THl5(o ajorncU UnioeraitH Eibrarg BOUGHT WITH THE INCOME OF THE SAGE ENDOWMENT FUND THE C3IFT OF HENRY W. SAGE 1891 Cornell University Ubrary TN 7S6.H62 Manufacture and uses of alloy steels, 3 1924 004 643 486 Date Due >^. ■f Cornell University Library The original of tiiis book is in tine Cornell University Library. There are no known copyright restrictions in the United States on the use of the text. http://www.archive.org/details/cu31924004643486 WILEY ENGINEERING SERIES The Wiley Engineering Series will embrace books devoted to single subjects. The object of the Series is to place in the hands of the reader all the essential information regarding the particular subject in which he may be interested. Extraneous topics are excluded, and the contents of each book are confined to the field indicated by its title. It has been considered advisable to make these books manuals of practice, rather than theoretical discussions of the subjects treated. The theory is fully discussed in text-books, hence the engineer who has previously mastered it there, is, as a rule, more interested in the practice. The Wiley En- gineering Series therefore will present the most approved practice, with only such theoretical discussion as may be necessary to elucidate such practice. WILEY ENGINEERING SERIES MANUFACTURE AND USES OF ALLOY STEELS BY HENRY D. HIBBARD NEW YORK JOHN WILEY & SONS, Inc. London: CHAPMAN & HALL, Limited 1919 4^ ^ This monograph is reprinted with the permission of the Bureau of Mines, Department of the Interior, which issued it as a bulletin. PRESS or BRAUNWORTH & CO. BOOK MANUFACTURERS BROOKLYN, N. V. CONTENTS PAGE Definitions vii Acknowledgment xi Introduction xiii CHAPTER I LIST OF USEFUL ALLOY STEELS Alloy-treated Steels The uses of alloy steels 3 Manufacture of alloy steel 4 Structural Alloy Steels General considerations 6 Selected bibliography lo General articles dealing with two or more alloy steels lo CHAPTER II SIMPLE TUNGSTEN STEEL Manufacture of tungsten steel 13 Method of working 14 Properties and uses 14 Theory of tungsten steel 16 Bibliography on tungsten steel 16 CHAPTER III SIMPLE CHROMIUM STEEL Methods of working 20 Uses of simple chromium steels 21 Bibliography of chromium steel 23 iii IV CONTENTS CHAPTER IV MANGANESE STEEL PACE Manufacture 24 Composition 27 General properties 28 Properties of manganese steel in the raw state 29 Heat treatment of manganese steel 29 Properties of heat-treated manganese steel 31 Manganese-steel castings 34 Uses of manganese steel 35 Hot-worked manganese steel 37 Conclusions 39 Bibliography on manganese steel , , , 39 CHAPTER V SIMPLE NICKEL STEELS Manufacture of simple nickel steel 42 Working of simple nickel steel 43 General character of nickel steel used for structural purposes 45 Characteristics of different nickel steels used in rails 46 Properties of ordinary nickel steel 46 Nickel-iron alloy discovered by Arnold and Read 49 Properties of different steels having different percentages of nickel 5° Invar 53 Platinite 53 Bibliography on nickel steel 54 CHAPTER VI NICKEL-CHROMIUM STEELS Composition and properties 56 Use in automobiles 58 Use in armor plate 59 Use in projectiles and in rails 60 Details of manufacture of a specific piece of nickel-chromium steel 60 Mayari steel . , 61 Castings of nickel-chromium steels 62 Bibliography on nickel-chromium steel 62 CONTENTS V CHAPTER VII SILICON STEELS PAGE Manufacture of silicon steel 63 Properties of silicon steels 64 Uses of silicon steels 64 Bibliography on silicon steel 66 CHAPTER Vril HIGH-SPEED TOOL STEELS Manufacture of high-speed tool steel 68 Composition of high-speed tool steel 70 Carbon in high-speed tool steel 72 Tungsten in high-speed tool steel 72 Chromium in high-speed tool steel 73 Molybdenum in high-speed tool steel ._ 73 Vanadium in high-speed tool steel 74 Cobalt in high-speed tool steel 75 Copper in high-speed tool steel 76 Sulphur and phosphorus in high-speed tool steel 76 Stellite 76 Heat treatment of high-speed tools 77 Theory of high-speed steels 80 Testing and using high-speed steel 81 Machine-tool design 83 Patents on high-speed steels 84 Miscellaneous uses of high-speed steels 84 Bibliography on high-speed tool steel 84 CHAPTER IX CHROMIUM-VANADIUM STEELS Example of satisfactory use of chrome- vanadium steel 88 Bibliography on chromium-vanadium steel 90 Recovering Alloyed Elements 91 Cerium Pyrophoric Alloy gi Conclusion 91 Index 93 DEFINITIONS Definitions of terms used throughout this monograph are presented below : Simple steel, often called "carbon steel," consists chiefly of iron, carbon, and manganese. Other elements are always pres- ent, but are not essential to the formation of the steel, and the content of carbon or manganese, or both, may be very small. Alloy steel is steel that contains one or more elements other than carbon in sufiicient proportion to modify or improve sub- stantially and positively some of its useful properties. Simple alloy steel is alloy steel containing one alloying ele- ment, as, for example, simple nickel steel. Ternary steel is alloy steel that contains one alloying ele- ment, the term being synonymous with "simple alloy steel." Quaternary steel is an alloy steel that contains two alloying elements, such as chromium-vanadium steel. Complex steel is an alloy steel containing more than two alloy- ing elements, such as high-speed tool steel. Alloy-treated steel is a simple steel to which one or more alloying elements have been added for curative purposes, but in which the excess of the element or elements is" not enough to make it an alloy steel. Raw steel is steel as cast, either an ingot or casting. Natural steel is steel in the condition left by a hot-working operation, and cooled in the open air. Normalized steel is steel that has been given a normalizing heat treatment intended to bring all of a lot of samples under consideration into the same condition. Annealed steel is steel that has been subjected to an anneal- ing operation. viil DEFINITIONS Hardened steel is steel that has been hardened by quench- ing from or above the hardening temperature. Tempered steel is steel that has been hardened and sub- sequently tempered by a second lower heating. These definitions are based on the definition of steel that states that steel must be usefully malleable. The definitions of alloy steels do not include effects which are negative, or the prevention or cure of ills which the steel might possess were the alloying element or elements not added. An iron alloy is not herein considered as useful unless it pre- sents some useful property or modification of a property not offered to the same degree by a simple steel. The definition of alloy steel given does not agree with that of all writers on the subject of mixtures of iron with other ele- ments than carbon; but it does agree with that of some who have been careful enough when considering the whole range of ele- ments to designate them as alloys, such as silicon-iron alloys and chrome-vanadium alloys, the range covering the useful alloys or steels as well as those in which the alloying element is added for curative purposes and others that have only a scientific interest. Elements other than carbon may be desired in steel, and therefore be added to or permitted to remain in it for three distinct purposes, as follows : 1. To give the composition desired and to cure in simple steels some ills or defects that the final product might other- wise possess. 2. To make alloy steels. Such elements are manganese, silicon, tungsten, nickel, chromium, vanadium, cobalt, and others of less importance. 3. To make alloys which, though they excite only a scien- tific interest, form a great part of the whole field of iron metal- lurgy. Many a one of these alloys would have a commercial value if another alloy were not known that meets particular requirements more satisfactorily either as to efficiency or as to cost or both. The various additions of the element manganese to iron DEFINITIONS ix illustrate well the three purposes of alloys as above specified. A moderate amount, usually less than i| per cent, is added to molten steel made by an oxidation process (pneumatic or open hearth) to prevent red-shortness. A much larger amount is added to make commercial manganese steel, which should contain ii to 14 per cent of manganese. Outside of these lim- its, a great number of manganese-iron alloys may be made, most of which have only a scientific value, though the num- ber of useful ones is always Uable to be extended as new require- ments and methods of manufacture and treatment arise. Sim- ple commercial steels containing between 1.5 and 2 per cent of manganese are made, and manganese steels containing less than II per cent manganese are useful for certain purposes; but the manganese content of the great bulk of the steels made is within the limits given. The total number of possible alloys of iron with varying proportions of other elements is of course practically infinite. So, indeed, is the number of u.seful alloys, though they form only a small fraction of the whole number. This monograph deals exclusively with alloy steels, as defined above, in which the alloying element or elements modify directly, positively, and usefully some of the properties of the products. ACKNOWLEDGMENT The author desires to make grateful acknowledgment of the cooperation of the following firms or individuals, who are some of the many who have contributed information for this monograph: Pond Machine Tool Co.; C. W. Leavitt & Co.; Bethlehem Steel Co. ; Crucible Steel Company of America ; Carbon Steel Co. ; Firth- Stirling Steel Co.; Carnegie Steel Co.; Peerless Motor Car Co.; Society of Automobile Engineers; Fore River Engine & Ship Building Co.; Tabor Manufacturing Co.; United Steel Co. ; Car- penter Steel Co.; Pennsylvania Steel Co.; Cambria Steel Co.; Columbia Tool Steel Co.; Edgar Allen Manganese Steel Co.; Primos Chemical Co.; Henry Disston's Sons Co.; Simonds Manufacturing Co.; Ford Motor Co.; Perfection Spring Co.; Chrome Steel Works; Standard Roller Bearing Co.; Central Railroad of New Jersey; New York Central & Hudson River Railroad Co.; Delaware, Lackawanna & Western Railroad Co., Pennsylvania Railroad Co.; R. R. Abbott; E. O'C. Acker; West- inghouse Electric & Manufacturing Co.; J. A. Mathews; F. V. Sargent; HansBoker; W. A. Bostwick; B. E. Eldred; Dr. Paul R. Heyl; Illinois Steel Co.; W. M. Stein; and Leonard Waldo. INTRODUCTION The object of this monograph is to give briefly information of present value relating to the manufacture and uses of the various commercial alloy steels, with the hope of stimulating the demand for such steels and extending their practical use. Alloy steels are included in the so-called special steels, but as the latter term is often used in the mills to designate broadly any steels intended for purposes other than those served by the regular product, it has seemed best to use the more specific term of alloy steels in this monograph. Alloy steels are bringing about a series of revolutions in various industrial fields in which steel plays an important part. Most elements that could be procured in sufl&cient quantity have been alloyed with iron in various proportions, either alone or in combination with others, in the search for useful alloy steels. Those steels that have gained and maintained for themselves a place in current use are discussed in this monograph. Some of them have had an ephemeral life of usefulness which would no doubt have been prolonged had not some other more satisfactory steel been developed. Probably the first useful alloy steel was Mushet's self- hardening tungsten tool steel, patented in 1868. Fifteen years later chromium steel, really containing chromium, was strug- gling for recognition for some purposes, the chief of which was for the manufacture of solid shot for piercing armor. In both of these steels the effect of the alloying element as used was in a way proportional to the amount contained. In 1882 Hadfield made his epoch-making discovery of manganese steel and demonstrated that in iron metallurgy it is not safe to take for xiv INTRODUCTION granted anything as to the properties of an alloy of iron with other elements, basing one's opinion on past experience and knowledge, and that the effect of an alloying element may not be proportional to its content. The development of useful nickel steels followed in a few years, and the field thus opened has since then been worked by many able and zealous men, with results of great importance and value. MANUFACTURE AND USES OF ALLOY STEELS CHAPTER I LIST OF USEFUL ALLOY STEELS The eight alloy steels named below in the chronological order of their introduction are considered to meet this require- ment: 1. Simple tungsten steels. 2. Simple chromium steels. 3. Manganese steel. 4. Simple nickel steels. 5. Nickel-chromium steels. 6. Silicon steels. 7. High-speed tool steels. 8. Chromium- vanadium steels. The first four and the sixth of these are ternary steels, the fifth and eighth are quaternary, and the seventh is of complex composition. Some of these steels may be treated while molten by the addition of a purifying or solidifying element or ele- ments in such a small quantity as not greatly to affect the final properties. Thus a small amount of titaniiun, aluminum or vanadium may be added to a chromium or nickel steel and hardly appear in the final analysis. Such a result is seen in the alloy-treated steels. 2 MANUFACTURE AND USES OF ALLOY STEELS ALLOY-TREATED STEELS Alloy-treated steels need be only briefly alluded to here. The method of manufacturing all steels made by the oxidation processes involves the presence in suspension or solution of harmful amounts of oxygen or oxides, and before the metal is cast means must be taken to lessen the oxygen or oxide con- tent to or below an allowable maximum. One or more of cer- tain elements having at steel-melting temperatures a stronger afiinity for oxygen than iron has, are added to the molten metal. The oxygen leaves the iron to seize such added elements, form- ing new products insoluble in the iron, which in time are pre- cipitated, gather together, and leave the metal. Such unfinished steel also contains in solution a quantity of gases which require to be decomposed or kept in solution, for, if not, when the steel is sohdifying, part of the gases will leave it and part will be imprisoned in the metal and form gas holes, of the variety commonly called blowholes. The addition of certain elements to the metal tends to prevent the separation of the gases. Further there is a tendency of certain of the ingredients of steel to collect or segregate in an injurious way in the upper central part of a large ingot or casting, but the addition of certain elements lessens this tendency. Elements that are added to prevent, minimize, or cure these ills are manganese, which is the most important, silicon, alumi- num, titantium, vanadium, and others of less importance. The effects aimed at are therapeutic and though real and valu- able, are mostly negative rather than positive; that is, effort is made to cause the steel to be free from some or all of the defects cited. The proportions of these elements added are, generally speaking, only enough to cure the defects to be removed or counteracted, with a suitable excess to reasonably assure such a result in view of the uncertainties and irregularities of steel making. The excess of any of the elements named has indeed some effect on the final properties of the steel, but not enough LIST OF USEFUL ALLOY STEELS 3 to put the product in the class of the alloy steels. Steels so treated are considered as alloy-treated steels, they being simple steels, outside the subject of this monograph, as the alloying elements do not give new or modified properties of important commercial value. Some alloying elements are added to simple steel in such proportions as to produce only a curative effect, and the product can not definitely be classified as a simple or an alloy steel, as can be done when a rather large excess of the element is added. The elements vanadium and silicon are examples, both being added to cure ills in the steel, and an excess of either causes the physical properties of the steel to vary to some extent. Both are used also in undoubted alloy steels that have unique properties, which would not be anticipated from the observa- tion of the effect of a moderate excess of either in a simple steel. Crude alloys of the alloying elements that are used as ingre- dients in steel making and are not useful themselves in their crude state are not herein considered. THE USES OF ALLOY STEELS With few exceptions all alloy steels are heat treated for use, the treatment developing in them the high physical properties they are capable of possessing. No general law regarding the effects of heat treatment of alloy steels can be laid down. Some steels when quenched from a high heat are hardened and others are softened, the latter being generally those with the higher contents of certain of the alloying elements. In respect to the effects of heat treatment each steel is considered by itself. Developments in the manufacture of alloy steel and in the heat treatment of steel have occurred somewhat simulta- neously during the past 30 years, and care is needed lest the benefits gained from one be confounded with those afforded by the other. The highest merit is obtained from the adoption of both developments together — that is, the use of heat-treated 4 MANUFACTURE AND USES OF ALLOY STEELS alloy steels. Usually heat treatment has contributed more to the superior properties of the metal than has the use of alloys. The alloy steels discussed in this monograph are considered as regards their value for structural, cutting, or electrical pur- poses. Steel used for structural purposes is taken to include that used for the stationary as well as the moving parts of structures and machines, including bridges, buildings, vehicles, machine tools (except the cutting tools), armor plate, ships, ores involving resistance to abrasion or corrosion, and wire, except electrical wire, and in general all steel not used in the other two fields. Steel used for cutting purposes includes that employed to form an actual cutting edge and that used in projectiles for war. Steel for electrical purposes is used in magnets, core steel; non-magnetic articles, and electrical-resistance devices. No steel suitable in a commercial sense for two of these purposes is made, though some steels might be used for more than one purpose if a better kind for the other specific purpose were not known; thus a fair tool steel might be made of some of the harder structural steels, and a fair magnet might be made of some of the tool steels. The effects of the alloying elements in alloy steels are vari- ous; thus nickel increases the elastic limit as compared to tensility; chromium increases the hardness of quenched steel; and manganese destroys magnetic susceptibihty — effects all of which are valuable for certain purposes. MANUFACTURE OF ALLOY STEEL Alloy steels are made by any of the steel-making processes, that is, by any of the variations of the pneumatic processes, by the acid or basic open hearth, by the electric furnace, and by the crucible. For each of the various purposes, however, the practice is more limited, the general rule being of course that the cheapest process is employed that will yield a product satisfactory for the purpose in view. All alloy-steel ingots or castings should be made sound and LIST OF USEFUL ALLOY STEELS 5 with full tendency to pipe. Soundness, which means freedom from gas holes, is, generally speaking, a necessary require- ment in order that the product may be sound, as ahnost any of the alloying elements interferes with or prevents the welding of steel that contains that element so that any contained gas holes in ingots will not be welded up by hot working. There- fore they may, if near the surface, be opened to the air by scaUng in heating or by forging and rolling and then be oxi- dized within and form seams. Chromium and nickel more than other alloying metals prevent welding in steel. Pipe in the ingot may be shortened in length by casting the ingot with the larger end up, or it may be avoided if the ingot when so cast is squeezed laterally, or if the top is maintained in the molten state until the remainder of the ingot is solid. If neither of these means is employed enough of the top of the ingot must be discarded to get rid of any objectionable pipe. Whether any pipe is permissible depends on the use to be made of the steel, there being many uses for which steel containing a pipe is adapted, or a hole may even be drilled where the pipe would naturally be as is often done to favor heat treatment in massive articles. The amounts given in this monograph of the different steels produced in the United States have for the most part been determined by indirect means. They are therefore not exact, but are, it is believed, near enough to the truth to warrant presenting them. The temperatures are given in both centigrade and Fahren- heit degrees. Alloy steels and other alloys of iron with other elements have been discussed by numerous writers chiefly in their gen- eral or purely scientific aspects. The selected bibliography, at the end of each chapter, relating to the different alloy steels is intended to be limited to articles that bear upon the useful steels. Many of the articles themselves have bibliographies more or less complete. The bibliography is arranged chronologically. MANUFACTURE AND USES OF ALLOY STEELS STRUCTURAL ALLOY STEELS GENERAL CONSIDERATIONS Structural steels, whose fields of use have already been noted, have some attributes in common, which makes it worth while to consider them collectively to a certain extent. These steels are working great improvements in the production of structures for various purposes, especially where the saving of weight or increase of strength or both are important, the most conspicuous example being undoubtedly the automobile industry. Heat-treated alloy steels with double or treble the strength of the simple steels they replace and with as great or greater reliability are now in regular and most advantageous use. In common with other alloy steels, structural alloy steels owe a part of their superior properties to the presence of the alloying element, but usually far more to heat treatment when it can be given to them. In automobiles the use of alloy steels is generally not advised unless the steels are heat treated, as the gain from their use in the natural or untreated state does not compensate for the increased cost. Most structural alloy steels are therefore used in the heat- treated condition, when the articles made of them are, like auto- mobile parts, not too bulky or massive. Large pieces Hke nickel-steel rails and nickel-steel members of bridges are used without heat treatment, the advantages of increased strength and ductility that the metal possesses being due solely to the presence of the alloying element. The difiiculties attending the heat treatment of large steel parts that are bulky for their weight are holding back their general introduction. They require, as nearly as is practicable, to be uniformly heated, uniformly cooled in quenching, and afterward, when cold, to be made true to form, as the quench- ing operation, however carefully done, usually leaves them warped or twisted. No doubt, in time, means will be found to overcome these drawbacks and such pieces as rails and bridge LIST OF USEFUL ALLOY STEELS 7 members of alloy steels will be used regularly in the heat- treated condition. A compact object like an armor plate, though very large, may be quenched without unmanageable warping because of its simple shape. The diflSculty in making straight and true such an article as a heat-treated rail of pearlitic alloy steels lies largely in the springiness of the treated metal. It is not easy to give it the correct amount of set needed to counteract or obliterate a crook, bend, or twist that may result from quenching. Yet this is necessary when the piece must be straight or true to shape. Stretching slightly beyond the elastic limit as is done to some thin steel sheets and relatively small bars to straighten them might be efficacious, but is not to be easily done with a piece of such irregular cross-section as a rail. The effects of heat treatment are so great that a certain steel may be given a very wide range of properties, depending on the treatment, and any desired set of properties within that range may be obtained solely by varying the heat treat- ment. The principal variant is the degree of the second heat- ing. The lower this is, the stronger and stiffer the steel, and the higher, the weaker and more ductile it is. This effect of heat treatment on steel is illustrated by a table published by a producer giving the results of 40 tensile tests made from one heat of steel, each test piece having had a dif- ferent heat treatment. Five, which cover the range, are given in the table below. RESULTS OF TENSILE-STRENGTH TESTS OF 5 PIECES OF STEEL EACH RECEIVING A DIFFERENT HEAT TREATMENT Tensility. Elastic Limit. Elastic Ratio. Elongation in 2 Inches. Contraction of Area. Pounds. Pounds. Per Cent. Per Cent. Per Cent. 84,850 50,500 60 28 67.5 120,975 90,000 74-5 14-5 51 166,950 157,500 94 12-5 44 20 ,600 200,000 97 13 48.7 240,975 225,000 93 9 20.5 8 MANUFACTURE AND USES OF ALLOY STEELS Analysis of the original steel showed C, 0.25; Mn, 0.50; Cr, 1.07; and V, 0.17 per cent, but similar results could be obtained with a variety of compositions. For making small parts that must be true and well finished the structural alloy steels are generally heat treated before they are machined, and this requirement prevents the use in such parts of steel of the highest strength attainable, because steel having that strength is not commercially machinable. Generally speaking, any part that is to have an elastic limit of more than ioo,cxio pounds per square inch must be treated after having been machined, not before, because most steels having a higher elastic limit than that are too hard to allow machining by commercial processes, though chromium-vanadium steels with an elastic limit of 150,000 pounds per square inch are claimed to be machinable, that is, they may be cut with high- speed steels at a profitable rate. An elastic limit of 100,000 pounds or more per square inch can be imparted to steel only by heat treatment, as no untreated steel of a commercial grade will have so high a limit. Some of the makers of structural alloy steels are publishing for each of their steels a graph showing the physical properties the steel will have when hardened and then drawn to different temperatures. Of course, the graphs give ex parte information which is subject to confirmation before acceptance, but the plan is excellent as giving the most information in the least space. Similar graphs of many alloy steels prepared by consumers are expected to be soon available for comparison. From these graphs a new user of these steels may choose the properties he desires and specify the steel he wishes, making some allow- ance of course (say 10 per cent) for the uncertainties of manu- facture and treatment. The steel maker or treater, to be reasonably sure of meeting the requirements, will aim to exceed the properties specified, and the net result will usually be that the steel will have practically the properties desired. The table of properties given later show how much more the properties possessed are imparted by treatment than by composition. LIST OF USEFUL ALLOY STEELS 9 The size or massiveness of the article has a great effect on the results obtained by any given heat treatment. The greater the mass the lower the qualities, though not in exact proportion. Thus the mass must always be considered in connection with the properties desired, and the composition and heat treat- ment prescribed must be modified accordingly, though even then the effect of mass may be only partly compensated for. The modulus of elasticity of many, if not all, structural alloy steels in common with other steels is not changed much by heat treatment or variations in composition* and is usually between 28,000,000 and 30,000,000 pounds per square inch; that is, the modulus of the steel in its annealed, hardened, and tempered condition remains practically unchanged. The fol- lowing table was compiled from data given by Landau.f MODULI OF ELASTICITY OF SOME ALLOY STEELS Composition of Steel. C Si Mn P S Cr Ni V Modulus. Per Cent 0.50 •47 .48 ■30 •25 • 24 •25 Per Cent 0^13 i^83 ,16 •19 .21 . 21 .16 Per Cent 0.82 •70 •44 .64 • 74 • 46 •50 Per Cent O.OI .01 .01 .01 .01 .01 .01 Per Cent 0.02 .01 .01 .01 .01 .02 Per Cent I-2S .98 .96 I -05 Per Cent 2.02 3^25 3^55 2.02 Per Cent 0.14 .18 .16 29,240,000 28,950,000 28,840,000 28,260,000 28,170,000 28,200,000 30,158,000 Because of the unchangeability of the modulus of elasticity the stiffness or rigidity of steel within the elastic limit is not changed either by heat treatment or the presence of any of the alloying elements, except perhaps manganese in manganese steel and nickel in high-nickel steels. Heat treatment does increase the elasticity, however, so that a piece of heat-treated steel may return to its original * Landau, David, Influences affecting the fundamental deflection of leaf springs:; Bull. Soc. Automobile Eng., vol. 5, March, 1914, p. 430. t Landau, David, op. cit., pp. 431-434. 10 MANUFACTURE AND USES OF ALLOY STEELS form after having endured a stress that would have permanently deformed it in its untreated condition; that is, it is given some of the springiness of heat-treated springs. Many of the structural steels, particularly those used in automobile manufacture, have a great endurance against fatigue when subjected to repeated alternating stresses. The heat treat- ment increases their durability in this test even more noticeably than it does the properties determined by the tensile test. SELECTED BIBLIOGRAPHY * General Aeticles Dealing with Two or More Alloy Steels Metcalf, William. Alloy steels. Proc. Am. Soc. Test. Mat., vol. 4, 1904, pp. 204-214. GuiLLET, L60N. Les aciers speciaux. 2 tomes, Paris, 1904-1905; also in Rev. met., t. 1. 1904; t. 2, 1905. Grenet, L. Note sur la trempe de I'acier. Bull. Soc. I'ind. min., t. 4, ser. 4, 1905, pp. 973-999- Noble, H. Fabrication de I'acier. Paris, 1905, pp. 543-563. Guillet, Leon. Etude industrielle des alliages metalliques. 2 tomes, Paris, 1906. The industrial future of special steels. Iron and Steel Mfg., vol. 11, February, 1906, pp. 89-95. Quaternary steels. Jour. Iron and Steel Inst., 1906, pt. 2, pp. 1-141. Howe, H. M. Iron, steel, and other alloys. 2d ed., 1906. Ledebur, A. Handbuch der Eisenhiittenkunde. Leipzig, 1906, pp. 348- 399- Campbell, H. H. The manufacture and properties of iron and steel. 4th ed., 1907, pp. 343-391. Describes the influence of certain elements on the physical properties of steel. Fay, T. J. Special auto steel. Proc. Am. Soc. Mech. Eng., vol. 28, June, 1907, pp. 1745-1777. Haynes, Elwood. Material for automobiles. Trans. Am. Soc. Mech. Eng., vol. 29, 1907, pp. 209-216. Lake, E. F. Heat treatment of alloyed steels. Am. Machinist, 1907, vol. 30, pp. 152, 196, 289. Steels used in automobile construction. Am. Machinist, vol. 30, March 14, 1907, pp. 376-382. * This bibliography and those at the end of subsequent chapters were compiled by the United Engineering Library, 29 West Thirty-ninth Street, New York City. The references are arranged chronologically. LIST OF USEFUL ALLOY STEELS 11 GuiLLET, L£oN. Special alloy steels and their mechanical applications. Eng. Mag., vol. 36, October, 1908, pp. 65-75. Revillon, Louis. Les aciers speciaux au salon de I'autoniobile. Rev. m^t., t. 5, February, 1908, pp. S3~68. Turner, W. L. The static and dynamic properties of steels. Iron Age, vol. 82, July 2, 1908, pp. 53-SS- GiESEN, Walter. The special steels in theory and practice. Carnegie Scholarship Mem., Iron and Steel Inst., vol. i, 1909, pp. 1-59. GuiLLET, LfioN. Les aciers speciaux industriels. Rev. met., t. 6, June, 1909, pp. 810-813. Law, E. F. AUoys and their industrial applications. London, 1909, 269 pp. LONGMUIR, Percy. High-tension steels. Jour. Iron and Steel Inst., pt. I, 1909, pp. 383-403. Gives results of tests of nickel steels, nickel chromium, and chromium vanadium steels. Mathews, J. A. Alloy steels for motor-car construction. Jour. Franklin Inst., vol. 167, May, 1909, pp. 379-397. The nature and treatment of alloy steels. Iron Age, vol. 83, Jan. 7, 1909, pp. 24-26. PORTEVIN, A. M. Contribution a I'Etude des aciers speciaux ternaires. Rev. m6t., t. 6, December, 1909, pp. 1 164-1303. Carnegie Scholarship Mem., Iron and Steel Inst., vol. i, 1909, pp. 230-264. Includes bibliog- raphy. GuiLLET, L60N. Special steels. Iron Trade Rev., vol. 46, Feb. 3, 1910, pp. 367-369. Translated from a paper read before the International Association for Testing Materials. Haenig, A. Der Konstruktionstahl und seine Mikrostruktur, unter besonderer Beriicksichtigung des modernen Automobilstahls. Berlin, 1910. Souther, Henry. The selection and treatment of alloy steels for auto- mobiles. Jour. Franklin Inst., vol. 170, December, 1910, pp. 437-450. Specifications for materials — specifications for steel. Trans. Soc. Automobile Eng., vol. 5, 1910, pp. 168-175. Notes and instructions referring to materials spedfied hereinbefore. Trans. Soc. Automobile Eng., vol. 5, 1910, pp. 176-202. Alloy steels for railroad use. Am. Eng. and R. R. Jour., vol. 85, March, 1911, pp. 95-98. Abstract of paper read at joint meeting of the Engineering Club and Altoona Railroad Club. Harbord, F. W., and Hall, J. W. The metallurgy of steel. 4th ed., London, vol. 2, 191 1, pp. 387-417. Discusses special steels or steel alloys. Lake, E. F. Alloy steel for automobiles. Automobile, vol. 24, June 29, 1911, pp. 1436-1440. Sandelin, Folke. Specialstal for Konstruktionsandamal. Stockholm, 12 MANUFACTURE AND USES OF ALLOY STEELS 191 1, 173 pp. Includes a bibliography. Paper printed also in Jern Kontorets Annaler, vol. 66, 191 1, p. 524. Stoughton, Bradley. The metallurgy of iron and steel. 1911, pp. 389- 411, 514-516. Discusses alloy steels and presents a bibliography. International Railway Congress. The use of steel; special steels. Bulletin, vol. 25, August, 1911, pp. 849-881. Report and discussion. Edwards, E. T. Recognizing alloy steels by ingot structure. Iron Age, vol. 89, Feb. IS, 1912, pp. 399-402. Transactions of the Faraday Society. Magnetic properties of alloys; symposium. Vol. 8, 1912, pp. 94-219. Maes, G. Spezialstahle; ihre Geschichte, Eigenschaften, Behandlung und Herstellung. Stuttgart, 1912. Robin, Felix. Traite de metaUographie. Paris, 1912. Sauveur, Albert. The metallography of iron and steel. 1912. 386 pp. Society of Automobile Engineers. Fourth report of the iron and steel division. Revised notes and instructions referring to materials specified. Transactions, vol. 8, pp. 2, 1913, pp. 7-50. Includes a bibhography. Hudson, O. F., and Bengough, G. D. Iron and steel; an introductory textbook for engineers and metallurgists. London, 1913. Del Mar, Algernon. Wrought iron and steel for stamp-mill parts. Min. and Eng. World, vol. 40, April 11, 1914, pp. 687-693. Hall, J. H. The steel foundry. 1914. 271 pp. Landau, David. Influences affecting the fundamental deflection of leaf springs. Bull. Soc. Automobile Eng., vol. 5, March, 1914, pp. 428-464. CHAPTER II SIMPLE TUNGSTEN STEEL Mushet's air-hardening steel, the first of the alloy steels, may be considered as a simple tungsten steel, though it con- tained so much manganese (about 2 per cent) that it might with some reason be classed as a quaternary steel, as it contained also about 2 per cent of carbon and 6 per cent of tungsten. The manganese was essential to give the self -hardening property. The steel is now becoming obsolete, having had a useful career and having formed an indispensable link in the development of the high-speed tool steels discussed later. Tungsten is very heavy, its specific gravity being, according to recent determinations, about 19.3, and it is the most infusible substance known except carbon and, perhaps, boron. These properties have some effect on the production of tungsten steel. MANUFACTURE OF TUNGSTEN STEEL Tungsten steel is generally, if not always, made by the crucible process. The pots are charged cold by packing in the materials, the tungsten being placed at the top to counteract in a measure its tendency to settle because of its high specific gravity. If this tendency operated unchecked there might be at the bottom of the pot a rather infusible mush of high-tungsten alloy which would not pour out, and if it did the ingot would have an irregular composition because of the uneven distribu- tion of the tungsten. The steel is melted and then "killed" in the crucibles by holding them in the furnace for 30 or 40 minutes after the charge has melted, until the steel ceases to bubble or work and lies dead in the pot. 13 14 MANUFACTURE AND USES OF ALLOY STEELS The pots are sometimes cast singly or doubly by hand pour- ing or collectively by means of a ladle into which all the pots of a furnace charge are emptied. Good tungsten steel makes remarkably sound solid ingots, except for the pipe, though tungsten itself is not considered to aid in removing or control- ling either the oxides or the gases. It is added solely for its effect on the finished and treated steel. This lack of power of tungsten to deal with oxides and gases arises no doubt from its low calorific power, its heat of com- bustion being given (with qualification) as about i,ooo calories, whereas iron burned to Fe304 gives 1,612 calories. METHOD OF WORKING Simple tungsten steels of commercial grades are heated, forged, and rolled in much the same manner as other high- carbon steels, presenting no special problems or difficulties. PROPERTIES AND USES Simple tungsten steel is at present chiefly used in perma- nent magnets for electric meters, in small dynamos, and hand use, for which it has been used for 30 or 40 years. The con- sumption in 1913 is thought to have been between 5,000 and 6,000 tons. This steel contains about 0.6 per cent of carbon and 6 per cent of tungsten. Some has been made in recent years containing 0.2 to 0.3 per cent of vanadium, chromium, or molybdenum which were considered at the time to give greater retentivity to the steel, but those ingredients are now generally held to be of no practical value, adding nothing to the fitness of the steel for its purpose. Some buyers of magnet steel do not specify composition but only performance, that is, what magnetic properties the steel must have. To make permanent magnets retain their magnetism as much as possible they are made very hard by heating and quenching. They are then magnetized, and if they are to be used for electric SIMPLE TUNGSTEN STEEL 15 meters they are seasoned by a treatment involving protracted heating to ioo° C. (212° F.) to make their magnetism as nearly constant as possible. A variety of tungsten steel containing about i per cent of carbon and 3 to 4 per cent of tungsten is made and used as a tool steel for taking finishing cuts on iron and steel in the machine shop. It acts more like a simple steel than a self-hardening steel, as it requires to be hardened by quenching in water and then drawn in the same general way that simple steels have been . drawn, presumably for thousands of years. It will cut at a higher speed than a simple steel, say 40 feet per minute on steel having a tensile strength of 80,000 pounds per square inch, and is also more durable. The presence of tungsten in steel is generally stated to lower the fusion point of the steel. Mars* gives a table of fusion points of tungsten steels with contents of tungsten ranging from 0.5 to 17 per cent, from which he concludes that tungsten lowers the fusion point. However, when his results are corrected for the lowering effects of the contained carbon, silicon, and manganese doubt arises as to the correctness of his conclusion. Thus, a steel containing 0.66 per cent C, 0.03 per cent Si, 0.04 per cent Mn, and 3.1 1 per cent W fused at 1,488° C. The car- bon would lower the fusion point about 60° C, and the silicon and manganese slightly, so that the plain iron-tungsten alloy should have a fusion point a little above 1,548° C, which is about 20° C. above that of pure iron. Seemingly this is the effect of 3.11 per cent tungsten. The erosion of the bore of cannon by the powder gases is held to depend largely on the fusion point of the metal of the tube or hner, the higher the point the greater being the resist- ance to erosion. So it has been found that the nearer the metal comes to being pure iron the higher its fusion temperature and the better it resists erosion, but the strength required compels a certain amount of hardening and strengthening elements to be present in the steel. Tungsten raises the strength and pos- * Mars, G., Die Specialstahle, ihre Geschichte, Eigenschaften, Behandlung und Herstellung. Stuttgart, 191 2. 16 MANUFACTURE AND USES OF ALLOY STEELS sibly the temperature of fusion and so has been employed for the tubes of cannon, particularly by the Government of Austria. Arnold and Read* found that steel with 0.71 per cent carbon and 5.4 per cent tungsten had in the annealed state a tensihty of 88,900 pounds per square inch, an elastic limit of 60,200 pounds, an elongation of 20 per cent, and a contraction of area of 34.7 per cent, values that compare favorably with those of the steels usually employed in the manufacture of carmon. They give data regarding a series of annealed tungsten steels as follows: The strength and hardness of these steels may be greatly increased by heat treatment involving quenching and with only relatively small decrease in ductiUty. THEORY OF TUNGSTEN STEEL Arnold and Read concluded that the carbon in the steels they examined was combined with iron when the tungsten was low, but that the higher the tungsten the more of the carbon was combined with it until in steel containing 11. 5 per cent of tungsten none of the carbon was combined with iron, but all of it with tungsten. With still higher tungsten content the excess of tungsten was combined with iron. BIBLIOGRAPHY ON TUNGSTEN STEEL Forbes, David. Quarterly report on the progress of the iron and steel industries in foreign countries. Jour. Iron and Steel Inst., voL 2, 1872, pp. 255-294. Gives chemical analysis of Mushet's " special steel " or tungsten steel. Hadfield, R. A. Alloys of iron and tungsten. Jour. Iron and Steel Inst., 1903, pt. 2, pp. 14-1 18. Presents bibliography of tungsten and tungsten steels dating from 1590. GuiLLET, Leon. Aciers au tungstene. Rev. met., vol. i, 1904, pp. 263-283. Constitution et proprietes des aciers au tungstene. Comp. rend., t. 139, Sept. 26, 1904, pp. 519-521. * Arnold, J. O., and Read, A. A., The chemical and mechanical relations of iron, tungsten and carbon, and of iron, nickel and carbon: Proc. Inst. Mech. Eng., pt. 2, March-May, 1914, pp. 223-248. SIMPLE TUNGSTEN STEEL 17 m h-l W W w H O H Q W < o Q O < •d 1 g ^ >. t3 S ja J3 ,2 2 ^ 60 ^ ^ » >< J3 J3 J=" ■s, 1 Moderate! Tough 5 Very toug' Very toug' Very toug hard 2^ g u > . *j U tw c ontra ion Area. S CO CO (N ^ CO •* t-t H o *- p< . .^J s S.-Sj « lo lo o § g g 0< d> •-^ .^ hH A< O « P, o ^'888 8 u ^ c M S 8 CO •J i oo" G~ g" Tl tC Tj cS ■* « » tn >^ >, » 8 8 8 8 8 8 XI S T|- -* I>- O M 00 ^ ^ 0^3 ^ M W M h G loco^vo t^^OvOO »0»^0*0 -• L, .O 1^ IH (U 4) 4* Sj _ O lU +j *J *J ^ tj ■<-> ■*-> rt 2 2 «i S £? i? & & fr ^ ^ & & c .c .S c '5 .E .S ■O "O T3 Ti 3 TJ ^3 (U « "l> QJ ^-' 0) ■' J- j3 J3 (H u) J- jU o o o tj o' o o d C C c t C C S 3 3 3 ,M 3 3 octoofe aa 3 " 9 3 p.-" M G -a - ^ g d a t : a ^ M 00 o c i -s s ^1 ^ ^2 S J iJ 3 -a S o c - am s 5 E o 48 MANUFACTURE AND USES OF ALLOY STEELS. One per cent of nickel in ordinary nickel steel in the natural state raises the tensility about 6,000 to 8,000 pounds per square inch. The table shows that ordinary nickel steels may be so made as to have a wide range of properties that make them suitable for any structural purposes for which they are not too expensive. The properties of one grade of nickel-steel castings made for special purposes are as foUows: Composition, C 0.20 per cent, Mn 0.50 per cent, Si 0.35 per cent, Ni 2.50 per. cent; tensile strength, 85,000 pounds per square inch; elongation, 25 per cent; contraction, 40 per cent. This steel was not given treat- ment involving quenching, but was merely armealed. Steel containing 5 to 8 per cent of nickel presents a sort of critical point, that proportion being the lowest at which, with the usual range of carbon, the structure is all martensitic and consequently very hard, the martensitic state being equivalent to the hardened state of simple steels. Such steel is difficult to work hot or cold, but can be rolled if proper care is used. It finds some usefulness in places where great resistance to shock is required, particularly in thin shield plates about 0.15 inch thick which are used on one side of the caisson of field artillery to protect the ammunition, and the men who serve it, from rifle fire. A sample analyzed for "Tests of Metals"* gave the following composition in percentages: C 0.42, Mn 0.49, Si 0.26, S 0.02, P 0.02, Ni 6.68. The content of carbon determines the minimimi amount of nickel which must be present to make the steel wholly martensi- tic. Thus if the carbon content is low, about 0.20 per cent, 8 per cent of nickel is required, whereas if the carbon content is about 0.80 per cent the steel is martenistic when there is 5 per cent of nickel contained. The analysis given last above represents martensitic steel. Guilletf gives the properties of a similar steel, with 6 per cent of nickel and 0.38 per cent carbon, as follows: * Report of the tests of metals and other materials for industrial purposes, 1907, War Department, igo8, p, 42. t Guillet, Leon, Nouveaux essais au choc a temperature variables: Rev. m6t. t. 7, October, 1910, pp. 837-844. SIMPLE NICKEL STEELS 49 PROPERTIES OF NICKEL STEEL CONTAINING 6 PER CENT OF NICKEL Condition. C Ni Tensile Strength. Elastic Limit. Elonga- tion. Contrac- tion. Shock. Annealed Air hardened at 850° C Quenched in water Per Cent 0.38 Per Cent 6.0 Pounds 113,760 177,750 199,080 Pounds 99,540 156,420 177,750 Per Cent 20 II 10 Per Cent 65 53 50 30 19 17 He does not say whether this steel was martensitic, but the high elastic limits indicate that it was probably largely so, even in the annealed condition. Steel with 8 per cent nickel has one transformation point at 510° C. (950° F.) where points Ari, Ar2, and Ara are all merged into one. Eight per cent is the highest useful content of nickel in nickel steel that is amenable to ordinary annealing and quench- ing operations. Hardening by quenching does not occur in steels containing 10 per cent or more of nickel which are on the contrary softened by heating and quenching. NICKEL-IRON ALLOY DISCOVERED BY ARNOLD AND READ The 13 per cent nickel-iron alloy with 0.55 per cent carbon discovered recently by Arnold and Read* is noteworthy as it seems to possess the highest strength of any of the nickel steels. It is so hard as to be unmachinable and the investigators men- tioned were not able to drill it even to get some drillings for analysis, the composition mentioned being what they aimed at when making the steel. It has a yield point of about 134,000 pounds per square inch, a tensile strength of about 195,000 pounds, with 12 per cent of elongation in 2 inches. This gives a merit figure of about 2,300,000, which is very high for such a hard steel, though it does not compare with the 7,000,000 of forged manganese steel. Steel of this composition might have * Arnold J. O., and Read, A. A., The chemical and mechanical relations of iron, tungsten, and carbon, and of nickel, iron, and carbon: Proc. Inst. Mech. Eng., March-May, 1914, PP- 223-279. &0 MANUFACTURE AND USES OF ALLOY STEELS been expected to show maximum strength as a result of Had- field's experiments,* though he did not include this grade in his series of samples. He found that low-carbon steels with 11.4 and 15.5 per cent of nickel each had a tensihty of 210,560 pounds, which was more than was possessed by the steels next above and below. The curve therefore should have reached a maximimi between them with a nickel content of about 13.5 per cent. Arnold and Read's steel should, of course, have a higher tensility, or about 215,000 pounds, to harmonize with Had- field's, and further tests are needed to estabhsh the exact path of the curve. Arnold and Read note that the composition of this steel nearly corresponds with the formula FerNi. With such properties as it possesses this steel is likely to find at least a limited field of usefulness. PROPERTIES OF DIFFERENT STEELS HAVING DIFFERENT PERCENT- AGES OF NICKEL Before Arnold and Read's discovery of the 13 per cent grade, 1 5 per cent nickel steel was thought to have the greatest strength of all the nickel steels — that is, in the natural state. This variety has been employed in a few instances for shafting and similar service for which other steels failed, but the amount of it used is negligible in statistics. It is hard to machine, and heating followed by slow cooling does not soften it, though heating and quenching does enough to allow it to be machined slowly. It has a tensility of about 170,000 pounds and an elastic hmit of 150,000 pounds per square inch, according to one observer, though, as stated above, Hadfield obtained 210,560 pounds, tensihty, with httle ductility. It is hkely that the properties, desired when this steel was used, particularly its ductility, could now be surpassed by the much cheaper heat-treated ordi- nary nickel or nickel-chromium steels. Eighteen per cent nickel-iron alloy, although not useful, is. * Hadfield, R. A., Alloys of iron and nickel: Proc. Inst. Civ. Eng., vol. 138,, 1899, pp. 1-124. SIMPLE NICKEL STEELS 51 worthy of note here because of its anomalous action (according to Sexton and Primrose*) when cooled from 200° C. (392° F.). At first it contracts uniformly until its temperature falls to 130° C. (266° F.). Then it expands while cooling to 60° C. (140° F.), when it again contracts as the temperature falls. Twenty-two per cent nickel steel is used when resistance to rusting or corrosion is desired. A noted example is the valve stems of the salt-water fire-protection service of the city of New York where the apparatus may not be allowed to become inoperative or hard of action from the formation of rust. It is also used sometimes for the spark poles in the spark plugs of internal-combustion engines, including automobiles, though commercial nickel wire is more commonly used. High-nickel steels having 25 per cent or more of nickel and low carbon content (about 3 per cent) are austenitic in structure and in the natural state are softer and tougher than the medium- nickel martenistic steels. High-nickel steel containing 24 to 32 per cent nickel in the form of wire is used for electrical resistance in small quantity, probably between 5 and 10 tons per year in this country. The analysis and resistance of samples of Krupp nickel- steel resistance wire are shown below. This wire is used in elec- tric toasters, cookers, irons, and similar devices. ANALYSIS AND RESISTANCE OF SAMPLES OF KRUPP NICKEL-STEEL RESISTANCE WIRE Specific Sample No. C Mn Si s P Cr Ni Resistance per Cubic Centimeter. Per Cent Per Cent Per Cent Per Cent Per Cent Per Cent Per Cent Microhms. I 0.52 0.7s O.IO 0.03s 0.024 30.6 87.9 2 •39 1. 00 .70 •03s .025 24.2 Steel with 27 per cent of nickel is used in bits, stirrups, and spurs in riding harness because of its resistance to rusting. It * Sexton, A. H., and Primrose, J. S., The metallurgy of iron 52 MANUFACTURE AND USES OF ALLOY STEELS will nevertheless rust slowly at ordinary temperature under conditions that strongly induce oxidation. Steels containing more than 24 per cent of nickel are prac- tically normiagnetic in their ordinary condition, a rather remark- able fact when the high magnetic susceptibility of both iron and nickel alone is considered. The explanation that the critical point marking the change from the nonmagnetic to the mag- netic state of iron is lowered by the nickel from about 700° C. (1,292° F.) to below ordinary atmospheric temperatures is, no doubt, sound as far as it goes. When 25 per cent nickel steel is cooled to —40° C. (—40° F.) it becomes magnetic, and retains its magnetism at ordinar}'^ atmospheric temperatures. On being heated to sSo'' C. (1,076° F.), however, the alloy reverts to the nonmagnetic state. This separation of 620° C. between the critical points marking the magnetic states in heating and cooling is great in comparison with the 25° to 50° C. of simple steels, and because of it this steel is classed as irreversible. The nonmagnetic quality of high-nickel steels is not utilized chiefly because of its capacity for becoming magnetic, as described above, for if it happened to be cooled enough to make it mag- netic it could not in most cases be easily demagnetized. The fact that high-nickel austenitic steels have a somewhat lower modulus of elasticity than the low-nickel or simple steels does not affect their value for the uses made of them. These steels also have low elastic limits, though they are tough and show up well in the shock test. Nevertheless they are generally used not because of superior physical properties, but because of their resistance to rusting and corrosion or their electrical resistance. With a carbon content of 0.25 to 0.30 per cent and 32 per cent nickel they are used in valves for gasoline motors with good results. Nickel steel with 30 per cent of nickel is used in boiler tubes, particularly in marine boilers, for which it is admirable. These tubes are in the natural, not heat-treated state. They resist corrosion better than simple steel tubes and last three times as long. Hence their use is sometimes economical in spite of the much higher cost. SIMPLE NICKEL STEELS 53 INVAR The 36 per cent nickel steel known as Invar is used to the extent of perhaps a few hundred pounds a year in clock pen- dulums, rods for measuring instruments, and such parts for which its exceedingly slight expansion and contraction when heated and cooled within the atmospheric range gives it a par- ticular value. Nevertheless, its coefficient of expansion, even though small, is not negligible, and compensating means must be used in Invar clock pendulums and in the Invar balance- wheels of watches. A watch with an Invar balance-wheel varied 20 seconds per day during a temperature change of 40° to 90° F., the usual test change, a variation too great for a good watch. Some Invar has as low a coefficient of expansion as 0.0000008 per degree C, and samples have been made that con- tracted slightly when warmed. The coefficient given indicates an expansion of 0.05 inch in a mile per degree C. When Invar is heated to about 300° C. (572° F.) and higher its coefficient of expansion is greatly increased and its lack of expansion at ordinary temperatures appears to be merely a belated and not destroyed function. With excessive cold there is likewise a resumption of contraction. PLATINITE Forty-six per cent nickel steel with 0.15 per cent carbon known as platinite, has about the same coefficient of expansion as platinum and glass and for that reason may be imbedded in glass without breaking the latter by a difference in expansion. It has been used in leading wires in the glass bases of electric incandescent lamp bulbs as a substitute for platinum, which was formerly held to be indispensable. In those lamp bulbs the preservation of the vacuum is necessary and the joint between the wire and glass must be kept tight. Platinite has not been found wholly suitable for this purpose and is not now so used, a compound wire with a 38 per cent nickel-steel core encased in copper and sometimes coated with platinum being now generally 54 MANUFACTURE AND USES OF ALLOY STEELS employed. The nickel-steel core, if free, will expand less than the glass and the copper more, so that each resists the other, and the wire as a whole will have the desired rate of expansion. About 2 tons of nickel steel per year is used in this wire. Many other alloys of iron and nickel have been studied by Guillet and others.* In fact the whole range has received more or less thorough attention, and much knowledge of scientific value has been gained concerning the varieties that so far have not found useful application. BIBLIOGRAPHY ON NICKEL STEEL Browne, D. H. Nickel steel; a synopsis of experiment and opinion. Trans. Am. Inst. Min. Eng., vol. 29, 1899, pp. 569-648. Includes a bibliography dating from 1889. Souther, Henry. Nickel and iron alloys. Mineral Ind., vol. 8, 1899, pp. 438-439. Briefly discusses the uses of nickel steel. Dumas, L. Recherches sur les aciers au nickel a haute teneurs. Ann. des mines, t. i, ser. 10, 1902, pp. 357-561. Includes a bibUography. Porter, H. F. J. Nickel steel; its practical development in the United States. Cassier's Mag., vol. 22, 1902, pp. 480-500. Colby, A. I. A comparison of certain physical properties of nickel steel and carbon steel. 1903. Contains numerous bibliographies. Nickel steel; its properties and applications. Proc. Am. Soc. Test. Mat., vol. 3, 1903, pp. 141-168. Noncorrosive nickel-steel boiler tubes. Trans. Soc. Naval Arch, and Marine Eng., vol. 11, 1903, pp. 115-137. War Department. Report of the tests of metals and other materials for industrial purposes, 1903. 1904, pp. 167-309. Discusses carbon and nickel-steel ingots. GuiLLAUME, C. E. Les applicationes des aciers au nickel. Paris, 1904. Johns, Cosmo. Notes on the production and thermal treatment of steel in large masses. Jour. Iron and Steel Inst., 1904, pt. i, pp. 61-97. One table gives results of tests of hollow forged nickel steel forgings. Carpenter, H. C. H., Hadfield, R. A., and Longmuir, Percy. Seventh report to the Alloys Research Committee; on the properties of a series of iron-nickel-manganese-carbon alloys. Proc. Inst. Mech. Eng., 1905, pts. 3 and 4, pp. 857-1041. Dixon, Edward. Nickel and carbon steels. Engineering, vol. 82, July 6, 1906, pp. 22-23. * See bibliography following. SIMPLE NICKEL STEELS 55 WATEEHOtrSE, G. B. The influence of nickel and carbon on iron. Elec- trochem. and Met. Ind., vol. 4, 1906, pp. 451, 482. Nickel steel and its application to boiler construction. Iron Age, vol. 77, Feb. 8, 1906, pp. 490-491. Lake, E. F. The forging of alloy steels. Am. Machinist, vol. 30, pt. 2, Aug. 29, 1907, pp. 289-291. Gregoretti, U. F. La Corazza " Krupp cementata " esaminata al micro- scopio. Rivista Marittima, vol. 41, November, 1908, pp. 227-238. Translation in Rev. met., t. 7, 1910, pp. 260-285. Describes Krupp process of armor-plate manufacture at the Terni Steel Works. Preuss, Ernst. The strength of nickel-steel riveted joints. Carnegie Scholarship Mem., Iron and Steel Inst., vol. i, 1909, pp. 60-142. Includes a bibliography. Preuss, Ernst. Zur Kenntnis der Festigkeitseigenschaften des Nickel- stahles. Stahl und Eisen, Jahrg. 29, Mar. 24, 1909, pp. 422-425. Webster, W. R. Nickel-steel eyebars for Blackwell's Island Bridge. Trans. Am. Soc. Civ. Eng., vol. 64, 1909, pp. 289-302. Waddell, J. A. L. Nickel steel for bridges. Trans. Am. Soc. Civ. Eng., vol. 63, 1909, pp. 101-387. GuiLLET, LfioN, and R£villon, Louis. Nouveaux essais au choc a tem- peratures variables. Rev. met., t. 7, October, 1910, pp. 837-844. BoHNY, F. Ueber die Verwendung von Nickelstahl im Briickenbau. Stahl und Eisen, Jahrg. 31, 1911, pp. 89-97, 184-193- Paper read before the Verein Deutscher Eisenhuttenleute. McWiLiJAM, Andrew, and Barnes, E. J. Some properties of heat-treated 3 per cent nickel steels. Jour. Iron and Steel Inst., 1911, pt. 1, pp. 269-293. Colver-Glauert, E., and Hilpert, S. The thermal magnetic transfor- mations of 25 per cent nickel steel. Jour. Iron and Steel Inst., 1912, pt. 2, pp. 295-301. Cone, E. F. Properties of nickel cast steel. Iron Age, vol. 90, Aug. 8, 1912, pp. 287-288. Hodge, H. W. Tests of two large nickel-steel columns. Eng. Rec, vol. 67, March 1, 1913, PP- 234-235. Arnold, J. O., and Read, A. A. The chemical and mechanical relations of iron, tungsten, and carbon, and of iron, nickel, and carbon. Proc. Inst. Mech. Eng., March-May, 1914, pp. 223-279. Engineering Record. Ultimate strength of carbon and nickel-steel models of Quebec Bridge members. Vol. 69, Mar. 21, 1914, pp. 333- 336; vol. 70, Nov. 14, I914> pp. S4I-S43- CHAPTER VI NICKEL-CHROMIUM STEELS Nickel-chromium steels, known in the trade as chrome- nickel steels, are perhaps the most important of the structural alloy steels. Their field of usefulness is continually being en- larged by their application for new purposes and also by encroach- ment on the premises of some of the other alloy steels, notably of simple nickel steel, and they have almost wholly displaced nickel-vanadium and nickel-chromium-vanadium steels, which several years ago were in some considerable demand. The amount of nickel-chromium steels produced in 1913 was thought to be about 100,000 tons of ingots, all made in the open-hearth furnace with the exception of 2,000 or 3,000 tons melted in crucibles and electric furnaces. The steel is made by 10 or 12 companies, 2 of which make it at several different plants. Nickel-chromium steels are seldom used in any but a heat- treated condition. By suitable treatment pieces of small mass can be made to have as high physical properties as any steels known, with any elastic limit between 40,000 and 250,000 pounds per square inch, accompanied by ductiUty that is high as compared with its strength, as the ductility naturally lessens as the elastic limit increases. Nickel-chromium steels can be made somewhat more cheaply than simple nickel steel of the same strength and ductility con- taining a smaller total of the alloying elements, and chromium is less costly than nickel. COMPOSITION AND PROPERTIES The upper limit of nickel in useful chrome-nickel steels is about 3.5 per cent, and all useful steels of this class are pearlitic 56 NICKEL-CHROMIUM STEELS 57 according to Guillet.* According to the same authority, when a chrome-nickel steel is casehardened, the case is harder than that of a simple nickel steel. Some of the defects and troubles of chrome-nickel steels are like those of simple nickel steels previously considered. The composition and properties of six nickel-chromium steels in the natural or untreated state are given in the table following: COMPOSITION AND PROPERTIES OF NICKEL-CHROMIUM STEELS IN NATURAL OR UNTREATED STATE Composition. Tensile Properties. Sam- ple. Con- Elon- Remarks. C Mn Si S P Ni Or Tensile Strength Elastic Limit. trac- tion of gation in 2 Ball Hard- Area. Inches. ness. % % % % % % % Pounds Pounds % % I O.SS 0.41 0.22 0.03 0.02 I. S3 1. 14 96,000 75.000 66 31 185 Annealed 2 .18 .27 .05 .04 .02 1.28 1.59 72,000 51,000 71 37 134 Annealed .1 • IS .34 .13 .02 .01 1.28 .37 59,000 42,000 64 38 115 Annealed 4 .29 .42 .07 .06 .02 3.86 1.48 Natural S .25 .32 .10 .03 .02 1.45 1.20 96,500 81,500 68 25 Test piece 6 .25 .32 .10 .03 .02 1-45 1.20 97,loo 8o,goo 49 '7 Eyebar; full size 1 In 21 feet. Sample 4 is from a plate similar to that used in the mast of the yacht Vaniiie. It was not heat treated, but was used as rolled. Samples 5 and 6 represent the same steel and show the rela- tive properties of the small test piece and the full-size eyebar for a bridge the section of which was 14 by 2 inches. The dif- ference in elongation is particularly noticeable, the great local stretch near the point of rupture being only a small part of the total length of the bar. The composition and properties of six nickel chromium steels in the heat-treated condition were as follows: ♦ Guillet, L^on, Aciers nickel chrome: Rev. de m6t., t. 3, 1906, pp. 462-484. 58 MANUFACTURE AND USES OF ALLOY STEELS COMPOSITION AND PROPERTIES OF NICKEL-CHROMIUM STEELS IN HEAT-TREATED CONDITION Composition. Tensile Properties. Heat Treatment. 1 B a CO C Mn Si s P Ni Cr Ten- sility. Elastic Limit. Con- trac- tion of Area. Elon- gation in 2 Ins. Ball Hard- ness. Tem- per- ature at which Steel was quench ed in Water. Tem- per- ature at which Tem- per was Drawn in Air. I 2 3 4 S 6 o Vo 40 36 21 48 48 38 o 7" 74 53 41 44 44 28 % 0.24 . II .22 .16 .16 .27 % 0.03 .04 • 03 .OI .01 .02 % 0.02 .01 .02 .01 .01 .01 % 3-45 l.SS 3. 52 2.02 2.02 3-OI % 1.20 .70 I. II .98 .98 .6s Pounds 187,000 145,000 110,000 212,000 140,000 114,000 Pounds 175,000 125,000 75.000 186,000 120,000 90,000 % 43 65 66 46 61 69 % 10 20 24 10 18 25 352 233 215 145 287 266 °C. 830 830 830 843 843 843 °C. 371 566 682 427 649 649 Any one of the first three samples could be given substan- tially the properties of either of the other two by varying the temperature of the second heating. Most of the nickel-chromium steel goes into armor plate, projectiles, and automobile parts. USE IN AUTOMOBILES For automobiles — and the practice might be advantageously extended to other fields — three grades of nickel-chromium steel are used. They are called low, medium, or high according to their contents of nickel and chromium. The carbon content may be varied for each grade within the limits shown in the following table: COMPOSITION OF NICKEL-CHROMIUM AUTOMOBILE STEELS Grade. C Mn Si S P Ni Cr . 20 to . 40 . 2G to . 4G . 20 to . 4Q 65 .65 .65 Low Low Low 0.045 .045 .045 0.04 .04 .04 1.25 1.75 3SO 0.6 I.IO I 50 High NICKEL-CHROMIUM STEELS 59 These steels are almost invariably heat treated for use in automobiles, a wide range of properties being attainable by varying the heat treatment with each steel. The properties overlap those of steels of both harder and softer grades, so that a wide choice of properties is afforded as well as a choice of steels for the set of properties desired. USE IN ARMOR PLATE An important use for chrome-nickel steel is in both thick and medium armor plate for war vessels. The thick heavy side armor, 6 to 14 inches thick, is face hardened bj- the well-known methods. A recent analysis of the body of a plate gave: C 0.33 per cent, Mn 0.32 per cent, Si 0.06 per cent, S 0.03 per cent, P 0.014 per cent, Ni 4 per cent, Cr 2 per cent, and its tensile properties after treatment were : Tensile strength, pounds per square inch 101,000 Elastic limit, pounds per square inch 77,Soo Elongation in 2 inches, per cent 24 Contraction of area, per cent 60 The results from such a great mass of metal were excellent. Medium armor, between 3 to 5 inches thick, is rather similar in composition. It is not face hardened, but is given high properties as a whole by the heat treatment to which it is sub- jected. An analysis lately made gave: C 0.30 per cent, Mn 0.34 per cent. Si 0.13 per cent, S c 03 per cent, P 0.03 per cent, Ni 3.66 per cent, Cr 1.45 per cent. Its physical properties were those given below as sample i. Sample 2 represented another chrome-nickel steel made for the same purpose, containing 3^ per cent of nickel. Sample i. Sample 2. Tensile strength, pounds per square inch. . . iig.ooo 138,000 Elastic limit, pounds per square inch 106,000 119,000 Elongation in 2 inches, per cent 22 22 Contraction of area, per cent 61 49 Such steel is most excellent for use on warships to form pro- tective decks and barriers to protect from secondary battery fire. Chrome-nickel- vanadium steel is also used for this pur- pose, as noted elsewhere. 60 MANUFACTURE AND USES OF ALLOY STEELS USE IN PROJECTILES AND IN RAILS Nickel-chromium steel is used in the manufacture of most armor-piercing projectiles. Cubillo* cites a steel for projectiles, having 0.48 per cent C, 0.58 per cent Mn, 0.75 per cent Cr, 2.55 per cent Ni, 0.40 per cent Si, 0.04 per cent P. A test piece quenched in oil and tem- pered had an elastic Hmit of 129,400 pounds per square inch, a tensile strength of 150,300 pounds per square inch, and an elongation of 19 per cent. For large projectiles Girodf prefers chromium-tungsten steel having 0.50 per cent C, 4 per cent Ni, o to 1.5 per cent Cr, and 0.25 per cent W. It is curious that nickel is considered to improve the quality of shot, although generally held to injure the quahty of high- speed tool steels. In use there seems to be a parallel between the requirements of the two, except for the important and vital difference as to the required speed at which they respectively meet the metal to be penetrated. The speed of impact of the shot enables it to enter when no amount of pressure will effect the same result. Chrome-nickel steel rails having 2 per cent of nickel and 0.7 per cent of chromium have been tried by several railroads, but with unsatisfactory results. They resisted wear well as compared with simple steel rails, but broke badly both trans- versely and lengthwise, so that they were considered unsafe and consequently were removed. They were made by the Bessemer process and were not heat treated. DETAILS OF MANUFACTURE OF A SPECIFIC PIECE OF NICKEL- CHROMIUM STEEL Following is a description of the manuiacture of a large shaft of mild chrome-nickel steel for marine purposes. A cor- * Cubillo, L., Armor-piercing projectiles: Jour. Iron and Steel Inst., 1913, p. 251- t Girod, P., Discussion of paper on armor-piercing projectiles: Jour. Iron and Steel Inst., 1913, p. 252. NICKEL CHROMIUM STEELS 61 ruga ted 3S-ton ingot 45 inches in diameter was made of basic open-hearth steel having 0.24 per cent C, 0.70 per cent Mn, 0.013 per cent P, 0.015 psr cent S, 0.18 per cent Si, 1.60 per cent Ni, and 0.32 per cent Cr. A few hundredths per cent of titanixmi was added in the ladle, but did not appear in the steel. The shaft when finished was 14I inches in diameter, with an 8-inch hole through on the center line. The steel was melted without the addition of ore late in the heat, a method that favored soundness and tended to allow the steel to clean itself of insoluble impurities such as oxides and silicates. The ingot was forged, annealed at 866° C. (1590° F.), bored, rough-turned, heated to 750° C. (1382° F.), quenched in oil, and drawn at 593° C. (1100° F.). The shaft was merely raised to the drawing temperature, 593° C, when firing at once ceased, the furnace was closed, and the shaft allowed to cool with the furnace. The averages of the tests, which were longitudinal, were as follows: Tensile strength, 83,300 pounds per square inch, elastic limit, 52,500 pounds per square inch, elongation in 2 inches 26 per cent, contraction 60 per cent. The results were excellent, though seemingly a lower drawing temperature, which would have resulted in a higher elastic limit, would have been justified. MAYARI STEEL A so-called natural chrome-nickel steel is now made from certain ores mined at Mayari, Cuba. The ores carry enough nickel to give 1.3 to 1.5 per cent of nickel, and enough chromium to give 2^ to 3 per cent of chromimn in the crude iron smelted therefrom. When the iron is converted into steel by the pneu- matic or open-hearth processes, the nickel is practically all present in the steel, but the chromium is of necessity largely wasted by being oxidized. Steel made in part of Mayari iron is giving good service in rails and particularly in track bolts, which are heat treated to give the metal an elastic limit of 75,000 pounds per square inch. Why these rails are satisfactory when other chrome-nickel 62 MANUFACTURE AND USES OF ALLOY STEELS steels were not has not been explained. The chief differences seem to be (i) that these Mayari steel rails have less of the alloying elements because Mayari iron is used only in part in them, and (2) that the steel is made in the open-hearth furnace. The use of steel containing Mayari iron is increasing, and the demand is enough to induce the production synthetically of steels of the same composition by adding nickel and chromiimi to simple steels in the Mayari proportions. The Mayari steels are not included in the estimated quantity of the chrome-nickel steels made, as already given. In fact it is likely that in the near future the tonnage of Mayari steels will surpass that of all the other chrome-nickel steels taken together. CASTINGS OF NICKEL-CHROMIUM STEELS Castings are made also of chrome-nickel steel and may be used in the annealed or heat-treated condition. COMPOSITION AND PROPERTIES OF CHROME-NICKEL STEEL CASTINGS Sam- Composition. Tensile Properties. ple No. C Mn Si S P Ni Cr Tensile Strength. Elastic Limit. Con- traction of Area. Elonga- tion in 2 Ins. Condition. I 2 % 0.30 ■ 33 .30 % 0,41 ■ 39 .20 % 0.3S % 0.04 .□4 % 0.03 .03 % 3.64 3. 58 2.50 % 1.49 1. 61 .so Pounds 91. 500 90,500 110,000 Pounds 45.550 46,500 80,000 % 24 27 30 % 16.5 18. 5 20 Annealed Annealed Heat-treated BIBLIOGRAPHY ON NICKEL-CHROMIUM STEEL GuiLLET, Leon. Aciers nickel chrome. Rev. met., t. 3, 1906, pp. 462-484. Lake, E. F. Nickel-chrome steel Machinery (N. Y.), voL 13, July, 1907, pp. 615-617. SCHAEFBERS, JOSEPH. Alloy-steel tubing for the automobile industry. Horseless Age., vol. 26, Dec. 7, 1910, p. 782. Iron Age. Mayari steel; its properties and uses. Vol. 89, Jan. 4, 1912, pp. 69-72. CHAPTER VII SILICON STEELS Although silicon is an ingredient of practically all steels its presence is often accidental or unavoidable, and if it is added to simple structural and tool steels the purpose is to promote soundness rather than to improve the properties of the finished steel. In tool steels silicon is always present, and in times past high-silicon steels have been advocated for tools, but they are not now so used in a commercial way. MANUFACTURE OF SILICON STEEL Silicon steels are generally made in the open-hearth furnace, preferably on an acid hearth, as the acid slag does not waste the silicon in the final additions as rapidly as does a basic slag that contains free oxide of iron, and therefore the final content of silicon desired may be more closely controlled. Silicon in true silicon steels must be added to the charge only a short time before teeming, as any oxygen that reaches the metal will largely be taken up by the silicon which will be wasted by burning to silicic acid (Si02). When so added to a bath in proper condition as to temperature and amount of dissolved oxygen or oxides the silicon will overwhelm the gases in solution, and the steel as cast will be free from blowholes and with a maximum tendency to pipe. Because of the large proportion of silicon in silicon steels and because of the short time allowable after the silicon has been added to the bath it should be added in the heated or molten state. Silicon steels containing about 2 per cent of silicon or more 63 64 MANUFACTURE AND USES OF ALLOY STEELS roll very "dry," that is, they are hable to be cracked by the heavy reductions of the first passages through the blooming mill. PROPERTIES OF SILICON STEELS Silicon steel containing 0.20 per cent of carbon may be rolled if the silicon content is less than 7 per cent. With 0.90 per cent carbon it may be rolled if the silicon is less than 5 per cent. With a sihcon content higher than 5 per cent the metal is use- less.* In structural steels the effect of the silicon is to raise the elastic limit to a moderate degree. Sihcon lowers the coefficient of expansion of steel somewhat as nickel does. The treated test piece comprising sample 5 was heated to 954° C. (1,750° F.), quenched in water, and drawn at 427° C. (800° F.). The hardening temperature of samples 8 and 9 was probably about the same as that of sample 5. USES OF SILICON STEELS The dividing Hne between siUcon-treated steels and siUcon- alloy steels is not clearly defined, but the latter are used for several important purposes. In structural hnes their employ- ment is Umited, as their properties can, generally speaking, be readily equaled or excelled by simple steels. The chief structural use of silicon-alloy steel is in springs of the leaf type for automobiles and other vehicles. The sihcon is considered to make the springs somewhat tougher, so that they are less liable to break in service than springs of simple steel. In the trade this steel is called siUco-manganese steel, though its content of manganese is usually no more than is common in simple steels and not enough to properly cause the steel to be classified as a manganese-alloy steel. In electricity, an important use for siUcon-alloy steel is in the cores of static transformers. With the exception of man- ganese most of the elements employed in making alloy steels, * Guillet, L6on, Aciers au silicium: Rev. m6t., t. i, 1904, p. 67. SILICON STEELS 65 o O CM 8 B _0 .^ « s a a a ■C 6Z w 00 -^ lO W ■^ CO »o r^ ^ 00 VI M N M M N M IN 8 o 8 o o 8 IH rv. r- M <:> CO o n '* '^ o\ ^o O 0} fO M -«:*■ o o o o (J o o i; o 1^ CJ O CO o ■* •* lo r- r^ O O "^ ■* CU ai t/i ta V o u J3 O I ■".,"« ,13 C ■e -e -h; c U H H H < Q Q w PO-^ir)\o r^oo 0\ 66 MANUFACTURE AND USES OF ALLOY STEELS although not greatly decreasing the magnetic susceptibility of the iron that contains them, lower its hysteresis loss. Silicon is the element most used for that purpose because it is the cheapest, but aluminum, phosphorus, nickel (3^ per cent), and tungsten have a similar effect. The silicon content in silicon transformer metal is usually between 3I and 4^ per cent or, more exactly, 4 to 4^ per cent. Some 25,000 tons was used in 1913 for this purpose. The steel is rolled into thin sheets which, for one large user, are 0.014 inch thick; the transformer cores are built up of these sheets, which are cut to shape separately by stamping. For low induc- tion the permeabihty of this steel is nearly as great if not greater than that of any other variety of iron or iron alloy known, and its hysteresis loss is less than that of any other of nearly as low cost. The results of an analysis of a transformer core made of sihcon-alloy steel are as follows: C, 0.08 per cent; Si, 4.18 per cent; Mn, o.ii per cent; S, 0.06 per cent; P, o.oi per cent; Al, o.oi per cent. Silicon steels can not be case hardened, as the silicon retards the absorption of carbon; the silicon content must therefore be low, not over 0.04 per cent, in steel intended to be so treated. BIBLIOGRAPHY ON SILICON STEEL Hadfield, R. a. On alloys of iron and silicon. Jour. Iron and Steel Inst., 1889, pt. 2, pp. 222-255. Heyn, E. Einfluss des Siliciums auf die Festigkeitseigenschaften des Flussstahls. Stahl und Eisen, Jahrg. 21, May i, 1901, pp. 460-464. GuiLLET, Leon. Aciers au silicium. Rev. met. t. i, 1904, p. 67. GoNTERMANN, W. Iron-silicon-carbon alloys. Jour. Iron and Steel Inst., vol. 83, 1911, pp. 421-475. Ruder, W. E. Grain growth in silicon steel. Bull. Am. Inst. Min. Eng., December, 1913, pp. 2805-2822. CHAPTER VIII HIGH-SPEED TOOL STEELS High-speed tool steels, also called rapid steels, have in the past fifteen years worked a remarkable revolution in the machine- shop business of the whole world, affording largely increased outputs and commensurate lower costs. As a consequence they are now being used very generally and in some shops almost exclusively for machining iron and steel as well as some other metals by cutting operations by machine tools. The revolutionary feature wherein tools made of these steels differ from and exceed in service the tools formerly used is their ability to maintain a sharp strong cutting edge while heated to a temperature far above that which would at once destroy the cutting ability of a simple steel tool. Because of this prop- erty a tool made of high-speed tool steel can be made to cut continuously at speeds three to five times as great as that practicable with other tools, and when, as the result of the fric- tion of the chip on the tool, it may be red-hot at the point on top where the chip rubs hardest, and the chip itself may, by its friction on the tool and the internal work done on it by up- setting it, be heated to a blue heat of 296° C. (565° F.) or even hotter to perhaps 340° C. (644° F.). This property of red-hardness or abiHty to retain hardness at a red heat may be imparted to steels of suitable composition, comprising chromium and tungsten, by a unique heat treat- ment to which they may be subjected. This treatment, described later, was introduced by F. W. Taylor and Maunsel White, as has been described by Taylor,* at the works of the Bethle- * Taylor, F. W., On the art of cutting tools: Trans. Am. Soc. Mech. Eng., vol. 28, 1906, pp. 31-35^- 67 68 MANUFACTURE AND USES OF ALLOY STEELS hem Steel Co. in 1899, and tools so treated were shown at the Paris Exposition in 1900, where they naturally created a great sensation among those familiar with the machining of metals. White, when giving the writer his first knowledge of these tools in 1899 or early in 1900, said that a young man in the Bethlehem shop had lighted a cigarette with a newly cut chip, a statement that seemed ahnost unbelievable at the time. In this country in 1913 about 7,000 tons of high-speed or rapid tool steels was made by some 15 makers, that output requiring about 8,000 tons of ingots. MANUFACTURE OF HIGH-SPEED TOOL STEEL High-speed tool steels are all made by the crucible or elec- tric-furnace process. Except at one works, the crucibles or pots are made of graphite. The average Hfe of the crucibles or pots varies in different works from six to nine melts. Some makers use clay-lined graphite pots in melting this steel to prevent or hinder the absorption of carbon from the pot. The clay lining is only one-eighth to three-sixteenths of an inch thick and is sometimes cut through on the second or third melt; in that event the molten steel may absorb too much carbon. Other makers use a graphite pot twice — first for melting other kinds of steel and then for rapid steel when the inner surface of the pot is somewhat slagged over, because of which the absorp- tion of carbon is much less than when the pot was new. The large producers use gas-fired melting furnaces for heat- ing the pots, which are charged into the furnace at the top. Each melting hole contains six pots and each pot takes a charge of 90 or 100 pounds. The charge is melted and then "killed" in the usual way by being held 30 to 40 minutes. Such pro- cedure, together with the presence of the large amount of alloy, regularly gives sound piping steel. If run continuously a fur- naceful of pots will be melted about every four hours. In packing a pot with a charge for rapid steel the tungsten must be placed on top of the charge — as with simple tungsten steel — to guard as far as possible against the tendency of the HIGH-SPEED TOOL STEELS 69 tungsten to settle because of its high specific gravity. That tendency seems to be less with the rapid steels than with the simple tungsten steels. Whether the chromium of the former influences or hinders the settling of the tungtsen is conjectural. The smaller ingots, which are made from one pot of steel, vary from 3I to 5 inches square. The steel is sometimes teemed directly into the mold by hand-pouring, but in some works clay funnels are placed on top of the mold to direct the stream down the center of the mold to avoid cutting its wall, as might happen if the stream impinged on it. Funnel pouring is also advantageous when two pots are to be combined to make a larger ingot, as the steel can be poured into the funnel from opposite sides at the same time, a procedure that will mix the Uquid steel and give a more uniform ingot than when one pot follows another, as in hand-pouring when no furmel is used. Some of the larger producers of rapid steels use for casting a large bottom-pouring ladle into which the steel is poured from the pots of one or more furnaces, and from which the ingots are top-cast; that is, the molds are filled from the top. This method presents the advantages that (i) the product is more uniform; (2) individual pot charges, which might not be of the prescribed composition or might be otherwise unsatis- factory, are merged with the others without detriment to the whole; (3) large ingots are easily made; (4) one analysis serves for the whole nimiber of pots; (5) one test serves for the whole ladleful of steel. It is a matter of experience that complaints from customers became much less frequent after the introduc- tion of the ladle for casting this steel. The strong tendency of rapid steel to pipe is checked con- siderably in most plants by the use on each ingot of a hot "doz- zler," which is a clay ring preheated red hot, that is placed on the ingot top and filled with molten steel. This arrangement keeps the top of the ingot molten long enough so that the pipe is of diminished size and nearly or quite all contained within the part of the ingot surrounded by the dozzler. The propor- tion of the ingot to be rejected on account of the pipe is there- fore much decreased. The molds are usually closed at the 70 MANUFACTURE AND USES OF ALLOY STEELS bottom end and are either made with parallel walls or tapered so that the ingot is larger at the top than at the bottom. The molds must be spHt when the walls are parallel, and are some- times split when the ingots are tapered. High-speed tool steel as cast has a coarse structure and dark color as compared with the structure and color of simple steels of the same carbon content. A corner is broken from the top of each ingot, to show the grain, and the ingots when hand- poured directly from the pots are classified by the eye as in the production of simple crucible steels. If the ingots are cast from the large ladle a test is taken for analysis which determines the disposition of the whole ladleful of steel. As a rule the ingots show a strong columnar structure or arrangement of crystals whose axes are normal to the coohng surface. Some makers refer to the structure as a "lemon structure," the crystals of the metal being thought to resemble the cells forming the pulp of a lemon. If the casting tempera- ture is lower than usual, this lemon structure may be absent, and in that case the interior of the ingot will have a much finer grain than the ingots cast at the usual higher temperature. The subsequent heating and working of the steel entirely destroys the crystalline structure of the ingot, and the worked steel, on a fresh fracture, shows a most beautiful porcelanic structure. The ingots run from 3I by 3I inches to 16 by 16 inches, but most of them are from 5 by 5 inches to 9 by 9 inches. For hot- working they are heated in a furnace chamber having a tem- perature of about 1,180° C. (2,156° F.). At this high heat the steel may be worked satisfactorily under the hammer or press and may be quickly worked down to the dimension desired. COMPOSITION OF HIGH-SPEED TOOL STEELS The tendency of the makers is toward a somewhat uniform composition as regards the contents of the alloying elements, whose benefits have become fairly well known, and whose use as a consequence may be considered as estabhshed. Specifically, HIGH-SPEED TOOL STEELS 71 these alloying elements are tungsten and chromium. The addi- tion of vanadium and cobalt in important proportions is con- sidered by some makers to give distinct improvement to high- speed steel, and some vanadium is almost always present. The following analyses are of steels recently made, most of which are considered to be good commercial steels: RESULTS OF ANALYSES OF HIGH-SPEED STEELS MADE IN 1913 OR 1914. Sample.^ Mn Si Cr W Co Mo Remarks. A— B— I B— 2 B— 3 B— 4 C— I C— 2 C— 3 D— I D— 2 D— 3 D— 4 E— I E— 2 E— 3 E— 4 F G H— I H— 2 I J— I J— 2 K— I K— 2 K— 3 % o.6s .65 .74 .63 .69 .66 .64 .67 .75 .68 .69 .57 .61 .68 .70 .60 .64 .72 .77 .67 .64 .64 .71 .55 .70 .74 % 0.15 .27 .31 ■ 14 .34 .22 .21 .33 .28 .38 .36 .20 .23 ■ 45 .50 • 23 2, 29 .37 .16 .16 .23 .30 .14 Tr. Tr. .31 % o. 20 .14 .13 .07 • 14 .17 .16 .25 .36 .40 .38 .26 .35 .40 .39 .29 .26 .26 .23 .18 .13 % 0.02 .04 .04 .04 .03 .03 .03 .02 .03 .03 .04 .02 .04 .04 .OS .03 .02 .03 .02 .03 .02 .04 % 0.03 .OS .02 .05 .04 .02 .03 .02 % 4.75 26 28 44 30 8S 4. 10 4.6s 4.67 4.82 4.10 4.00 4.08 3.90 4.39 4-50 .03 .04 % 17. SO 17.48 IS 63 17. 16 16.3s 16.51 16.06 16.06 19.00 17.8s 17.90 15.38 17.20 14.26 14.50 17.27 16.09 13.30 18.64 13.86 19. 10 18.71 IS.2I 16.05 IS so IS.63 % 0.90 • 70 .67 • 45 .64 .73 .66 .70 .75 .53 .50 • SO 1. 00 1.09 1.07 .90 .59 2.50 1.35 1.08 .54 I. 22 .97 .80 .88 .67 % 4.22 2.70 3.80 S.28 4.02 4.72 4-72 2.70 Good Inferior Inferior Inferior Good Inferior Inferior Inferior .18 0.72 .67 I Samples A to I represented American steels, the numerals indicating different samples from the same maker; sample J represented an English steel; sample K represented a German steel. Samples D— i and E— i gave excellent results in a com- petitive test, whereas samples D— 2, D— 3, E— 2, and E— 3, manufactured by the same makers, gave distinctiy inferior results in the same shop. The occurrence of nickel in four of the samples may have been accidental, having been due to nickel in some of the scrap steel used in the charge. Most makers now put in vanadium, 72 MANUFACTURE AND USES OF ALLOY STEELS and steel like that represented by sample G, which had the highest vanadium content of all the samples represented in the table, was the winner in a recent competitive test. The average specific gravity of the steels represented in the table was about 8.8, the increase over the specific gravity of iron being due chiefly to the tungsten content. There are so many factors beside the ultimate composition that affect the value of rapid tool steels that no conclusion can be drawn from the analysis alone. The melting, hot working, and heat treatment all must be done correctly or the final result will not conform to expectations. CARBON IN HIGH-SPEED TOOL STEEL The proportion of carbon aimed at in high-speed tool steels is about 0.65 per cent, which in a simple steel would not be enough to give the maximum hardness even if the steel were heated above the critical point and quenched in water, and still less so when the steel is cooled as slowly as these steels are in their treatment. This shows that the carbon acts in a different way from what it does in simple steels, as is discussed later. TUNGSTEN IN HIGH-SPEED TOOL STEEL Tungsten is well estabhshed as a most important if not indis- pensable ingredient of commercial tool steels, being almost or quite universally used in quantity therein. The best proportion of tungsten, all things considered, seems to lie between 16 and 20 per cent, the tungsten content in 95 per cent of all the Ameri- can steels coming within these limits. Some pubHshed analyses of European high-speed tool steels show a higher content of tungsten than this, but American makers generally agree that any tungsten in excess of 20 per cent adds nothing to the use- fulness of the steel, and they therefore make that proportion the upper limit of the amount added. One effect of the tungsten is that the best percentage of carbon in rapid steel is but about half that required in simple tool steels intended for the same kind of service. HIGH-SPEED TOOL STEELS 73 CHEOMTUM IN HIGH-SPEED TOOL STEEL The effect of chromium in high-speed tool steel, as in other Steels, is undoubtedly as a hardener, entering into the double carbide of tungsten and chromium which gives or causes the proper cutting edge. Although the proportion of this element present in these steels varies considerably, it is always large, perhaps never less than 2 per cent or more than 6 per cent in American steels, and in European steels the upper hmits is at least 9 per cent. MOLYBDENUM IN HIGH-SPEED TOOL STEEL The use of molybdenum in high-speed tool steels is being generally discontinued. Some makers for years manufactured molybdenum tool steels, but as a rule they have either wholly discontinued its use or use a much smaller proportion than formerly, employing it as an auxiliary rather than a major constituent.. The effect of molybdenum is similar' to that of tungsten, but is more intense in that i per cent molybdenum is cur- rently considered to give about the same or greater hardening effect than 2 per cent of tungsten. It gives a fine cutting edge. Various reasons are assigned for the discontinuance of the use of molybdenum in these steels. Taylor* found that molyb- denum in rapid steels caused irregular performance; that steels of nearly the same composition and having had seemingly the same treatment gave large variations in the cutting speeds they would stand. One user specifies no molybdenum because it causes the tools to crack in quenching. A maker objected to molybdenum because molybdenum steel was apt to be seamy and to contain physical imperfections. A maker of ferro- alloys understands that molybdenum steel deteriorated upon repeated heating for dressing and treatment, seemingly because the molybdenum disappeared from the outer parts of the steel * Taylor, F. W., On the art of cutting metals: Trans. Am. Chem. Soc, vol. 28, 1906, pp. 31-3S0- 74 MANUFACTURE AND USES OF ALLOY STEELS where it was exposed to the heat and where any volatile con- stituent could escape. This phenomenon recalls a proposal of Moissan to use molybdenum as a means of freeing molten iron of oxygen, as he found that the oxide of molybdenum was much more volatile than the metal itself. It may be, therefore, that the molybdeniun at the surface is oxidized and volatilized, but for this waste to extend to any considerable depth implies either that molybdenum moves through the heated steel to reach the oxygen of the air, or, as is more Ukely, that the oxygen of the air penetrates the steel, reaching the molybdenum and oxidizing it, the volatile oxide escaping from the steel. The cost of molybdenum when its use was most general was much more than that of tungsten. Because of the falling off of the demand in recent years, however, the price of molyb- denum has fallen to about that of tungsten, or to a fraction of what it was a few years ago. It has been observed that in the Eggertz color determina- tion a high molybdenum content (4 to 8 per cent) causes "miss- ing" or invisible carbon when the content of latter element is high (0.4 to 1.2 per cent). VANADIUM IN HIGH-SPEED TOOL STEEL Vanadium is used for high-speed tool steel in varying amounts, most makers using at least 0.5 per cent, although some run the vanadium content up to i| or if per cent, or even more, con- sidering that such an addition increases in an important degree the value of the steel for tools. The effect of vanadium is considered to resemble in some ways that of chromium in increasing the hardness or red-hard- ness of the cutting edge. One maker makes two kinds of high- speed tool steel, the essential difference between the two being that one contains about i| per cent of vanadium and thereby commands a higher price, whereas the other has little of this element, both kinds being intended for substantially the same service. High-speed steels containing vanadium are generally classed HIGH-SPEED TOOL STEELS 75 as "superior" steels and many, though not all, makers and users consider them distinctly better than the "standard" steels containing no vanadium, both on account of their actual cutting qualities at high speeds and on account of the length of time a tool will cut before it needs regrinding. The true value of vanadium in rapid steels must probably be held as not yet fully determined. The analyses given in the table show that all the samples contained vanadium but in greatlv varying amounts. COBALT IN HIGH-SPEED TOOL STEEL Cobalt now threatens to change tool-steel manufacture because of the properties it imparts. The recent great decline in price following the increase of the supply from the silver ores of the Cobalt district in Ontario naturally led to its trial as a steel-alloying element, and some most excellent high-speed steels containing, in addition to the usual ingredients, about 4 per cent of cobalt, have been obtained. This result was hardly to have been expected in view of the experience with nickel, which cobalt much resembles, as nickel has been condemned by nearly every manufacturer as not being a desirable ingredient of high- speed tool steels, because of the effect it has of making the edge soft or "leady." The cobalt steel, however, has shown, in some products at least, increased ability to hold its edge in work. One user of cobalt steel found it better suited for turning manganese steel than any other steel he tried, his success being so marked as to make it practically a commercial operation. Manganese steel, as noted elsewhere, is so hard as to be con- sidered practically urmiachinable, the usual practice having been to finish it by grinding when necessary. Another user found that an imported cobalt high-speed steel proved excellent for cutting a hard nickel-chromium steel in a lathe, whereas the same steel in a cold saw was not satisfactory. The direct reason seemed to be that this steel to do its best work must be run nearly if not quite red hot; at least that was the condition in which it was used in the lathe, while in the cold saw its tem- perature was not raised to an important degree, and when cold 76 MANUFACTURE AND USES OF ALLOY STEELS its properties were different than when it was hot. This behavior is more or less common to high-speed steel, as is mentioned later. The valuable effect of cobalt is claimed to be that it increases the red-hardness of high-speed tool steel, enabling the steel to cut at a higher speed. COPPER IN HIGH-SPEED TOOL STEEL Copper has been considered to be highly injurious in high- speed tool steel, even as little as 0.05 per cent being inadmissible; and it is thought to be particularly harmful if much sulphur is present in the steel; also the higher the carbon content the more harmful is the copper. SULPHUR AND PHOSPHORUS IN HIGH-SPEED TOOL STEEL Sulphur and phosphorus, which are so deleterious in simple tool steels, are considered to be somewhat less so in high-speed steels, in which the effect is either modified or else masked by the large quantities of other ingredients. Some commercial brands of high-speed steels have as much as 0.05 per cent of each of these impurities, to which no inferior quality is attribut- able. STELLITE Stellite, though a competitor of high-speed steels, is not within the scope of our subject, but a recent analysis is given of a sample for such interest as it may have in relation to cutting steels. ANALYSIS OF STELLITE Constituent. Per Cent. Co 59.50 Cr. . . .■ lo- 77 Mo 22.50 C 87 Si 77 Mn 2.04 S... 084 P 040 Fe 3" W o Ni o 99 . 684 HIGH-SPEED TOOL STEELS 77 HEAT TREATMENT OF HIGH-SPEED TOOLS The heat treatment given to high-speed steels for the com- moner uses as lathe and planer tools has generally been simpli- fied to heating to incipient fusion and quenching in oil. Cooling by an air blast and double treatment, which were formerly recommended, are now not common, except that a second (drawing) heating is given to milling cutters and similar tools, the temperature imparted to the tool depending on the material to be cut. The treatment is usually done by the blacksmith who heats the tool in his forge fire and then immerses it in a tank con- taining enough oil so that its temperature does not rise materially. Ten gallons of oil is a common quantity to use when the size and number of the tools is moderate, as in most shops. The fire is a deep compact coal fire, the coal in the center where the tool is heated being pretty thoroughly coked, that is, most of its volatile matter distilled out. This manner of beating has the advantage that free oxygen does not get at the tool to oxi- dize it, but its environment is nonoxidizing or even reducing, owing to the presence of an excess of burning carbon surround- ing the tool. Any flame is more or less oxidizing, at least unless heavily charged with smoke or free carbon, and a piece of steel heated directly by a flame as in the ordinary heating chamber of a furnace is likely to be somewhat oxidized on its surface, the depth to which the oxygen penetrates varying according to the conditions, particularly the temperature, the access of air, and the length of time. Heating in a muffle will also result in oxi- izing the steel unless extraordinary precautions are taken to keep out oxygen or to consume all that enters. The temperature of quenching, usually about 1,260° C. (2,300° F.), is determined by the fusion of the scale and its visible collection into drops or beads on the surface of the tool. Quenching is done by quickly plunging the heated tool into the oil as soon as it has reached the desired temperature and moving it about in the oil until cold. Cooling in oil is thought by some to give a better tool than cooling in the air blast, one 78 MANUFACTURE AND USES OF ALLOY STEELS reason seemingly being the protection of the steel from free oxygen while it is hot enough to be oxidized thereby. The oxy- gen of the air blast forms a scale of oxide on the hot steel and the oxygen probably penetrates the metal below the scale to some extent, injuring the quality as deep as it goes. A tool on its second grinding when the oxidized metal is removed may then give better service than on the first, unless the first grind- ing has for that reason been heavy enough to remove the oxi- dized metal. In some shops, however, the original treatment recommended by Taylor and White* is given, the cutting edge of the tool being heated to incipient fusion and then immersed in a bath of melted lead at about 565° C. (1,050° F.). The heating is done in a small furnace over a deep coke fire, blown by an air blast, so that the environment of the tool while being heated is substantially ponoxidizing. Flames of carbonic oxide play out of the openings through which the tools are inserted, indi- cating little if any free oxygen within. In these shops, however, milling cutters and other tools that are machined to a particular form are treated by heating them to a shghtly lower temperature, in order not to damage the cutting edges, and then plunging them into cold oil. When cooled to the temperature of the lead it is taken out and placed in an air blast to complete the cooling. Some tools desired to be especially tough so as not to break in service are given a second heating to 565° C. and then cooled in the open air or air blast if saving time is important. Rapid steel when well annealed will bend considerably without breaking, even in as large a section as 2^ by ij inches, the bending being edgewise, as in a tool at work. Gledhillf found that one of these steels after having been annealed 12 to 18 hours at 760° C. (1,400° F.) had a tensility of 129,200 pounds per square inch, an elastic Hmit of 89,600 * Taylor, F. W., On the art of cutting metals: Trans. Am. Soc. Mech. Eng., vol. 28, 1906, p. 228. t Gledhill, J. M., The development and use of high-speed tool steel: Jour. Iron and Steel Inst., pt. 2, 1904, pp. 127-181. HIGH-SPEED TOOL STEELS 79 pounds per square inch, an elongation of i8 per cent in 2 inches, and a contraction of area of 35 per cent. The ductility is rather high and would enable a tool to be bent considerably without breaking. Such annealed steel may be rather easily machined for making milUng cutters and other shapes that require ma- chining. Carpenter* found that the higher tbe temperature from which rapid steel is cooled the more it resisted etching for metallographic work. He also found that no tempering change occurred when it was reheated at a temperature of less than 550° C. (1,022° F). to a visible red in the dark, indicating a stability that is doubt- less the cause of its property of red-hardness. Whether a rapid steel is made harder by the heat treatment given it depends somewhat on the condition of the bar before treatment. If it has previously been annealed, the treatment hardens it, whereas heat treatment may not harden a piece in the natural state. Taylorf found that some tools having useful red-hardness could be filed rather readily. Edwards f on the other hand found treated high-speed steels to be exceed- ingly hard — as hard as any steel could be made by quenching. Gledhin§ found that high-speed steel was good for turning chilled ■ rolls which are extremely hard and require the hardest kind of tool to cut them. Trials on window glass of a number of different rapid steels showed that the cutting edge of some but not of all would scratch it. The same was true of the untreated ends of the same tools, as some would and some would not scratch the window pane. The hardness of the steel when cold is not the determining factor of usefulness in any case. It is the hardness when heated under conditions of work. * Carpenter, H. C. H., The tjfpes of structure and the critical ranges on heating and cooling of high-speed tool steels under varying thermal treatment: Jour. Iron and Steel Inst., pt. i, 1905, pp. 433-473- t Taylor, F. W., On the art of cutting metals: Trans. Am. Soc. Jlech. Eng., vol. 28, 1906, pp. 31-350- t Edwards, C. A., Function of chromium and tungsten in high-speed tool steel: Jour. Iron and Steel Inst., pt. ^, 1908, pp. 104-132. § Gledhill, J. M., loc. cit. 80 MANUFACTURE AND USES OF ALLOY STEELS The cutting edge of a rapid-steel tool at work is probably never as hot as the metal just back of it, where the heating caused by the friction of the chip, as it is deflected and rubs hard on the tool, is most intense. The edge itself is kept rela- tively cool by the cold metal flowing upon it. THEORY OF HIGH-SPEED STEELS Carpenter* found the heating and cooHng curves of a rapid steel to be radically different from each other, and also that the coohng curve when the steel was cooled from 930° C. (1,706° F.) was greatly different from that when the steel was cooled from 1,250° C. (2,282° F.). When the steel was cooled from 930° C. the curve had an abrupt jog, which showed a great retardation in rate of cooUng occurring between 700° C. and 750° C. (1,292° F. to 1,382° F.). The jog did not occur when the steel was cooled from 1,250° C, 320° higher, the line representing varia- tions in rate of coohng being nearly straight. The rate of cool- ing to get these curves was slow or at least not accelerated, and one can not say what the curves would be like if the rate of cooling were hastened, as in quenching, but the curves obtained seem to throw much hght on the question. The prop- erty of red-hardness seems to be connected with the eUmination of the great retardation mentioned. The following explanation, based on the work of Carpenter* and Edwardsj, of the properties of high-speed steels, seems to be helpful or even satisfactory: Their researches on the heating and cooling of these steels have shown that such steels have an extraordinary stability of composition after they have been heated to 1,200° C. (2,192° F.) or more, and that a second heating of 550° C. (1,022° F.) has no softening or drawing effect. It seems fairly evident that red- hardness depends on or is the natural result of these facts. At a temperature higher than 1,200° C. (2,192° F.) a double carbide of chromium and tungsten is formed, which persists largely even when the steel is cooled slowly as in the open air, * Carpenter, H. C. H., loc. cit. t Edwards, C. A., loc. cit. HIGH-SPEED TOOL STEELS 81 and more so when cooling is accelerated. This double carbide imparts to the steel a high degree of hardness and is stable at all temperatures up to 550° C. (1,022° F.) or somewhat higher. At 550° C. the steel has a low red color visible in the dark.'^ If the above theory be true then at a temperature of 1,200° C. (2,192° F.) the chromium and tungtsen must have a stronger affinity for carbon than iron has, whereas at lower temperatures, say from around 930° C. down to the critical point, the affinity of carbon for iron is slightly stronger than that of either chromium or tungsten or both, and the carbon then exists wholly or in part as carbide of iron, or a complex carbide of iron with one or both of the other elements. Carbide of iron, or hardening carbon which causes the hard condition of iron in simple steel that has been quenched from a temperature higher than the critical point, is unstable at even slight elevations of temperature above atmospheric tempera- ture, its unstableness increasing with the degree of heat, though not being proportional thereto. Boynton* has shown that between 400° C. (752° F.) and 500° C. (952° F.) the amount of change and consequent softening is much greater than at other temperatures, either lower or higher. The proportion of carbon in rapid steel should perhaps be only as much as will combine with the chromium and tungsten at 1,200° C. (2,192° F.) and leave none to exist as unstable hardening carbon of hardened simple steel. TESTING AND USING HIGH-SPEED STEEL A reliable and inexpensive method of quickly testing high- speed steels to show their value is much needed, as Taylorf has explained. HerbertJ and Edwards§ have used and recom- * Boynton, H. C, Hardness of the constituents of iron and steel: Jour. Iron and Steel Inst., igo6, p. 287. t Taylor, F. W., On the art of cutting metals: Trans. Am. Mech. Eng., vol. 28, 1906, pp. 31-350- i Herbert, E. G., The testing of files and tool steels: Trans. Manchester Assn. Eng., 1908-1909, pp. 302-317. § Edwards, E. T., Composition of high-speed tool steel: Iron Age, vol. 89, April, 191 2, pp. 957-960. 82 MANUFACTURE AND USES OF ALLOY STEELS mended machines and methods that lessen the time and trouble of testing, but no test seems to take the place of a trial at actual work, because the performance of a tool in one line of work with certain conditions may not be foretold positively by its per- formance in another with different conditions. Among the reasons are that (i) sometimes greater durability is obtained by changing, that is, increasing or lessening, the speed of the cut, thus changing also the temperature of the tool, or (2) a given tool when used at its best speed may be excellent for cutting a certain material, yet prove inferior to another tool for cut- ting a different material. Thus if selected as the best by trial for cutting a 0.20 per cent carbon steel, it may be surpassed by others in cutting a 0.70 per cent carbon steel. Physical tests of rapid steels at different temperatures up to 800° C. (1,472° F.) are needed to show the effect of heat on the physical properties of those steels. New uses would probably be suggested by the results of such a series of tests. A rapid-steel tool does not finish the piece being cut as nicely as does a simple steel tool, as the rapid steel does not keep a fine edge with a light cut and slow speed of, say, 20 feet per minute. The durabihty of such a tool taking a light cut is much greater at a higher cutting speed, at which the tool is hotter, showing that the strength or the toughness of the steel or both are augmented by the higher temperature. Unhardened simple steels with c.6 to 0.7 per cent carbon get stronger but less ductile with a rise of temperature up to about 300° C. (572° F.). If, as the temperature rises, high-speed steels get stronger without loss of ductility but perhaps with an increase, within limits of course, a physical reason for their great dura- bility is provided. In 1910 Herbert* announced the discovery that any rapid- steel tool and some simple steel tools may have two rather widely separated cutting speeds at which the tool is more dur- able than at speeds above, below, or between. Thus out of many cases described, one tool cooled in an air jet had nearly equal * Herbert, E. G., The cutting properties of tool steel: Jour. Iron and Steel Inst., 1910, pt. i, p. 216. HIGH-SPEED TOOL STEELS 83 maximum durability at two speeds — 50 and 90 feet per minute, whereas at 65 feet the durability was less than one-half of that at either of the other speeds. This discovery no doubt accounts for some of the anomalies encountered in tool steels as well as other steels the properties or performances of which are not what would be expected from their composition and other attributes. Thus a tool may be condemned when an increase of its cutting fepeed would cause it to give satisfactory service and durability. Rapid steel will do its best cutting when hot. A desirable practice, followed in some shops, is to heat a tool to near redness before putting it to work. MACHINE-TOOL DESIGN When Taylor and AVhite first introduced rapid steels it was thought that the higher cutting speeds afforded constituted the sole benefit to be derived from them, and as the higher speeds, although consuming more power about in proportion to the increase in speed, did not increase materially the stresses on the machine tools, it was thought that the latter merely needed to be speeded up in order to get the full benefit from the new steels. But it was soon found that the rapid steels in addition to cutting at higher speeds were capable of taking much heavier cuts, which proportionately increased the stresses on the tools. To take full advantage of the heavier as well as the more rapid cuts, machine tools were generally redesigned to provide the greater strength required, and were supplied with proportionately more power. The resulting economies all over the world have been enormous. The advantages from the use of rapid steels as compared with the use of simple tool steels are in the lessened costs of the ordinary operations of finishing iron and steel because of: 1. More rapid cutting speed. 2. Heavier chips cut, hence larger cuts and feeds. 3. Saving of power per unit of metal cut off. 4. Lower cost of plant for a given output. 84 MANUFACTURE AND USES OF ALLOY STEELS 5. Lower general and overhead charges connected with manufacturing iron and steel products. PATENTS ON HIGH-SPEED STEELS Since the original Taylor and White patents for treatment of high-speed steels were issued in 1901, others have been granted for almost every possible combination of elements which were in any way thought to be useful or valuable constituents of tool steel. Chromiiun and tungsten were generally included, though not always. Nevertheless most makers now aim at substan- tially the same foundation composition, with varying amounts of vanadium and sometimes with cobalt. MISCELLANEOUS USES OF HIGH-SPEED STEELS An important use for high-speed steel is in the exhaust valves for automobile engines, where it has given excellent results. These valves operate sometimes at a red heat and seemingly the property of red-hardness that the steel possesses enables it to give good service in these valves. High-speed steel is being used also in the manufacture of extruded brass to form the die through which the extruded metal is forced. The temperature of the brass is high, near its fusion point, and seemingly the red-hardness of the steel enables the steel to perform this service satisfactorily. A good file or a good cold chisel may be made of rapid steel, but they are not good enough to justify their cost as compared with those made of simole steels. BIBLIOGRAPHY ON HIGH-SPEED TOOL STEEL Engineering. Rapid tool steels. Vol. 76, Aug. 21, 1903, pp. 255-256. Gledhill, J. M. The development and use of high-speed tool steel. Jour. Iron and Steel Inst., 1904, pt. 2, pp. 1 27-181. Markham, E. a. The use of high-speed steels. Am. Machinist, vol. 27, pt. I, Apr. 7, 1904, pp. 443-444. NiCOLSON, J. T. Experiments with a lathe-tool dynamometer. Proc. Inst. Mech. Eng., 1904, pts. 3-4, pp. 883-935. HIGH-SPEED TOOL STEELS 85 Pendlebtjey, C. Notes on tests of rapid-cuttmg steel tools. Engineer (London), voL 97, Apr. i, 1904, pp. 331-332. Carpenter, H. C. H. The types of structure and the critical ranges on heating and cooling of high-speed tool steels under varying thermal treatment. Jour. Iron and Steel Inst., pt. i, 1905, pp. 433-473. Newbold, S. The Taylor-Newbold saw. Foundry, vol. 27, November, 1905, pp. 118-121. Carpenter, H. C. H. Tempering and cutting tests of high-speed steels. Jour. Iron and Steel Inst., pt. 3, 1906, pp. 377-396. Clarage, E. T. The manufacture of tool steel. Am. Machinist, vol. 29, pt. 2, Nov. I, 1906, pp. 573-576. An address delivered before the Northwest Railway Club. Taylor, F. W. On the art of cutting metals. Trans. Am. Soc. Mech. Eng., vol. 28, igo6, pp. 31-350. AucHY, George. The theory of high-speed tool steel. Iron Age, vol. 80, Dec. 26, 1907, pp. 1818-1822. Carpenter, H. C. H. An analysis of the evolution of modern tool steel. Engineering, vol. 83, 1907, pp. 569, 633. Edwards, C. A. Function of chromium and tungsten in high-speed tool steel. Jour. Iron and Steel Inst., pt. 2, 1908, pp. 104-132. Valentine, A. L. Making and using of high-speed steel tools. Am. Machinist, vol. 31, pt. 2, July 2, 1908, pp. 6-9. Carpenter, H. C. H. Possible methods of improving modern high-speed turning tools. Trans. Manchester Assn. Eng., 1908-1909, pp. 81-120. Herbert, E. G. The testing of files and tool steel. Trans. Manchester Assn. Eng., 1908-1909, pp. 317-402. Engineer (London). High-speed tool steels. Vol. 107, 1909, pp. 289, 347. Describes results of tests at Shef&eld works. Becker, O. M. High-speed steel. 1910. 360 pp. Berg, C. P. Heat treatment of high-speed tools. Jour. West. Soc. Eng., vol. IS, 1910, pp. 738-764- Brackenbury, H. I. High-speed tools and machines to fit them. Proc. Inst. Mech. Eng., 1910, pts. 3 and 4, pp. 929-955, 986-1026. Smith, W. G. High-speed steel and its heat treatment. Mech. Eng. (Manchester), vol. 25, May 6, 1910, pp. 537-540. Brearley, Harry. The heat treatment of tool steel. London, 191 1. Gledhill, J. M. The practical use of high-speed tool steel. Mech. Eng. (Manchester) vol. 27, June 23, 1911, pp. 762-766. Sullivan, W. B. Tool steel. Proc New York Railroad Club, vol. 22, 1911, pp. 2595-2633. Edwards, E. T. Composition of high-speed tool steel. Iron Age, vol. 89, April 18, 191 2, pp. 957-960. Hammond, E. K. The manufacture of tool steel. Iron Age, vol. 90, Oct. 3, 1912, pp. 766-771. 86 MANUFACTURE AND USES OF ALLOY STEELS Herbert, E. G. The influence of heat on hardened tool steels, with special reference to the heat generated in cutting operations. Jour. Iron and Steel Inst., 1912, pt. i, pp. 338-377- Kenney, L. H. Tool steel for the United States Navy. Trans. Soc. Naval Arch, and Marine Eng., vol. 20, 191 2, pp. 345-574. Machinery. Steels for taps, drills, and milling cutters. Vol. 19, Novem- ber, 1912, pp. 181-182. Sullivan, W. B. A study of the proper hardening and classification of tool steels. Proc. Railway Club of Pittsburgh, vol, 11, April 26, 1912, pp. 155-185. Gives results of drilling tests. Bigger, C. M. Tool steel from a salesman's point of view. Iron Age, vol. 91, March 20, 1913, pp. 706-708. Ripper, William, and Burley, G. W. Cutting power of lathe turning tools. Proc. Inst. Mech. Eng., 1913, pts. 3 and 4, pp. 1067-1210. ScHLESiNGiER, G. Die Fortschritte deutscher Stahlwerke bei der Herstel- lung hochlegierter Schnellarbeitsstahle. Stahl und JEisen, Jahrg. 33, June 5, 1913, pp. 929-939- CHAPTER IX CHROMIUM-VANADIUM STEELS Chromium-vanadium steels, usually called in the trade chrome- vanadium steels, are the latest development in structural alloy steels that have gained an extensive market. In 1913 about 90,000 tons of ingots is thought to have been made, of which about 75,000 tons was sold in rolled and forged products. These steels are almost all made in the open-hearth furnace, the chromium and vanadium alloys being added shortly before casting. The hot working of chrome-vanadium steels presents no especial difficulties. The total amount of alloying elements is not large in the commercial grades, and the steel acts in the press and rolls much like simple steels with somewhat higher carbon contents. Chrome-vanadium steels are in their physical properties much like chrome-nickel steels, but they have a greater con- traction of area for a given elastic limit than the latter. This higher contraction of area in the pulling test seems in some way to be associated with machinability, as chrome- vanadium steel with an elastic limit of 150,000 pounds per square inch may be machined rapidly, whereas a chrome-nickel steel having such an elastic limit would quickly dull the cut- ting tool if cut at the same speed. The greater part of the chrome-vanadium steels made goes into automobiles. They . are preferred by some because of their greater freedom from surface imperfections, notably seams, which steels, containing nickel are prone to have if the ingots are at all unsound. Vanadium is a deoxidizer, whereas nickel is not, so that vanadium, when present, favors quality, and the 87 88 MANUFACTURE AND USES OF ALLOY STEELS smaller proportion required enables it to compete with nickel even though its cost is five or six times as great. Chrome-vanadiiun steels are nearly always used in the heat- treated condition, but there are exceptions even in automobiles, as some frames, forgings, and shafts are made of the steel in its natural state. When heat-treated these steels are both hard- ened and drawn at slightly higher temperatures than are used with nickel-chromium steels to get similar properties. These temperatures are given in the table of heat-treated chrome- vanadium steels. Some chrome-vanadium steel is said to be used in armor plate of medium thickness (4 inches), which is not face-hard- ened but has high properties imparted by heat treatment. Some such steel is used in high-duty forgings and structural parts of machines. COMPOSITION AND PROPERTIES OF CHROME-VANADIUM STEELS IN NATURAL STATE Composition. Tei^sile Properties. Sam- ple No. C Mn Si S P V Cr Tensile strength Elastic Limit. Contrac- tion of Area. Elonga- tion in 2 Inches. Ball Hard- ness. % % % % % % % Pounds Pounds % % I 0.S7 0.84 0.27 0.03 O.OI 0.31 1.36 98,000 75,750 68.5 28.1 175 2 .46 .48 .20 .02 .01 ■ 14 1. 17 82,250 52,500 71.0 34." 160 3 .18 .32 .18 .02 .01 .20 .74 60,500 42,900 75." 43.0 133 4 .30 .6s .10 .04 .04 .18 .90 45,000 69.0 35. 'ISS ^ Annealed. EXAMPLE OF SATISFACTORY USE OF CHROME-VANADIUM STEEL A hydroelectric plant had shafts 6| inches in diameter, which transmitted 3,000 kw. each at 480 revolutions per minute, and all broke in service. The shafts were made of untreated nickel steel having an elastic limit of about 40,000 pounds per square inch. To make stronger shafts by increasing their size not being practicable, other shafts were made under the specifica- tion that the elastic limit of the steel should be at least 105,000 CHROMIUM-VANADIUM STEELS 89 H 1/3 Q H H K w &5 I— I p <; < > H o CJ fa o H H O Ph < o en O O o <<<:<<< 000000 4J Tt rh 10 'O < < < ti 10 (-1 r^ r*. oi 1 r^ ■* CO ro tN 00 t^ fO CO ■* 10 «!SS W -"^l- ^ M (H ^ CO tN H d oi tJO C N 2 Co ^ vP Tf t-t 0^ - ''t ^ „ „ „ „ „ » r» M M r^ V4 ^o ON OS 0^ so OS 9 10 OS M M H "-• ^0 M M H CN «H CN e< . . . • , . • « W t-) 10 10 to »o to i/^ r^ so OS kO SO SO SO Tt c^ t^ d CO CO -* 10 00 t^ SO M 10 ko ro CO fO w -^t- *:*- d 10 ■^ w •-< 0) & « « CO ■* >o vo r* 00 OS I2 03 M 1 5 2 0. a E S •a S to a T3 "2 5 S Bo ^ & 90 MANUFACTURE AND USES OF ALLOY STEELS pounds per square inch, its contraction of area 40 per cent, and its ball hardness uniform within 5 per cent. Shafts to meet such qualifications were made of chromium-vanadium steel containing 0.33 per cent C, 0.54 per cent Mn, 0.022 per cent P, 0.030 per cent S, 0.89 per cent Cr, and 0.24 per cent V. The ingot, which was 30 by 25 inches in section, was rolled to an 18 by 18 inch bloom or billet, and the shafts were forged there- from. The shafts were heat-treated, and a test from one of them, about the average of all those made, pulled at Watertown Arsenal on a 2-inch by 0.505 diameter section, gave results as follows : RESULTS OF TESTS OF HEAT-TREATED CHROME-VANADIUM STEEL SHAFT Elastic Limit. Tensile Strength. Elongation. Contraction. Ball Hardness. Pounds 105,260 Pounds 127,310 Per Cent IS Per Cent. 46.2 278 283 278 These shafts met the specifications and proved satisfactory in service. BIBLIOGRAPHY ON CHROMIUM- VANADIUM STEEL Sankey, H. R., and Smith, J. K. Heat-treatment experiments with chrome- vanadium steel. Proc. Inst. Mech. Eng., 1904, pts. 3 and 4, pp. 1235- 1317- Lake, E. F. Some properties of vanadium steel. Am. Machinist, vol. 30, pt. I, May 2, 1907, pp. 632-634. Gives results of tests of chrome- vanadium steel. GiBBS, W. E. Vanadium steel. Cassier's Mag., vol. 38, June, 1910, pp. 174-181. Smith, J. K., and Turner, W. L. Vanadium and metallurgy. Iron and Coal Trades Rev., vol. 81, 1910, pp. 389, 463, 585, 663. Iron Trade Review. Chrome-vanadium tire tests. Vol. 51, Dec. 26, 1912, pp. 1217-1218. Mitchell, A. F. Heat treatment of chrome-vanadium steel. Proc. Railway Club of Pittsburgh, vol. 12, Dec. 19, 1912, pp. 38-66. Iron Age. Chrome-vanadium rolled-steel wheels. Vol. 92, Nov. 13, 1913, p. 1106. CHROMIUM-VANADIUM STEELS 91 RECOVERING ALLOYED ELEMENTS As the alloying elements of alloy steels are all more valuable than iron, some of them very much so, makers of alloy steels wish, of course, to save such elements in their alloy-steel scrap, if practicable without too great cost. The makers can save tungsten, cooper, nickel, and cobalt, each of which has an affinity for oxygen and a heat of combustion with oxygen less than the similar properties of iron; however, the makers can not at present save the manganese, silicon, vanadium, titanium, calcium, magnesium, and chromium, each of which has an affinity for oxygen and a heat of combustion greater than the similar properties of iron. Plans have been proposed for saving some of them. Saving a part of these oxidizable elements in reworking the scrap is in some instances of no benefit, because in replacing the wasted part by the addition of a fresh quan- tity of the ferro-alloy saturated with carbon there will be too much carbon in the finished steel. This is particularly true of manganese in manganese-steel scrap. The carbon in the alloy- steel scrap is protected from oxidation by the alloying element while the latter is being oxidized. With low-carbon alloy avail- able the case is different, as the content of carbon in the steel may then be controlled. CERIUM PYROPHORIC ALLOY The pyrophoric metal used on cigar lighters and for igniters in miner's lamps might be considered as an alloy steel, as it consists substantially of 30 per cent of iron with 70 per cent of cerium. It was patented by Welsbach, whose name is identified with the Welsbach light. The striker is of the grade of hard- ened file steel with about 1.50 per cent carbon. The detached particles of the cerium-iron alloy take fire in the air, ignition being quickened no doubt by the heat generated in the impact of the striker. CONCLUSION Further advance in the development of new alloy steels as well as many new applications of those alloy steels already 92 MANUFACTURE AND USES OF ALLOY STEELS established, are to be expected. Trials are continually being made of new alloys of promise, some of which will doubtless win place in the list of useful alloy steels. Hadfield's iron alloy containing 5 per cent manganese and 15 per cent nickel, although not at present of use, may become so in the future, as its prop- erties are rather remarkable. As some of the alloys in steel, as well as any heat treatment it may have received, affect the carbon contained so that its effect in the color determination is changed, the regular practice in some steel-works laboratories is to make all carbon determina- tions gravimetrically by direct combustion of the whole sample with oxygen. This procedure avoids the uncertainties and errors of the color determination in analyzing heat-treated alloy steels. INDEX A Agricultural implements, steel used in 38 Alloy steel, definition of vii development of xiii heat treatment of 4 manufacture of 3, 4 useful list of I uses of 4 value of xiii See also various steels named. Alloy-steel scrap, recovery of alloys from g I Alloys, effects of, in steel 4 See also various alloys named. Alloy-treated steel, definition of. . vii manufacture of 2 method of treating 2,3 Aluminum in steel, purpose of ... . 2 Annealed steel, definition of vii Armor plate, steel for 59 properties of 59 Arnold, J. O., on nickel-iron, alloy of 49, 5° — on tungsten steels 16 Automobiles, steels used in 22, 64, 84, 87 composition of 58 B Ball bearings, steel used in 21 Bibliography on alloy steel, 10, 12, 17, 18, 23, 39-41, S4. 55, 62, 66, 84, 88, 90 Boynton, H. C, on heat treatment of high-speed steels 81 Bridges, steel used for 4S C Carbon in steel, effect of 48 proportion of 25, 72, 81 Carbon steel. See Simple steel. Carpenter, H. C. H., on high-speed tool steels 79, 80 Cast iron, merit number of 34 tensile strength of 33 Cerium pyrophoric alloy, composi- tion of 91 uses of gi Chrome-nickel steel. See Nickel- chromium steel. Chromium in steel, effect of 5, 20 proportion of 19, 73 Chromium steel, bibliography on . . 23 composition of 19 manufacture of 19, 20 methods of working 20 production of 19 properties of 20 uses of xiii, 21, 22 Chromium-vanadium steel, bibliog- raphy on 90 composition of 87, 88 production of 87 properties of 87, 89 results of test of 90 uses of 88, 89 Clay for lining ladle, advantages of 26 Cobalt in steel, effect of 75 — recovery of, from alloy- steel scrap 91 Complex, steel, definition of vii Copper, in tool steel, objections to . 76 — recovery of, from alloy-steel scrap 9"^ 93 94 INDEX Crucibles, types of, for melting steel 68 Cubillo, L., on steel for projectiles. 60 Cupola, melting of ferromanganese in 26 E •Edwards, C. A., on high-speed tool steels 79) 80 Edwards, E. T., on high-speed steels 81 Electrical appliances, steel used in . 4, 65 composition of 66 Ferrochromium, consumption of.. . 19 Ferromanganese, melting of, in steel making 13 — wastes, in melting 26 G Girod, P., on steel for projectiles. . 60 Gledhill, J. M., on tool steels 78 Guillet, L^on, on nickel steel 48 — on nickel-chromium steel 57 H Hadfield, R. A., on manganese steel ix, 24, 29, 31, 34, 38 — on iron and nickel alloys 50 Hardened steel, definition of viii Heat treatment of steels 6,7 description of 77-79 difficulties in 6 eUects of 7,9 method for 30 See also Manganese steel; Tool steel. Herbert, E. J., on high-speed tool steels 81, 82 High-nickel steel, properties of . . . . 51 structure of 51 uses of Sij 52 See also Invar; Platinite. I Ingots, alloy-steel, manufacture of. 4 Invar, definition of 53 — properties of 53 — uses of 53 K Kansas City viaduct, steel used in. 45 L Ladle, bottom-pouring, advantages of 69 — lining for, corrosion of 26, ^7 types of 26 for manganese steel. . . 26, 27 Landau, David, on modulus of elas- ticity of alloy steels .... 9, 10 "Loman steel," definition of 28 M Magnets, steel used in 14 Manganese, in steel, effect of 2, 4 proportion of ix conditions deter- mining 25, 26 Manganese steel, analyses of * 33 bibliography on 39-41 casting of 24, 34, 35 cold working of, objections to 38 composition of 24, 25, 27 variations in 27 compression tests of, results of 33 discovery of ix ductility of 31 • elastic limit of 32 heat treatment of 29, 30 hot-worked, uses of. . . 37, 38, 39 manufacture of 24-27 melting-point of 27 merit number of 33 production of 24 properties of 29 pulling test of, results of . . 31, 32 quenching of 29 raw, properties of 29 tensile strength of 33 toughening of 34 uses of 35,36 economy in 39 Manhattan bridge, N. Y., steel used in 4S INDEX 95 Mars, G., on fusion point of tung- sten steels IS Mayari, Cuba, iron ore, steel from. 6i Mayari steel, merits of 6i uses of 6i Molybdenum, in steels, effect of . . . 73 use of, objections to . . . 73, 74 Mushet, — ., alloy steel of xiii N Naural steel, definition of vii Nickel, in steel, effect of 4, 42, 48 proportion of, 42, 45, 46, 49, 56 use of 43 — recovery of, from scrap gi Nickel-chromium steel, bibliogra- phy on 62 composition of 56,57,62 properties of 56, 57, 61, 62 grades of 58 manufacture of, details of.. 60, 61 production of 56 relative cost of 56 uses of 56, 58, 59. 60 Nickel-iron alloy, merit figure of . . 49 properties of 49 Nickel-steel, bibliography on. . . 54, 55 composition of 47 development of xiv magnetism of 52 manufacture of 42, 43 merit number of 33 production of 42 properties of 42, 47, 49 seams in, causes of 44 structure of 42, 48, 49 uses of 4Si 46 working of 43 See also High-nickel steel. Normalized steel, definition of ... . vii O Oxidation process, steel making by . 2 P Phosphorus in tool steel, effect of . . 77 Pipes in ingots, prevention of — 5, 69 Platinite, definition of 53 — properties of 53, 54 — uses of 53, 54. Primrose, J. S., on nickel-iron alloys 51 Projectiles, armor-piercing, steel used for 22, 60 properties of 22 Quaternary steel, definition of ... . vii mention of i Quebec bridge, steel used in 45 Queensboro bridge, N. Y., steel used in 45 Quenching of steel, precautions in . 29 R Rails, steel used in manufacture of 35. 36> 38.46, 60 Rapid steels. See Tool steel, high- speed. Raw steel, definition of vii Read, A. A., nickel-iron alloy of. 49, 50 — on annealed tungsten steels. . 16, 17 Safes, burglar-proof, steel used in, 21,35,36 St. Louis municipal bridge, steel used in 45 Scale on nickel steel, removal of.. 43, 44 Sexton, A. H., on nickel-iron alloys. 51 "Silico-manganese" steel. See SiU- con steel. Silicon, in steel, purpose of 2, 3, 63 Silicon steel, bibliography on 66 composition of 65 manufacture of 63, 64 properties of 64 uses of 65, 66 Simple alloy steel, definition of . . . . vii Simple steel, definition of vii Steel, elements added to 2 . proportion of 2 purpose of viii — heat treatment of, effects of 3 — soft, merit number of 33 96 INDEX Steel, soft, tensile strength of 33 See also Alloy steel and va- rious steels named. Stellite, analysis of 76 Structural steels, alloys in, value of. 6 bibliography on 10-12 heat treatment of 6, 7, 9 difficulties in 6 effects of 6, 7, 9 modulus of elasticity of 9 ■ properties of 6, 8 uses of 4 Sulphur in tool steel, effect of 76 Taylor, F. W., on tool steels, 67, 73. 78, 79, 81 Tempered steel, definition of viii Ternary steel, definition of xi mention of i Titanium in steel, effect of 2 Tool steels, high-speed, advantages of 83 bibliography on 84-86 composition of 70, 71, 72 cutting speed of 83 variations in 83 heat treatment of, 67, 68, 77, 79 effect of 79 manufacture of 68-70 need of testing 81 patents on 84 production of 68 properties of. . . 33, 67, 68, 79 quenching of 77 specific gravity of 72 Tool steels, high-speed, structure of 70 theory of 80 uses of 84 treatment of 14 Tungsten, calorific power of 14 — in steel, effect of 14, 15, 16 proportion of 72 — properties of 14 — recovery of, from scrap 91 Tungsten steel, annealed, composi- tion of 17 properties of r6 — — bibliography on i7, 18 composition of 14 fusion point of iS, 16 manufacture of 13, i4 production of 14 properties of 14, 15, 16 theory of 17 uses of 14 V Vanadium in steel, effect of 74 • proportion of 74 purpose of 2,3 value of 75 Vaults, burglar-proof, steel used iJi 21, 35, 36 W Watertown Arsenal, Mass., tests of steel at 33, 90 White, Maunsel, on heat treatment of tool steels 67, 78 Wire, Krupp nickel-steel, analyses of SI resistance of 51