessary as analysis1 for if steel will not refine thoroughly it will not make good tools4 ,battering-tools1 such as sledges1 hammers1 flatters1 etc41 should be refined carefully1 for although their work is mainly compressive they are liable to receive1 and do get1 blows on the corners and edges that would ruin them if they were not in the strongest condition possible4 ,the reasons for refining hot-working tools have been stated already4 ,engraved dies for use in drop-presses where they are subjected to heavy blows are undoubtedly in the most durable condition when they are refined1 but they are subjected not only to impact1 but to enormous compression1 and therefore they must be hardened deeply4 ,when a die-block is heated so as to refine1 and then is quenched1 it hardens perfectly on the surface and not very deeply1 and it is quite common in such a case to see a die crushed by a few blows3 the hardened part is driven bodily into the soft steel below it1 and the die is ruined2 thus3 ,illustration ,to avoid this1 such a die should be heated to ,no4 #e1 or a dark lemon1 and quenched suddenly in a large volume of rushing water4 ,it will then have the enormous resistance to compression that is so well known in very hard steel1 and it will be hardened so deeply that the blow of the hammer will not crush through the hard part4 ,this is the best condition1 too1 of an armor-plate that is to resist the impact of a projectile4 ,it will be brittle1 a light blow of a hammer will snip the corners1 but it cannot be crushed by ordinary work4 ,dies made in this way have turned out thousands of gross of stamped pieces1 showing no appreciable wear4 ,to harden a die in this way is a critical operation1 because the strains are so enormous that a very trifling unevenness in the heat will break the piece1 but the skill of expert temperers is so great that they will harden hundreds of dies in this way and not lose one if the steel be sound4 ,,heating ,,for ,,hardening4 ,a smith can heat an occasional piece for hardening1 in his ordinary fire by using care and taking a little time4 ,where there are many pieces to be hardened1 special furnaces should be used4 ,for thousands of little pieces1 such as saw-teeth or little springs1 a large furnace with a brick floor1 and so arranged that the flame will not impinge on the pieces1 is good4 ,the operator can watch the pieces1 and as soon as any come to the right color he can draw them out1 letting them drop into the quenching-tank1 which should be right under the door or close at hand4 ,for twist-drills1 reamers1 etc41 a lead bath1 or a bath of melted salt and soda1 is used4 ,the lead bath is the best if care be taken to draw off the fumes so as not to poison the heaters4 ,because a bath of this kind is of exactly the right color at the top it is not to be assumed that pieces can be heated in it and hardened without further attention4 ,thousands of tools are ruined1 and thousands of dollars are thrown away annually1 by unobserving men who assume that because a lead bath appears to be exactly the right color at the surface it is therefore just right4 ,a dark orange color surface may have underneath it an increasingly higher temperature1 up to a bright lemon at the bottom1 and tools heated in such a bath will have all of the varying temperatures of the bath2 then cracked tools1 twisted tools1 brittle tools1 tools too hard at one end and not hard enough at the other1 will come out with exasperating regularity4 ,all of this can be avoided by a simple thorough stirring of the bath1 to be done as often as may be necessary to keep it uniform4 ,in heating toothed tools1 taps1 reamers1 milling-cutters1 and the like1 care should be taken that the points of the teeth never get above the refining-heat1 the dark or medium orange required4 ,it is no easy matter to do this except in a uniform bath1 but it must be done4 ,if the teeth are bright lemon1 or even bright orange1 when the body of the tool is at medium orange refining-heat1 the probabilities are that they will shell off from the hardened tool as easily as the grains from a cob of corn4 ,even if they are not so bad1 if they do not crack off1 they will be coarse-grained and brittle2 they will not hold a good edge1 and they will not do good work4 ,if a long tool1 such as a drill1 etc41 be heated medium orange on one side and bright orange on the other1--a difference of #ajj to #bjj ,f41--and be quenched1 it will come out of the bath curved2 it must be curved4 ,in quenching a long tool which it is desired to have straight it should be dipped vertically1 so as to cool all around the axis simultaneously4 ,if such a tool be dipped sideways1 it will come out bent4 ,in heating edge-tools of all kinds it is best to heat first the thicker part1 away from the edge1 and then when the body has come up to the refining-heat to draw the edge into the fire and let it come up last2 as soon as a uniform color is reached quench promptly4 ,if the edge be exposed to the fire in the beginning of the operation1 it will almost certainly become too hot before the thicker parts are hot enough4 ,when a smooth1 cylindrical piece is to be hardened1 it should be rolled around from time to time while heating1 unless it is in a lead bath2 if it be left to lie quietly in a furnace until it is hot1 it will have a soft streak along the part that was uppermost4 ,the cause of this is not clear2 the fact is as certain as hundreds of tests can make any fact4 ,the experiment can be made by re-heating the piece with the soft streak down2 then the original soft streak will come out hard1 and another soft streak will be found on top4 ,the changes can be rung upon this indefinitely4 ,a maker of roller-tube expanders had great trouble with his expander-pins2 they cut1 and wore out on one side4 ,he tried many makes and many tempers of steel with the same result4 ,he was told to turn his pins over and over as he heated them and his troubles would end4 ,he replied3 8,why1 of course2 ,i can see the reason and sense in that40 ,if he did see the reason1 he is the only person known1 so far1 who has done so4 ,his pins worked all right from that time4 ,in hardening ,,round ,,sections it is necessary to use great care to have the heat perfectly uniform and not too high1 because the circular form is the most rigid1 offering the greatest resistance to change4 ,for this reason a round piece will be almost certain to split if it be heated above a medium orange1 or if it be heated unevenly4 ,many a round piece is cracked by a heat1 or by a little unevenness of heat1 that another section would endure safely4 ,a roll with journals is perhaps the most difficult of all tools to harden successfully2 the most expert temperers will not be surprised at losing as many as one roll in five4 ,engraved dies require to be hardened without oxidizing the engraved face1 so that the finest lines will be preserved clear and clean4 ,this is done by burying the engraved face in carbonaceous material in such a way as to prevent the flame or any hot air from coming in contact with it4 ,there are many ways of doing this1 and many different carbonaceous mixtures are used2 one simple1 and known to be satisfactory1 plan will be explained as sufficient to give any intending operator a good starting-point4 ,the carbonaceous material preferred is burnt leather powdered--and the older it is the better--until it is reduced to ash1 so that the material should be saved after each operation to be used again mixed with enough new material to make up the necessary quantity4 ,illustration ,d is the die to be heated2 ,b is an open box about two inches deep and one inch larger each way than the die2 ,l is the burnt leather packed in thoroughly1 and as full as the box will hold4 ,the engraved face is down1 embedded in the burnt leather1 and secure from contact with flame or air4 ,sometimes powdered charcoal is used1 with or without a mixture of tar1 according to the fancy of the operator4 ,some operators prefer to have the box so high as to leave only the top surface of the embedded die exposed1 but the most successful workers prefer the plan sketched1 because they can see more of the die1 and so regulate better the even heating4 ,the die and box are put in the furnace1 and the heating is watched1 the die being turned and moved about in the furnace so as to obtain a perfectly even heat4 ,when the right temperature is reached1 the whole is withdrawn from the furnace2 the die is lifted out of the box and plunged into the water immediately4 ,there must be no delay at this point whatever2 a few moments' exposure of the hot die to the air will result in oxidation and scaling of the engraving4 ,in heating such a die a furnace should be used4 ,it can be done in a smith's fire1 but it is a hazardous plan1 and gives many chances for a failure4 ,a furnace with an even bed of incandescent coke is good1 and such a furnace is very useful for many other purposes4 ,where many dies are to be hardened1 the handiest appliance is a little furnace with brick floor and lining1 and heated by petroleum or gas1 so arranged that the flames will not impinge upon the piece to be heated4 ,such furnaces are now made to work so perfectly that illuminating-gas is found to be an economical fuel4 ,for quenching there should be plenty of water4 ,for small dies that can be handled easily by one man a large tub or tank of water will answer if the operator will keep the die in rapid motion in the water4 ,running water is the best4 ,a handy plan is to have the inlet-pipe project vertically a short distance through the bottom of the tank1 producing a strong upward current which will strike directly against the face of the submerged die4 ,some prefer a downward stream2 others a side stream2 others1 again1 prefer a shower-bath2 and1 again1 some use side jets4 ,a very efficient tank has a partition running from a few inches from the bottom to within a few inches of the surface of the water1 and so placed as to separate1 say1 nine tenths of the tank from one tenth4 ,in the smaller compartment there is an ,archimedean screw driven at a speed of #bjj to #cjj revolutions2 this drives the water under the partition and out over the top in a violent current4 ,the steel is quenched in the larger space4 ,where water is an item of expense1 this plan is economical1 and it is certainly efficient4 ,an excellent way of quenching large faces1 such as anvils1 is to have a tank raised twelve to fifteen feet from the floor4 ,in the bottom of the tank is a pipe with a valve1 to be operated by a lever4 ,the whole is enclosed in a sort of closet with a door in one side4 ,when the piece is hot1 it is placed immediately under the pipe1 the door is closed1 the valve is opened1 and a great body of water is dashed down upon the face that is to be hardened4 ,a slight modification of this plan is used in hardening armor-plates1 where many jets are used to insure even quenching of the large surface4 ,this plan is supposed to be patented1 or1 more properly1 it is patented2 but as it is very old and well known the patent should not be allowed to disturb anybody4 ,water only has been mentioned so far as a quenching medium1 because it is the simplest and the cheapest generally4 ,oil is used frequently where extreme hardness is not necessary and toughness is desirable4 ,oil gives a good hardness with toughness1 and it is used almost universally for springs1 and it is sometimes used to toughen railroad axles and similar work4 ,the oil acts more slowly than water and leaves the piece in more nearly a tempered condition2 it is neither so hard nor so brittle as it would be if quenched in water4 ,straits fish-oil is good and cheap2 lard-oil gives greater hardness than fish-oil2 mineral oil is too fiery to use safely2 but there are mixed oils in the market made expressly for hardening which are cheap and efficient4 ,if it is desired to get the greatest hardness1 brine will harden harder than fresh water2 and mercury will give the greatest hardness of all4 ,it is a rather expensive cooling medium4 ,acid added to water increases its hardening power2 but those who know the effects of acids will be very chary of using them4 ,as to heating1 too much emphasis cannot be given to the importance of even temperature throughout the mass4 ,the illustration of the painted piece mentioned in connection with heating for forging applies more forcibly here4 ,every piece that is to be quenched should look as if it were covered with a perfectly even coat of paint of the exact tint necessary to give the best result4 ,all hardening should be done on a rising temperature1 because then the grain and strains cannot be greater than those due to the highest heat1 and this maximum heat can be watched and kept within limits4 ,if a piece be quenched from a falling temperature1 the grain and strains will be those due to the highest temperature1 modified slightly by the distance through which it has cooled1 and always coarser and more brittle than if quenched at the same heat produced by rising temperature4 ,if by accident a piece gets too hot to be quenched1 it should be allowed to go entirely cold1 and then be heated again to the right color4 ,after a piece of steel is hardened it is usually tempered to relieve some of the strain1 reduce brittleness1 and increase the toughness4 ,this is done by heating2 usually the piece is held over the fire1 or in contact with a large piece of steel or iron heated for the purpose1 until it takes on a certain color which indicates the degree of tempering that is wanted4 ,where great numbers of pieces are to be tempered1 a bath is very convenient4 ,boiling in water produces only a slight tempering sufficient for some purposes4 ,steaming under given pressure will produce even heating and uniform tempering4 ,when pieces are quenched in oil1 they can be tempered easily and nicely by watching the oil that adheres to them4 ,when the oil is dried off and begins to char1 the tempering is good1 about right for saw-teeth4 ,if the heat is run up until the oil flashes1 the tempering is pretty thorough and is about right for good springs4 ,if the oil be all burned off1 there will be little temper left except in very high steel4 ,high steel becomes much harder when quenched than low steel2 consequently very high hardened steel may be heated until it begins to show color and still retain considerable hardness or temper1 whereas a milder steel1 under #ij or #ajj carbon1 when heated to such a degree will retain no temper1 it will be soft4 ,saw-teeth1 tap1 reamer1 and milling-cutter teeth1 may be drawn1 and usually should be drawn1 down until a file will barely catch them2 then they will do excellent work4 ,many inexperienced temperers are apt to complain if such tools can be filed at all when drawn to the proper color1 forgetful or ignorant of the fact that a file should always contain about twice as much carbon as a tap or reamer1 and that if both are drawn to the same color the file must necessarily be the harder4 ,such men often destroy much good work by trying to get the tools too hard4 ,if a tap-tooth be left file hard1 it will be pretty certain to snip off when put to work4 ,,temper ,,colors4 ,when a clean piece of iron or steel1 hardened or unhardened1 is exposed to heat in the air1 it will assume different colors as the heat increases4 ,first will be noticed a light1 delicate straw color2 then in order a deep straw1 light brown2 darker brown2 brown shaded with purple1 known as pigeon-wing2 as the brown dies out a light bluish cast2 light brilliant blue2 dark blue2 black4 ,when black1 the temper is gone4 ,it is well established that these colors are due to thin films of oxide that are formed as the heat progresses4 ,these colors are very beautiful1 and as useful as they are beautiful1 furnishing an unvarying guide to the condition of hardened steel4 ,the drawing of hardened steel to any of these colors is tempering4 ,so we have the different tempers3 ,light straw ,for lathe-tools1 files1 etc4 ,straw 8 8 8 8 8 ,light brown 8 taps1 reamers1 drills1 etc4 ,darker brown 8 8 8 8 8 ,pigeon-wing 8 axes1 hatchets1 and some drills ,light blue 8 springs ,dark blue 8 some springs2 but seldom used ,this is the unfortunate second use of the word temper1 which must be borne in mind if confusion is to be avoided in consulting with steel-makers and steel-workers4 ,the meanings may be tabulated thus3 ---------------------------------------- --------------------------- ,temper4 ,steel-maker's ,meaning4 ,steel-worker's ,meaning4 ---------------------------------------- --------------------------- ,very high #aej carbon light straw ,high #ajj to #abj ,c straw ,medium #gj to #hj ,c brown to pigeon-wing ,mild #dj to #fj ,c light blue ,low #bj to #cj ,c dark blue ,soft or dead-soft under #bj ,c black ---------------------------------------- --------------------------- ,the uses given for temper colors are not meant to be absolute2 they merely give a good general idea2 experienced men are guided by results1 and temper in every case in the way that proves to be most satisfactory4 ,,difference ,,between ,,cracks ,,and ,,seams4 ,when temperers find that their tools are cracking under their treatment1 they are apt to assume that1 as they are working in their ordinary way1 there must be something wrong with the steel4 ,it is either seamy1 or harder than usual1 or not uniform in temper1 or it is of inferior quality4 ,all or any of these conditions may exist and be the cause of the trouble2 but every man should bear in mind that he is also a variable quantity2 he may be unwell and not see and observe as closely as usual2 there may be a long spell of unusual weather giving him a light differing from that to which he is accustomed2 or1 as is often the case1 he may simply have unconsciously departed from the even track by not having his mind carefully intent upon the routine which has become a sort of second nature to him1 so that for a time he ceases to think1 makes of himself an animated machine1 and the machine left to itself does not run with perfect regularity4 ,if personal pride1 egotism1 or ill temper be set aside1 it is always easy to find out whether the fault is in the steel or in the man2 that once determined the remedy is easily applied1 and the sooner the better for all parties4 ,how to ,break a ,tool4 ,let an ordinary axe be considered4 ,illustration ,illustration ,illustration ,if the axe be cracked as shown in ,fig4 #a1 the corners have been hotter than the middle of the blade2 probably by snipping the corners and the middle and comparing the fractures the coarser grain at the corners will tell the tale4 ,if the crack be as shown in ,no4 #b1 the middle of the blade has been hotter than the corners3 snipping and comparing the grains will tell the story4 ,if the crack be more nearly a straight line1 as shown in number #c1 the chances are that there is a seam there and the steel is at fault4 ,how to ,tell a ,seam from a ,water-crack4--,a seam is caused by a gas-bubble in the ingot which has not been closed up by hammering or rolling2 it always runs in the direction of the work2 in bars it is parallel to the axis4 ,the walls of a seam are always more or less smooth1 the surfaces having been rubbed together under heavy pressure during hammering or rolling1 and they are black usually1 being coated with oxide4 ,the walls of a water-crack are never smooth1 they are rough and gritty1 and they may have any of the temper colors caused by the action of water and heat4 ,there need never be any question as to which is which4 ,if a long tool cracks down the middle1 it may be from too much heat1 from seams1 or from a lap4 ,a lap is caused by careless working under a hammer1 or by bad draughts in the rolls1 folding part of the steel over on itself4 ,laps1 like seams1 run parallel to the axis of a bar1 and usually in very straight lines4 ,any long piece of steel may be split in hardening by too much heat4 ,in making the experiment of heating a piece continuously from scintillating1 or creamy color1 down to black1 to show the differences of grain due to the different heats1 the sample almost invariably splits down the middle as far as the strong1 refined grain1 or nearly that far4 ,as stated before1 a round bar will be almost certain to split if it be heated up to medium lemon1 although a square bar may endure the same heat without cracking4 ,an examination of the walls of a split will settle at once whether it is a seam1 a lap1 or a water-crack4 ,a seam will not necessarily be long2 its walls will be smooth4 ,a lap usually runs the whole length of the bar1 and the walls are smooth4 ,by smooth walls of seams and laps comparative smoothness is meant2 they are sometimes polished1 but not always1 and they are never granular like the walls of water-cracks4 ,if the split be a water-crack1 the walls will be rough and granular4 ,after a temperer has straightened himself out1 and brought his work to usual accuracy and uniformity1 if his tools continue to crack and indicate weakness in the steel1 it is time for him to suspect the character of his material and to require the steel-maker to either show up the faults in tempering1 or improve the quality of his product4 ,a ,,word ,,for ,,the ,,workman4 ,give him a chance4 ,a steel-worker to be expert must have a well-trained eye and know how to use it4 ,he must work with delicate tints1 ranging in the yellows from creamy yellow to dark orange or orange red as extremes1 and most of his work must be done between bright lemon and medium orange in forging1 and between rather dark to medium orange1 or possibly nearly light orange1 when hardening and tempering4 ,probably in no other business is there such ridiculous waste as is often found in steel-working where the manufacturer economizes in his blacksmiths4 ,a large1 wealthy railroad condemns a brand of steel4 ,the steel-maker goes to the shop and is informed by a bright1 intelligent blacksmith that the steel will not make a track-chisel4 ,it is a hot summer day2 the smith is working over a huge fire with a large piece of work in the middle of the fire and a number of small pieces of steel stuck in the edge of the fire4 ,he is welding large iron frog-points1 and in the interval he is filling a hurried order for four dozen track-chisels for which the trackmen are waiting4 ,he is not merely forging the chisels1 he is hardening and tempering them4 ,the glare of the welding-work makes him color-blind1 the hurry gives him no time for manipulation1 and the trackmen have no chisels4 ,after a thorough expression of sympathy for the smith the steel-maker turns upon the foreman and master mechanic1 and gives them such a tongue-lashing that they turn away silenced and ashamed4 ,page after page of such cases could be written1 but one should be enough4 ,a steel-maker has a thoroughly skilled and expert steel-worker2 he rushes into the shop and says1 8,mike1 refine this right away1 please2 ,i want to know what it is40 ,mike replies1 8,i will do that to-morrow2 ,i am welding to-day40 ,that is entirely satisfactory2 those men understand one another1 and they know a little something about their business4 ,a temperer should do no other work when he is heating for hardening1 and he should always be allowed to use as much time about it as he pleases1 assuming that he is a decently honest man who prefers good work to bad2 and as a rule such honest men are in the majority1 if they are given a fair chance4 ,,ix4 ,,on ,,the ,,surface4 ,the condition of the surface of steel has much to do with its successful hardening and working4 ,a slight film adherent to the surface of steel will prevent its hardening properly2 the steel may harden under such a film and not be hard upon the immediate surface1 and1 as in almost every case a hard1 strong surface is necessary to good work1 it is important that a piece of steel to harden well should have a clean surface of sound steel4 ,it has been stated already that all bars and forgings of steel have upon the surface a coat of oxide of iron1 and immediately beneath this a thin film of decarbonized iron4 ,neither of these substances will harden1 and in every case where a hard-bearing surface or a keen cutting-edge is desired these coatings must be removed4 ,polished drill-wire and cold-rolled spring-steel for watches1 clocks1 etc41 should have perfect surfaces1 and it is the duty of steel-makers to turn them out in that condition4 ,all black steel1 or hot-finished steel1 contains these coatings4 ,in the manufacture of railroad1 wagon1 and carriage springs it is not necessary or customary to pay any attention to these coatings2 the body of the steel hardens well1 giving the required resilience and elasticity1 so that an unhardened coat of 4#ja to 4#jja inch thick does no harm4 ,to all bearing-surfaces and cutting-edges such coatings are fatal4 ,the ordinary way of preparing steel is to cut the skin off1 and this is sufficient if enough be taken off2 it happens often that a purchaser1 in pursuit of economy and unaware of the importance of this skin1 orders his bars or forgings so close to size that when they are finished the decarbonized skin is not all removed1 and the result is an expensive tap1 reamer1 milling-cutter1 or some tool of that sort with the points of the teeth soft and worthless4 ,in small tools _/ inch1 in medium-size tools1 say up to two or three inches in diameter1 inch cut off should be plenty2 in large tools and dies1 especially in shaped forgings1 it would be wiser to cut away _/ inch4 ,in many cases sufficient hardness can be obtained by pickling off the surface-scale1 but this will not do where thorough hardening is required1 because the acid does not remove the thin decarbonized surface4 ,it seems to be impracticable to remove the decarbonized skin by the action of acid1 for if the steel be left in the acid long enough to accomplish this the acid will penetrate deeper1 oxidizing and ruining the steel as it advances4 ,grinding is frequently resorted to1 being quicker and cheaper than turning1 planing1 or milling4 ,when grinding is used1 care must be taken not to glaze the surface of the steel1 or if it should be glazed the glaze must be removed by filing or scraping4 ,in the manufacture of files it is customary to grind the blanks after they are forged and before the teeth are cut4 ,after the blanks are ground they are held up to the light and examined carefully for glaze4 ,every blank that shows by the flash of light that it is glazed is put to one side2 then these glazed blanks are taken by other operatives and filed until all traces of glaze are removed4 ,the file-maker will explain that if this be not done the files when hardened will be soft at the tips of the teeth over the whole of the glazed surface4 ,this inspection and filing of blanks involves considerable expense1 and it is certain that such an expense would not be incurred if it were not necessary4 ,this glaze does not appear to be due to burning1 at least the stones are run in water2 the blanks are handled by the bare hands of the grinders1 and do not appear to be hot4 ,after pieces are hardened and tempered they frequently require grinding to bring them to exact dimensions4 ,this is usually done on emery-wheels with an abundance of water1 and as no temper colors are developed indicating heat it is assumed that no harm can be done4 ,just here much valuable work is destroyed4 ,the tempered piece is put on the wheel1 in a 8flood of water02 the work is rushed1 and the piece comes out literally covered with little surface-cracks running in every direction1 perfectly visible to the naked eye4 ,until the steel-worker learns better he blames and condemns the steel4 ,this result is very common in the manufacture of shear-knives1 scissors1 shear-blades1 dies1 etc4 ,sometimes too a round bearing or expander-pin is hardened2 examined by means of a file it appears perfectly hard2 it is then ground1 not quite heavily enough to produce surface-cracks1 but still heavily1 and on a glazed wheel4 ,it is found now that the surface is soft2 only a thousandth of an inch or so has been cut off1 and the steel is condemned at once because it will harden only skin deep4 ,let the file be drawn heavily over the surface and it will be found that the soft surface is only about a thousandth of an inch thick1 and underneath the steel is perfectly hard4 ,now grind slightly on a sharp1 clean wheel and re-harden2 the surface will be found to be perfectly hard4 ,ground heavily again on the glazed wheel1 it will become soft1 as before4 ,these operations can be repeated with unvarying results until the whole piece is ground away4 ,these difficulties occur more with emery-wheels than with grindstones1 either because emery-wheels glaze more easily than grindstones1 or because1 owing to their superior cutting powers under any circumstances1 they are more neglected than grindstones4 ,experience shows that these bad results occur almost invariably on glazed wheels4 ,it is rare to find any bad work come off from a clean1 sharp wheel1 unless the pressure has been so excessive as to show that the operator is either foolish or stupid4 ,the remedy is simple3 ,keep the wheels clean and sharp4 ,many grinders who understand this matter will not run any wheel more than one day without dressing1 nor even a whole day if the work is continuous and they have reason to apprehend danger4 ,a ,,few ,,words ,,in ,,regard ,,to ,,pickling4 ,pickling is the placing of steel in a bath of dilute acid to remove the scale4 ,it is a necessary operation in wire-making and for many other purposes1 and it may be hastened by having the acid hot4 ,sulphuric acid is used generally2 it is efficient and cheap4 ,when thin sheets are to be pickled1 the acid should not be too hot1 or it will raise a rash all over the sheet in many cases4 ,this indicates some unsoundness in the steel1 the presence probably of innumerable little bubbles of occluded gases4 ,this is possibly true1 yet the same sheets pickled properly and brought out smooth will polish perfectly1 or if cut up will make thousands of little tools that will show no evidence of unsoundness4 ,steel should never be left in the pickling-bath any longer than is necessary to remove the scale2 it seems unnecessary to warn readers that the acid will continue to act on the steel1 eat the steel after the scale is removed4 ,when taken from the pickle1 the steel should be washed in limewater and plenty of clean running water2 but this does not take out all of the acid4 ,it should then be baked for several hours at a heat of #djj to #dej ,f4 to decompose the remaining acid4 ,this is just below a bluing heat1 and it does not discolor or oxidize the surface4 ,it is known as the sizzling-heat1 the heat that the expert laundry-woman gets on her flat-iron which she tests with her moistened finger4 ,acid if not taken off completely will continue to act upon and rot the steel2 how far this will go on is not known exactly2 for instance1 it is not known whether if a block six inches cube were pickled and merely washed1 the remaining acid would penetrate and rot the whole mass or not4 ,there must be some relation between the mass of the steel and the power of a small amount of acid to penetrate4 ,the power of acid can be illustrated on the other extreme3 ,a lot of watch-spring steel is finished in long coils and 4#jaj inch thick2 when last pickled1 the baking was neglected2 the steel is tough1 it hardens well1 and when tempered it is springy and strong2 by all of the tests it is just right in every coil4 ,it is shipped away and in three or four weeks the spring-maker begins work on it4 ,he reports at once that it is rotten and worthless1 it will not make a spring at all1 and he is angry4 ,the steel is returned to the maker and he finds the report true3 the steel is rotten and worthless4 ,then by diligent inquiry he finds that the last baking was omitted1 and he pockets his loss1 sending an humble apology to the irate spring-maker4 ,whether the residual acid can ruin a large piece of steel or not need not be considered when the simple operation of baking will remove the possibility of harm4 ,x4 ,,impurities ,,in ,,steel4 ,any elements in steel which reduce its strength or durability in any way may be classed as impurities4 ,a theoretical ideal of pure steel is a compound of iron and carbon2 it is an ideal that is never reached in practice1 but it is one that is aimed at by many manufacturers and consumers1 because experience shows that1 especially in high steels1 the more nearly it is attained the more reliable and safe is the product4 ,all steel contains silicon1 phosphorus1 sulphur1 oxygen1 hydrogen1 and nitrogen1 none of which add any useful property to the material4 ,it is admitted that1 starting with very small quantities of silicon or phosphorus in mild steel1 small additions of either element will increase the tensile strength of the steel perceptibly up to a given amount1 and that then the addition of more of either one will cause a reduction of strength4 ,the same increase of strength can be obtained by the addition of a little carbon1 producing a much more reliable material4 ,it is not known that even such slight apparent gain in strength can be made by using oxygen1 nitrogen1 or hydrogen4 ,manganese is present in all steel as a necessary ingredient1 it gives an increase in strength in the same way as phosphorus1 and when increased beyond a small limit it causes brittleness4 ,hadfield's manganese steel is a unique material1 not to be considered in connection with the ordinary steel of commerce4 ,webster's experiments are perhaps the most complete of any that show the effects of small increases of silicon1 phosphorus1 sulphur1 and manganese1 but as these are not completed they are not quoted here1 because ,mr4 ,webster may reach additional and different results before these pages are printed4 ,the chief bad qualities of steel that are caused by these impurities are known as 8red-shortness10 8cold-shortness10 and 8hot-shortness40 ,a steel is called red-short when it is brittle and friable at what is known commonly as a low red heat--8cherry red10 8orange red40 ,red-shortness is caused chiefly by sulphur or by oxygen2 many other elements may produce the same effects2 it seems probable that nitrogen may be one of these1 but the real action of nitrogen is as yet obscure4 ,a red-short steel is difficult to work2 it must be worked at a high heat--from bright orange up to near the heat of granulation--or it will crack4 ,when hardened1 it is almost certain to crack4 ,when red-short steel is worked with care into a sound condition1 it may when cold be reasonably strong1 but hardly any engineer of experience would be willing to trust it4 ,hot-short steel is that which cannot be worked at a high heat1 say above a medium to light orange1 but which is generally malleable and works soundly at medium orange down to dark orange1 or almost black4 ,this is a characteristic of most of the so-called alloy steels1 or steels containing considerable quantities of tungsten1 manganese1 or silicon4 ,it is claimed that chrome steel may be worked at high heats and that it is less easily injured in the fire than carbon steel4 ,this is not within the author's experience4 ,it is this property of hot-shortness that makes the alloy steels so expensive2 the ingots cannot be heated hot enough nor worked heavily enough to close up porosities1 and therefore1 there is a heavy loss from seams4 ,the range of heat at which they can be worked is so small that many re-heatings are required1 increasing greatly the cost of working4 ,as compared to good carbon steel they are liable to crack in hardening1 and when hardened they are friable1 although they may be excessively hard4 ,cold-short steel is steel which is weak and brittle when cold1 either hardened or unhardened4 ,of those which are always found in steel1 phosphorus is the one well-known element which produces cold-shortness4 ,it is clear that no one can have any use for cold-short steel4 ,red-short or hot-short steel may be of some use when worked successfully into a cold condition1 but cold-short steel is to be avoided in all cases where the steel is used ultimately cold4 ,if the theoretically perfect steel is a compound of iron and carbon1 it cannot be obtained in practice1 and the only safeguard is to fix a maximum above which other elements are not to be tolerated4 ,in tool-steel of ordinary standard excellence such maximum should be 4#jb of one per cent2 it may be worked to easily and economically1 except perhaps in silicon1 which element is generally given off to some extent by the crucible2 it should be kept as low as possible1 however1 say well under #aj1 one tenth of one per cent4 ,some people claim that a little higher silicon makes steel sounder and better2 but any expert temperer will soon observe the difference between steels of 4#aj and 4#ja silicon4 ,for the highest and best grade of tool-steel the maximum should be the least attainable4 ,every one hundredth of one per cent of phosphorus1 silicon1 or sulphur will show itself in fine tool-steel when it is hardened4 ,it is assumed1 of course1 that such impurities as copper1 antimony1 arsenic1 etc41 exist only as mere traces1 or not at all4 ,as oxygen must be at a minimum1 no one has yet succeeded in making a really fine tool-steel from the products of the ,bessemer or of the open-hearth process4 ,the removal of the last fractions of these impurities is difficult and expensive2 for instance1 a steel melting iron of ,silicon 4#jc to 4#jf ,phosphorus 4#jc 8 4#jb ,sulphur 4#jjb or less may be bought for #b cents a pound or less1 whereas an iron of ,silicon 4#jb ,phosphorus 4#ja ,sulphur trace can hardly be bought for less than #e cents a pound4 ,this difference of three cents a pound is justifiable when the highest grade of tool-steel is to be made2 and it would be silly to require any such material in any spring1 machinery1 or structural steel4 ,in addition to these impurities there are other difficulties to be guarded against1 chief among which is an uneven distribution of elements4 ,in all steel there is some segregation2 that is to say1 as the liquid metal freezes1 the elements are to some extent squeezed out and collected in that part of the ingot which congeals last4 ,it is claimed that in the ,bessemer and ,open-hearth processes any ferro-silicon added to quiet a heat1 or any ferro-manganese added to remove oxygen1 are at once absorbed and distributed through the mass1 and so when any serious irregularity is discovered it is charged to segregation4 ,a heat may produce billets of #ge carbon and #abj carbon1 and again it is called segregation4 ,as a rule1 inertia has more to do with such differences than segregation4 ,one crucible of steel may produce an ingot containing #ij carbon and #acj carbon4 ,segregation has nothing to do with this3 a careless mixer has put a heavy lump of #adj- or #aej-;carbon steel in the bottom of the pot and covered it up with iron4 ,the steel melted first and settled in the bottom of the pot1 the iron melted later and settled on top of the steel1 and they did not mix4 ,the teeming was not sufficient to cause a thorough mixing4 ,segregation covers a multitude of sins4 ,exactly how much is sin and how much is segregation will not be known until analyses are made of the top1 middle1 and bottom of the bath1 and of the contents of the ladle1 these to be compared to analyses of the top1 bottom1 and middle of the ingots4 ,there is certainly an unavoidable amount of segregation1 and as equally certain an amount of curable irregularity due to inertia4 ,,wild ,,heats4 ,after steel is melted1 whether in a crucible1 an open hearth1 or a ,bessemer vessel1 it boils with more or less violence4 ,this boiling is caused by ebullition of gases1 and if steel be poured into moulds while it is boiling the resulting ingot will be found to be honeycombed to an extent that is governed by the degree of the boiling4 ,if a heat boils violently and persistently1 it is said to be 8wild10 and if a wild heat be teemed the ingots will be honeycombed completely2 such ingots cannot be worked into thoroughly sound steel1 and no melter who has any regard for his work will teem a wild heat if he knows it4 ,to stop the boiling is called 8dead-melting10 8killing0 the steel1 so that it shall be quiet in the furnace and in the moulds4 ,a crucible-steel maker who knows his business can1 and he will1 always dead-melt his steel4 ,it only requires a few minutes of application of a heat a little above melting temperature1 and this can be applied by a skilled melter without burning his crucible or cutting down his furnace2 this is indeed about all of the art there is in crucible-melting1 the remaining operations being easy and simple4 ,dead-melting in the ,bessemer vessel is not possible by increase of time2 wild heats are managed differently1 probably by adding manganese or silicon1 or both1 but exactly how is not within the author's experience4 ,dead-melting in the open hearth would appear at first sight to be always possible1 but there are more difficulties in the way than in the case of crucible-melting4 ,the heat may be wild when the right carbon is reached1 and then the melter must use a little ferro-silicon1 or silico-spiegel1 or highly silicious pig1 or aluminum1 and he must use good judgment so as not to have his steel overdosed with any of these4 ,from half an ounce to an ounce of aluminum to a ton of steel is usually sufficient1 and although any considerable content of aluminum is injurious to steel there is little danger of its being added1 because of its cost1 and because a little too much aluminum will cause the ingots to pipe from top to bottom4 ,silicon seems to be the most kindly element to use1 and it is claimed that a content of silicon as high as #bj is not injurious2 some people claim that it is beneficial4 ,that it does help materially in the production of sound steel there can be no doubt1 and if such steel meets all of the requirements of the engineer and of practice it would seem to be wise not to place the upper limit for silicon so low as to prevent its sufficient use in securing soundness4 ,but the author cannot concede that as much as #bj silicon is necessary4 ,in crucible practice high silicon is not necessary2 in 8melting-iron10 or iron to be melted1 it means so much dirt1 indicating careless workmanship2 but there will always be a little silicon present which the steel has absorbed from the walls of the crucible during the operation of melting4 ,in high tool-steel silicon should be at the lowest minimum that is attainable4 ,this discussion of wild heats may appear to be outside of the scope of this work1 and to belong exclusively to the art of manufacturing steel1 of which this book does not pretend to treat4 ,this is true so far that it is not recommended that the engineer shall meddle in any way with the manufacturer in the management of his work2 on the other hand1 it is vital to the engineer that he should know about it1 because wild steel may hammer or roll perfectly well1 it may appear to be sound1 but the author cannot believe that it is ever sound and reliable4 ,again1 it has a scientific interest2 that wildness is due to too much gas1 and probably to carbon-gas1 may be shown by an illustration4 ,it has its parallel in the rising of the iron in a puddling-furnace at the close of the boil1 a phenomenon with which every one is familiar who has watched a heat being boiled or puddled4 ,that all of the iron does not run out of the puddling-furnace at this stage is owing to the fact that there is not heat enough in the puddling-furnace to keep the iron liquid after it has been decarbonized4 ,during the running of a basic open-hearth furnace an apparently dead heat was tapped2 before the steel reached the ladle there was a sort of explosion2 the steel was blown all over the shop1 the men had to run for their lives1 and not one tenth of the steel reached the ladle4 ,the manager was rated roundly for carelessness in not having dried his spout1 and the incident closed4 ,a few days later another quiet heat was tapped and it ran into the ladle2 about the time the ladle was full the steel rose rapidly1 like a beaten egg or whipped cream1 and ran out on to the floor1 cutting the sides of the ladle1 the ladle-chains1 and the crane-beams as it flowed4 ,the men ran1 and there was no injury to the person4 ,again the manager was blamed1 this time for having a damp ladle1 and he was notified of an impending dismissal if such a thing occurred again4 ,he protested that he knew the ladle and the stopper were red-hot1 that he had examined them personally and carefully1 and knew he stated the truth4 ,there were several reasons for looking into the matter farther3 first1 the man in charge was known to be truthful and careful1 so that there was no reason for doubting his word2 second1 if the vessel and rod were red-hot1 there could be no aqueous moisture there2 and1 finally1 such an ebullition from dampness was contrary to experience1 as a small quantity of water under a mass of molten iron1 or slag1 results almost invariably in a violent explosion1 like that of gunpowder or dynamite4 ,upon inquiry it was found that prior to both ebullitions there had been a large hole in the furnace-bottom1 requiring about a peck of material to fill it in each case4 ,magnesite was used2 the magnesite was bought raw1 and burned in the place4 ,it is well known that it takes a long time and high heat to drive carbonic acid out of magnesite1 and it was surmised that insufficient roasting might have caused the trouble4 ,samples of burned and of raw magnesite were sent to the laboratory1 and the burned was found to contain about as much carbonic acid as the raw magnesite4 ,then the case seemed clear3 ,this heavily charged magnesite was packed into the hole2 the heat was charged and melted4 ,the magnesite held the carbonic acid until near the close of the operation2 then the intense heat of the steel forced the release of the gas1 which was at once absorbed by the steel4 ,owing to the superincumbent weight of the steel the gas was absorbed quietly1 and when the weight was removed the gas escaped1 exactly as it does at the close of puddling or in the frothing of yeast4 ,whether the carbonic acid remained such1 or whether it took up an equivalent of carbon and became carbonic oxide1 and then again took up oxygen from the bath1 and so kept on increasing in volume1 is not known4 ,the facts seem clear1 and the collateral proof is that thorough burning of the magnesite1 and of any dolomite that was used1 prevented a recurrence of any such accidents4 ,such ebullitions have occurred and caused the burning to death of pitmen1 and the statement of the above case may be of use to melters in the future who have not met such an experience4 ,,oxygen ,,and ,,nitrogen4 ,oxygen and nitrogen are present in all steel and both are injurious1 probably the most so of all impurities4 ,the oxides of iron are too well known to need discussion or description2 they are the iron ores mixed with gangue4 ,they are brittle1 friable1 hard1 and weak1 like sandstones4 ,mixed in steel they can be nothing but weakeners1 elements of disintegration4 ,let any one take a handful of scale--or rust--oxide of iron1 in his fingers and crumble it1 and it will be difficult for him to imagine how such material could be anything but harmful when incorporated in steel4 ,langley has shown1 and other scientists have confirmed him1 that oxygen may exist in iron in solution1 and not as oxide2 the discovery was attended with the assertion that such dissolved oxygen produced excessive red-shortness4 ,the proof that red-shortness was caused in this way was completed by the removal of the oxygen from some extremely red-short steel2 the red-shortness disappeared with the oxygen and the steel worked perfectly4 ,when steel is melted very low in carbon1 by any process1 it is certain to be red-short and rotten unless the greatest care be used to prevent the introduction of oxygen4 ,crucible-steel of #ae carbon or less will as a rule be red-short and cold-short2 it will not weld1 and is generally thoroughly worthless4 ,the same material melted to contain #ah to #be carbon will be tough and waxlike1 hot or cold4 ,it will weld easily into tubes1 and may be stamped cold into almost any desired shape4 ,bessemer or open-hearth steel of less than #h carbon is almost certain to be equally worthless1 whereas the same material blown or melted not below #aj or #ab carbon1 and re-carbonized not above #bj1 will be tough and good at any heat under granulation1 and equally good and tough when cold4 ,as to ,bessemer steel1 the author cannot say whether it would be possible to stop the blow between #aj and #ae carbon or not1 but it seems certain that if there be no overblowing red-shortness and cold-shortness may be avoided by carbonizing back to about #ae by the use of manganese or silicon1 or both together4 ,in the open hearth it is always possible to stop the melt at #aj carbon1 and to deoxidize the heat so as to avoid shortness1 and not to go above #bj carbon4 ,such steel will be sound and tough2 it will weld and stamp perfectly1 and will be satisfactory for all reasonable requirements4 ,the reason of this seems to be simple and plain3 ,in melting or blowing out the last fractions of carbon below #aj to #ae the same quantity of air per second or minute must be used as when burning out the higher quantities1 and now there is so little carbon to be attacked that the oxygen necessarily attacks the iron in greater and greater force as the carbon decreases4 ,this leaves an excess of oxygen in the steel which cannot be removed by the ordinary quantities of silicon1 or manganese1 or aluminum4 ,if more manganese or silicon be used1 the red-shortness and weakness can be cured largely2 but then the carbon is raised considerably1 and thus the steel is brought up to where it would have been without this excessive decarbonizing1 with the difference that it is not quite so strong4 ,what good is there1 then1 in extremely low melting8 ,it must be admitted that there are tough1 good-working steels in the market of carbon #e1 manganese #bj4 ,they are made in small furnaces1 worked with great care2 the product is expensive1 and1 unless it is wanted to be welded in place of common wrought iron1 it is in no case as good as well-made steel of #ab to #bj carbon2 even for welding the latter is superior if the worker will only be satisfied to work at a lemon instead of a scintillating heat4 ,these special cases do not militate against the general fact that extremely low steel is usually red-short and weak4 ,the above is written for the consideration of those engineers who think they are going safe when they prescribe low tensile strength and excessive ductility4 ,if these requirements meant the reception of pure1 or nearly pure1 iron1 indicated by the low tenacity and high stretch1 then they would be wise2 but if they result1 as they almost certainly do1 in initially good material rotted by overdoses of oxygen the wisdom may not be so apparent4 ,,nitrogen4 ,the real influence of nitrogen is not known to the author4 ,percy shows that nitrogenized iron is hard1 exceedingly friable1 and causes a brilliant1 brassy lustre4 ,he also says nitrogen is driven out at a yellow heat2 doubtless this is true of the excess of nitrogen1 but it has been shown in ,chapter ,,ii that melting in a crucible will not drive the nitrogen out of ,bessemer steel4 ,when crucible-steel not made from ,bessemer scrap and ,bessemer steel of equal analysis are compared in the tempered condition1 there is almost invariably a yellowish tinge over the fresh ,bessemer fracture which distinguishes it from the crucible-steel4 ,the ,bessemer steel is also the weaker4 ,these differences are believed to be due to nitrogen4 ,langley maintains his belief that oxygen is still the chief mischief-maker2 the author believes nitrogen to be the more potent of the two2 there is no known way to remove the nitrogen1 and there the question stands4 ,,elements ,,of ,,disintegration4 ,it has been stated time and again that these impurities are elements of disintegration1 and that it would be wise in every case to restrict the quantities allowable within reasonable limits1 giving the steel-maker sufficient leeway to enable him to work efficiently and economically1 and at the same time to keep the quantities of these impurities as low as possible4 ,on the other hand1 able1 successful1 and conservative engineers have claimed that if the steel-maker meets their physical requirements as shown by prescribed tests they1 the engineers1 should be satisfied2 that they should not interfere with chemical composition1 as they had no fear of subsequent disintegrations4 ,this argument was answered by the statement that skilled steel-workers could manipulate poor steel so as to bring it up to the requirements2 that the well-trained workers in the bridge-shops would not abuse the steel2 that the inherent deficiencies would not be developed2 the work would go out apparently satisfactory2 and that it might remain so for a long time1 in the absence of unusual shocks or strains1 but that in an emergency such material might fail because of deterioration where a purer material would have held on4 ,in the absence of proofs such statements have been met with a smile of incredulity4 ,fortunately some proofs are now at hand1 and as the method of getting them has been obtained1 more will follow from time to time4 ,in ,engineering1 ,jan4 #ag1 #ahif1 ,mr4 ,thomas ,andrews1 ,f4,r4,s41 ,m4,inst4,c4,e41 gives the following cases3 ,a fracture of a rail into many pieces1 causing a serious accident4 ,a broken propeller-shaft which nearly caused a disastrous accident4 ,analysis of the rail3 ,carbon #j4ddj ,silicon #j4jdj ,manganese #j4hjj ,sulphur #j4ajj ,phosphorus #j4jfd ,it is clear that the sulphur is excessive1 and that it was neutralized so as to make the steel workable by an excess of manganese4 ,of the propeller-shaft ,mr4 ,andrews says chemical analysis of outside and central portions of the shaft showed serious segregation4 8,the percentage of combined carbon was nearly #ej per cent greater in the inside of the shaft than on the outside2 the manganese was also in excess in the inside of the shaft2 the phosphorus and sulphur had also segregated in the interior of the shaft to nearly three times the percentage of these elements found near the outside of the shaft40 ,unfortunately ,mr4 ,andrews does not give the analysis of the shaft4 ,a number of micro-sections of the rail and of the shaft were made and examined4 8,numerous micro-sulphur flaws were found1 varying in size from #j4jae inch downward1 interspersed or segregated in the intercrystalline junctions of the ultimate crystals of the steel1 and being located in such a manner as to prevent metallic cohesion between the facets of the crystals1 thus inducing lines of internal weakness liable to be acted upon by the stress and strain of actual wear40 ,the dimensions of these flaws in the rail varied from 4#jaej 4#jjab to 4#jjaj 4#jjjd parts of an inch4 ,in the shaft from 4#jafj 4#jjcj to 4#jjbj 4#jjaf parts of an inch4 ,in the rail he found as many as #ad flaws in an area of only #j4jjjah square inch1 equal to nearly #fj1jjj flaws per square inch4 ,in the shaft he found as many as #cd flaws in an area of only #j4jjjah square inch1 equal to nearly #aij1jjj per square inch4 ,in speaking of the shaft he says3 8,in addition to blow-holes1 air-cavities1 etc41 the interior of the shaft was literally honeycombed with micro-sulphide of iron flaws1 which were meshed about and around the primary crystals of the metal in every direction40 8,the deleterious effects of an excess of manganese in interfering with the normal crystallization of the normal carbide of iron areas were also perceptible40 ,as the number of micro-sulphur flaws in the shaft were about three times as many as in the rail1 we may assume that the shaft contained at least as large a percentage of sulphur as the rail1 and1 owing to the general honeycombed structure1 it would not be a far guess to assume that the steel was teemed wild4 8,the deleterious effect of these treacherous sulphur areas and other microscopic flaws1 with their prolonged ramifications spreading along the intercrystalline spaces of the ultimate crystals of the metal and destroying metallic cohesion1 will be easily understood40 8,constant vibration gradually loosens the metallic adherence of the crystals1 especially in areas where these micro-flaws exist4 ,cankering by internal corrosion and disintegration is induced whenever the terminations of any of the sulphide areas or other flaws in any way become exposed at the surface of the metal1 either to the action of sea-water1 or atmospheric or other oxidizing influences4 ,in many other ways1 also1 it will be seen how deleterious is their presence40 8,internal micro-flaws of various character are nevertheless almost invariably present in masses of steel1 and constitute sources of initial weakness which not unfrequently produce those mysterious and sudden fractures of steel axles1 rails1 tires1 and shafts productive of such calamitous results4 ,a fracture once commencing at one of these micro-flaws 7started probably by some sudden shock or vibration1 or owing to the deterioration caused by fatigue in the metal7 runs straight through a steel forging on the line of least resistance1 in a similar manner to the fracture of glass or ice40 ,it is understood that similar investigations are being carried out on an extensive scale by ,prof4 ,arnold2 in the meantime the above cases should satisfy any one that these impurities are elements of disintegration1 and that the less there are of them in any steel the better for the steel4 ,it seems clear that if #aj sulphur will cause #fj1jjj flaws per square inch1 #ja sulphur ought not to cause more than one tenth of that number2 or1 if an equal number1 then they could only be one tenth of the size4 ,the segregation found in the shaft is so excessive that it would seem probable that there was a good deal of sin there also2 but1 even if it were unavoidable segregation1 the harm would have been just so much the less if there had been less of total impurities present to segregate4 ,,arsenic4 ,arsenic is known to be very harmful in tool-steel1 and it is proper to assume that it can do no good in structural steel4 ,in any case where the properties of steel do not come up to the standard to be expected from the regular analysis examination should be made for arsenic1 antimony1 copper1 etc4 ,these are not as universal constituents of steel as silicon1 phosphorus1 sulphur1 and manganese1 but they are present frequently1 and in any appreciable amount they are bad4 ,,xi4 ,,theories ,,of ,,hardening4 ,the hardening of steel is such a marked phenomenon1 and one of so great importance1 that it has always attracted a great deal of attention1 and many theories have been put forward in explanation4 ,before chemistry was brought to bear upon the subject the proposed theories were based upon assumption1 and as there were no proofs one had as much right to consideration as another1 and none seemed to be altogether satisfactory4 ,since science has taken up the question the theories are about as numerous as the investigators1 and while no one can claim as yet to have settled the matter definitely1 each one has an apparent basis of reason deduced from observed facts4 ,among early observations it was noted that when unhardened steel and hardened steel were dissolved in acid a much larger amount of carbon was found in the solution of the unhardened than in that of the hardened steel4 ,this led1 first1 to the distinction of combined carbon and graphitic carbon1 a distinction that has been maintained through subsequent investigations4 ,it seems to be well established now that there is a definite carbide of iron1 ,fe,c1 and some observers believe it to be the hard substance in hardened steel4 ,following this came the announcement that these conditions1 combined and graphitic carbon1 represented two different forms of carbon1 and they were designated as cement carbon and hardening carbon2 also as non-hardening and hardening carbon4 ,later investigation having established the existence of the carbide ,fe,c1 this was claimed to be the hard body1 but this has not met universal acceptance4 ,another investigator1 studying by means of the pyrometer and observing heat phenomena1 concludes that hardening is due to an allotropic condition of the iron itself2 that when iron is heated above the recalescent-point1 and presumably below granulation1 it becomes in itself excessively hard2 that sudden cooling prevents its changing from this form1 and so1 when there is carbon present1 the result of quenching is great hardness4 ,when steel is allowed to cool slowly to below recalescence1 the iron assumes another form1 and one which cannot be hardened by quenching2 this latter is known as iron1 and the hardening kind as iron4 ,a later investigator finds it necessary to have a third allotropic form to meet some of the phenomena1 which he designates by another ,greek letter4 ,another investigator establishes independently the saturation-point1 which was pointed out and published twenty years ago1 viz41 somewhere about #ij to #ajj carbon2 he fixes the saturation-point at #hi carbon and gives the formula ,fe,c4 ,he assumes that this is an exceedingly unstable carbide1 that it is formed between recalescence and granulation1 and can only be fixed by quenching1 and that when steel is quenched the fixing of this carbide is the cause of hardness4 ,a still later investigation establishes this saturation-point at about #ajj carbon by observing that in hardened steel of #ace carbon there is a combination of #ajj carbon which is the excessively hard part of the steel1 and a portion containing the remaining #ce parts of carbon that is not quite so hard1 and he suggests a fourth allotropic form to cover this part4 ,it is also suggested that steel should be considered and treated as an igneous rock2 judging from the appearance of magnified micro-sections1 this suggestion appears to be a happy one for the purpose of making comparisons4 ,the above theories of hardening1 and others1 are not to be regarded as antagonistic or contradictory1 doubtless there are germs of truth in every one of them1 or each one may be merely the individual's way of suggesting an explanation of the same observed phenomena1 so that when a final conclusion is reached each may be found to have been travelling in the same direction by a different path4 ,it is certain that able1 patient1 painstaking1 men are working faithfully to produce a solution of the problem1 and even if their ideas1 as briefly given above1 do seem to be contradictory it would only evince deeper ignorance and a stupid mind in any who should attempt to ridicule or unduly criticise honest work before it is completed4 ,while these investigations are going on1 and before any definite conclusion is reached1 is there any well-established safe ground for the steel-worker and the engineer to stand upon8 ,there certainly is a good working hypothesis for all to use1 and one which it is believed will always be the right one to follow no matter what the final explanation of the remarkable phenomena of hardening1 tempering1 and annealing may prove to be4 ,after many years of careful experimenting and study ,prof4 ,j4 ,w4 ,langley came to the conclusion that no matter what the final result might be as to carbides1 allotropic conditions1 etc41 that if steel were considered as iron containing carbon in solution1 whether it were a chemical combination or a mere solution1 and that cold steel be regarded as a congealed liquid in a state of tension1 then all known phenomena could be accounted for1 and all known conditions could be produced with certainty by well-known applications of heat and force4 ,when carbon is in the so-called combined condition1 then the solution maybe compared to pure sea-water2 when the carbon is partly combined and partly graphitic1 the solution may be compared to muddy sea-water1 the mud representing the graphitic carbon4 ,when the carbon is practically all graphitic1 as in over-annealed steel1 then the solution may be compared to thoroughly muddy fresh water4 ,this hypothesis of solution agrees well with the saturation noted2 then about #ajj carbon is all that iron will dissolve without extraneous force2 and higher carbon must be forced into solution by the work of hammers1 presses1 or rolls4 ,this gives reason to the experienced tool-maker's well-known preference for well-hammered steel4 ,the hypothesis of tension1 probably molecular1 covers all of the phenomena of excessive hardness due to high heat1 which means high molecular motion checked violently by sudden quenching4 ,it accounts for the progressive softening due to every added degree of heat1 and it accounts for rupture1 cracking1 due to excessive heat or to any unevenness of heat4 ,without this hypothesis of tension it is difficult to understand why quenching should rupture a piece of steel1 no matter what the degree of heat1 or how uneven it might be4 ,without it1 too1 it is hard to see how successive additions of heat can cause gradual changes from to iron1 or from an unstable carbide to an imperfect solution4 ,it would seem that the allotropic changes1 or the decompositions of carbides1 must be more marked than the gradual changes from hard to soft which we know to take place by slow and gentle accretions of heat4 ,there is no property of steel known to the author which is not covered by ,langley's hypothesis1 and therefore it is put forward with confidence for engineers and steel-users to work by until the scientists shall have completed their investigations1 and after that it is believed that it will be a safe working hypothesis1 because science does not change facts1 it only collates them and reveals the laws of action4 ,under this hypothesis of ,langley's we may define hardness as tension1 softness as absence of tension4 ,this is not stated as established fact2 it is given as a simple definition to cover the known phenomena until the final solution of the problem shall lead to a better explanation4 ,regarding steel as a solution of carbon in iron1 one important fact may be set down as established thoroughly3 that is1 that the more perfect the solution under all circumstances the better the steel4 ,continued application of heat in any part of the plastic condition allows carbon to separate out of solution into a condition of mere mixture2 it converts the clear sea-water into muddy water2 this is the reason why so much emphasis has been given in previous chapters to the harmfulness of long-continued heating4 ,in every case1 when steel is hot enough for the purpose desired1 it should be removed at once from the fire4 ,,xii4 ,,inspection4 ,careful and systematic inspection is of the utmost importance from the first operation of melting to the last act of the finisher4 ,assuming that every operator is honest and conscientious in the performance of his work1 the personal equation must be considered1 as well as the exigencies of the many operations4 ,the steel-maker must inspect his ingots to see that they are melted well and teemed properly1 that they are sound and clean1 and to determine their proper temper4 ,when work is finished1 he must inspect it to see that it has been worked at proper1 even heats1 that it is correct in dimensions1 and that all pipes and seams have been cut out4 ,after all this has been done faithfully it were well that his work were done when it were well done4 ,such is not his happy lot2 every successive manipulator may ruin the steel by carelessness or ignorance1 and it is a gala day for a steel-maker when he does not receive some sample of stupid ignorance or gross carelessness1 with an intimation that it would be well for him to learn how to make steel before he presumed to offend by sending out such worthless material4 ,and sometimes1 though not so often if he knows his business1 he finds a complaint well founded2 then he must regulate his own household and make his peace with his angry customer as best he can4 ,the engineer must inspect his steel to see that it is sound1 and clean1 and finished properly1 as he has a right to expect that it should be4 ,it is not intended here to lay down rules for shop and field inspection1--that is an art in itself outside of the function or the experience of a steel-maker1--but some hints may be given as to the examination of steel as it comes from the mill1 and it has been the aim in previous chapters to give such information as may enable an engineer to form a good judgment as to matters which are not likely to come to his knowledge in the course of ordinary practice4 ,steel should be sound2 it should be examined before it is oiled or painted4 ,all pipe should be cut off2 a pipe of any considerable size will show in the end of a sheared bar1 and a careful observer will soon learn to detect it4 ,if there is reason to suspect a pipe1 file the place and the pipe will be revealed if it is there4 ,do not chip at it1 for a chisel will often smooth a line which a file will bring out4 ,in tool-steel there should not only be no pipe1 there should be no star left in the bar4 ,a 8star0 is a bright spot which shows the last of the pipe1 not quite cut away2 the steel is not solid in the star and it will not make a good cutting-edge2 it may even cause a sledge to split4 ,,seams4 ,in tool-steel there should be no seams at all4 ,some makers declare that in high steel1 seams are evidences of good quality2 such a statement is the veriest fraud2 it is hard to get any high steel free from seams1 and therefore if the maker can get the user to believe that a seam is a good thing he can enhance his profit2 that is1 he can enhance it for a time until his fraud is understood4 ,some seams are hard to see2 when there is reason to suspect one1 a little filing across the line will show it in a distinct black line if it is there4 ,a file is an indispensable tool for an inspector1 better than a chisel or a grindstone4 ,in machinery and structural steel a few small seams may be unobjectionable2 too close inspection may lead to unnecessary cost without a compensating gain2 still every engineer should reserve the right to determine what seams are allowable and what are not1 for his own safety4 ,laps should not be tolerated in any work4 ,torn cracks on edges or surface indicate burned steel or red-short steel2 they should not be allowed4 ,the grain of steel should be practically uniform1 not too coarse1 not with brilliant lustre1 nor with a dark india-ink tint4 ,with an even fine grain1 a bright lustre may indicate a mild steel not worked badly4 ,inspectors must learn by practice what is tolerable and what is not1 as it is impossible to lay down hard and fast rules2 it is safe1 however1 to say that a fairly fine grain of even texture1 not much lustre1 and no india-ink shade1 is indicative of good heating and proper working4 ,with these few general hints the subject must be left1 for1 like tempering1 inspecting is an art in itself1 and it cannot be taught in a book4 ,an expert inspector will see seams and pipes with his naked eye that a novice could not detect with an ordinary magnifying-glass4 ,it may do no harm to the inspector to suggest to him that amiability and good sense are the best ingredients to mix with sound judgment4 ,if he will cultivate these1 and learn to distinguish between a mere blemish and a real defect1 he will find his work made easy and pleasant2 and he will be far less likely to have bad work thrust at him than he will if he makes it apparent that he regards himself as the only honest man4 ,,xiii4 ,,specifications4 ,specifications should cover three principal points3 ,physical properties3 ,elastic limit2 ultimate tensile strength2 elongation2 reduction of area4 ,chemical constituents3 ,limiting silicon1 phosphorus1 sulphur1 manganese1 and copper2 all other elements to be absent or mere traces in quantity1 except carbon4 ,finish and general condition3 ,fixing limit of variation in size from a given standard2 conditions as to pipes1 seams1 laps1 uniformity of grain1 and other defects2 no red-shortness4 ,,physical ,,properties4 ,it has been shown in ,chap4 ,v that tensile strength may be had from #df1hjj lbs4 per square inch to #bdh1gjj lbs4 per square inch4 ,there are published in many transactions and technical periodicals thousands of tests giving elastic and ultimate strength1 ductility1 etc41 so that every engineer can find easily what has been done to guide him as to what he can get4 ,in almost every case the engineer must be the judge as to the requirements in each2 therefore it would be useless to attempt to lay down any fixed rules or limits4 ,many engineers adhere to low tenacity and high ductility in the belief that they are securing that material which will be safest against sudden shocks and violent accidental strains4 ,theoretically this appears to be correct1 but if the statements made in the preceding chapters are credible it is plain that the limit to such safety can be passed1 and that in insisting upon too low tenacity and high ductility the engineer may be getting simply a rotten1 microscopically unsound material1 through no fault of the manufacturer1 who has been compelled to overmelt or overblow his steel to meet the requirements1 and so reducing the quality of otherwise good material at no saving in cost to himself1 and at a considerable cost in quality to the consumer4 ,any manufacturer would rather check his melt between #aj and #ae carbon1 or stop his blow so as to be sure not to overblow1 if he were asked to do so1 because it would save him time and expense1 and it would yield sounder1 better1 and easier working steel4 ,it may not be wise yet for an engineer to fix limits as to blowing or melting1 for the reason that neither he nor his assistants would know how to insure compliance1 and in attempting to do it they might interfere too far with manufacturing operations and so involve themselves in responsibilities which they ought not to assume4 ,on the other hand1 if they will let the carbon and tensile strength run up a little and reduce ductility slightly1 it is safe to say that any manufacturer will be glad of the chance to help them to get the best results1 which involve no extra cost4 ,boiler-steel and rivet-steel usually suffer the most in this respect4 ,a boiler should be tough1 yet it is the belief of the author that boilers made of the #df1hjj-lb4 steel of which the analysis is given in ,chap4 ,v would not last half as long as boilers made of #fe1jjj-lb4 to #gj1jjj-lb4 steel when the increased strength was gained by added carbon and no overmelting was allowed4 ,in the same table the 8,crucible-sheet0 column gives a mean of #bd tests1 and a mean analysis1 of boiler-steel which has been in use in #ab boilers for nearly #af years4 ,the boilers are in perfectly good condition2 they have been subjected to severe and very irregular usage1 and they have been in every way satisfactory4 ,only one test-piece of the #bd was mild enough to stand the ordinary bending test after quenching4 ,that #df1hjj-lb4 steel is remarkably pure chemically2 it is unusually red-short4 ,it would appear to some to be an ideal rivet-steel2 it would stand a very high heat1 it would head well and finish beautifully under a button-set4 ,there is every probability that the majority of rivets driven of that steel would be cracked on the under side of the head1 where the cracks would never be discovered until in service the heads flew off4 ,rails are usually made of #dj to #de carbon1 tires from 4#fe up to #hj carbon1 crank-pins as high as #gj carbon1 with #he1jjj lbs4 to #ie1jjj lbs4 tensile strength and #ab to #ae elongation4 ,it is difficult to see how a bridge or a boiler is to be subjected to any such violent usage as these receive daily2 and while it is not advised that even #dj carbon should be used in boilers or bridges1 although it would be perfectly safe1 it does seem to be unreasonable to run to the other extreme to the injury of the material4 ,for steel for springs1 and for all sorts of tools that are to be tempered1 there is no need of a specification of physical properties as they are indicated by testing-machines4 ,the requirement that they shall harden safely and do good work afterwards involves necessarily1 high steel of suitable quality4 ,,chemical ,,constituents4 ,no engineer should1 unless he be an expert steel-maker1 attempt to specify an exact chemical formula and a corresponding physical requirement2 in doing so he would probably make two requirements which could not be obtained in one piece of steel1 and so subject himself to a back down or to ridicule1 or both4 ,on the other hand1 he may properly1 and he should fix1 a limit beyond which the hurtful elements would not be tolerated4 ,notwithstanding satisfactory machine tests1 successful shop-work1 and a liberal margin of safety1 no steel can be relied upon that is overloaded with phosphorus1 sulphur1 manganese1 oxygen1 antimony1 arsenic1 or nitrogen4 ,in regard to silicon1 it is common to have as much as #bj to #be points in tires1 with #ee to #hj carbon2 such tires are made by the best manufacturers1 and they endure well4 ,but it is certain that good1 sound steel can be made for any purpose with silicon not exceeding #aj4 ,structural steel can be made cheaply within the following limits3 ,silicon 4#aj ,phosphorus 4#je ,sulphur 4#jb ,manganese 4#ej or even 4#cj ,copper 4#jc ,carbon to meet the physical requirements4 ,steel made within these limits and not overblown or overmelted must be better in every way than steel of ,silicon 4#bj ,phosphorus 4#jh ,sulphur 4#je ,manganese 4#fj ,carbon to meet the same requirements ,a steel of the latter composition1 or with no fixed limits1 may be made cheaper than the first by a dollar or two a ton2 but for any large lot it is believed that the first specification would be bid to at as low a price as if there were no specification2 competition among manufacturers would fix that4 ,at any rate there is no reason why an engineer should refuse to demand fairly pure material when he can do so at little or no extra cost4 ,arsenic1 antimony1 or any other elements should be absent1 or 4#jje4 ,,finish ,,and ,,general ,,conditions4 ,as there can be no such thing as exact work done1 there must be some tolerance as to variation in size4 ,in standard sections1 sheets1 and plates this is usually covered by a percentage of weight2 in forgings or any pieces that are to be machined the consumer should allow enough to insure a clean1 sound surface4 ,but it would be unwise to lay down any rule here1 because conditions vary2 a rolled round bar may finish nicely by a cut of from _/ to _/ of an inch1 and so also a neatly dropped forging2 an ordinary hammered forging might require a cut of or of an inch2 such a forging might be made closer to size at a cost for extra time at the hammer far exceeding the saving of cost in the lathe4 ,these are cases where common-sense and good judgment must govern4 ,pipes should not be tolerated if they can be discovered2 because a pipe appears small in the end of a bar it is no evidence that it is not larger farther in4 ,seams should not be allowed in any steel that is to be hardened2 they should be a minimum in any steel1 as they are of no possible use2 small seams when not too numerous may do no harm in structural or machinery steel1 and consumers should be reasonable in regard to them1 or else they may have too high prices put upon their work1 or too high heat used in efforts to close the last few harmless seams4 ,burns1 rough1 ragged holes in the faces or on the corners1 are inexcusable and should be rejected2 the steel has been abused1 or it is red-short2 in either case the ragged breaks are good starting-points for final rupture4 ,laps should not be permitted2 they are evidences of carelessness2 there can be no excuse for them4 ,fins are sometimes unavoidable in a difficult shape2 for instance1 if a trapezoid is wanted1 it may be rolled in this form3 ,illustration or in this3 ,illustration ,the consumer must decide which2 if he wants sharp angles he must accept the fin and cut it off1 or have it cut off by the manufacturer4 ,rivet-steel should be tested rigidly for red-shortness1 because red-short steel may crack under the head as the steel cools4 ,emphasis is laid upon this because engineers will insist upon excessive ductility in rivet-steel1 not realizing that they may be requiring the manufacturer to overdose his steel with oxygen to its serious injury4 ,no sharp re-entrant angles should be allowed under any circumstances where there is a possibility of vibrations running through the mass4 ,all re-entrant angles should be filleted neatly4 ,no deep tool-marks should be allowed2 a fine line scored around a piece by a lathe-tool1 or a sharp line cut in a surface by a planing-tool will fix a line of fracture as neatly as a diamond-scratch will do it on a piece of glass4 ,indentations by hammers or sledges should be avoided2 they may not be as dangerous as lathe-cuts1 but they can do no good1 and therefore they are of no use4 ,,xiv4 ,,humbugs4 ,steel is of such universal use and interest in all of the arts that it attracts the attention of would-be inventors perhaps more than any other one material4 ,half-informed1 or wholly uninformed1 men get a smattering of knowledge of some one or more of the well-known properties of steel1 make an experiment which produces a result that is new and startling to them1 and at once imagine that they have made a discovery2 this they proceed to patent and then offer it to the world with a great flourish of trumpets4 ,many steel-workers1 even men of skill1 who know something of the difficulties that follow irregular work1 or who are not quite fully informed as to the properties of steel1 seize upon these discoveries in the hope that they have found a royal road to success where all old pitfalls are removed and their path is made easy4 ,not wishing to discourage pioneers in legitimate efforts to improve1 it is the object of this chapter to warn them against being too ready to spend their money because of flaming circulars or glib tongues4 ,it is the duty and the interest of a steel-maker to examine and test every apparently new suggestion1 for the reason that there is still room for improvement1 and he should let no opportunity for a betterment slip past him4 ,as a rule the steel-maker does test every claim that is laid before him1 unless it be a repetition of some old plan long since tried and found worthless4 ,this is the bane of the steel-maker's life1 and yet he must keep at this work so that he may know for himself whether anything of value has been discovered1 and also that he may advise his clientage properly4 ,inventions relating to the manufacture of steel have no interest for steel-users except as lively manufacturers may adopt the mistaken plan of flourishing trumpets to attract trade1 not always giving a corresponding benefit to the consumer4 ,examples of this sort of thing may be illustrated by so-called phosphorus steel1 silicon steel1 and aluminum steel2 also the case mentioned before of parties recommending seams as evidences of excellence in high steel4 ,such efforts are sometimes costly to consumers until active competitive manufacturers expose the humbug4 ,among the most absurd of such claims are those where a nostrum is used to convert ordinary ,bessemer or open-hearth steel into the finest of tool-steel1 equal to the best crucible-steel2 for example1 a patent to convert mild ,bessemer steel into the finest tool-steel by merely carbonizing it by the old cementation process2 this takes no account of the silicon1 manganese1 oxygen1 and nitrogen in the mild ,bessemer1 makes no provision for their removal1 and involves a costly method of putting carbon into poor stock in face of the fact that a ,bessemer steel maker can put the same amount of carbon there at practically no cost1 and so produce a better material4 ,among the humbugs that do not involve the manufacturer1 the pet one is a nostrum for restoring burnt steel2 these have been evolved by the dozen1 in face of the fact that burned steel cannot be restored except by smelting1 and that overheated steel1 coarse-grained steel1 can be restored by merely heating it to the right temperature1 a process which has been explained fully in ,chapter ,,vi4 ,another pet is some greasy compound for toughening high steel so as to make it do more work4 ,this is done by heating the steel to about recalescence and plunging it into the grease1 perhaps once1 or possibly two or three times2 then working it into a tool and proceeding in the ordinary way4 ,this will make a good tool2 it is the partial annealing plan explained in a previous chapter4 ,now take a similar piece of steel1 heat it the same way1 lay it down in a warm1 dry place alongside the forge-fire1 and let it cool2 then heat it and work it into a tool and it will beat the greased tool4 ,when all of these operations of restoring1 partial annealing1 annealing1 etc41 depend merely upon temperature and rate of cooling1 why spend money for nostrums that add no possible benefit8 ,there is room for improvement in steel1 great room for great improvements2 they will come in time as science and knowledge advance1 and great benefits to the consumers will come with them4 ,this chapter is not written to place difficulties in the way of legitimate improvement1 but to warn unsuspecting people against quackery4 ,some of the humbugs are honest productions of well-meaning ignorance1 and some that come from designing manufacturers are not entitled to such charitable designation4 ,a knowledge of the simplest properties of steel will enable a thoughtful man to judge as to whether a proposed improvement is likely to be of any value or not1 and the warnings given are intended as a protection to the unsuspecting and credulous4 ,,xv4 ,,conclusions4 ,after perusal of the preceding chapters the reader may form a hasty conclusion that if steel be so sensitive as it is stated to be its use may be difficult and precarious1 and that it must be handled in fear and trembling1 lest the result should be a dangerous structure1 and the builder must be in doubt as to its safety4 ,the conveyance of any such impressions is not intended at all2 emphasis has been laid upon practices that are hurtful in order that every steel-user may know what to avoid1 solely that he may then be sure that he has the best1 the most reliable1 and most useful material that is known to man4 ,,what ,,to ,,avoid4 ,he should avoid uneven heat1 excessive heat1 or too low heat4 ,the range between orange red and the heat that will granulate is so great that no one who is not a bungler or indifferent need ever get outside of it4 ,the uniformity of temperature that is insisted upon is so easily seen that any person who is not color-blind should have no trouble in securing it by the simplest manipulations of the furnace4 ,practical uniformity of the work put on a piece is readily secured by any mechanic of ordinary skill4 ,red-short1 cold-short1 or honeycombed steel are easily detected1 and1 under reasonable specifications1 the steel-makers can as easily avoid them4 ,steel a little higher than most engineers favor in their specifications is certainly as safe as1 and likely to be sounder than1 extremely ductile steel4 ,wild steel1 resulting almost certainly in micro-honeycombs1 if not worse1 can only be avoided by the co-operation of the manufacturer1 and engineers should impress this point with energy4 ,such micro-unsoundness as is shown in ,mr4 ,andrews's report upon a broken rail and propeller-shaft can be reduced to a minimum by insisting upon reasonably pure steel4 ,if sulphur1 phosphorus1 silicon1 and oxygen are kept at a reasonable minimum1 sulphides1 phosphides1 silicides or silicates1 and oxides must be at a corresponding minimum4 ,that there is much room for improvement in the manufacture of steel is evident1 and when means of getting rid of oxygen1 nitrogen1 and all other undesirable elements have been found the steel of the future will be very different in kindliness of working and in endurance of strains than that with which we are familiar4 ,it is believed1 however1 that no matter how perfect the manufacture may become1 nor what the final theories of hardening1 etc41 may be1 the properties stated in these pages will remain the same as long as steel continues to be essentially a union of iron and carbon4 ,some other alloy or compound may displace carbon steel1 and present an entirely new set of properties1 but there is nothing of the kind in sight now1 and engineers need have no fear of having a new art to learn very soon4 ,to one who has spent an ordinary business lifetime in making steel1 studying it1 and working with it it becomes a subject of absorbing interest1 if not of love2 and steel when handled reasonably is so true that 8true as steel0 ceases to be a metaphor1 it is then a fact which fills him with the most entire confidence4 ,once more1 steel highly charged with sulphur1 phosphorus1 arsenic1 oxygen1 and nitrogen is certainly highly charged with so many elements of disintegration2 it takes more serious harm from ordinary deviations from good practice1 such little irregularities as occur inevitably in daily working1 than steel does which is more free from these elements4 ,reasonably pure1 sound1 reliable steel can be had at moderate cost1 and all consumers should insist upon having it4 ,regular1 uniform1 reliable working can be had where it is required1 and there should be no excuse for irregular grain1 overheated work1 uneven work1 or any other bungling4 ,where skill is required and reasonable discipline is enforced1 good work will not cost any more than bad work4 ,many people still hold to the idea that there are many mysteries connected with steel1 and that many unaccountable breaks occur which make it an unreliable material4 ,it is hoped that what has been set down in these pages will go far to dissipate these supposed mysteries1 and to give confidence to steel-users4 ,many breaks are unaccounted for1 but it is not within the author's experience that any fracture ever occurred that could not have been explained if it had been examined thoroughly in the light of what we know now4 ,there is much to be learned1 but there are no mysteries4 ,,glossary4 ,there are many shop terms used in this book which may not be familiar to all steel-users4 ,they are in common use in steel-manufactories1 and definitions of them will enable a steel-user to understand more clearly the common talk he will hear in the shops4 ,blow-holes4--,blow-holes are the small cavities1 usually spherical1 which are formed in ingots as the steel congeals by bubbles of gas which cannot escape through the already frozen surface4 ,burned4--,burned steel is steel that is reduced to oxide in part by excessive heating4 ,check4--,a check is a small rupture caused by water2 it may run in any direction2 it is usually not visible until steel is ruptured4 ,chemical ,numeration4--,chemical quantities are almost universally expressed in hundredths of one per cent1 as explained in the body of the work4 ,it is a very convenient numeration2 any steel-worker1 melter1 hammerman1 etc41 will talk of #bj1 or #ej1 or #acj carbon2 or #h phosphorus2 or #aj1 #ae1 or #be silicon1 etc42 and will talk intelligently1 although he may not know the exact mathematical value of these points4 ,dead-melting2 synonym1 killing4--,dead-melting--killing--means melting steel in the crucible or open hearth until it ceases to boil or evolve gases2 it is then dead1 it lies quiet in the furnace1 and killed properly it will set in the moulds without rising or boiling4 ,dry4--,steel is called dry when its fracture is sandy-looking1 without lustre or sheen1 and without a proper blue cast4 ,there is more of a shade of yellowish sandstone4 ,it is an evidence of impurity and weakness4 ,fiery4--,fiery steel has a brilliant lustre2 it is an evidence of high heat4 ,if the grain be fairly fine and of bluish cast1 it is not necessarily bad in mild steel2 in high steel or in tool-steel it should not be tolerated4 ,if the grain be large and of brassy cast1 it is sure evidence of bad condition2 the grain should be restored before the steel is used4 ,in hardened steel it is always bad1 except in dies to be used under the impact of drop-hammers2 in this case steel must be so hard as to be slightly fiery4 ,grade4--,grade applies to quality1 as crucible1 ,bessemer1 or open-hearth grade4 ,or in the crucible1 common1 spring1 machinery1 tool1 special tool1 etc41 etc4 ,it does not indicate temper or relative hardness4 ,honeycombed4--,unsound from many blow-holes4 ,usually applied to ingots4 ,it is a bad condition4 ,lap4--,a lap is caused by careless hammering1 or by badly proportioned grooves in rolls1 or by careless rolling4 ,a portion of the steel is folded over on itself1 the walls are oxidized and cannot unite4 ,a lap generally runs clear along a bar1 practically parallel with its axis2 it may be seen by a novice4 ,lapped steel should be rejected always4 ,overblown4--,steel that has been blown in a ,bessemer converter after the carbon is all burned2 then there is nothing but steel to burn1 and the result is bad4 ,overheated4--,steel that has been heated too hot1 and not quite burned2 its fiery fracture exposes it4 ,the grain of overheated steel may be restored1 but restored steel is never as reliable as steel that has not been overheated4 ,overheating is a disintegrating operation4 ,overmelted4--,steel that has been kept too long in fusion4 ,the finest material may be ruined in a crucible by being kept in the furnace any considerable time after it has been killed4 ,open-hearth steel may be injured seriously in the same way4 ,prompt teeming after killing should be the rule4 ,pipe4--,a pipe is the cavity formed in an ingot when it cools2 the walls chill first and nearly to the full size of the mould1 then the shrinking mass separates in the middle1 forming a pipe4 ,a pipe should be at the top of the ingot2 it may occur anywhere by bad teeming4 ,point4--,one hundredth of one per cent of any element4 ,you have say #aj points of carbon1 or #aj carbon2 you want it raised a few points to #ae or #ah carbon4 ,recalescence4--,when a piece of steel is heated above medium orange color and cools slowly1 at about medium orange--#aajj to #abjj ,f4--the change of color ceases1 then the color rises sometimes to bright orange1 and afterwards the cooling goes on2 this phenomenon is called recalescence4 ,this is not yet a common shop term4 ,restoring4--,when a piece of overheated steel is re-heated to recalescence1 kept there a few minutes1 and then cooled slowly1 its grain becomes fine and its fiery lustre disappears2 this is called restoring4 ,no nostrums are necessary4 ,sappy4--,well-worked1 good steel has a bluish cast1 a fine grain1 and a silky sheen4 ,it is sappy2 it is as good as it can be made4 ,seam4--,a seam is a longer or shorter defect1 caused by a blow-hole which working has brought out to the surface and not eliminated4 ,it usually1 or always1 runs in the direction of working4 ,seams are distinguished from laps by not being continuous2 they are usually only an inch or two in length4 ,short 7,cold1 ,red1 ,hot74-- ,cold-short steel is weak and brittle when cold4 ,red-short steel is brittle at dark orange or medium orange heat or at the common cherry red heat4 ,it may forge well at a lemon heat1 and be reasonably tough when cold4 ,hot-short steel is brittle and friable above a medium orange color2 it may forge well from medium orange down to black heat4 ,star4--,a brilliant spot in mid-section showing that the pipe is not all cut away4 ,it should be removed from tool-steel especially1 as it may have considerable depth4 ,it is of no use in any steel4 ,temper4--,used by the steel-maker it means the quantity of carbon present4 ,it is low temper1 medium1 or high2 or number so and so by his shop numbers4 ,used by the steel-user or the temperer it means the color to which hardened steel is drawn3 straw1 brown1 pigeon-wing1 blue1 etc41 etc4 ,or1 it is the steel-maker's measure of initial hardness2 and it is the steel-user's measure of final hardness4 ,water-crack4--,a crack caused in hardening2 it may run in any direction governed by lines of stress in the mass4 ,it is distinguished from a check by being larger1 and usually plainly visible4 ,wild ,steel4--,steel in fusion that boils violently1 and acts in the moulds like lively soda-water or beer does when poured into a glass4