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By Walter V. Knopp, Laurence Delisle

The aim of this work was the preparation of nickel-steels from elemental metal powders by powder metallurgy techniques. It was known that plain carbon steels could be made from a mixtufe of iron powder and graphite and that the effect of carbon on iron in powder form was of the same nature as that produced in fusion metallurgy. The problem in making nickel steels from elemental powders consisted therefore in finding out whether sufficient diffusion of the nickel and other incidental metals . normally present in such steels could be induced in the solid state to modify the properties of plain carbon steels made from powders and produce the beneficial effect of alloying. The composition selected originally was that of an S.A.E. 2330 steel. Metal powders, in the proportion correspending to that composition, were mixed with graphite, pressed, and heated at different temperatures for different periods of time, to produce bonding of the metal particles and mutual diffusion of the various elements without melting. Temperatures up to 1325°C and sintering periods as long as 6 hr were first investigated because it was expected.that such conditions would produce maximum diffusion with an accompanying improvement in the properties of the alloy. It was found that, although diffusion proceeded to a large extent under the conditions investigated, it would not be complete unless sintering were carried out at a high temperature for much longer than 6 hr. Relatively high temperatures and long sintering times are objectionable from a practical point of view, particularly when a low COSt material is to be produced, because they necessitate the use of special, costly equipment. Work could be done to improve the diffusion of iron and nickel by changing conditions other than the sintering temperature and time, that is, finer primary or alloy powders could be used. However, a marked change in the properties of the steel had been observed even with only partial diffusion. It was thought, therefore, that instead of trying to improve the diffusion, advantage might be taken of its incompleteness to produce a special structure consisting, in the unquenched condition, of a hard constituent, rich in nickel, dispersed in a tough pearlitic matrix. Steels with such a structure, not readily obtainable by fusion, should have desirable mechanical properties. Besides, it should be possible to prepare them from elemelltal powders under economical conditions. This latter alternative was therefore adopted for the second phase of this work. This report is divided into four parts: I. General Procedure. 2. Effect of Sintering Temperature. 3. Effect of Varying the Nickel Content. 4. Effect of Alloying Elements. General Procedure The general technique of cold pressing as used in powder metallurgy was applied.

Jan 1, 1949

By N. S. Stoloff, M. Gensamer

The effects of temperature, grain size, and magnesium content on the strength and ductility of cadmium were studied in the range -269° to 23 °C. A sharp drop in ductility between -140° and -190°C marked a transition in fracture mode from ductile shear to inter gvanular fracture. The addition of up to 15.35 wt pct Mg in solid solution raised the transition temperature, and for two compositions produced basal cleavages. The relatively high ductility of unalloyed cadmium at cryogenic temperatures is attributed to temperature independence of the yield stress and the absence of dislocation locking. ALTHOUGH numerous studies have been made of the mechanical properties of cadmium single crystals,1-5 no comprehensive investigation of deformation and fracture in polycrystalline cadmium has been carried out. This investigation was initiated to determine the mechanisms of deformation and fracture in polycrystalline cadmium, and to attempt to correlate these mechanisms with the behavior of other metals of hexagonal close-packed structure. A second objective of this work was to determine whether the slip systems and mode of fracture of polycrystalline cadmium could be altered by reduction of the axial ratio, which is 1.886, through alloying. Dorn and co-workers' have been able to induce prismatic slip in magnesium through alloying to reduce the axial ratio. Single crystals of cadmium are so highly ductile that glide strains of 400 pct are observed at room temperature, and 80 pct at -269°c.l Failure in every reported case is by necking down and shearing off of the crystal. Cleavage in cadmium single crystals has never been observed. Magnusson and aldwin reported a ductile to brittle transition for polycrystalline cadmium at about —160 C for specimens tested at a strain rate of 0.05 in. per in. per min in tension. However, even at -196° substantial ductility was retained. The transition temperature was strain rate dependent, impact loading at 19,000 in. per in. per min raising the transition temperature to about -85°C while leaving the low temperature ductility unchanged. No information was given on microstructures or fracture mode, nor were stress-strain characteristics reported. In the present investigation, tensile tests were carried out on polycrystalline cadmium and solid solution Cd-Mg alloys to determine flow stresses, work-hardening behavior, fracture strength, and fracture ductility. Variables employed included temperature, alloy content (and c/a ratio), and grain size.Some compression data also have been obtained for comparison purposes. I) EXPERIMENTAL PROCEDURES A) Polycrystalline Cadmium. Two purities of cadmium were employed in this investigation. Cadmium of 99.95 pct purity was supplied by Belmont Smelting and Refining Co. Cadmium of 99.99+ pct purity was supplied by American Smelting and Refining Co. Threaded cylindrical tensile specimens were machined to give approximately a 1/2 in. long straight gage section with a reduced diameter of about 0.110 in. Specimens were heat treated in evacuated pyrex capsules in the range 140" to 290°C to produce desired grain sizes. All specimens were polished in a solution containing 320 g Cr03 and 20 g NaS04 in 1000 cc of H20. Occasionally this solution caused staining of the specimen, in which case a further polish with a solution of one part HN03 and two parts H202 in two parts ethyl alcohol was employed.' Tensile testing was carried out on a screw-driven Instron machine, at a constant rate of crosshead movement, which for most tests was 0.01 in. per in. per min. Load vs time, and therefore load vs total strain, were recorded. Temperatures from -196" to -40°C were obtained by passing nitrogen gas through a copper coil immersed in liquid nitrogen, and then feeding the gas into a jacket around the specimen. Tests at -269°C were carried out in a helium cryostat, at a crosshead rate of 0.1 in. per in. per min, with specimens of 1 in. gage length. Compression specimens were tested in a jig similar to one designed by ilman. The jig was mounted on the under side of the Instron crosshead. Load was transmitted by means of a rod connected to a movable part of the jig at one end, and the load cell at the other end. A downward movement of the crosshead applied a compressive load to the specimen.

Jan 1, 1963

By Thomas Fraser, Alvaro Abreu

The work described in this paper was carried out under the sponsorship of the Foreign Economics Administration and in cooperation with the Departamento Nacional da Produggo Mineral, Rio de Janeiro. The project was undertaken to obtain complete data on the variations in washability of coal to be used for coke manufacture in the steel industry and to determine the economy of preliminary hand-sorting operations. The coal-producing industry of Brazil is in that pioneering stage in which operating practices and methods are just being developed. Increased wartime demand for fuel, coincident with a drastic curtailment of foreign supplies due to lack of shipping facilities, has put a tremendous pressure on the national industry to furnish more coal. Under this incentive, production facilities are being -expanded- and new methods of operation are being tested. Such changes are being developed both by improvement of existing methods that originated in the field and by adaptation and modification of methods introduced from the United States and Europe. These mining conditions and mining practices in Brazil are typical of what the American mining engineer will find in many instances when he goes pioneering into the developing coal fields of the Southern Hemisphere. The producing coal fields of Brazil are all in the southern states of that country. The coal measures are in a band roughly paralleling the coast and extending in a generally southwesterly direction from northern Sao Paulo through the states of Paraná, Santa Catarina and Rio Grande do Sul to near the Uruguayan border in the vicinity of Bajé. The accompanying map1 (Fig. I) shows the general location of these fields and also the principal routes of movement of both national and imported coal in a late pre-war year (1940). Statistical data on production by states up to that year are given in Table I. Rio Grande do Sul is still the largest producer among the coal states; but wartime

Jan 1, 1947

By Alvaro Abreu, Thomas Fraser

The work described in this paper was carried out under the sponsorship of the Foreign Economics Administration and in cooperation with the Departamento Nacional da Produggo Mineral, Rio de Janeiro. The project was undertaken to obtain complete data on the variations in washability of coal to be used for coke manufacture in the steel industry and to determine the economy of preliminary hand-sorting operations. The coal-producing industry of Brazil is in that pioneering stage in which operating practices and methods are just being developed. Increased wartime demand for fuel, coincident with a drastic curtailment of foreign supplies due to lack of shipping facilities, has put a tremendous pressure on the national industry to furnish more coal. Under this incentive, production facilities are being -expanded- and new methods of operation are being tested. Such changes are being developed both by improvement of existing methods that originated in the field and by adaptation and modification of methods introduced from the United States and Europe. These mining conditions and mining practices in Brazil are typical of what the American mining engineer will find in many instances when he goes pioneering into the developing coal fields of the Southern Hemisphere. The producing coal fields of Brazil are all in the southern states of that country. The coal measures are in a band roughly paralleling the coast and extending in a generally southwesterly direction from northern Sao Paulo through the states of Paraná, Santa Catarina and Rio Grande do Sul to near the Uruguayan border in the vicinity of Bajé. The accompanying map1 (Fig. I) shows the general location of these fields and also the principal routes of movement of both national and imported coal in a late pre-war year (1940). Statistical data on production by states up to that year are given in Table I. Rio Grande do Sul is still the largest producer among the coal states; but wartime

Jan 1, 1947

By W. W. Colpitts

To me, as to many other students of railroad needs, the necessity for reducing the dead weight in railroad rolling stock, both passenger and freight, has been apparent for, many years. The problem of weight reduction of passenger cars is so entirely different from that of freight cars, is so much more to the fore at the present moment and would seem to be so much nearer solution, that I shall confine myself in these remarks to the former. On the surface of things there would appear to be no close association of thought between the decline in traffic on the railroads, which is largely responsible for their present deplorable financial condition, and new metal alloys. It sounds like a trick riddle a school boy might propound to his parents. But that there is a relationship between the two, and one that bids fair to be of great mutual benefit to the railroads and the makers of .high-strength metal alloys, I hope I shall be able to show before I have finished. To make the situation understandable to those who are not entirely familiar with the problems of railroad management, and, who feel that the railroads have not moved as rapidly as they should in the direction of greater use of newer materials and newer appliances, I shall have to review briefly the course of recent railroad history. If in this part of my talk I seem to the professional man to be a little off key I feel sure my remarks will be fully appreciated by the business man who cannot understand why he is not making better headway in selling things to the railroads. To do this I shall have to go back to war times for a moment.

Jan 1, 1936

By Allan J. Clark

It is nearly three years since the metallurgy of the Homestake ore was discussed with considerable thoroughness, in a paper1 read before the Institution of .Mining and Metallurgy. Certain changes have been made in this period which are perhaps of sufficient interest to justify a brief description, and it is chiefly with such details and miscellanies that this paper will deal. In the circumstances, a certain amount of repetition is inevitable, but matter treated of in the former paper will be referred to here only when it is necessary for the sake of coherency. For full descriptions of equipment and technique, the former paper should be consulted. The mineralized slates and schists which constitute the ore vary considerably in composition, but the unoxidized ore, perhaps constituting the major part of the reserves, contains either chlorite or hornblende (cummingtonite), with quartz, carbonates of lime, magnesia and iron, and arsenopyrite, pyrite, and pyrrhotite. Ferrous minerals predominate, and this fact has been an important factor in determining the metallurgical treatment. With one or two exceptions the minerals noted are of relatively high specific gravity, and the ore as a whole is exceptionally heavy, many determinations giving an average specific gravity of 3.00. This high specific gravity presents one decided advantage, when the cost of treatment is compared with operations elsewhere, in that the ton, almost universally the basic unit, represents a volume probably less by 10 per cent. than that of many gold ores. On the other hand, this high gravity renders more difficult the discharge of pulp from mortars, its distribution on amalgam tables, and its transportation in launders. In the same way, as attesting the usual balance of such variations of different ores, it may be noted that the needle-like fibers of hornblende (cummingtonite), interlacing throughout the mass, render the ore more difficult to crush than would be anticipated, but on the other hand assist

Jan 1, 1916

By H. I. Aaronson, H. A. Domian

ELectvon-probe analgsis has been used to in7:estigatr the partition ot alloying- elements between aus-tenite and proeutectoid ferrite (or the Jerritic component of bainite) in high-purity Fe-C-X alloys, lsuully at tzco levels of carbon content fca 0.1 and 0.4 pct in ntost steels) at temperatures between the M, and the Ae3 in Si, mn, Ni, mo, Co, Al, Cr, Cu, and PI steels. No partition ous found during the early stages of transformation at any temperature studied in the Si, ,mo. Co, Al, Cr, and Cu steels. Partition did take place, Jrowel'er, in Ihe Mn, ATi, and Pt steels, occurring in lewtperature. regions below the Ae3 of ca 130°, 65", UNDERSTANDING the mechanisms through which alloying elements influence the kinetics of austenite decomposition reactions which proceed by nucleation and 35c respectively. A break was discovered in the TTT curve for the initiation oj the proeutectoid ferrite reaction in the latter steels at the temperature at which partition began. The alloy content in ferrite at the a:y bondavy remained at constart lecels, shown experimentally to be significantly above those corresponding to eqiilib+iu??l, e'en at the longest reaction times investigated (ca 1o6sec). The partition and the TTT curve observations foere rationalized on the basis of the thermodynamic treatment developed in an accompany ing paper. and diffusional growth has been a major research objective of physical metallurgy since the latter part of the 19th century. The measurements made on the dif-fusivities of carbon and of substitutional alloying elements in austenite during the 1930's and 1940's seemed to provide a useful clue as to the nature of these mechanisms. These measurements showed that the diffu-sivity of carbon is several orders of magnitude higher than that of the alloying elements at a given tempera-

Jan 1, 1967

By B. C. Allen, W. D. Kingery

Surface tension and its temperature dependence have been determined for pure liquid Fe, Cu, Co, Ni, and Sn and for Fe-C, Co-C, and Ni-C alloys. The temperature coefficient of surface tension is negative for all these liquids. The surface tension and wetting behavior of tin and tin-titanium alloys on A120,, Si,N,, MoSi,, and Sic, as well as the behavior of titanium-containing nickel alloys on A1 20, have been determined over a wide temperature range. For all the solids investigated titanium additims markedly lower the contact angle. Some limits for the solid-surface energies have been calculated from liquid surface tension and wetting behavior. SURFACE tension and interface energy are important variables in a number of metallurgical and ceramic phenomena, and have been discussed at some length in connection with determining micro-structure of polyphase systems,' solid-state sintering,' thermal etching of grain boundaries, heats of solution and fine powders,'1 grain-growth phenomena,' the mechanical behavior of fine foils and fibers, nucleation, soldering and brazing,' and other phenomenz of academic or practical interest However, until recently few quantitative data have been available for high-temperature systems. Among available data are some indicating positive temperature coefficients for the surface tension of liquid copper,*,11,'2 cast iron,l3 and iron-carbon14 alloys. Although carbon was found to be not surface active in iron at 1570" some preliminary studies had indicated the possibility of a positive temperature coefficient for the eutectic composition at lower temperatures.16 One part of the present study has been largely concerned with determining the temperature coefficient of surface tension for several metals at elevated temperatures, In addition to surface-tension studies, the wetting behavior of alloys containing titanium has been investigated over a wide temperature range. Previous measurements indicated that titanium was selectively adsorbed from nickel at a liquid nickel-solid alumina interface,17 and the use of titanium hydride or titanium-alloy techniques for metal-ceramic soldering is well known. In the present study, previous data have been extended to new alloy systems, and measurements have been carried out with other oxidation-resistant ceramics. EXPERIMENTAL The sessile-drop method was employed to measure liquid surface tension and contact angle between liquid and solid, utilizing apparatus and techniques which have been described previously.'g The shape of a sessile drop depends on equilibrium between forces of surface tension tending to form a spherical surface of minimum area and forces of gravity tending to flatten the drop. Typical sessile drops are shown in Fig. 1. From precise measurements of maximum drop diameter and drop height the surface tension and drop volume were calculated. Four solid materials were employed as supporting plaques for the liquid-metal drops. Aluminum oxide (99.9 pct, J, T. Baker, reagent grade) was pressed and sintered at 1800°C. Molybdenum-disilicide powder (99.0 pct, Electro Metallurgical Co.) was pressed and sintered at 1650°C. Plaques were cut from silicon carbide (99.4 pct, hot-pressed at Alfred University) and silicon nitride (95.1 pct, with Al, Fe, 0 as major impurities, Norton Co.) rods. All plaques were polished, cleaned, and dried prior to use. A number of metals and alloys were employed. Chemical analyses of vacuum-melted ingots of iron, nickel, cobalt (National Research Corp.), commercial nickel-base alloys, electrolytic copper (International Smelting and Refining Co.), and tin (Mal-linckrodt Chemical Works) are given in Table I. Alloys were prepared in the laboratory by vacuum melting the base metal with either titanium hydride (Metal Hydrides, Xnc.) or spectroscopic-grade carbon (National Carbon Corp.). Nickel-titanium alloys contained between 0.001 and 0.005 pct oxygen and the ferromagnetic metal-carbon alloys contained 0.001 pct. Cylindrical metal specimens (1 to 2.5 g) were machined and bevelled at the bottom to insure a uniform advancing contact angle on melting. Before use the samples were acid-etched, cleaned with acetone, and rinsed in petrol ether.

Jan 1, 1960

By Howard Willey

Mining operations of the Charcas unit at present are limited to the Tiro General mine at Charcas, in the State of san Luis Potosi, Mexico. The Tiro General mine was first operated during the Spanish occupation of Mexico for rich silver ores in an oxidized zone along the outcrop of the principal vein. In depth the ore is a complex sulfide with widely varying proportions of sphalerite, argentiferous galena and chalcopyrite ; and until recent years, it was economically impossible to carry on mining otherwise than irregularly in sections of the veins richest in galena and chalcopyrite. The advent of selective flotation brought the orebody as a whole within the field of economic interest, and a flotation mill of 650 metric tons daily capacity was constructed in the year 1925. The mining of partly worked-out sections of the mine, as well as the very heavy ground in most of the stopes opened in virgin ore, presented an unusually difficult problem. This paper describes the so-called "filled top slice" stoping method finally adopted as the standard system. Physical and Geological Conditions The principal orebody of the mine is an oreshoot about 1400 ft ng in a fissure vein striking about east and west and with an average lip of 70" to the north. The footwall of the orebody is fairly cleancu and regular both longitudinally and vertically and generally shows a dell-marked post-mineral slip. The footwall rock varies from a fairly strong limestone to a broken, metamorphosed limestone which requires heavy timbering. In some sections it is an altered, crumbly porphyry, which swells badly and necessitates frequent renewal of drift and raise tirnber. The hanging wall is irregular and frequently an assay wall. The stopina width ranges from a few feet up to more than 90 ft.; it averages about 30 ft. For the most part the hanging-wall rock is a shattered and altered monzonite porphyry, nearly aways requiring heavy timbering. The orebody is greatly fractured by post-mineral movement, which usually followed the footwall and left it as a smooth surface frequently covered with a slippery clay gouge. Two well marked transverse faults

Jan 1, 1931

By E. W. Engle

Fox several years the Fansteel Products Co. has been engaged in the production and development of various of the rarer metals. It is at present engaged in the commercial production of tantalum, tungsten, and molybdenum in a very high state of purity. The information contained in this paper is partly a general compilation from various sources and partly information obtained as a result of recent years of work in the laboratory of this company. Tantalum, tungsten, and molybdenum form a group peculiar to themselves among the commercially available metals. Their very high melting points (tantalum 2770° C., tungsten 3350° C., and molybdenum 2550° C.) set them apart so far as the metallurgical processes for their production are concerned. Further, when properly prepared and treated they will stand a somewhat unusual degree of cold work, that is work below the temperature at which marked crystal growth takes place. Such cold-worked metal may show a high tensile strength; tantalum to 130,000 lb. per sq. in., tungsten to 490,000 lb., and molybdenum to 260,000 lb., in the form of fine wire. In physical appearance, these metals are not unlike some steels; they may be better described by saying that polished tantalum some¬what resembles lead; polished tungsten, iron; and polished molybdenum, nickel. The polished surfaces of all three remain untarnished in ordinary air. Air containing corrosion-producing impurities will, in general, show molybdenum the least resistant to corrosion and tantalum the most resistant. Molybdenum has, however, a high degree of resistance to corrosion by hydrochloric acid, a property that should render it of commercial interest. On the other hand, it is markedly attacked by some of the weaker organic acids.

Jan 3, 1925

By Leonard Grimshaw

DIFFUSION Of carbon from gases into iron has been the object of much research, because of its long recognized importance in carburizing processes, but the direct diffusion of carbon from steel into iron has received relatively little attention. Because of the increasing use of clad metals in industry, direct diffusion from steel into iron is becoming of practical importance. Therefore, the object of this investigation was to study the diffusion of carbon from several different kinds of steel directly into relatively pure iron, realizing that elements in the steels other than carbon might influence the rate of carbon diffusion. The previous work on diffusion of carbon into iron has been consider-able, and includes many reports in foreign languages. This work has recently been well reviewed by Mehl1 and Krynitsky,2 and the reader is referred to their excellent bibliographies.

Jan 1, 1937

By W. T. Allan

RAW bituminous coal has been in general use as a blast-furnace fuel in Scotland for the last century, and although its use has now been largely abandoned and it has been replaced by coke in the majority of the few furnaces which are at, present in blast in this country, coal-smelted pig iron is not yet a thing of the past; it is still being produced and mar-keted in competition with the more cheaply smelted product of the coke-fired furnace. Various factors have influenced this change in practice; the once plentiful deposits of coal of a suitable nature for the blast furnace are now not so easily obtainable; native blackband and clayband ironstones which are easily smelted in the coal-fired blast furnace, although still far from being exhausted, are not available except at a. cost that is somewhat higher than that of imported ores, making them unattractive to the ironmaster that is compelled by circumstances to smelt his iron at the lowest possible cost. Within the last 15 years overproduction of synthetic nitrogen has led to progressive reductions in the price of sulphate of ammonia, the recovery of which together with the other by-products before that time materially assisted in reducing the working costs of the coal-fired furnace. Now the sale of the by-products recovered yields a diminished profit. When the cost of the product is the only consideration the small, slow-smelting, coal-fired blast furnace cannot compare with its large, modern, coke-fired competitor. Other `considerations do not by any means all support the same side of the argument. In the smelting of pig iron to be used in the manufacture of steel where the quality of the final product depends so largely upon the control of the conversion process and so much less upon the physical quality of the pig iron used, the physical properties of the pig iron do not exert any appreciable influence upon the quality of the steel produced, therefore the methods employed in the smelting of the pig iron matter but little so long as the requisite chemical composi-tion is reached. On the other hand, in ironfounding where the simple melting of the pig iron, which is the only treatment it receives before being cast into its final form, does little or nothing to modify its original charac-

Jan 1, 1937

By E. S. Davenport

WHEN annealed carbon, or low-alloy, steels are suitably heated the ferrite (alpha iron solid solution) and the carbide, of which they are composed, react together to form a single solid solution of carbon (and other elements) in gamma iron (austenite). This reaction may begin only at a certain minimum temperature called the eutectoid temperature. The first ferrite and carbide thus to react together do so in definite proportions known as the eutectoid composition. With further heating the original constituent that is present in excess is dissolved in the austenite until exhausted. Whether the excess constituent be ferrite (hypoeutectoid steels) or carbide (hypereutectoid steels) the procedure is much the same, and upon slow cooling the homogeneous austenite expels the excess of either (proeutectoid ferrite or carbide) until the eutectoid composition is reached. Thus the reaction upon heating is strictly reversed upon cooling and accordingly an equilibrium diagram of this process may be constructed. Such an equilibrium diagram concerns itself only with the tempera¬tures involved and with the proportions and compositions of the phases developed under conditions that suffice to permit equilibrium. Specifically it has no concern for the type or mode of distribution of these constituents nor with any extra-equilibrium conditions such as undercooling, which is almost universally encountered in metals. Actually, however, of great importance is the sluggishness toward equilibration caused by the not inconsiderable time involved in diffusion. Thus instead of the theoretical transformation point AE, we find for a certain rate of heating or cooling the use of the designations Ar and Ac (transformation temperature found on cooling and upon heating). These figures obviously have no particular meaning except as measured and expressed for a definite heating or cooling rate, and represent the apparent temperature displacement caused by an inadequate time allowance. In this paper are presented the results of a study of the time required for' the transformation of austenite to ferrite and carbide at a variety of temperatures and also of the time required for the reaction austenite ?martensite at the temperatures at which this reaction occurs instead of

Jan 1, 1930

By J. R. Long, R. S. Dean, F. S. Wartman, E. T. Hayes

The production of titanium in I5-lb. lots and with a purity sufficient to be consolidated into ductile metal, as described in a previous paper,' has provided adequate material for a study of the physical properties of titanium and a more thorough examination of its working qualities. Data on the physical properties reported in that paper were obtained on metal fabricated by a fixed procedure, standardized for the purpose of control of the reduction, and are representative only of material fabricated under those conditions. There are many possible variables in the working schedule, which will have significant effects on the properties of the finished material; and since the previous working methods were not necessarily the best, an investigation of the fabrication of titanium by other methods was undertaken. In this work the consolidation of the powder by pressing and sintering was conducted essentially as outlined in the report cited' and all efforts were centered on fabrication methods for those powders and the proper- ties produced by them. Hardness, density, microstructure, and tensile properties were determined at various stages in the working and annealing; and resistivity measurements were made on a few bars and drawn wire. Consolidation of the PowdeR The screen analysis of the available titanium powder is given in Table I. No attempt was made to alter the size distribution from that noted because this powder, although coarse by normal powder-metallurgy standards, produced acceptable compacts suitable for the present work. Because of their large specific surface, finer powders are more contaminated by oxygen and produce harder compacts, which are difficult to work. The powder as produced is soft, compresses in a normal fashion, and exhibits very little tendency to adhere to the die surfaces. Unlike aluminum and magnesium powders, it can be readily pressed without the use of die lubricants. When compacted at 50 tons per

Jan 1, 1946

By J. R. Long, E. T. Hayes, R. S. Dean, F. S. Wartman

The production of titanium in I5-lb. lots and with a purity sufficient to be consolidated into ductile metal, as described in a previous paper,' has provided adequate material for a study of the physical properties of titanium and a more thorough examination of its working qualities. Data on the physical properties reported in that paper were obtained on metal fabricated by a fixed procedure, standardized for the purpose of control of the reduction, and are representative only of material fabricated under those conditions. There are many possible variables in the working schedule, which will have significant effects on the properties of the finished material; and since the previous working methods were not necessarily the best, an investigation of the fabrication of titanium by other methods was undertaken. In this work the consolidation of the powder by pressing and sintering was conducted essentially as outlined in the report cited' and all efforts were centered on fabrication methods for those powders and the proper- ties produced by them. Hardness, density, microstructure, and tensile properties were determined at various stages in the working and annealing; and resistivity measurements were made on a few bars and drawn wire. Consolidation of the PowdeR The screen analysis of the available titanium powder is given in Table I. No attempt was made to alter the size distribution from that noted because this powder, although coarse by normal powder-metallurgy standards, produced acceptable compacts suitable for the present work. Because of their large specific surface, finer powders are more contaminated by oxygen and produce harder compacts, which are difficult to work. The powder as produced is soft, compresses in a normal fashion, and exhibits very little tendency to adhere to the die surfaces. Unlike aluminum and magnesium powders, it can be readily pressed without the use of die lubricants. When compacted at 50 tons per

Jan 1, 1946

By Gordon M. Yocom

A PROPER consideration of the subject of this paper should include economic aspects as well as the technical phases of the metallurgy, production, and properties of the product. The metallurgical phases of the processing and properties of the product will be considered only from practical aspects and within the scope of the writer's experience with tonnage production. The Bessemer process was invented 85 years ago and became important because it put steel manufacture upon a larger and less costly basis. In America the Bessemer production has declined for many years and has not maintained its proportionate place with the rapid advances of the open hearth. The achievements in the open-hearth field were attained by the greater number of technical people attracted to that branch of the industry. The antipathy of technical students for the older and less popular Bessemer field gradually weakened the forces defending it and retarded the development of new and better methods. In Europe the economic advantage of the basic Bessemer process has not been overlooked and the tonnage usually is greater than that of the open hearth. The acid process has been the subject of renewed attention in America during the past few years and those who are more familiar with it are striving to show that the method is too valuable to abandon. A considerable tonnage of Bessemer-blown metal, in both molten and ingot forms, used in connection with the open-hearth practice makes it an important auxiliary unit to the industry. This practice aids in modifying the price level of heavy remelting scrap in addition to speeding up the open-hearth operation. The use of Bessemer steel has continued not only because of periodic economic advantages but also because of certain inherent qualities of machinability, weldability and stiffness, which are valuable for many applications. The properties of stiffness and rather high reaction to cold-work require some modification in order to meet the demands of modern methods of processing, which involve cold-reduction and cold-forming. At least one factor contributing to the stiffness of this steel is the relatively high phosphorus content of the acid product. The phosphorus content of the Thomas or basic Bessemer steel of Europe is considerably lower than the normal acid product in America. The American industry has continued the use of the acid process chiefly for the reason that the available ores are more easily adapted to this process from both metallurgical and economic standpoints. In European practice the basic process is necessary with the highly phosphoric ores available and it is sustained to some degree by the sale of the rich phosphate slag as a by-product. The basic process was used in this country at several plants many years ago, but was abandoned for economic reasons. A part of the past history of these trials is given here because the author believes it has not been published and it has some bearing on the subject of this paper. The information is authentic to the extent that

Jan 1, 1941

By Research Staff ? Verde Copper Mines

FLOTATION is now commonly practiced in alkaline ore pulps, yet little is known regarding the action of the alkaline solutions on the ore particles beyond the fact that films of oxidized material form. We wish to chronicle our discovery of the presence of soluble reducing agents in alkaline ore pulps of the United Verde, and present some data on lime consumption. During the grinding and flotation of a pyritic ore containing small amounts of ferrous sulfate and other soluble salts, an excess of lime was added to precipitate the salts, and filtered samples of the solution were titrated with standard permanganate solution. Even in pulps of high causticity an appreciable permanganate titration was always obtained, in spite of the fact that the solutions were shown to contain little iron. Investigation of the cause brought about the discovery of several previously unsuspected compounds in flotation pulps made from pyritic ore. Not only the reducing agents present had to be identified, but also the amount of dissolved oxygen, and a survey was finally made of the free oxygen content and reducing agents of the mill pulp in the concentrating mill at Clarkdale. A great many. compounds might form, caused by oxidation of pyrite or other metal sulfides or by reaction between a lime solution and pyrite. The most probable compounds considered were calcium sulfides, polysulfides, thiosulfates, and polythionates. Later it was discovered in the literature that in alkaline pulp polythionates do not exist and if introduced are decomposed into sulfites and thiosulfates.1 Any precipitated sulfur is changed by alkali into thiosulfate and polysulfide. Sulfites and sulfides react to form thiosulfate, so that in the end it is possible to have in an alkaline solution only thiosulfate and an excess either of sulfide or sulfite. Confirmatory tests were made and it was finally established that the alkaline mill pulps made from the United Verde ore contained

Jan 1, 1929

[Note.—The paper of Mr. Hoffman on " Practical Results in the Magnetic Concentration of Iron-Ore " (page 602); that of Mr. Langdon on "The Use of Magnetic Concentrates in the Port Henry Blast-Furnaaces" (page 599); and those of Mr. Landis on "The Determination of Iron in the Tails from Magnetic Concentration " (page 609) and "Note on Sampling Iron-Ore" (page 611), were all prepared as contributions to this discussion.] The papers of Mr. Langdon and Mr. Hoffman were presented. W. H. Hoffman, Croton Mines, N. Y.: I will add a few remarks, by way of answer to inquiries for further details. The Croton Mines are particularly well located for cheap mining. The ore-bed is very large, and so lies in relation to the railway tracks of the Harlem and other railroads that a very large proportion of our mining for several years to come can be done above these tracks. The concentrating-mill is now 400 feet from where we are working in the quarry. In blasting we never remove less than 2500 tons at a blast,

Jan 1, 1892

By George Sachs, S. M. Clark, George Espey

he tendency of a commercially drawn cartridge case to crack in the mercury test and the relation of cracking tendency to residual stress retained after drawing were studied. The fourth drawpiece (next to the final) of caliber 0.30 cartridge cases produced by Frankford Arsenal were selected as test pieces. These exhibited an exceptionally high cracking tendency, making a detailed study possible. To obtain fast cracking in the mercury test, about 0.0015 to 0.003 in. must be removed from the wall thickness of the drawpiece by pickling, and it must be subjected to the mercury test immediately after washing. Removal of the adhering mercury by annealing and subsequent squeezing of the case in a vise was used to reveal definitely the presence or absence of cracks. Various lots of apparently identically fabricated cases were shown to possess a different cracking tendency. Machining off or boring a hole in the base gradually reduced and eventually eliminated the cracking tendency. On the contrary, shortening of the wall (body) reduced the cracking tendency only if the wall became so short that the cracking zone was directly affected. By boring out the base and pickling from the outside and then splitting the resulting rings, it was possible to determine the approximate stress distribution in the base and in the adjacent part of the wall. Small compression stresses were present in the core and the major part of the base, while the surface of the base and the adjacent wall contained high circumferential tensile stresses. On the contrary, the wall when parted from the base contained only insignificant residual stress. The conception is advanced, that the stress distribution in a drawn cartridge case corresponds fundamentally to that of a tube (wall) shrunk on a disk (base). Such a stress distribution results from the tendency of the base to recover elastically by an increase in diameter from the biaxial compression during drawing while the wall exhibits little tendency to change its diameter after progressing through the die. This is confirmed by measurements which show the base diameter to be slightly larger than the wall diameter.

Jan 1, 1945

By H. E. McKinstry

MOVEMENT on a fracture of irregular shape can cause local widening of the fissure and thereby offer freer channelways for circulation of ore-depositing solutions. This influence, coupled with large areas of wall rock available for reacting with ore solutions in brecciated and shattered ground can account for locally active deposition of metals and the resulting ore shoots. Such irregularities in the fracture system may be caused by local variations in the strength of rocks and by pre-existing lines of weakness, especially if these stand at favorable angles to certain components of the fracturing stress. Therefore correct interpretation of the mechanics of fracturing should permit deductions as to structurally favorable places on unexplored portions of the vein system. INTRODUCTION IT has long been recognized that movement on a curved or irregular fault surface is capable of separating the walls in certain portions of the fault, but until very recent years the importance of this mechanism as a factor in localizing ore shoots has escaped proper recognition. A short time ago W. H. Newhouse' presented a careful analytical study of displacements and their corresponding open spaces. For reasons that will be discussed later, it frequently happens that portions of the vein which are favorably oriented are not merely wider but also richer than the average. In many cases the widening with its accompanying richness coincides with very minor changes in the dip or strike of the vein, irregularities that commonly escape notice unless the vein is mapped in detail and a careful geometrical analysis made. While the relationship between the width of the vein and the changes in dip or strike has been recognized as a matter of observation, the irregularities have been accepted as more or less the result of accident. There has been very little effort except in isolated cases to find out the causes of these changes in dip or strike. Yet it is clear that if the causes can be recognized and expressed in terms of geologic structure the geologist will know where to look for repetitions of these favorable conditions either on extensions of the same vein or on adjoining veins. Any lack of understanding of the causes is due to the limitations of our ability to interpret our observations and not to the sheer capriciousness of

Jan 1, 1941