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By Gilbert E. Doan, William C. Schulte

An extensive program of investigation is being carried out at Lehigh University in the study of arcs and arc welds of high-purity iron1, sponsored by the Engineering Foundation. The part of that program reported in the present paper deals with welds made of high-purity iron in an argon atmosphere and for comparison with them welds made of the same iron in ordinary air. Welds of commercial steel also were made in argon and in air. The primary purpose of the study is to discover the basic physical constants of iron welds when not contaminated either by impurities in the iron or by the action of oxygen and nitrogen of the air during welding. Upon these constants can be founded such future studies as will determine what effects the various impurities and alloy elements present in steel have upon its welding characteristics, and what influence is exerted by the action of oxygen and nitrogen. The welding of steel involves such a multitude of variables, both of composition and of procedure, that development in the fabrication of this most important metal has necessarily been slow, wasteful, and in many instances discouraging. In the present investigation, the simplest possible condition has been selected; namely, iron practically free from contamination and a nonparticipating atmosphere, the inert gas argon. This simplification reduces the number of variables to a point where more rigid control of the system is possible. Although this study is significant for the contributions it makes to the science of steel fabrication, yet it is hoped that it will not be without value also in increasing knowledge of the. nature and behavior of iron and steel in general. From the standpoint of open-hearth practice, and to some extent from the standpoint of electric-furnace practice also, the conditions of melting and casting iron in this investigation are extraordinary. The casting temperature is high, the mean temperature of the metal probably reaching 2000' C. (3600' F.)? The rate of chilling of

Jan 1, 1936

By William C. Schulte, Gilbert E. Doan

An extensive program of investigation is being carried out at Lehigh University in the study of arcs and arc welds of high-purity iron1, sponsored by the Engineering Foundation. The part of that program reported in the present paper deals with welds made of high-purity iron in an argon atmosphere and for comparison with them welds made of the same iron in ordinary air. Welds of commercial steel also were made in argon and in air. The primary purpose of the study is to discover the basic physical constants of iron welds when not contaminated either by impurities in the iron or by the action of oxygen and nitrogen of the air during welding. Upon these constants can be founded such future studies as will determine what effects the various impurities and alloy elements present in steel have upon its welding characteristics, and what influence is exerted by the action of oxygen and nitrogen. The welding of steel involves such a multitude of variables, both of composition and of procedure, that development in the fabrication of this most important metal has necessarily been slow, wasteful, and in many instances discouraging. In the present investigation, the simplest possible condition has been selected; namely, iron practically free from contamination and a nonparticipating atmosphere, the inert gas argon. This simplification reduces the number of variables to a point where more rigid control of the system is possible. Although this study is significant for the contributions it makes to the science of steel fabrication, yet it is hoped that it will not be without value also in increasing knowledge of the. nature and behavior of iron and steel in general. From the standpoint of open-hearth practice, and to some extent from the standpoint of electric-furnace practice also, the conditions of melting and casting iron in this investigation are extraordinary. The casting temperature is high, the mean temperature of the metal probably reaching 2000' C. (3600' F.)? The rate of chilling of

Jan 1, 1936

By R. L. Stephenson

IN plants casting electric-furnace ingots and converting them immediately into blooms, billets, slabs, bars or forgings, the criterion of quality performance is the soundness of the semifinished or finished product. When rejections are necessary, it is not always obvious whether the defects were caused by an unsound ingot or by improper treatment during the heating and forming operations. To evaluate the effects of the numerous factors involved, it is necessary to accumulate a large number of detailed observations and to analyze and interpret these data properly. Even after a thorough investigation has been conducted, it is impossible, in some cases, to isolate the cause of the defect and say that it is definitely the result of an unsound condition in the ingot or mistreatment of the ingot during further processing. Two factors that are extremely difficult to evaluate are the chemical composition of the steel and time from finish pour to charge in the soaking pits or "track time," and it is necessary to evaluate their combined effects before many other factors can be studied. Plain carbon, fine-grained steel in the range of 0.18 to 0.23 pct carbon, is very susceptible to cracking and the longer the elapsed time between the pouring of the ingots and stripping for charging into the soaking pits, the higher the billet rejections for cracks are found to be. Below 0.15 pct carbon and above 0.30 pct the track time

Jan 1, 1947

By R. Bakish, M. A. Badiali, N. W. Kirshenbaum

One pound of ultra pul-e molybdenum has been produced containing both metallic and nonmetallic impuvities close to or less than the limits of detection. various purification methods were investigated; althouglz the use of move than one purification step was consideved, it was found that a single, caefully-controlled sublimation of MoCl5 yielded a highly puvified product without prior treatment or recourse to repeated sublimation. Hydrogen reduction of MoC1, to metal was attempted at atmospheric pressure; however, reduced pressure was necessary to obtain substantial yields. The tubular deposits of metal were consolidated into bulk fovm by electron beam melting undev high vacuum yielding a very low gas content. Boblems involved in monitoring the puvity of these materials and analytical results obtained are also presented. THE pronounced effect of even trace amounts of impurities upon fundamental properties of materials is well known to metallurgists and solid-state physicists. Consequently, groups interested in basic studies of metals have in recent years immensely stimulated the preparation and production of numerous ultra-pure metals. Increased demand by scientists for these high purity materials has necessitated development of facilities to prepare them in significant quantities; the procedures reported here were devised to produce significant quantities of ultra-pure molybdenum. Previous work performed in the field of vapor phase purification and hydrogen reduction of several other refractory metal chlorides had demonstrated valuable techniques applicable to molybdenum.' Various purification and reduction steps were individually investigated. Those procedures which showed the most favorable results with respect both to attainment of high purity and to ease of operation were then incorporated in the process utilized to produce the metal.' STARTING MATERIALS It is well known that because of differences in volatility, chlorides may be separated by fractional distillation. It was presumed that distillation of molybdenum pentachloride offered a simple and straightforward method of purification due to its relatively low boiling point. Alternatively, sublimation of the solid chloride also appeared feasible since MoC15 has both a reasonably narrow temperature range in which it exists as a liquid (a property typical of refractory metal chlorides) and a low enthalpy of sublimation. Pertinent thermochemical data of MoC15 are given in Table I. It should be noted that this compound must be handled with care as it is extremely hygroscopic. Anhydrous MoC15 was obtained from the A Metal Climax Co. METHODS OF PURIFYING MOLYBDENUM PENTACHLORIDE Distillation. It was expected that distillation methods, while affording an efficient purification, would prove simple to control and would have a higher production rate than sublimation processes. Also considered was the possibility of effecting a high degree of purification by using both these volatilization methods in conjunction—possibly a distillation followed by sublimation of the solidified condensate. Distillation of MoC15 was investigated using a single stage distillation column packed with chemically resistant glass beads. Heating coils were wound around the column and collection tube (condenser). As-received MoCl5 was charged into a flask connected with the column using a side loading arm under an argon flow. After the column and condenser were brought to about 270" and 210°C, respectively, the apparatus was lowered until the flask was fully immersed in a constant temperature fused salt bath maintained at about 285 °C. Distillation was continued for about 10 or 15 min until 50 to 70 g of distillate had been collected. Analyses of these distillations indicated that several elements, e.g., Cu, Fe, Ni, Cr, and Mg, were lowered in quantity although not all were removed to the same extent. The occurrence of Na, B, Si, and A1 in the distillates appeared to be due to contamination, possibly from corrosion of the pyrex glass. An improved distillation system of larger capacity and longer distilling column was built. Improvements were effected in lowering the amounts of such impurities as B, Mn, Ni, Na, Mg, Cr, Cu, and Fe. These studies were pursued concomitantly with efforts to purify by sublimation; it was subsequently found that although improvements in purity were obtained by distillation, sublimation processes were simpler to control and effected a high degree of purity.

Jan 1, 1963

By Edward Martinez

The reactions occurring in the copper segregation process were studied by heating mixtures of chryso-colla, salt, and a reducing agent. The techniques used in this investigation were differential thermal analysis (DTA) and thermal gravimetric analysis (TGA). The initial chloridizing of the oxide copper occurs below 500°C and cupric chloride may be the compound formed. Volatilization and reduction of the copper chloride take place above 550°C, although these reactions do occur to some extent below 550°C. A difference in the distribution of the metallic copper in the reducing agent was found when sodium chloride was used compared to magnesium or calcium chloride. Segregation was obtained with mixtures of cupric oxide, salt, and charcoal with no quartz or silicate present. Preliminary tests indicate that segregation may occur even in the absence of water vapor. The DTA and TGA techniques were found to be of great value in studying these reactions. The copper segregation process is a method for treating oxide copper ores. The ore is heated, most commonly in a kiln, with a reducing agent and a halide salt, generally sodium chloride, to approximately 700°-750°C and held for 30 to 60 min. The addition of the salt results in the migration and reduction of the oxide copper to metallic copper on the surface of the reducing agent rather than in the original mineral structure. The metallic copper can then be recovered by a subsequent leaching or flotation step.1-4 Experimental work in 1923 on oxide copper ores from the Sagasca mines in Chile led to the discovery of the reduction process. It was found that during the reduction of the copper mineral with coal, at about 700°C, the copper migrated to the surface of the coal instead of remaining disseminated in the ore. The unusual behavior of the copper, which caused it to migrate from the ore particles to the coal, was traced to the presence of a small quantity of sodium chloride occurring in the ore. Further experiments with oxide copper ores proved that the presence of a halide, either occurring naturally or admixed with the ore, caused the copper to migrate from the ore particles and to segregate in the charge. The ratio of salt to reducing agent may vary somewhat, but in general 0.5% to 1.5% sodium chloride and 0.5% to 1.0% coal or coke have been mixed with the ore. Less than stoichiometric amounts of salt are required to convert all the oxide copper to a chloride, so that a cycle of reactions appears to be occurring. Several investigations reported in the literature have proposed reactions to explain the mechanism of the process.5-10 There appears to be general agreement that water is necessary for the reactions to occur; that once the sodium chloride reacts with silica or silicates in the ore, the hydrochloric acid formed will convert the cupric oxide in the mineral structure to cuprous chloride. However, there appears to be a conflict of opinion on the reactions involved in the reduction of the cuprous chloride to metallic copper on the surface of the carbon. Rey has indicated that salt, water vapor, and

Jan 1, 1968

By R. F. Mehl, G. V. Smith

THE decomposition of austenite in steels, because of its immense practical importance, has been subjected to extensive study in recent years from the point of view of the mechanism of the process.1-3 Although much information has been acquired, a number of questions, principally of theoretical interest, remain. One is that of the atomic-crystallographic mechanism by which each of the various reaction products forms. The isothermal reaction products of the eutectoid decomposition in plain carbon steels (to which this study is restricted) have conveniently been classified in three general groupings-pearlite, bainite, and martensite. Of these several products, pearlite and martensite have been studied extensively, but bainite has received only scant attention. As a result, the mechanism of the formation of pearlite and that of martensite are now fairly well understood while a great deal of uncertainty exists regarding bainite. PEARLITE Pearlite forms from austenite by the precipitation of alternate platelets of cementite and ferrite, which grow into the austenite matrix .2-5 The rate of reaction may be described in terms of a rate of nucleation and a rate of growth.2.3 Mehl and Smith6 have attempted to determine the lattice relationships existing between the ferrite in pearlite and the parent austenite. Using a pole-figure method of analysis, it was found that a limited number of ferrite orientations resulted from the decomposition of a single grain of austenite; it was not possible, however, to decide between two assumed ideal relationships, both of which appeared to account for the experimentally determined pole figure. It was definitely shown, however, that the relationship obtaining was quite different from that determined for the proeutectoid separation of ferrite.7 No attempt was made to determine the habit plane (matrix plane to which the precipitate lies parallel) of the pearlite lamellae. Belaiew8 earlier had stated that the number of directions assumed by the pearlite lamellae in a single grain of austenite was 12 (no details were given) and concluded wrongly, as Mehl and Smiths have pointed out, that the lamellae delineate the [210] planes of ferrite.* MARTENSITE It is known that martensite is a transitional constituent of body-centered tetrag-

Jan 1, 1942

By D. J. Salley, M. Burke, G. L. Simard

A PREVIOUS paper1 described experiments on the interaction of dithiophosphate with galena and suggested that the process had characteristics of both chemisorption and surface chemical reaction. In order to add to this knowledge, a study has been made of the competition of a second ion with the dithiophosphate for a galena surface. Use again was made of radiotracer methods. Since radiophosphate was readily available, it was chosen as the competing ion. It is a feature of the tracer method that, in spite of similarity in the chemical behavior of the ions, the measurement of one ion in the presence of another can be made as simply as if only one ion species were present. In order to study the competition effectively, it naturally was necessary to examine the interaction of phosphate with galena alone as well as in the presence of dithiophosphate; consequently, this report consists of two parts. The first is devoted to a study of the rates, the isotherms, the desorption, and the exchange in the phosphate-galena system in the same manner as was done for the dithio-phosphate-galena system. The second portion is concerned with the studies on the competition. Flotation experiments on the three-component sys- tem are also outlined and the relationships involved are discussed briefly. The experimental method was that of the previous paper. The preparation of the galena, the radioactive and the nonradioactive dithiophosphate, and the procedures for radioactive counting, for sorp-tion, and for flotation measurements were identical to those previously employed. The radiophosphate* was used in the form of disodium phosphate solution. In the competition experiments the effect of the phosphate ion in depressing dithiophosphate uptake was followed by holding the initial concentration of nonradioactive phosphate constant while varying the initial concentration of the radioactive dithiophosphate. Counterfashion, the depression of phosphate by dithiophosphate was obtained by keeping the initial nonradioactive dithiophosphate ion concentration constant and altering the initial concentration of the radioactive phosphate ion. All solutions were buffered at a pH of 7.8 a0.1 by 20x10-' mol per cc of sodium carbonate. Measurements with radiocarbonate indicated that little or no carbonate could be sorbed in the presence of

Jan 1, 1952

By R. E. H. Pomeroy

THE statistical data given in this paper are taken from the actual performance of the No. 2 reverberatory furnace of the Nevada Consolidated Copper Co., Me Gill, Nev., for a period of four months, from April to July, 1914. The principal furnace dimensions are: Length, 132 ft. ½ in. at the skim-line level; average width, 18 ft., 10 in. at the skim-line level. The roof is 7 ft. above the skim-line level at the firing end. The average area in the uptake flue is 36 sq. ft., and the area above the skim line under the vulcatory arch is 24.3 sq. ft. Fig. 1 shows a diagrammatic plan and sectional elevation of this furnace. The furnace is equipped with two 400-b.h.p. Stirling waste-heat boilers set in parallel. California crude petroleum is used for fuel and has a specific gravity of 16.5° B., flashing in open test at 199° F. The oil is heated to about 200° F. in a steam heater before going to the burners, requiring about 9 b.h.p. per furnace day to heat it from the line temperature to the burning temperature. Measurement is made by oil meter, checked daily by reservoir readings. The oil is fed by gravity (34 lb. static pressure) to seven low-pressure blast burners of the Steptoe type (Fig. 2). The blast for these burners is supplied at about 40-oz. pressure by a motor-driven Connersville blower of 42 cu. ft. capacity per revolution. The air supplied by the blower through the burners for atomizing the oil amounts to about 10 per cent. of the theoretical air necessary for complete combustion of the oil. The remainder of the necessary air enters the furnace through the burner openings in the firing wall. No checker holes are provided, and the charge holes in the roof are equipped with slide gates and "dog houses? to minimize air leakages. The combustion of the fuel, as shown by gas analysis at the front of the furnace, is practically complete, the carbon monoxide in the gases being less than 0.5 per cent.

Jan 2, 1915

By G. R. Gardner, D. H. Davis

Increasing realization of the importance of dust control, and the recommendations of various agencies, have led the mining industry to become actively concerned with this problem. The background and necessity for adequate dust-suppression measures have been discussed in a number of publications, including those of the U. S. Bureau of Mines, and the use of spray water to reduce dust at the face and on roadways has been recommended. The problem resolves itself into obtaining adequate dust reduction at a reasonable cost. Inasmuch as the term "adequate dust suppression" has never been clearly defined, nor have permissible limits of dustiness (in terms of dust count) been established, it is apparent that any method selected may be required to meet additional demands. Until the industry has been given some indication of permissible limits of dustiness, no permanent solution is possible. Progress will be somewhat handicapped until such information is available. In addition, dust reduction must be obtained without the addition of any excessive moisture to the coal, since consideration must often be given to: I. Quality standards, particularly reduction in heat value. 2. Handling characteristics, particularly in regard to unloading from railroad cars and bins. 3. Application of dry methods of coal cleaning. 4. Necessity for fine screening within specified limits of oversize and undersize. Little detailed information is available as to the advantages and disadvantages of the several methods of water distribution, the location and protection of sprays, operating data on pressure, quantity of water, and so forth, and results obtained. In 1940 an investigation was undertaken to determine and evaluate the principal factors involved. This paper constitutes a progress report on this work and cannot in any way be regarded as complete on any one of the several phases. Classification of Dust Sources The various sources of underground dust may be classified as primary or secondary. A primary source is one associated with appreciable degradation of size, that is, where the greater part of the actual fines capable of becoming air-borne dust are produced. A secondary source may be considered as one in which the greater part of the fines have been produced at some previous operation and are in such condition that they can be dispersed as air-borne dust. These conceptions appear to be of practical significance, as experience indicates that when dust is controlled at the primary sources the importance of secondary sources is minimized. For these reasons, investigations to date have been concerned principally with the primary sources of dust, and this paper is concerned particularly with one of these—namely, undercutting. In accord with the foregoing definitions, the sources to which the following opera-

Jan 1, 1942

By G. R. Gardner, D. H. Davis

Increasing realization of the importance of dust control, and the recommendations of various agencies, have led the mining industry to become actively concerned with this problem. The background and necessity for adequate dust-suppression measures have been discussed in a number of publications, including those of the U. S. Bureau of Mines, and the use of spray water to reduce dust at the face and on roadways has been recommended. The problem resolves itself into obtaining adequate dust reduction at a reasonable cost. Inasmuch as the term "adequate dust suppression" has never been clearly defined, nor have permissible limits of dustiness (in terms of dust count) been established, it is apparent that any method selected may be required to meet additional demands. Until the industry has been given some indication of permissible limits of dustiness, no permanent solution is possible. Progress will be somewhat handicapped until such information is available. In addition, dust reduction must be obtained without the addition of any excessive moisture to the coal, since consideration must often be given to: I. Quality standards, particularly reduction in heat value. 2. Handling characteristics, particularly in regard to unloading from railroad cars and bins. 3. Application of dry methods of coal cleaning. 4. Necessity for fine screening within specified limits of oversize and undersize. Little detailed information is available as to the advantages and disadvantages of the several methods of water distribution, the location and protection of sprays, operating data on pressure, quantity of water, and so forth, and results obtained. In 1940 an investigation was undertaken to determine and evaluate the principal factors involved. This paper constitutes a progress report on this work and cannot in any way be regarded as complete on any one of the several phases. Classification of Dust Sources The various sources of underground dust may be classified as primary or secondary. A primary source is one associated with appreciable degradation of size, that is, where the greater part of the actual fines capable of becoming air-borne dust are produced. A secondary source may be considered as one in which the greater part of the fines have been produced at some previous operation and are in such condition that they can be dispersed as air-borne dust. These conceptions appear to be of practical significance, as experience indicates that when dust is controlled at the primary sources the importance of secondary sources is minimized. For these reasons, investigations to date have been concerned principally with the primary sources of dust, and this paper is concerned particularly with one of these—namely, undercutting. In accord with the foregoing definitions, the sources to which the following opera-

Jan 1, 1942

By Carl D. Broadbent

In 1956, Kennecott Copper Corp. instituted a slope mechanics program. Its objective was to obtain effi-ient and safe pit slopes. Since then, Kennecott has onducted a great deal of research into the area, most otably at the Kimbley Pit. This paper, which describes the transitional work at this period and draws from the pertinent experimental work done by others, paves the way for the next step of the program: refining the design process and applying it for profit. The goal of slope mechanics is to achieve efficient and safe pit slopes. In the case of ultimate mine slopes, the objective is to minimize the stripping ratio by steepening the slopes to their maximum stable limit. On the other hand, the inclination of working slopes is normally established by operating space requirements and the function of slope mechanics should be the continuous surveillance of slope conditions to assure long-term stability and provide timely warning of impending slides so that corrective measures may be incorporated in production planning. In 1956, Kennecott instituted a program to provide

Jan 1, 1970

By P. A. Boeck

The thermal insulation of high-temperature equipment for industrial purposes is a subject that has not received from engineers and designers the attention its importance deserves. This may be attributed to a number of causes: In the first place, heat flow is a rather difficult factor to measure under the working conditions of an industrial furnace, and until the comparatively recent introduction into certain operations of the heat balance sheet, with a systematic attempt to account for the discrepancies in the totals, the various causes of heat losses and the reasons for their existence were not brought to light. Moreover, such rapid advancement and radical changes in the design of equipment, especially in metallurgical lines, have occurred that practice has apparently outdistanced the theory of design. In the modern tendency toward greatly increased size of units, effort has seemingly been made to utilize the heat of fuel gases without proper attention having been paid to conserving heat energy and confining it strictly to the points of maximum activity. The systematic study of the thermal properties of structural materials, which is being carried out by various government bureaus and also by a number of technical societies, is forming the basis for more intelligent and consistent work in the economically important subject of prevention of fuel waste. Advantages of Insulation It is not necessary in this practical and utilitarian age to enlarge upon the need of prevention of heat losses, but attention may advantageously be called to the other benefits derived simultaneously with the saving in fuel and the increase in thermal capacity of furnaces when properly insulated. In most industrial furnaces—which are here spoken of in the broadest sense, indicating general high-temperature equipment for any purpose and heated in any manner—the operations are generally carried on through a temperature range which has been found by practice to give the most ef-

Jan 1, 1916

By A. Phillips, H. J. Fisher

The influence of temperature and composition on the viscosity of high-purity liquid metals and alloys of the Pb-Sn and Sb-Cd systems was investigated by the logarithmic-decrement method. The variation of viscosity with temperature above the liquidus followed the equation: n = AeE/RT No large increase in viscosity was found just before normal freezing of any of the metals or alloys investigated. Certain alloys, supercooled below their stable liquidus, however, did show a marked increase in viscosity. Experimental activation energies for viscosity were determined for the metals investigated. Liquid-metal density values were obtained by a modified Joeger's method. IK an investigation of the properties of molten metals, the study of viscosity as a suitable means for studying the physical nature of the metallic liquid state has been utilized. Although interest in the relationship of the liquid to the solid-metal state holds promise of broadening the knowledge of metals in general, much information that is available regarding the influence of temperature and composition on viscosity, especially near the freezing point, is still controversial. The purpose of this paper is to present the results of recent work on this subject. Although interest in factors influencing the fluid behavior of metals and alloys has arisen from theoretical as well as applied studies of liquid-metal properties, the development of a comprehensive theory of the mechanism of viscosity has been handicapped because so little is known about the liquid state. Several theories of viscosity have been proposed and among the more recent are those of Andrade,1 Bernal,2 Frenkel,3 Eyring,4 and Gutmann and Simmons.5 Athough these contributions have helped to establish a basis of approach for studying the nature of viscosity, the fundamental aspects of the variation of viscosity with alloy composition have, in general, been neglected. Experimental Metals and Alloys Investigated: The Pb-Sn and Sb-Cd alloy systems were selected for investigation because they form constitutional features of theo-

Jan 1, 1955

By W. F. Hosford, E. W. Kelley

By testing polycrystalline specimens from textured plates which had Previously been used to provide materials for growing single crystals, it has been possible to relate the plastic anisotropy of textured materials to the deformation behavior of single crystals. The deformation studies have been conducted at room temperature on textured polycrystalline magnesium and binary Mg-Th and Mg-Li alloys. Variously oriented specimens of the textured materials were deformed in plane-strain compression and in uniaxial tension and compression. The stress-strain curves are similar in their general jorm of anisotropy and stress levels to those obtained on single crystals of the same alloys. The degree of anisotropy is lower, however, in the polycrystalline materials and correlates with the intensity of the basal texture. Yield loci for the textured materials appear reasonable in terms of the deformation mechanisms, and deviate sharply from the form predicted by the Hill analysis for aniso-tropic material. A N earlier study1 of single crystals has shown that magnesium and magnesium alloys with thorium and with lithium deform at room temperature primarily by basal slip, {10i2) twinning, and (1011) banding. The (10i1) banding mode is a combination of {10ll) twinning followed by (1012) twinning and basal slip within the doubly twinned material.2, 3 Magnesium with lithium can also deform by {1010)(1210) prism slip.1'4'5 Still other deformation modes have been reported for magnesium6-11 but these are considered to play a minor role in room-temperature deformation. In a polycrystalline material, plastic deformation must occur in the individual grains through the operation of one or more of the various deformation modes. Because the critical shear stress for basal slip is very low compared to the activation stresses for the other deformation modes,' basal slip accounts for much of the deformation in the polycrystalline aggregate. However, since there are only two mutually independent basal slip systems, and because five independent systems must be active for an arbitrary shape change in any material,'' modes other than basal slip must account for some of the strain. The deformation of textured magnesium, like that of other hcp metals, must be controlled by the same mechanisms observed in single crystals. In strongly textured material, the form of the anisotropy should be similar to that of single crystals, and the degree of anisotropy should depend on the intensity of the texture. EXPERIMENTAL PROCEDURE The anisotropy of deformation was investigated through the use of plane-strain compression tests, as well as uniaxial tension and compression tests. Materials. Test specimens were cut from the three textured plates of magnesium which had previously been used to provide material for single crystals.' These plates, furnished by Dow Chemical Co., had been reduced about 80 pct during the process of being hot-rolled to their final 1/4-in. thicknesses. The plates had the three respective compositions, pure magnesium, Mg-0.5 wt pct Th (0.49 pct Th by spectro-graphic analysis), and Mg-4 wt pct Li (3.84 pct Li by chemical analysis). Impurities other than iron were less than 0.0005 pct Al, 0.01 pct Ca, 0.001 pct Cu, 0.0006 pct Mn, 0.001 pct Ni, 0.003 pct Pb, 0.001 pct Si, 0.001 pct Sn, and 0.01 pct Zn. Iron was 0.001 pct in the pure magnesium, 0.002 pct in the Mg-0.5 pct Th, and 0.014 pct in the Mg-4 pct Li. The textures of the three plates were determined by X-ray diffraction utilizing only the reflection technique out to an angle of 50 deg from the sheet normal. The resulting basal pole figures are presented in Figs. 1, 3, and 5. Grain sizes in the plates were ASTM number 4 in the pure magnesium and number 7 in each of the alloys. Plane-Strain Compression Tests. Plane-strain compression specimens approximately $ in. thick by 4 in. wide by $ in. long were prepared for each of the three compositions. These specimens were prepared in a manner similar to that used for the single-crystal specimens of the earlier study.' All polycrystalline specimens were stress-relieved at 500°F for hr as the final step in their preparation for testing. The testing procedure was identical to that used for the single crystals, involving compression in a channel and using 2-mil Teflon film as a lubricant. The specimens were tested in six orientations of interest, these being the six combinations of the rolling, transverse, and thickness directions of the material serving as loading, extension, and constraint directions in the plane-strain compression test. Each of the six orientations was assigned a two-letter identifying code. These are combinations of the letters (thickness direction), R (rolling direction), and T (transverse direction) with the first letter signifying the loading direction and the second letter the extension direction. For example, ZR specimens were compressed in the thickness direction while extension was permitted to operate in the rolling direction of the textured material. To facilitate comparison of the present work with that of the single-crystal study1 the orientations used for single crystals are given in Table I along with the polycrystalline orientations that most nearly correspond. To insure reproducibility, at least three duplicate

Jan 1, 1969

By L. D. Jaffe

From the limited experimental data in the literature, preliminary values were derived for the thermal diffusivity of titanium alloys and for the quenching severity of various mediums used in heat treating them. The thermal diffusivity, under quenching conditions, was found to be approximately 0.006 sq in. per sec. The quenching severity H for brine is approximately 8, for water 4, for oil 0.9, for air 0.08, and for argon 0.02 in. -' The quenching severity of the Jominy-Boegehold end quench water jet against titanium alloys appeared effectively infinite. Using these results, graphs were prepared showing ideal round sizes and Jominy positions having cooled conditions equivalent to those at the center and surface of titanium alloy rounds, plates, and sheets quenched in various media. THE importance of proper quenching of steel parts has long been recognized, and much quantitative work has been done on the subject. Recently, it has become evident that for titanium alloys, too, the rate of cooling from high temperature is important in obtaining high strength and hardness. Maximum hardness and strength may not be attained in the as-quenched condition but rather after a subsequent tempering or aging treatment. Nevertheless, if cooling from temperatures near the ß transus is too slow, for the hardenability of the alloy used, a soft a-ß structure will be produced which will not harden on subsequent aging.'-" The quenching of parts of practical interest can usually be approximated by simple shapes, such as cylinders (rounds) and plates (or sheets) of various thickness and combinations of these. A standard that has been used extensively for comparison purposes is the center of an ideal round: a cylinder quenched in a medium that instantly cools its surface to room temperature." For steel, considerable practical use has been made of the Jominy-Boegehold end quench hardenability specimen,".' and its value for titanium alloys is becoming evident. It therefore appeared worthwhile to attempt comparison of cooling conditions in titanium alloy rounds and plates of various sizes quenched in various media with cooling conditions in ideal round and Jominy quenches. These comparisons are based upon measurements reported in the literature. Quenching Severity of Jominy Water Jet and of Brine As one starting point, there were available the data of Phillips and Tobin8 for positions on a Jominy specimen having the same hardness as the centers of round bars of various size quenched in 5 pct NaOH brine, shown in Table I. The Jominy speci- men is a round bar, normally 1 in. diam and 4 in. long, quenched by a water jet at one end and air cooled on the other surfaces.' After quenching, hardness is measured vs distance from the quenched end on longitudinal flats ground 0.015 to 0.10 in. deep. The data of Table I were based on a subsized specimen of 3/4 in. diam. Since the positions tested are close to the jet quenched end, cooling there may be taken as due solely to the jet, and air cooling can be neglected. These positions are then equivalent to various locations near one surface of an 8 in. plate jet quenched on both sides. Assuming that the thermal diffusivity is constant and that Newton's law of cooling holds, temperature vs time curves at corresponding positions in Jominy specimen and round bar then may be calculated for various assumed quenching severities of the water jet and of the brine. Cooling curves are generally taken to be metallurgically equivalent when they show the same time to reach a temperature halfway between the initial (heat treating) temperature and the final (quenching medium) temperature.5 On this basis, using Russell's tables,9 upplemented by heat flow tables derived in similar fashion by the author for positions near the surface of severely quenched plates, it was found that the experimentally observed equivalence, Table I, was best matched if the quenching severity H of the Jominy water jet was taken as infinite (H = co). This means that the jet quenched surface should be considered as instantly cooled to the temperature of the water

Jan 1, 1956

By A. H. Daane, W. J. Wunderlin, B. J. Beaudry

The solid solubility of holmium in copper, silver, and gold, determined using metallographic techniques, was found to be a maximum of 0.06, 2.4, and 3.2 wt pct, respectively, nt the eutectic temperatures. The temperatures of these eutectic horizontals, determined by differential thermal analysis, were found to be 868", 787", and 778"C, respectively. The first compound on the silver-rich side of the Ag-Ho system was found to be A&Ho2. In a study by Gold et al.,' on the effect of small amounts of soluble impurities on the electrical resistance and thermoelectrical properties of copper, traces of iron were shown to have drastic effects on the thermoelectric power due to the magnetic scattering of the conduction electrons. Since little is known about the state of the iron ion when dissolved in copper, Gold had hoped to repeat these experiments using certain rare earths as the magnetic scattering centers; because of the tightly bound 4f electrons it is not expected that their spectroscopic state would be affected by alloying. In such an experiment the sole role of the trace rare-earth impurity would be to magnetically scatter the copper conduction electrons without producing appreciable distortions in the otherwise pure copper matrix. Since holmium was chosen for such a study because of its high magnetic moment, it was necessary to establish precisely its solid solubility in copper. The study was extended to include the solvents silver and gold, so that an evaluation of the data using classical solubility parameters could be made. No previously reported work on the systems of holmium with copper, silver, or gold was found in the literature. Information on the solubility of other rare earths in these three metals is also very meager. The solubility limit of yttrium in copper was reported as less than 1 wt pct2 and the solubility of praseodymium in gold as 0.35 wt pct,3 while no references were found on solubility studies of rare earths in silver. EXPERIMENTAL Materials. The materials used in this investigation were distilled holmium prepared in this Laboratory, OFHC* copper, electrorefined silver (99.9 *OFHC = oxygen-free high conductivity. pct), and gold with the analyses given in Table I. Sample Preparation. Samples weighing 1 to 2 g were prepared by arc-melting the components together on a water-cooled copper plate under purified argon atmosphere. The samples, turned and remelted at least five times to ensure homogeneity, showed weight changes of less than 0.1 wt pct after melting. Samples containing less than 0.7 wt pct Ho were prepared by diluting 1 to 2 wt pct Ho alloys with the pure solvent, while samples with concentrations greater than 0.7 wt pct Ho were prepared directly from the metals. The samples were wrapped in tantalum foil, sealed in outgassed Vycor tubing under helium, annealed at the desired temperature for at least 24 hr, and then quenched by shattering the Vycor tube in cold water. Metallographic Methods. Standard mechanical polishing methods were used in preparing the silver and gold alloys for examination, while the copper alloys were electropolished using a 40 pct solution

Jan 1, 1963

By C. H. Mathewson, Robert Maddin, W. R. Hibbard

A SATISFACTORY mathematical relationship between shear, elongation and change of orientation in the axial straining of a single crystalline rod or wire may be based on a simple model in which blocks, representing glide lamellae, glide over one another and rotate so as to maintain the original fixed position of the axis as the wire elongates.1 Obviously such a model gives no information concerning strain-hardening or the atomic adjustments at the sliding surfaces and their influence on the internal structure of the blocks. Moreover such an operation could be conducted with rigid blocks only by using self-aligning grips or a flexible attachment which would permit the adjacent blocks to freely assume their changing orientations. There are many unsolved problems (see Andrade2) concerning the manner in which nature departs from the simple model in permitting the essentials of slip, rotation and elongation to occur along with strain-hardening and the appearance of glide lamellae of various dimensions and special characteristics, not fully appreciated at the present time. This paper describes part of an extensive investigation on the development and characteristics of glide ellipses in single crystalline alpha brass rods and is especially concerned with the observation of cross-slip in crystals oriented wholly within the range of slip on a single system according to the generalizations first presented by Taylor and Elam in 1923.3 EXPERIMENTAL PROCEDURE Half inch rods of alpha brass (nominally 70 pct Cu, 30 pct Zn) * were converted into single crystals by melting and gradual solidification in a graphite mold according to the Bridgman method.' In order to remove any coring, the crystals were homogenized at 800°C for 16 hr and tested by etching with a 50 pct nitric acid solution. The back-reflection Laue technique as described by Greninger5 was used for determining the orientations of the crystals. Standard stereographic operations were employed to locate the specimen axis in a triangle of the Taylor and Elam3 projection so that the slip plane and direction could be predicted. The lineage structure reported by Buerger6 was present in the crystals used in this investigation. However, only crystals were used in which the internal differences in orientation did not exceed two degrees. Very little is known concerning the effect of the presence of a lineage structure on the detailed mechanism of plastic deformation.

Jan 1, 1948

By T. J. Woods

Tars paper deals with the origin, definition and prevention of scabs an semifinished rolled-steel product. Mold coatings, which are considered essential in scab prevention, were found to be effective only in relation to the ingot surface of semikilled and killed steels and not necessary for the rolled product. That is to say, the scabs on ingots caused by having been cast in uncoated molds are eliminated in the soaking and rolling operations, therefore are not present on the rolled product. This fact, which is contrary to the average opinion, was established after extensive and thorough experiments had proved the ordinary conception of the origin of scabs to be incorrect. This subject may be of little or no concern to steel plants producing small ingots for the manufacture of small billets and bars, except as it may be of interest in showing why their surface troubles with scabs do not exist on the product of heats with normal pouring practice. But to the producer of large ingots to be rolled into slabs for large plates used in shipbuilding, it is a very important subject. DEFINITION OF A SCAB The generally accepted opinion is that the individual scabs present on rolled products (as shown by Fig. I) are considered to have been individual splashes on the ingot surface. This opinion was found to be incorrect. Experiments showed that there were no individual scabs on the product that had appeared as individuals on the ingot surface. The single scabs seen are either pieces of a shell that is present near the bottom of all top-cast ingots, or a veneer that may be present on any part of an ingot improperly poured, as when the stream strikes the mold wall. This definition is based on a detailed study of scabs and their characteristics in which the following have been found true: Location.- On the product of heats poured without trouble, scabs, if present, are always on the product that corresponds to the bottom end of the ingot, and usually occur in clusters, This is true whether molds are coated or not. Shape.-There is no regularity as to shape, size or thickness. It is sometimes possible to separate a few pieces and place them together, like pieces of a jigsaw puzzle, indicating that at one time they had been united as one piece. If individual splashes were the origin of scabs, the foregoing would not be true. Instead, the splashes, which occur throughout the pouring of the ingots, would be present uniformly over the entire product and there would be considerable similarity in the shape and thickness of the scabs. EXPERIMENTAL WORK Our experimental work was conducted on 200-ton heats of semikilled plate steel tapped into an oval ladle 15 ft. high. All ingots were top-cast direct into 24 by 54 by 82-in. molds, straight-sided, set on fat stools. Two separate studies were made about one year apart, each study extending

Jan 1, 1943

By Charles Pack

Extensive progress has been made in the metallurgy of alloys for die castings. Enthusiastic proponents of some alloys are inclined to make extravagant claims for their materials, which may be justified by physical tests on test bars made from the respective alloys but are seldom justified by the results obtained with commercial die castings made from those alloys. Chemical analysis of the test bars and castings fails to determine the cause of these variations, since they are due to other physical factors entering into the commercial production of die castings. In this paper, an attempt will be made to outline some of the factors in commercial die-casting practice to which these variable results may be attributed, in the hope that the manufacturer of die castings, recognizing the importance of these factors, will devote more attention to them in the design and construction of dies and equipment. In 1914,l the author defined die castings as "metal castings made by forcing molten metal, under pressure, into metallic molds or dies." This definition was given in order to differentiate die castings from other molded metal products such as "permanent-mold" castings, L'slush" castings and similar products that are sometimes erroneously termed die castings. The term "die casting" could be interpreted to include all castings made in metal molds or dies; but since this term, like most of our technical nomenclature, has been developed by commercial practice we must look to this practice for its proper definition. The Germans, with their usual devotion to desecriptive names, have adopted the name of sprilzguss (squirt cast) for die castings. Undoubtedly this name is more descriptive of the die-casting process, where the metal is literally squirted into the die and serves to differentiate this process from other metal mold processes, where the metal is poured into the die. In the earlier paper mentioned, the author also emphasized the fact that the definition given for die castings indicated clearly that the satisfactory operation of the process must comprise three factors, all of which must be considered of vital importance to the successful operation of the die-casting process:

Jan 1, 1931

By Frank Miller

THE lower cost of producing oil from naturally flowing wells compared with pro-duction costs accruing from artificial lifting methods has stimulated much research, with the joint purpose of extending the natural flowing life of wells and of increas-ing the productivity of small wells. The laboratory investigation described herein was made to determine the effect of a slotted liner on the pressure gradient in the vicinity of the wall of a flowing well. Flow restrictions caused by the liner induce energy losses between the oil-bearing for-mation and the inside of the liner, which may be reduced by improved liner design, and thereby the flow capacity of wells may be increased. These losses have been evalu-ated for rectangular slots of different sizes, and means are suggested for reducing them. The dearth of information concerning the nature of the flow of fluids from uncon-solidated sands through small openings in the walls of pipes-as represented by the flow of oil from an oil sand into a slotted liner-is acknowledged. Although the bene-fits to be realized by operators through the use of optimum liners is just beginning to be recognized generally, Coberly1 in 1937 pointed out that the functioning of screen casing is an important factor in the pro-duction of oil. From his study on the selection of size of oil strings for wells in California, Parks2 concluded, in part, that the perforated section of the oil string de-serves continued study, especially with respect to the selection of perforations. The growing use of gravel packing result-ing from certain research findings lends even more significance to the problem of selecting optimum liners, as the application of these methods usually requires slotted liners or other kinds of perforated liners. The present study was made to obtain further information for the guidance of engineers and operators in selecting slotted liners and to develop a laboratory method that may be used in analyzing possible pressure conditions surrounding most types of perforated casings used in producing oil wells, so that the present inadequate fund of knowledge on this important subject may be expanded.

Jan 1, 1940