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Aalde, Kaare. ('40) Gen'I Del., Bisbee. Ariz. Aase, Glenn D., ('40) Univ. of North Dakota. Grand Forks. N. D. Abadesco, Enrique A., ('39) College of Engrg.. Univ. of the Philippines. Manila, P. I. Abbott. John L., ('40) Colorado School of Mines. Golden. Colo. Abdul-Ahad, A., ('39) Montana School of Mines. Residence Hall, Butte. Mont. Abreu, Ovidio M., ('38) Univ. of Nevada, Reno, Nev. Acomb, Allen. ('41) Louisiana State Univ., Box 1970, University. La. Acosta S., Gonzalo. ('40) Univ. of Texas, Univ. Sta., Box 1785. Austin, Tex. Adam, Howard W., ('41) Montana School of Mines. Butte, Mont. Adams, Albert, ('381 New Mexico School of Mines, Socorro. N. M. Adams. Charles W., ('39) Michigan College of Min. & Tech., Houghton, Mich. Adams. H. Travis, ('39) 316 South -5th St., Bur¬bank. Calif. Adams, Jack L., ('39) Univ. of Oklahoma, Nor¬man. Okla. Adams. John W., ('41) Colorado School of Mines, Golden. Colo. Adams. Lewis J.. ('39) 402 Del Mar Blvd., Corpus Christi, Tex. Adams, Rob L., ('40) Agricultural & Mech. Col¬ lege of Texas. Box 600, College Sta., Tex. Adamson. Charles R., ('41) Univ. of Utah, Salt Lake City. Utah.

Jan 1, 1941

By F. H. Daniels

IN this paper it is my intention to call your attention to a few of the many producers using blast, now in common use in Sweden, and also those constructed by the Washburn & Moèn Manufacturing Company at their Quinsigamond Works. During a prolonged stay in Sweden the writer had an opportunity

Jan 1, 1881

Jan 1, 1916

By Charles R. Austiuon, Carll H. Samans

It has been known for several years1 that certain alloys of the Konal type, containing commercial cobalt (99.32 per cent Co and 0.42 per cent Ni) and varying amounts of ferrotitanium, exhibit very high tensile strengths at 600°C. However, their proportional limits and yield pints are relatively low. published data' for the alloys quenched in water from 950°C. and then tested at 600°C. are summarized in the upper section of Fig. I. Similar specimens that were aged at 650°C. for 72 hr., after quench and prior to testing at 600°C., gave the result; shown in the: lower section of Fig. I. In the present work the investigation of the properties of these materials has been extended by a study of the tensile deformation characteristics in moderately longtime tests at 600°, 700' and 800°C. after quenching from various solution temperatures. In addition, some metallographic studies have been made to correlate with the deformation tests, and to obtain information on the quasi-binary system cobalt-Fe2Ti. The material, very kindly furnished by the Westinghouse Electric and Manufacturing Co. in the form of hot-swaged rods of 3/16-in. diameter, analyzed as shown in Table 1. The alloys, when originally made up,' were based upon an iron-titanium compound, Fe3Ti, as indicated by the work of

Jan 1, 1941

By E. S. Rowland, J. Welchner, R. H Marshall

This paper presents results on an extension into the realm of high-carbon steels of some work recently published1 on the effects of time at temperature, quenching temperature and prior structure on the hardenability of one 0.20 and four 0.40 per cent carbon alloy steels. It was shown at that time that unless the conditions of time, temperature and prior structure are substantially the same in performing the hardenability test as in conducting hardening of parts in production, the correlation of hardenability information with the hardness and properties of production parts is often not of satisfactory accuracy. The general effects of these variables on the austenitic grain size, distribution of excess carbides and critical cooling rate have been known for many years and one or more have been investigated by Shepherd,2,3 Davenport and Bain,4 Digges,5,6 Digges and Jordan,' Post and associates8 and Roberts and Mehl,9 to mention only a few. There has been no systematic investigation, however, into the quantitative variations produced on the hardenability of commercial high-carbon steels by changes in these factors of time, temperature and prior structure. Procedure A plain carbon hypereutectoid steel, S.A.E. 52100 and Graph-Mo, a molybdenum-bearing high-carbon steel containing some graphite, were chosen for this investigation. The chemical analyses of these electric-furnace steels are given in Table I. The procedure used was exactly that reported previously,' hence the details will not be repeated here. Normalized (165o°F.) and spheroidized prior structures were utilized on all steels with hot-rolled and quenched (I600°F. oil) prior conditions added for the plain carbon steel. The end-quench test developed by Jominy10 was sclected for use in this investigation and, with the noted exceptions, the American Society for Testing Materials standard procedure was followed. The effect of time at temperature was examined at intervals of o, 10 and 40 min. and 4 hr., and a few 16-hr. tests were run. Salt-bath heating of the specimens was employed to control and minimize the

Jan 1, 1944

By C. C. Wright, T. S. Spicer, R. G. Bowman

In recent years considerable publicity has been given to the problem of atmospheric pollution by fuel-burning equipment. Legislation has been stimulated and smoke ordinances have been enacted, the provisions of which show a definite trend toward stricter control of the emissions not only from the stacks of industrial fuel users but also from the chimneys of domestic consumers. As a result of war conditions, some slackening in the enforcement of these ordinances may be noted, but this is only a temporary expediency caused by the changes necessary in the distribution of the nation's fuel supplies and difficulties in securing the necessary equipment. Previous trends may be expected to continue in the postwar period. Largely because of the consumer demand for automatic heat, but partly because of the legislation against smoke emission, there has been a marked increase in the use of domestic underfeed stokers with the past decade. When correctly adjusted and operated, these units reduce the smoke emission materially, so that even the high-volatile bituminous coals may be burned with little or no emission of objectionable smoke. Unfortunately, however, the use of the domestic underfeed stoker introduces another problem; namely, fly-ash. Production of Fly-ash The term "fly-ash" is a misnomer, since the fly material is generally a mixture of small carbonaceous particles varying from green coal to coke, and inorganic particles ranging from fluffy ash to small particles of fused clinker. For want of a more comprehensive name, however, the term fly-ash is used throughout this paper to include all the fly material. Even with hand-fired furnaces a certain amount of fly-ash is produced, which necessitates periodic cleaning of the boiler flues or furnace radiator, the smoke pipe, and occasionally the chimney itself. With stoker operations the amount of fly-ash is increased many fold, because of the higher velocity of air travel through the fuel bed. Frequently the amount of this fly-ash attains such proportions as to constitute a definite nuisance to the householder and his neighbors and distracts very materially from the otherwise automatic or semi-automatic performance of the stoker. Virtually all the boilers and hot-air

Jan 1, 1944

By F. H. Kihlstedt

The Larap iron deposits, 125 miles east of Manila, are the biggest high-grade iron deposits in the Philippines, and have in seven years produced nearly 4 million tons of 60 per cent ore. Magnetic surveying followed by churn and diamond drilling cheaply developed a score of million tons. The ore zone is a wedge of metamorphic rocks in fresh, Miocene sediments overlain by agglomerates, which seem to have filled a river valley eroded in the sediments. A mild overthrust of the competent agglomerates crumbled the shale in front. Solutions gradually turned it into more competent hornfels and deposited pyrite, then magnetite and pyrite in the pores. As the temperature rose large bodies of magnetite with some pyrite were deposited by replacement and in open cavities in tensional areas of overthrust shears. At still higher temperature magnetite and calcium-magnesium silicates formed other bodies in similar cavities, and finally the thrust zone was invaded by syenite porphyry, causing high-temperature alteration products. Possibly, as temperature abated, more high-grade ore was deposited. The complicated faulting indicates dynamic, chronological and spatial changes of mineralization rather than zoning in a static system. Noncommercial copper, molybdenum and some gold accompanied the iron mineralization. In the thirties the Philippines gained a justified reputation as a country of considerable mineral wealth. Traces of Chinese workings show that these earliest travelers and traders had in a small way exploited the latent gold resources in the Islands. The Spaniards continued this for centuries, but did not succeed in establishing any steady mining industry. Modern technology was required to get it started. The rapid development in the last decade before the war got its impetus from several financial factors, the return to sugar growers of previously collected taxes, the influx of Spanish capital during the civil war in Spain, the influx of Chinese capital when the Japanese started their "China incident," and others. Directly or indirectly much of this capital reached the mining industry; in particular, gold mining. Out of the turmoil of an exceptional mining boom emerged a sufficient number of good and well managed gold properties to send the production to a level above that of any single state in the United States at the time. Other ore deposits besides those of gold also received their share, and for a country without any heavy industries at

Jan 1, 1949

By George E. Thackray

In December, 1894, the Cambria Iron Company made a number of heats of Bessemer steel to be used in structures by one of its customers, subject to inspection and tests by a firm of consulting engineers, one of the requirements being that the material should riot exceed .08 per cent. of phosphorus. In other respects the requirements were such that they could only be met by material of good quality; but the general spe cification is not introduced here, as it is not the purpose of this paper to deal with anything except certain difficulties encoun tered in determining the phosphorus-content of the material in a manner satisfactory to both seller and buyer. Preliminary determinations of phosphorus were made in sample-ingots from each of the heats from which material was rolled for the order in question, and these preliminary chemical tests, made in the laboratory of the Cambria Iron Company, showed that, with very few exceptions, every heat was within the prescribed limit of phosphorus. After the material had been rolled, sample-drilling8 of finished material were taken from the various heats in the regular manner in use at the works, these samples being thoroughly mixed and divided into two parts, one of which was analyzed at the works' laboratory and the other sent to the inspecting engineer. Several hundred determinations were made from this mate rial without reaching an agreement between the work of the inspector's chemist and that of the works' chemist; but as it is not the object of this memorandum to treat of this part of the subject at length, it is considered sufficient to present herewith only a few of these first determinations. The analyses given in Table I. are those of the original series made on the heats which were afterwards resampled for final determination by an arbitrator; and they are selected for this reason, as the entire " comparison is thus rendered more complete.

Jan 1, 1896

By W. R. Hibbard, Ming-Kao Yen

Various rationalizations of preferred orientations in cold worked polycrystalline metals have been based on the operation of at least two three2 five, an indefinite number, and all,6 slip systems of the type occurring in single crystals. Pickus and Mathewson3 suggested that the cold rolling texture in face-centered cubic metals could be rationalized on the basis of two or more operating slip directions symmetrically disposed about the direction of flow in such a manner that the resolved shear stress factor is equal for all operating slip systems and lattice rotations cancel each other. The importance of the direction of flow, the necessity for the operation of slip systems capable of producing the required changes in external dimensions, the maintenance of a common surface between adjacent grains and a symmetrical arrangement of the operating slip systems in order to produce an end orientation which is stable under additional deformation lead to the following rationalization of textures based on the type of slip systems operative in single crystals. The rationalization is intended to explain why certain orientations are suitable for deformational flow without a change in orientation and thus are stable end orientations or ideal texture orientations. It does not attempt to explain how the grains of a randomly oriented polycrystalline aggregate will reach this orientation. The rationalization is based on the following four postulates: 1. The ideal textures for polycrystalline aggregates are the result of reorientations of individual crystals toward the same stable end orientation at which no further reorientation will occur even during additional deformation. Since, in simple slip, the relative orientations of the stress axis and the active slip system determine the change in orientation during slip, it is considered that the orientation of the stress axis with respect to the ideal texture determines what slip systems must be active to retain the stable end orientation. Therefore the stable end orientation should be a symmetrical one around the stress axis with respect to the active slip systems such that lattice rotations resulting from slip will cancel each other and prevent a resultant change in orientation. (Rotational symmetry only—not translation, inversion, nor others—is considered here.) Thus a metal under a pure stress should develop a texture consisting of one or more of the crystallographically symmetrical directions, <100>, <110> or <111> for cubic metals or <0001>, <1010> or <1120> for hexagonal close-packed metals, parallel to the stress axis. 2. Since the active slip direction is the direction of glide during simple slip and thus the direction of maximum shear movement, in the ideal texture the active slip

Jan 1, 1949

By Henry D. Hibbard

FoR the purpose of this paper all steels will be divided into two divisions: effervescing and non-effervescing. This classification must be borne in mind as many statements true of one class are not true of the other. Effervescing steels are those that effervesce in the molds, evolving large volumes of gases, which, in escaping, throw up a spray of molten particles of steel and give the molten metal in the mold a rapid stirring or churning motion until it freezes, or, at least, becomes pasty. This effervescing is intended and proper. The non-effervescing steels, which are more or less completely killed, should not evolve any gas in the molds. Many years ago the writer proposed to call the two classes of steels evolution and solution steels, depending on whether the gases in the molds are evolved or kept in solution, but the present designations seem to be better. In America, at least, effervescing steels are in a class by themselves and include steels made for boiler, tank, and ship plates, steel pipe, soft steel wire, wire nails, soft machincry, and structural steels. These are all low-carbon steels with less than 0.40 per cent. carbon. Low-carbon steels that do not effervesce but are killed are also made; these are put into ingots and castings but they are outside the limits of this paper. Effervescing steel is cast into square or slab molds, either top or bottom poured. Most of the effervescing steel is made in the basic open-hearth furnace, though much is made by the acid Bessemer process and a little is made in the acid open-hearth. It is not made by the crucible or electric-furnace process, in which the volume of gas required cannot be produced in the steel and evolved from it in the mold to give the effervescence desired. Any steel ingot, when teeming is finished, is of a certain size or volume. Leaving out of consideration for the moment the lessening of the over-all dimensions of the ingot through contraction due to loss of heat, the ingot may be placed in one of three classes: It may settle, losing in volume; it may stand, that is, remain constant in volume; it may rise, that is, increase in volume. Into which class an ingot will fall depends on the gases of the steel,

Jan 1, 1920

NORTH AMERICA ALASKA Anchorage.-Ames, M. B. Culver, H. W. Fiedler, H. L. Geehan, R. V. Langneas, O. O. Layfield, R. A. Parent, A. Saarela, L. H. Strandberg, H. Candle.-Robbins, J. S. Chichagof.-Russell, J. C. College.-Fox, E. F. Joesting, H. R. Lyman, R. F. Smith, M. C. -Wilcox, H. G. Douglas.-Cahill, W. E. Fairbanks.-Adams, J. M. CANADA Canadian Army Overseas.¬Ball, H. D. Bridges, O. Butterill, H. J. M. Lane, H. C. Millar, W. A.

Jan 1, 1942

By B. A. Rogers

ACCORDING to petrographic investigations, 1-4 cooled steel furnace slags contain a number of substances that have been shown to be ferro-magnetic5,6 and hence capable of undergoing appreciable changes of susceptibility with temperature. Since any alteration of the suscepti-bility of a constituent affects the average susceptibility of the sample, information concerning the nature of the substance should be deducible from its magnetic behavior. The possibility of obtaining information concerning slags in this way led to the construction of the apparatus to be described. FUNDAMENTAL PRINCIPLES OF APPARATUS The most convenient method of observing changes in mass suscepti-bility? with temperature is the one employed by Curie7 in his original investigation of the changes in magnetic properties of substances at elevated temperatures. As the method has been described frequently in the literature and in textbooks, only a brief review of the fundamental principles need be given here, but the particular arrangements used in the present work require a more detailed description.

Jan 1, 1939

By A. L. Fentress, P. R. Bucky

The purpose of this paper is to present a scientific method for determining the proper span and shape of roof for safe and economical mining; at present, these two vital factors wherever pillars are left to support the roof are determined by local practice or general experience. To develop the method described here, experimental laboratory work was done. The arch adopted was a segment of a circle, a flat roof being considered an arch with an infinite radius. Hitherto, arches have been used underground without the background of stress analysis that generally precedes arch construction on the surface. In many cases results have not been as expected, because of the lack of knowledge of the factors affecting its strength and behavior. A theoretical and experimental study of arches should furnish information that will make it possible to design safe and economical surface structures as well as underground openings. For example, on the subject of mine drifts and tunnels, the present idea is that arching their backs increases their strength; this paper will indicate that this is not always true, and if it can be shown that under certain conditions arching becomes unnecessary an economic saving will result. In room-and-pillar work a question may arise as to whether arching the roof and gobbing the excavated material will result in timber saving, and a decrease in the dangers from falls of roof. It is to be distinctly understood that each mine must be treated as an individual problem, and that answers to these questions and many others can now be found after experimental laboratory data have been obtained. Mine-Arch Structure Fig. 1 shows the elements that affect the strength or behavior of the experimental arch. They are the span, crown thickness, radius of curvature, rise and restraint. The restraint in all cases was made sufficient to cause the arch to fail without displacing the restraining sides. Fig. 2a is a photograph of a model arch prepared for testing in the centri-

Jan 1, 1934

By F. H. Kihlstedt

The Larap iron deposits, 125 miles east of Manila, are the biggest high-grade iron deposits in the Philippines, and have in seven years produced nearly 4 million tons of 60 per cent ore. Magnetic surveying followed by churn and diamond drilling cheaply developed a score of million tons. The ore zone is a wedge of metamorphic rocks in fresh, Miocene sediments overlain by agglomerates, which seem to have filled a river valley eroded in the sediments. A mild overthrust of the competent agglomerates crumbled the shale in front. Solutions gradually turned it into more competent hornfels and deposited pyrite, then magnetite and pyrite in the pores. As the temperature rose large bodies of magnetite with some pyrite were deposited by replacement and in open cavities in tensional areas of overthrust shears. At still higher temperature magnetite and calcium-magnesium silicates formed other bodies in similar cavities, and finally the thrust zone was invaded by syenite porphyry, causing high-temperature alteration products. Possibly, as temperature abated, more high-grade ore was deposited. The complicated faulting indicates dynamic, chronological and spatial changes of mineralization rather than zoning in a static system. Noncommercial copper, molybdenum and some gold accompanied the iron mineralization. In the thirties the Philippines gained a justified reputation as a country of considerable mineral wealth. Traces of Chinese workings show that these earliest travelers and traders had in a small way exploited the latent gold resources in the Islands. The Spaniards continued this for centuries, but did not succeed in establishing any steady mining industry. Modern technology was required to get it started. The rapid development in the last decade before the war got its impetus from several financial factors, the return to sugar growers of previously collected taxes, the influx of Spanish capital during the civil war in Spain, the influx of Chinese capital when the Japanese started their "China incident," and others. Directly or indirectly much of this capital reached the mining industry; in particular, gold mining. Out of the turmoil of an exceptional mining boom emerged a sufficient number of good and well managed gold properties to send the production to a level above that of any single state in the United States at the time. Other ore deposits besides those of gold also received their share, and for a country without any heavy industries at

Jan 1, 1949

By Robert Forsyth

As the latest plant on a large scale, the new Bessemer works of the North Chicago Rolling Mill Company, at South Chicago, presents some features of interest to steel-makers, I have ventured to lay before the Institute a short description of that plant, and some* remarks upon the practice there. At the time the South Chicago works were designed the adoption of the basic process in this country seemed imminent. Experience in Europe had demonstrated the perfect success of the process technically, and the question of its commercial value was one which, for any particular works, would have to be settled by its special advantages for procuring the necessary ores and basic materials. Under the circumstances, it was thought best at South Chicago to so arrange the plant as to allow the introdnction of the basic whenever it became advisable, and to make such other changes from the standard type of Bessemer plant as the state of the art seemed to demand and to foreshadow. As the use of metal direct from the blast furnace, while generally condemned by experts here, was in such successful practice in Europe (particularly in connection with the basic process), there was no doubt about its feasibility, while its economy in fuel and labor made it especially attractive to the Western manufacturer. It was accordingly decided to build a direct-metal plant adapted to the basic process. The ingots made were to be rolled into rails at one heat, and were to be of such size (12 inches square and long enough for three and four rails) as to be readily and quickly handled by the rolling machinery proposed. This small size of ingots, and the large number cast from each heat of 10 tons, made it necessary to provide a good deal of room in the casting-pit—much more than in any previons plant—and to put down extra facilities for handling ingots. To meet the delays incident to the basic process—to insure that one vessel should be always blowing if necessary, and to provide opportunity for current repairs to linings, etc.—it was decided that three vessels should be used, and, to properly concentrate the work of

Jan 1, 1884

By Carll H. Samans, Charles R. Austiuon

It has been known for several years1 that certain alloys of the Konal type, containing commercial cobalt (99.32 per cent Co and 0.42 per cent Ni) and varying amounts of ferrotitanium, exhibit very high tensile strengths at 600°C. However, their proportional limits and yield pints are relatively low. published data&apos; for the alloys quenched in water from 950°C. and then tested at 600°C. are summarized in the upper section of Fig. I. Similar specimens that were aged at 650°C. for 72 hr., after quench and prior to testing at 600°C., gave the result; shown in the: lower section of Fig. I. In the present work the investigation of the properties of these materials has been extended by a study of the tensile deformation characteristics in moderately longtime tests at 600°, 700&apos; and 800°C. after quenching from various solution temperatures. In addition, some metallographic studies have been made to correlate with the deformation tests, and to obtain information on the quasi-binary system cobalt-Fe2Ti. The material, very kindly furnished by the Westinghouse Electric and Manufacturing Co. in the form of hot-swaged rods of 3/16-in. diameter, analyzed as shown in Table 1. The alloys, when originally made up,&apos; were based upon an iron-titanium compound, Fe3Ti, as indicated by the work of

Jan 1, 1941

By Dwight E. Woodbridge

DuriNg April, Max, and June, 1910, I was in charge of an examination of the greater part of the Moa iron-ore area in Oriente Province, Cuba, on the north coast, near the east end of the island. My instructions, on arrival at the properties, were to check former estimates of tonnages and grades, and to re-examine the ore comprised in claims covering 44,727 acres. This work included the running of lines dividing the properties into co-ordinate planes, the boring of many thousand feet of holes spaced at the intersections of these co-ordinates, the taking of samples of the ore penetrated, the analysis of these samples for their various constituent minerals, and the determination of the results as to tonnages, depths, and grades, both for individual properties and for the entire group. Each section of every one of the thousand holes drilled was to be compensated for depth and grade with every other, a series of simple arithmetical calculations of no slight magnitude, the mere mechanical labor of which consumed much time, but finally resulted in giving a complete average of all the essential facts for the entire area of 18,000 hectares, Had it not been for the more than willing, active, and able co-operation of the officers of the Spanish-American Iron Co., from Charles F. Rand, President, and Jennings S. Cox, General .Manager, down to the most humble water-carrier, the work would have consumed far more time than it did. The lands thus systematically explored by me were comprised in the following denouncements: Punta Gorda, Yaminiguey, Baracoa secunda, Sagua, Moa, Yajrumaje, Lirio, and Cabanas, all of which were massed as the Moa group, so called, and cover an area of 13,832 hectares, or 34,179 acres. Some 10,000 acres additional to this was included in neighboring properties, lying between Moa and the east end of the island, the Buena Vista,

Jan 1, 1912

By J. D. Prater, H. R. Spedden, E. E. Malouf

With the expansion of copper leaching of the various mine wastes at the Kennecott properties, additional copper recovery facilities have been required. A research and development program has been pursued to determine a suitable economic approach to the processing of the additional leach solutions contemplated. lnvestigations on laboratory and pilot plant scales covered electrowinning, solvent extraction, launder and vat type cells, activated launders, precipitation drums, and precipitation cones. This paper contains information on the development and use of a new precipitation-cone-type copper recovery plant, which provides many advantages over older systems. The application of research findings to the old art of leaching copper from copper-bearing mine waste has resulted in a significant contribution of copper to over-all copper production. For example, at the completion of the current expansion program at the Kennecott properties in the United States, copper produced from waste dump leaching will amount to about 25% of the total production. Formerly only 2% was derived from this source. This planned expansion of copper leaching focused attention on the problem of developing more efficient methods for the recovery of copper from greatly increased volumes of copper-bearing solutions.1 The detailed investigations which have been made in laboratory pilot plant and plant tests for the recovery of copper from copper-bearing solutions have included electrowinning, solvent extraction, ion exchange and cementation with iron in launders, precipitation drums, activated launders, and precipitation cones. The results of these investigations have led to the development of a new precipitation cone-type copper recovery system providing many advantages over older methods. ELECTROWINNING OF COPPER FROM COPPER-BEARING SOLUTIONS The direct electrowinning of copper from relatively dilute solutions of copper-bearing mine water, namely solutions containing 10 to 20 lbs of copper per 1000 gal, has always been an attractive possibility.2,3 By this method, high-purity copper powder can be recovered with a power consumption of 3.5 kwh per Ib of copper. However, once the solution strength de-

Jan 1, 1967

By R. H. Marshall, J. Welchner, E. S. Rowland

This paper presents results on an extension into the realm of high-carbon steels of some work recently published1 on the effects of time at temperature, quenching temperature and prior structure on the hardenability of one 0.20 and four 0.40 per cent carbon alloy steels. It was shown at that time that unless the conditions of time, temperature and prior structure are substantially the same in performing the hardenability test as in conducting hardening of parts in production, the correlation of hardenability information with the hardness and properties of production parts is often not of satisfactory accuracy. The general effects of these variables on the austenitic grain size, distribution of excess carbides and critical cooling rate have been known for many years and one or more have been investigated by Shepherd,2,3 Davenport and Bain,4 Digges,5,6 Digges and Jordan,&apos; Post and associates8 and Roberts and Mehl,9 to mention only a few. There has been no systematic investigation, however, into the quantitative variations produced on the hardenability of commercial high-carbon steels by changes in these factors of time, temperature and prior structure. Procedure A plain carbon hypereutectoid steel, S.A.E. 52100 and Graph-Mo, a molybdenum-bearing high-carbon steel containing some graphite, were chosen for this investigation. The chemical analyses of these electric-furnace steels are given in Table I. The procedure used was exactly that reported previously,&apos; hence the details will not be repeated here. Normalized (165o°F.) and spheroidized prior structures were utilized on all steels with hot-rolled and quenched (I600°F. oil) prior conditions added for the plain carbon steel. The end-quench test developed by Jominy10 was sclected for use in this investigation and, with the noted exceptions, the American Society for Testing Materials standard procedure was followed. The effect of time at temperature was examined at intervals of o, 10 and 40 min. and 4 hr., and a few 16-hr. tests were run. Salt-bath heating of the specimens was employed to control and minimize the

Jan 1, 1944

By Ming-Kao Yen, W. R. Hibbard

Various rationalizations of preferred orientations in cold worked polycrystalline metals have been based on the operation of at least two three2 five, an indefinite number, and all,6 slip systems of the type occurring in single crystals. Pickus and Mathewson3 suggested that the cold rolling texture in face-centered cubic metals could be rationalized on the basis of two or more operating slip directions symmetrically disposed about the direction of flow in such a manner that the resolved shear stress factor is equal for all operating slip systems and lattice rotations cancel each other. The importance of the direction of flow, the necessity for the operation of slip systems capable of producing the required changes in external dimensions, the maintenance of a common surface between adjacent grains and a symmetrical arrangement of the operating slip systems in order to produce an end orientation which is stable under additional deformation lead to the following rationalization of textures based on the type of slip systems operative in single crystals. The rationalization is intended to explain why certain orientations are suitable for deformational flow without a change in orientation and thus are stable end orientations or ideal texture orientations. It does not attempt to explain how the grains of a randomly oriented polycrystalline aggregate will reach this orientation. The rationalization is based on the following four postulates: 1. The ideal textures for polycrystalline aggregates are the result of reorientations of individual crystals toward the same stable end orientation at which no further reorientation will occur even during additional deformation. Since, in simple slip, the relative orientations of the stress axis and the active slip system determine the change in orientation during slip, it is considered that the orientation of the stress axis with respect to the ideal texture determines what slip systems must be active to retain the stable end orientation. Therefore the stable end orientation should be a symmetrical one around the stress axis with respect to the active slip systems such that lattice rotations resulting from slip will cancel each other and prevent a resultant change in orientation. (Rotational symmetry only—not translation, inversion, nor others—is considered here.) Thus a metal under a pure stress should develop a texture consisting of one or more of the crystallographically symmetrical directions, <100>, <110> or <111> for cubic metals or <0001>, <1010> or <1120> for hexagonal close-packed metals, parallel to the stress axis. 2. Since the active slip direction is the direction of glide during simple slip and thus the direction of maximum shear movement, in the ideal texture the active slip

Jan 1, 1949