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By James T. Gow, Oscar E. Harder, Anton de S. Brasunas

This paper deals with the results obtained and the techniques employed in determining: 1. Liquidus and solidus temperatures of the HH and HT type heat-resistant alloys. 2. The relation of true temperatures (thermocouple) to apparent temperatures (optical pyrometer) for the molten HH and HT type alloys. This work was the outgrowth of needing to know something definite about these temperatures in order to study the effect of pouring temperatures, shake-out times, and heat-treatments on the properties of some heat-resistant alloys. The information developed is thought to be of interest to industry for guidance in foundry practices and the industrial heat applications of the alloys. This paper is based upon work that has been done for the Alloy Casting Institute at Battellc Memorial Institute. Liquidus and Solidus Temperatures of HH and HT Type Alloys Experimenta1 Procedures Temperature-time curves were obtained during the cooling and solidification of several HH and HT type alloys. The metal was melted in an Ajax high-frequency, induction furnace and poured into a core-sand mold for cooling. The temperature measurements were obtained by means of a platinum, platinum-rhodium thermocouple contained within a fused silica sheath, which was extended through the side wall of the dry core-sand mold to a point at about the center of the mold cavity, which was 3 in. in diameter by 5 in. deep. The cold junction of the thermocouple was kept in an ice bottle, and the temperature was recorded automatically on a direct-reading potentiometer recorder. Through a switching arrangement, the temperature recorded was checked occasionally with a portable Leeds and North-rup potentiometer indicator. Less than a 5°F. variation in the two instruments was always found. This is within the limit of accuracy of readings. The thermocouple used was checked for accuracy against a standard couple, both before use on this work and after completion of the work, by the instrument laboratory. Temperature-time Cooling Curves Fig. I is an enlarged reproduction of a part of one of the cooling curves over the temperature range of 2600' to 2200°F. for an alloy of the HT type with 0.45 per cent carbon, 16 per cent chromium, and 36 per cent nickel. This is a typically shaped cooling curve as obtained for the alloys. It will be noted that two temperatures "re shown on Fig. I for the liquidus temperature. It is thought likely that the higher temperature, A, at the point at

Jan 1, 1945

By W. L. Phillips

Nickel alloys containing approximately 0.5, 2.0, and 6.0 at. pct of Os, Pd, Ru, and Rh were Prepared by vacuum melting. Tension tests were carried out at 25°, 500°, 800°, and 1000°C; stress-rupture tests were carried out at 650° and 800°C. The room- and elevated-temperature tensile strength, as well as the stress-rupture life, increased for the same atomic percent in the order palladium, rhodium, ruthenium, osmium. The ductility decreased with increasing concentration or temperature for a given concentration. The results are discussed in terms of solid-solution theory. BOTH solid-solution strengthening and weakening have been observed in alloys. The simple rules which have been suggested to explain alloy strengthening are subject to several exceptions and deviations based on atom size and valency effects. The purpose of the present investigation was to extend the knowledge of the effect of solid-solution alloying on the mechanical properties of several Ni-Pt group metal alloys at room and elevated temperatures. The platinum group metals, osmium, ruthenium, rhodium, and palladium were chosen as the solute elements because of their different valencies and atom sizes. Nickel was chosen as the base material because of the large amount of previous literature available on nickel alloys. EXPERIMENTAL PROCEDURE Grade A Carbonyl nickel powder having the following composition: C, 0.07 pct; Fe, 0.013 pct; Mn, 0.0005 pct; Si, 0.016 pct; Mg, 0.0003 pct; S, 0.003 pct, was purchased from the International Nickel Co. The platinum-group metal powders were purchased from A. D. Mackay Co. The powders were weighed, cone-blended for 4 hr, and vacuum-melted into 1-in.-diam billets, approximately 2 in. long. The ingots were homogenized for 5 hr at 1800°F before being extruded into 1/4-in. rods at 2100°F. The alloy compositions are shown in Table I. Typical impurity values were not significantly different than that of the as-received nickel. All alloys were single phase. The lattice parameter of each alloy after the heat treatment described below is also included in Table I. Each alloy was annealed at 2200°F for 1 hr and air-quenched to comparable grain sizes (ASTM G.S. No. 4-5). The rods were then machined into test samples 0.160-in. diam and 0.750-in. gage length. Tension testing was carried out in an In-stron tension-testing machine at a strain rate of 0.02 in. per in. per min. An extensometer was used to determine the room-temperature yield stress. Stress-rupture testing was carried out in an Arc Weld stress-rupture unit. All testing was performed in air. EXPERIMENTAL RESULTS A) Room-Temperature Mechanical Properties. The 0.2 pct yield stress, ultimate tensile strength, and elongation for all alloys tested at room temperature are plotted as a function of atomic percent solute element in Fig. 1. The ultimate tensile strength for the same atomic percent increases in the order palladium, rhodium, ruthenium, osmium. The yield strength at low concentrations, -0.5 at. pct, increases in the order osmium, palladium, ruthenium, rhodium. At higher concentrations, 3.0 and 10.0 pct, the yield strength increases in the same order as the tensile strength. Both yield strength and tensile strength increase rapidly ini-

Jan 1, 1964

By R. P. Rothwell

THE milling of silver ores has arrived at a great degree of perfection in the mining districts of our Western States and Territories, and I have thought the record of the practical results obtained at the present time, in a few of the principal districts, would prove of value and interest to many of our members, both at home and abroad. An American silver mill is composed, in descending order from where the ore is dumped, of: 1st. A rock-breaker, usually of the Blake or Alden pattern ; 2d. The battery of stamps, the number of which varies from 5 to 120, generally in batteries of 5 or 10 heads, so arranged that a single battery may stand while the others are running; 3d. The tanks where the crushed ore settles (if it is a wet stamping-mill), or of a drying-floor if the crushing is done dry; 4th. Amalgamating pans ; 5th. Settling pans ; 6th. Agitators or pans in which mercury escaping in the tailings is caught; 7th. Blanket sluices, over which the tailings run, and where mercury and unamalgamated sulphides are saved. A reference to the engravings (see plate), which show one of the latest forms of an 80-stamp silver-mill run by a turbine water-wheel, will show clearly the arrangement of the several parts. THE ONTARIO, UTAH, SILVER MILL. One of the best examples of a silver-mill, and at the same time one of the most successful concerns in the West, is the mill of the Ontario Silver Mining Company, near Salt Lake, in Utah. This mill treats the ore from the Ontario mine, ore which at present is very base, being composed of zinc, lead, and silver sulphides and silver chloride in a quartz gangue. This ore has become baser as the mine attained greater depth, though the vein holds its own, or rather increases, both in thickness and richness. The mill is man¬aged in a skilful and economical manner, though the necessity for * Read at the Montreal meeting, September, 1879.

Jan 1, 1880

By Leroy U. Gardner

EVERY reader of this paper is well aware of the fact that the prolonged inhalation of large amounts of free silica dust results in fibrosis of the lungs, and that other inorganic dusts, except those of asbestos and the mineral poisons, are thought to be relatively harmless. But probably few have had opportunity to visualize the effects of silica, asbestos and other minerals upon living tissues. The ideal demonstration would be based upon sections of lungs from human beings that had inhaled com- parable concentrations of different dusts for a unit period of time. Such material is generally difficult to obtain and in some instances is of questionable value because the subject has been exposed to more than one kind of dust. A demonstration could be prepared from the lungs of animals. However, so many months or even years are required to complete the exposure to each kind of dust that enough material has not been accumulated. For a general survey of the action of different types of dust, I am therefore compelled to use the tissues of animals that have been injected with suspensions of dust particles. The injection method offers certain advantages. The quantity, the particle size and the state of dispersion can be controlled with sufficient accuracy so that the tissue responses to different minerals can be accurately compared. The method insures contact between the tissues and the mineral particles; protective mechanisms, which may prevent the inhalation of certain types of foreign body, never come into play. If the pathway of injection be one that minimizes nonspecific injury, the tissue responses may simulate those produced by inhalation but they develop somewhat more rapidly. It should always be remembered that injection methods merely demonstrate the capacity of various kinds of minerals to provoke reaction in the tissues; whether the same substances are inhaled from atmospheric suspension and accumulate in the lungs in dangerous quantities can be demonstrated only by inhalation. The reactions that I shall discuss first took place not in the lungs but in the liver. For the purpose in hand this is quite immaterial for we are merely seeking to discover whether these minerals are capable of produc-

Jan 1, 1938

By H. J. Ramey

A general solution is presented for the transient temperature distribution caused by radial movement of a cylindrical heat source through a homogeneous medium of infinite extent. This problem represents a highly simplified model of the movement of a combustion front during the thermal recovery of oil. Numerical solutions are presented for a heat source moving at a constant velocity, and a velocity inversely proportional to the radial location of the heat source. Numerical solutions are presented for both finite and infinite vertical thickness of the heat source, i.e., with and without vertical heat losses. The numerical solutions are used to estimate the fuel concentration needed to maintain a combustion front during the thermal recovery of oil. The sensible heat carried to the combustion front by the injected gas stream is discussed in regard to the fuel concentration. Numerical solutions for a heat source (combustion front) of finite vertical thickness indicate the field conditions that may be necessary to sustain the temperature of a combustion front above the ignition temperature of the fuel over considerable distances from an injection well. The results also have implications in regard to the quantity of heat required during ignition. The results of this computation apply to a highly idealized model of a thermal recovery process. But the results may be used as a guide in engineering consideration of the thermal recovery process. INTRODUCTIO N The thermal recovery of crude oil has received considerable attention since the publication by Kuhn and Kochl of laboratory and field tests of this method of oil recovery. Other publications2,3,4,5,6, since that time have dealt with various features of the thermal recovery of oil and have illustrated the extremely complex nature of this process. Vogel and Krueger7 described an electric analog computer designed to solve a moving heat source problem which was analogous to movement of a combustion front during the thermal recovery of oil. The heat source was maintained at constant temperature and was a cylindrical source of infinite height (no vertical heat loss) moving radially at either constant velocity, or at a velocity inversely proportional to the radial location of the heat source. Jenkins and Ramey2 presented analytical solutions to a similar heat conduction problem and pointed out the possible importance of vertical heat losses. The following presents a general solution to the transient heat conduction problem introduced by Jenkins and Ramey4 as well as numerical solutions for a wide range of conditions possibly similar to those that might exist during field operation of the analogous thermal recovery process. DESCRIPTION OF PROBLEM The problem considered in this paper is determination of transient temperature distribution caused by a cylindrical heat source of infinite or finite vertical height, moving radially through an isotropic medium of infinite extent. It is further assumed that the heat flux generated at the surface of the moving heat source may be a function of time such that the fuel concentration required may be constant, or permitted to vary, and that heat is generated at the surface of the heat source only. In regard to the thermal recovery of oil the assumption that heat is generated at the surface of the front is equivalent to assuming that the thickness of the combustion zone is infinitely small, or that the reaction rate between fuel and oxidant gas is infinite. The last assumption does not appear stringent. See laboratory information published by Martin, et al3 Under these assumptions the temperature distribution throughout an infinite medium caused by a heat source moving radially with an arbitrary velocity may be described by The heat generation function or heat flux at the surface of the source, +(t), is Note that the fuel concentration may be defined as a function of time. Eq. 1 is derived in the Appendix.

By M. G. Corson

THE iron-silicon alloy series has always been one of the most puzzling among the binary alloys. Examining the well known mechanical properties of the iron-rich alloys only we meet the following situation: The ultimate strength and yield point of alloys worked and annealed under the usual conditions represent nearly a straight line function of the silicon content up to 4.5 per cent. silicon (Fig. 1). Starting at the ultimate strength of 35,000 lb. and at a yield-point of 16,000 lb. for pure electrolytic iron, one reaches a -maximum strength of 93,000 lb. and a maximum yield point of 74,000 lb. at 4.5 per cent. silicon. This corresponds to an increase in ultimate strength by 13,000 lb. per each per cent. of silicon added and nearly the same rate applies to the yield point. The data mentioned are taken from the investigation by T. D. Yensen,1 and while they do not exactly corroborate the results obtained by earlier investigators, they seem to be the most correct. Plastic properties of the alloys are controlled by a much more complicated relationship. Up to 2.5 per cent. Si, the elongation stays close to 50 per cent. (in 2 in.) and the area reduction amounts to 85 per cent., a situation that forms the usual feature of all alloys representing strictly solid solutions. The plasticity of the latter is always nearly equal to that of their base metal. Beyond 2.5 per cent. silicon, the situation becomes much more complicated Yensen observed an enormous drop in elongation and area reduction at about 2.65 per. cent. silicon, where the first hardly reaches 10 per cent. and the second is still lower; he found, however, a considerable recovery in plasticity at about 2.8 per cent. Si and up to. 4.5 per cent. Si it is represented by 20 per cent. for the elongation and 30 per cent. for area reduction.

Jan 1, 1928

By J. Laskowski

J. Laskowski (Associate Professor, Dept, of Mineral Processing and Coal Preparation, Silesian University of Technology, Gliwice, Poland) -Referring to the papers by J. A. L. Campbell and S. C. Sun, I must say that I am very pleased to see that type of work, because it is the only way to progress towards an understanding of flotation mechanisms. All those interested in the science of the surface chemistry of coals would find these papers a valuable contribution to the literature. In their extensive research, the authors attempt to synthesize their findings into a theory of coal flotation. To do this, the zeta potential of bituminous coals and their lithotypes, as well as that of an anthracite coal, was measured and H+ and OH- ions were found to be potential determining ions. The measured ZPC of bituminous coals was at a pH range from 3.5 to 4.6 and for the anthracites between 2.0 and 4.5. The authors have pointed out that since the hydrophobicity is pH-controlled, the flotation mechanism should also be. The Campbell and Sun papers confirm a good many of the conclusions on surface properties of coals reported in recent years. It is noteworthy to point out that the ZPC found in the paper on bituminous coals was approximately pH 4, similar to the ZPC for the anthracite coal. In fact, we have been investigating different coals from low to high ranks. Thus, the plot of the pH for ZPC against rank could be derived and this curve-an electrocapillary one-indicates a pH near which the hydrophobicity of the coal surface should be at maximum. This can be proved by so-called salt flotation, which, in a sense, can be treated as method of surface charge measurement. It is obvious that the salt flotation experiment is possible when the native hydrophobicity of the mineral surface is high, e.g., when the solid surface does not have an orienting influence on an adjacent water layer and the hydration layers are controlled by the electrical double-layer potential. The addition of electrolyte or a change of pH which decreases the thickness of the stabilizing double-layer "opens up" the hydrophobic surface micro-area mosaic. Thereby the surface becomes hydrophobic and particles become floatable. The orienting influence of surface on hydration layer increases even after very slight oxidation and flotation is affected by it. It seems that such an explanation agrees reasonably well with those of Campbell and Sun.

Jan 1, 1972

Joseph K. Stone, Jr. (Kaiser Engineers, Oakland, Calif.)—I would like to compliment the authors on their clear presentation of the results of their study of the pneumatic processes. We hope that the Inland Management decision to make this information available to all will induce others to release additional valuable fundamental data which they have accumulated in the field. There are two points upon which we would like to comment. In the discussion of Table VII it was indicated that the "oxygen consumptions were about the same as has been reported for other oxygen steelmaking processes". This conclusion is apparently based upon the consumption of 2100 cu ft per ton shown in Table VII. The data in Table IV also permits calculation of 2520, 2280, 2250 and 2700 cu ft per ton in heats 1 to 4, respectively. These figures are in the same general range as those reported for the Kal-Do and Rotor Processes using Thomas iron, but considerably above the following figures for four of the operating L-D Process Plants while using iron which is similar to American basic iron: Donawitz 1760 cu ft per ton Adapted from Cuscoleca' LinZ 1900 cu ft per ton Trenkler & Hauttmann2 Dofasco 1850 cu ft per ton D. O. Davis:3 In addition to the differences between the consumption of gaseous oxygen in the Inland operation and in the L-D Process, there is another closely related difference. The L-D plants for which data are cited are using approximately 1 pct ore while the authors' process used about 7 pct of sinter. Assuming 65 pct Fe in the sinter, the difference amounts to 400 to 500 cu ft

Jan 1, 1959

By Matsubara, A.

THE problem of the equilibrium between iron, carbon, and oxygen was first carefully investigated by E. Baur and A. Glaessner,1 who determined the equilibrium conditions of the two reactions Fe304 + CO ? 3FeO + C02 (1) FeO + CO ? Fe + C02 (2) within the range of temperature of 350 to 900° C. The next series of investigations was made by R. Schenck and his co-workers,2 who sought to check the results of Baur and Glaessner's work within the range of 550° to 700° C. and to elucidate the conditions of formation of iron carbide. The equilibrium conditions at the higher temperatures, however, are generally understood to be much more complicated, owing chiefly to the formation of solid solutions between iron, its oxides, and carbide; nevertheless their determination is of much more practical importance than those at the lower temperatures. It is well known that each of the reactions is reversible; equilibrium is established when the partial pressure of oxygen in the gaseous phase has become equal to the dissociation pressure of magnetic oxide in equation 1 and that of ferrous oxide in equation 2. These equilibria are subsequently designated by "the Fe304-FeO equilibrium" and "the FeO-Fe equilibrium," respectively. As the Fe304-FeO equilibrium has three phases with three components, it must be bivariant. But the reaction involves no pressure change in the gaseous phase, hence the final composition of the latter is practically unaffected by pressure. To know, the equilibrium conditions, the compositions of the gaseous phase at different temperatures must be determined. At the higher temperature, however, iron and its oxides dissolve one another in various proportions forming solid solutions; in many cases the content of oxygen in the solid phase becomes a new independent variable.

Jan 2, 1921

By B. T. Brady

Experimental data 1,2 on the energy dissipation in polycrystalline materials over a large frequency spectrum (10-2 cps to 106 cps) suggests that the quality factor [(e= Q )] is independent of the frequency providing both fluid-saturated and ferromagnetic materials are excluded from the test data. Additional data 3 suggest that the quality factors are less at high pressures than at low pressure, i.e., Q increases as the pressure increases. Observations on the dissipation of single quartz crystals with their polycrystalline counterparts indicate that the energy dissipation is less for the single crystal than for the aggregate .2 Both of the above observations, particularly the latter, are indicative of the fact that the dissipation increases with increasing surface contact within the polycrystal, i.e., a frictional attenuation scheme may be operative. Knopoff and MacDonald 4 have shown that a friction model gives rise to a quality factor frequency independence property. A partial listing of some values of Q, observed for both metals and non-metals, is given in Tables I, II, and III. In Tables I and II, the data all show Qs>Qp, i.e., the energy loss per cycle for compressional body waves is greater than that for shear waves of the same frequency. Most samples in Table III show the same effect. It is objective of this paper to suggest: (1) a frictional attenuation scheme may account for the observed losses incurred during the propagation of low amplitude stress waves in dry brittle rock and, in particular, that such a scheme can account for the observed relative magnitudes of the quality factors for P and S wave motion; (2) a friction scheme can readily explain the difference between the dynamic and static moduli in dry brittle rock; (3) a friction scheme, while in itself an intrinsically

Jan 1, 1968

By S. E. Maddigan, B. R. Zimmerman

Most metallurgists are well acquainted with the contributions already made to the study of metals by the use of X-rays. On the one hand, the radiographic method is constantly becoming of increasing importance as a nondestructive testing procedure, while on the other hand the techniques of X-ray diffraction have made important contributions to the fundamental knowledge in studies of phase diagrams, stress conditions, and so forth. A new, and as yet insufficiently appreciated, tool exists in the application of microradiography to alloy structures. This new procedure in many respects bears the same relation to microscopic investigations as does macroradiography to the gross inspection of metal surfaces. However, where macroradiography is used ordinarily to determine the soundness of the metal structure, this new method can be used not only to investigate micro-un-soundness but also to examine the distribution of the constituent elements within the body of the alloy. When combined with the normal procedures of microscopy, this offers a technique of great potential power. It is intended in this paper to present a few examples of copper-base alloys demonstrating the additional knowledge obtained from the microradiographic method. The detection of micro-unsoundness is demonstrated in Fig. I for a sample of cartridge brass as cast. The sample ap- peared quite sound when viewed under the microscope, but in reality was thickly populated with minute voids. This application of the method conforms in every way to conventional large-scale radiography and has been used to facilitate production of metal for vacuum devices.' The true potentialities of the technique are revealed by comparison of Figs, 2a and 2b, which are respectively a photomicrograph and a microradiograph of a cast alloy of 80 per cent Cu, 10 per cent Sn, 10 per cent Pb. The remarkable difference in appearance provides some concept of the additional information this method may yield when used as an auxiliary to microscopic studies. Fig. 2a shows two phases of the copper-tin system plus segregated_ lumps of lead. Fig. 2b, on the other hand, shows with exceptional clarity the actual dendritic growth of the metal crystals during solidification. The practice of microradiography depends upon the laws of absorption of X-rays. This subject has been reviewed thoroughly in recent papers,l,2,3 but for clarity a brief resume will be given here. As is well known, when a beam of X-rays is transmitted through a, layer of homogeneous material, the intensity is reduced according to the relation: where Il is the transmitted intensity, I0 is the incident intensity, µ1 is the linear absorption coefficient of the material, t1 is the thickness of the material.

Jan 1, 1944

By S. E. Maddigan, B. R. Zimmerman

Most metallurgists are well acquainted with the contributions already made to the study of metals by the use of X-rays. On the one hand, the radiographic method is constantly becoming of increasing importance as a nondestructive testing procedure, while on the other hand the techniques of X-ray diffraction have made important contributions to the fundamental knowledge in studies of phase diagrams, stress conditions, and so forth. A new, and as yet insufficiently appreciated, tool exists in the application of microradiography to alloy structures. This new procedure in many respects bears the same relation to microscopic investigations as does macroradiography to the gross inspection of metal surfaces. However, where macroradiography is used ordinarily to determine the soundness of the metal structure, this new method can be used not only to investigate micro-un-soundness but also to examine the distribution of the constituent elements within the body of the alloy. When combined with the normal procedures of microscopy, this offers a technique of great potential power. It is intended in this paper to present a few examples of copper-base alloys demonstrating the additional knowledge obtained from the microradiographic method. The detection of micro-unsoundness is demonstrated in Fig. I for a sample of cartridge brass as cast. The sample ap- peared quite sound when viewed under the microscope, but in reality was thickly populated with minute voids. This application of the method conforms in every way to conventional large-scale radiography and has been used to facilitate production of metal for vacuum devices.' The true potentialities of the technique are revealed by comparison of Figs, 2a and 2b, which are respectively a photomicrograph and a microradiograph of a cast alloy of 80 per cent Cu, 10 per cent Sn, 10 per cent Pb. The remarkable difference in appearance provides some concept of the additional information this method may yield when used as an auxiliary to microscopic studies. Fig. 2a shows two phases of the copper-tin system plus segregated_ lumps of lead. Fig. 2b, on the other hand, shows with exceptional clarity the actual dendritic growth of the metal crystals during solidification. The practice of microradiography depends upon the laws of absorption of X-rays. This subject has been reviewed thoroughly in recent papers,l,2,3 but for clarity a brief resume will be given here. As is well known, when a beam of X-rays is transmitted through a, layer of homogeneous material, the intensity is reduced according to the relation: where Il is the transmitted intensity, I0 is the incident intensity, µ1 is the linear absorption coefficient of the material, t1 is the thickness of the material.

Jan 1, 1944

By John Fritz

TROUGH it is not a condition of the Award, the fact is that the John Fritz Medal never has been given to an engineer who had not already received one or more similar awards. This "medal for medalists," on the evening of April 20, was presented to Daniel C. Jackling at a special dinner held at the Union League Club in New York. The citation read "For notable industrial achievement in initiating mass production of copper from low-grade ores through the application of engineering principles." The present award recognizes the same accomplishment-the launching and guiding to the port of marvelous success of the Utah Copper Co., first of the so-called "Porphyries"-as did the award of the William Lawrence Saunders Gold Medal by the A.I.M.E. in 1930, and before that the Award of the Gold Medal of the Mining and Metallurgical Society of America in 1926. Following the custom a biography of the Medalist had been published in a small pamphlet as a supplement to the John Fritz Medal Book. T. A. Rickard was the au¬thor of the sketch of Mr. Jackling, an innovation being the placing of a copy of the booklet at the place of each of the diners. The committee in charge of the dinner consisted of two past-presidents: R. E. Tally, of the A.I.M.E., who was chairman; Bancroft Gherardi, of the A.I.E.E.; and Thaddeus Merriman, director of the A. S. C. E., the John Fritz Medal being a joint award of the four societies. Frederick M. Becket, President of the A.I.M.E., as chairman for the occasion, briefly stated the purpose of the dinner. He stressed his satisfaction that the award was symbolic of the cooperative professional activities of the four great national organizations of engineers. He introduced Francis Lee Stuart, past-president of the A.S.C.E. and now chairman of the John Fritz Medal Board of Award. Mr. Stuart outlined the history and purpose of the Medal established in 1902 in memory of John Fritz, of Bethlehem, Pa., one of the great pioneers of America's iron and steel industry, metallurgist, and president of the A.I.M.E. in 1894. Mr. Stuart called the roll of former John Fritz Medalists, three of whom, Ralph Modjeski, J. Waldo Smith, and Ambrose Swasey, were present to do honor to Mr. Jackling. He then introduced George Otis Smith, whose privilege it was to present the Medalist for 1933. Dr. Smith was the senior of the four A.I.M.E. representatives on the Board that last year selected Mr. Jackling for the honor. His speech follows in full.

Jan 1, 1933

By J. J. Beeson

For the past fifty years or more, the structural features of the Cordil-leran mountain system of western United States have presented some most interesting problems. Any geologist or engineer living in this region, or even making occasional examinations of the mines, will lose much of interest and importance if he is not familiar with the literature. Some of the greatest works on geology have been the result of studies carried on in sections of this region. Among the more important of the earlier works are those of Dutton,l King,2 Gilbert3 and Powell;4 of the more recent Lindgren,5 Ransome,6 Spurr,7 Butler8 and others have contributed much. Many of the papers are largely of scientific interest but even these lay the foundation for the commercial application of the broader features of the geology. I have read many of these works with the keenest interest and pleasure; in fact, some have been read until some of the more important findings seem to be my own. In this paper, however, it is my aim to accept credit for little more than the labor of assembling some of the ideas of others. This is done with the hope that an interesting and valuable discussion will be the result. If some of the ideas presented should

Jan 1, 1927

By J. S. Koehler, F. Seitz

THE dislocation theory of plastic flow originated in 1928, when Prandtl1 suggested that the internal damping of metals of plastic origin might arise from the motion of a crystalline imperfection. Following this, Dehlinger2 employed a similar imperfection in a theory of recrystallization. The first detailed theoretical discussions were those of E. Orowan3 and G. I. Taylor4 in 1934. The resulting theory was gen- eralized by J. M. Burgers5 in 1939. Mott and Nabarro, in England, and Seitz and Read,6 in the United States, started an extensive examination of the atomic theory of dislocations in the period between 1939 and 1941. However, this development was arrested by the mar and was not taken up again until after 1945. Since 1946, the field has been the object of very intense activity, particularly in the United States and England. Dislocations are beautiful and intricate imperfections; they are sufficiently complicated to account for the great variety of phenomena encountered in the field of plastic flow. Above all, the dislocation concept enables us to understand how a metal or other plastic solid can deform inelastically under very small stresses at temperatures far below the melting point. Suppose we attempt to shear a perfect crystal plastically. This can be done by sliding one entire atomic plane simultaneously through one atomic distance with' respect to the near-

Jan 1, 1954

By P. Shahinian, R. L. Stegman, M. R. Achter

Creep strength has been determined as a function of oxygen pressure for nickel at 510" and 600°C. Creep-rupture life drops from its highest value at the ultimate vacuum of 10-7 torr to a high pressure plateau of nearly constant life which, at 600°C, commences at torr. This behavior is described in terms of a model that relates surface gas adsorption and the generation of fresh crack surfaces. In a calculation based a this model the predicted pressure beyond which the creep strength should not decrease further has been found to agree well with the observed value. The introduction of oxygen during creep in vacuum was found to cause a prompt rise of the creep rate. The magnitude of the environmental effect was much less than generally observed in fatigue and this is attributed to the diffarent crack morphologies in creep and fatigue. GASEOUS environments are known to affect creep resistance adversely1-5 but the effects have received less attention than the much larger ones in fatigue. At low temperatures it has been shown for nickel that the creep rates are faster and the rupture lives are shorter in air than in vacuum and that these environmental effects can be correlated with faster crack growth rates in the reactive environment.' In support of a mechanism of gas adsorption at the crack tip to explain the above effects, a calculation based on kinetic gas theory showed that surface coverage by gas was not as rapid as the exposure of fresh metal at the crack tip in the ultimate vacuum but was in air.7 In fatigue a number of investigations have demonstrated that the reduction of life with gas pressure usually follows a step curve with most of the reduction occurring in a transition range at intermediate pressures and little or no change at high and low pressure.8 There have been no studies, however, in which creep strength has been determined as a function of reactive gas pressure to see whether similar effects would be found. This investigation was undertaken to study the kinetics of the environmental effect in the creep of nickel. EXPERIMENTAL PROCEDURES The environmental creep apparatus was constructed to minimize many of the experimental conditions which can cause scatter in data. Dead weight loading is employed and weights are contained within the environmental chamber to eliminate bellows and the necessity for compensation for gas pressure changes. Elongation over the specimen gage length is recorded from a Riehle Model DV Controlled Environment Extensometer which provides readout to 2.5 x 10- in. Temperature is monitored and controlled from a thermocouple at- tached to the specimen gage length to +0.5oC or better. The freon trapped oil diffusion pump vacuum system included an auxiliary liquid nitrogen trap and, with a wide range variable conductance leak valve, pressures from the ultimate vacuum of 10"7 to l03 torr of any desired gas are obtainable. Pressure is measured by means of a hot filament ionization gage below 10"3 torr and a NRC Model 530 Alphatron Vacuum Gauge above 10-3 torr. The oxygen, which was leaked into the environmental chamber, was an Aviator's Grade of 99.5 pct purity with a dew point of -80°F. Analysis of the nominal 99.8 pct Ni showed the following percentages of major impurities: 0.02 C, 4.01 Mn, 0.005 Si, 0.01 Cu, 0.02 Fe, and 0.034 Mg. Cylindrical specimens were machined with a 0.180

Jan 1, 1970

By AIME AIME

American Institute of Mining Engineers. (Organized in 1871, and Incorporated in 1905.) OFFICERS. For the year ending February, 1906. Directors JAMES GAYLEY (President), R. W. RAYMOND (Secretary), FRANK LYMAN Treasurer). T. A. RICKARD NEW YORK, N. Y. CHARLES H. SNOW NEW YORK, N. Y. R. W. RAYMOND NEW YORK, N. Y. (Terms expire February, 1906.) JAMES GAYLEY NEW YORK, N. Y. FRANK KLEPETKO NEW YORK, N. Y. FRANK LYMAN NEW YORK, N. Y. (Terms expire February, 1907.) JAMES DOUGLAS NEW YORK, N. Y. JAMES F. KEMP NEW YORK, N. Y. ALBERT R. LEDOUX NEW YORK, N. Y. (Terms expire February, 1908.)

Jan 1, 1906

By James A. Roberson

THE mechanical behavior of molybdenum has become a matter of considerable interest in recent years because it has a reasonably high strength at high temperatures. Various aspects of its fatigue behavior have been investigated previously,1-3 and the results can be summarized as follows. Recrys-tallized molybdenum exhibits a fatigue limit which decreases continuously with increasing temperature. The ratio of fatigue-limit stress to ultimate tensile stress is high (0.6 to 0.8) and reasonably constant. The present work was undertaken to determine the effect of variations in environment on the fatigue of molybdenum stressed in fully reversed axial tension compression. In order to provide a basis to which these data could be compared, a complementary series of fatigue tests were made in vacuum. All of the specimens used were made from one mill lot of unalloyed molybdenum which had been vacuum-arc melted, worked down to 1-in.-diam bar, re-crystallized, then warm-worked to 5/8 in. diam. The interstitial content by weight was as follows: C—0.022 pet, 02-0.0026 pet, Hz-0.0001 pet, and N20.0002 pct. The average grain diameter in the transverse direction was about 0.035 mm, and the average grain length was about 0.15 mm. Typical tensile-test data are shown in Table I. None of the specimens tested exhibited an upper yield point.

Jan 1, 1965

By M. S. Burton, B. W. Christ, G. V. Smith

Evidence of the effects which high-angle grain boundaries and veining subgrain boundaries have on the yield phenomenon of zone-refined iron is reported. Room-temperature tensile tests on 50-mil wive at several gram sizes produced upon recrystallization at diffevent temperatures below 910C (a-y phase-transfornzatzon temperature) show that upper and lower yield stress decrease with increasing grain size. The upper yield point effectively disappears at grain sizes of 81 and 102 u in samples of this diameter. However, samples of 129 p grain size. produced during recrys-tallization at 950°C, exhibit a pronounced upper yield point and an increased lower yield stress. Possible causes of the reversal in the grain-size dependence of yielding are discussed. Veining substructure, detected with picval-HC1 etchant, but not with 2 pct nital, is formed during the a-y transformation, and is believed to account for the observed effecls. The strengthening associated with high-angle boundaries in zone-refined tron is discussed in terms of: 1) the stress dependence of slzp multiplicity, and 2) the stress dependence of dislocation emission from grain boundaries. WIDE use of transmission electron microscopy and dislocation etch-pitting techniques has led to a growing awareness of the presence of dislocation substructures in annealed pure metals. Whereas much speculation'-4 has developed about the influence which subgrain structures have on the mechanical behavior of metals, particularly the yield strength, only limited experimental evidence correlating subgrain structures with lower yield strength has been presented. 2,3,5-7 It is the purpose of this note to present experimental evidence of the effects which grain boundaries and subgrain boundaries have on both the upper and lower yield strength of zone-refined iron. Effects due to high-angle boundaries formed upon recrystallization below the a-y phase transformation are compared with effects due to veining subgrain boundaries formed upon "recrystallization" above the a-y phase-transformation temperature. These effects are further compared with the reported influence 2,3,5-7 which low-angle boundaries have on the lower yield strength of bcc transition metals. EXPERIMENTAL PROCEDURE The starting material for these experiments was a 1-in.-diam zone-refined ingot prepared at Battelle Memorial Institute. Initial purification of electrolytic iron by vacuum-induction melting was improved by a floating zone-melting treatment in ultrapure hydrogen.' Chemical analysis of this zone-refined iron appears in Table I. Tensile samples of 50-mil wire were prepared by rolling and drawing portions of the ingot. An intermediate recrystallization anneal at 625°C after rolling to a reduction in area of 85 pct was carried out in an evacuated Vycor capsule (10-=5 mm Hg). Further reduction in area of 91 pct was followed by recrystallization in evacuated Vycor capsules at temperatures between 600" and 950°C, see Table 111. All samples

Jan 1, 1967

By Chingyuan Y. Li, C. Y. Hsieh

Realizing that aluminum will have a great role to play in the coming industrialization of China, Chinese geologists have long been looking about for some aluminum deposits. The possible sources appear to be alunite, the alumina-rich shales, and the bauxite deposits. The locations of deposits are shown in Fig. I. Alunite Our attention was first directed to the alunite deposits along the southeastern coast of China. Table I summarizes the reserves now believed to exist in that region. Other alunite deposits have been found in Kiangpei, Szechuan province; Charming. Liuyang and Hsanshan, Hunnan province Tsingchow and Chowyuan, Shantung province. No reserve figures are available. High-alumina Shale Shale high enough in aluminum to serve as a source of that metal has been found in northeastern China(Tab1e 2). In Manchuria, the Manchuria Light Metals Co., at Antung and Fushun, operating under Japanese control, has been the only active producer of aluminum. It is not known, however, whether the company uses local raw materials or imports ore from elsewhere.* Shantung Bauxite Bauxite was first recognized in China at Paoshan, Shantung province. Although the reserve is reported to be large (estimated at 271 million tons), the high content of insoluble residue (SiO2) and mineral composition (diaspore) are dis-

Jan 1, 1948