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By W. O. Philbrook, K. M. Goldman, G. Derge

THIS is the third in a series of papers from the Metals Research Laboratory dealing with the transfer of sulphur across the iron-slag interface in a carbon-saturated system. The first paper' showed that the transfer obeyed first-order kinetics. The second' presented detailed evidence in support of the three-stage mechanism: FeS(Fe) FeS(slag) FeS(slag) + CaO(sing) ? CaS(slag) + FeO(slag) FeO(slag) + C ? Fe + CO. This emphasized the role of an iron-sulphur complex as the transfer agent across the interface and as an essential intermediate in the overall process. The present paper shows the influence on the process of the individual elements, carbon, silicon, manganese, and phosphorus, the alloying elements normally present and of interest in commercial blast furnace operations, aluminum, which has a pronounced accelerating influence, and nickel and copper, which are common minor impurities in the raw materials. The experimental methods and procedures for interpretation of data are the same as described earlier.1,2 Induction heated, graphite crucibles were used, and sulphur-free slag was added to the molten iron containing sulphur and the selected alloy. Slag samples were taken at regular time intervals and analyzed for sulphur and other components of interest. The authors wish to state specifically that these experiments were not intended to simulate industrial blast furnace operations. However, they do represent a study of the kinetics and mechanism of sulphur transfer at the slag-metal interface under specified laboratory control of the major variables in the system. It is believed that the results can be usefully applied to the blast furnace if consideration is given to the differences which are known to exist between the two conditions. A rigorous evaluation of the accuracy of rate studies is difficult. Recognized sources of error include sampling and analysis of both slag and metal, temperature measurement and control, selection of zero time, composition of the gaseous atmosphere over the reaction system, and extraneous sources of sulphur from the graphite crucible and reagent materials. In this study carefully standardized procedures were followed consistently in order to minimize the errors. It is believed that the reproducibil-ity of duplicate runs indicates that errors have been rendered negligible relative to the observed effects from intentional variables. For example, original experimental points for duplicate runs are shown in Figs. 1, 2, 7, etc. In most cases in this paper the drawn curves represent an average of at least two heats. The spread in sulphur values at a given time ranges from 0.02 to 0.08 pct, which is a small frac-tioi of the total values ranging up to 2 pct S in slag. In the systematic study of the influence of alloy additions, each element was added over a range of concentrations. The two slags used in this study were designated as "acid" or 1530 and "basic" or 1545. They had the nominal compositions given in Table I. Rates were measured in the temperature range 1500" to 1650°C. Data will now be presented to illustrate the various features of the study. Silicon The first alloying element examined was silicon, because its presence is unavoidable in any silicate slag system through the reaction y/2SiO2(slag) + xM?y/2Si(liq.Fe) + MxOy where M is any reducing agent such as iron or carbon. It is known that the attainment of equilibrium by this reaction is extremely slow and probably not reached in the blast furnace." The influence of silicon on the final stages of the sulphur reaction has also been studied.' It has been shown5 hat silicon increases the activity of sulphur in iron. For such reasons silicon may also be expected to influence the kinetics of the reaction. The observed effects will now be described. The general procedure was to melt 530 grams of ingot iron in a graphite crucible, 3 in. OD, 2 1/4 in.

Jan 1, 1955

By H. Schwartzbart, J. R. Low

Annealed, .Poly crystalline, low carbon steel exhibits a phenomenon known as the "yield point." If such a steel is loaded in tension, the load increases steadily with elastic strain, drops suddenly, fluctuates about some constant load value for a time and then rises with further strain. The load at which the sudden drop occurs is called the "upper yield point"; the load at which deformation proceeds at constant load is known as the "lower yield point"; the amount of elongation at constant load is termed the "yield point elongation." Deformation which occurs during the yield point elongation is heterogeneous in nature, deformed metal existing next to undeformed metal. The drop in load from the upper yield point is concurrent with the formation of a band of deformed metal which usually appears at a stress concentration such as a fillet and at an angle of approximately 45" with the direction of pull. As deformation proceeds during the yield point elongation, the deformed region grows until the entire specimen has been strained an amount equal to the strain in the first band. A phenomenon very often associated with the yield point is that of strain aging. Aging in steels may be of two types: quench aging, or precipitation hardening, and strain-aging. Strain aging differs from precipitation hardening in that if the metal is merely strained instead of given a solution anneal and quenched, it then undergoes changes in properties similar to those observed in quench aging. The yield point effect and strain aging are most markedly exhibited by low carbon steel, but have been observed in other alloys. Numerous explanations for the mechanisms of both phenomena have been advanced, but the evidence for the acceptance of any of the hypotheses is incomplete. One of the explanations of the yield point phenomenon frequently proposed is that there exists a honeycomb of grain boundary material that supports the load above the yield strength of the ferrite and that when this network ruptures, the ferrite flows with no increase in load. This notion was first advanced by Dalbyl in 1913 and has been since put forward in more concrete form by many investigators. The testing of this hypothesis was, in part, the object of the present investigation. Similarly, the mechanism by which strain aging occurs remains to be explained. Presumably, it is a precipitation hardening phenomenon similar to quench aging, the precipitation being initiated by strain. However, it is not known whether the process is a solution and precipitation effect or a change in solubility due to strain. One obvious method of determining whether or not the yield point is a grain boundary phenomenon is to determine if single crystals exhibit a yield point. Low and Gensamer2 have shown that carbon and nitrogen are responsible for the yield point and aging in steel and that these effects can be eliminated by the removal of these elements through wet hydrogen purification. Single crystals that have been grown in wet hydrogen treated material must then be recarburized or re-nitrided in order to evaluate the effect of grain boundaries. In the present investigation, single crystals of iron which had been annealed in wet hydrogen to remove the carbon and nitrogen were cut into two specimens having the same orientation with respect to the tension axis. Of these, one specimen was pulled in tension in the wet hydrogen treated state and the other was carburized or nitrided and tested similarly. All the crystals were examined for a yield-point and strain aging. The grain boundary hypothesis for the explanation of the yield point in steel has been tested only indirectly previously. Arrowsmith,3 Andrew and Lee,4 Edwards and Pfeil,5 Fell,6 Ludwik and Scheu,7 Winlock and Leiter8 and others found a decrease in proportional limit and yield point effect with an in-

Jan 1, 1950

By J. L. Giove, J. M. Hodge, R. G. Storm

The hardenability effect of molybdenum has been evaluated by a number of investigators, including one of the present authors.1,2,3,4,6 Considerable discreMncy exists, however, among the results of these various investigators, and two of them, Brophy3 and Kramer,4 have indicated that the apparent hardenability effect of molybdenun would vary, depending upon the other alloying elements in the steels being considered. The results of previous, unpublished work conducted at the Duquesne Works Laboratory of the Carnegie-Illinois Steel Corporation also have indicated significant differences in the hardenability effect of molybdenu~n in nickel and in chromium steels. The present investigation was undertaken in an effort to establish the mechanism governing this difference in the hardenability effect of molybdenum. This work involved both end-quench hardenability and isothermal transformation tests on two series of steels of varying molybdenum content. One steel contained 3 pct nickel and the other 1 pct chromium. It was hoped that such studies would shed further light on the mechanism of this behavior. Materials and Experimental Work MATERIALS The chemical compositions of the steels used in this investigation arc shown in Table 1. These steels were furnished by Battelle Memorial Institutc in the form of 100-lb induction furnace ingots. The top half of each ingot was forged to 1 3/8-in. square billets and then rolled to I-in. round bar stock for isothermal transforma- tion studies. The bottom half of each ingot was forged into approximately 1 1/4-in. rounds for end quench tests. All of the steels were normalized from 1650°F and tempered at 1100°F before nlachming to end quench or isothermal samples. END-QUENCH TESTS standard l-in. diam end-quench tests were made on each of the steels. The test bars were austenitized at 1600°F for 30 min,, quenched in a standard Jominy jig, and hardness surveys were made in all tests. The 95 pct martensite point was deterInined from hardness values5 and cheeked by metallographic examination. The jominy distance values for 95 pct martensite were converted to hardellability values in terms of ideal diameter (Dl), using a revised carve for the relationship between Jominy distance and ideal diameter. This curve was based on the cooling time from the A1 to the bainite nose temperatures rather than on the usual criterion of half-temperature time. The cooling rates as determined by Russell and Williamson9 were used as a basis for this relationship. The derivation of this curve is described in detail in the appendix. ISOTHERMAL TRANSFORMATION STUDIES Samples for the isothermal transformation studies were quarter sectors of 1/16.is-in. thick slices from the 1-in. round bars. All samples were austenitized for a total the of 15 min., transferred rapidly to a lead bath for isothermal transformation, and brine quenched from the lead bath. A time of 3 see was allowed for the sample to come to the temperature of the lead bath, and this time was not included in the isothermal transformation times. Each sample was examined metallo-graphically at a magnification of 100 diam. The per cent transformation was estimated by comparison with standard micrographs, and the values were plotted against the on log/log coordinate paper. At least 4 and as Inany as 10. points were plotted for each steel. A line was drawn through the points for each steel, and the times for 5 pct transformation were obtained from the plot for each steel. Isothermal transformation diagrams in terms of 5 pet total transformation, covering the temperature range of 800 to 1200°F, were determined in this manner for an austenitizing temperature of 1600°F. The times for 5 pct transformation at the bainite nose for austenitizing temperatures of 1800 and 2000°F were also determined in the same manner. These times for 5 pct total transfor-

Jan 1, 1950

By Gilbert Santoro

In this study tantalum carbide filaments of various compositions in the fcc region were prepared by heating a tantalum wire in a measured amount of hydrocarbon vapor. Such properties as tensile strength, transverse-rupture strength, microhard-ness, lattice parameter, electrical resistivity, and magnetic susceptibility were measured as a function of carbon content. Some of these properties showed a maximum or a minimum between a carbon-to-tantalum molar ratio of 0.80 and 0.85, the composition range at which the color changes from metallic gray to gold. The recent literature has shown that in the large homogeneity range for the fcc phase of the Ta-C system there is a marked variation for such properties as microhardness,' electrical resistivity, ' thermodynamic properties,z'3 lattice parameter and superconductivity. In addition to the technological interest of these variations within a single phase, important theoretical benefits may ensue from a continuous investigation of properties vs stoichiometry in tantalum carbide and other refractory defect compounds, for example the effect of the metal-metal distance and crystal structure upon bond formation and electronic structure. Whether there is a similar variation of the tensile strength is of practical importance. Of theoretical interest would be the knowledge of how the magnetic susceptibility varies with carbon composition. Both of these properties, as well as the transverse-rupture strength, were determined for tantalum carbide filaments in the fcc phase region. The lattice parameter, the electrical resistivity, and the microhardness were also investigated and compared with values appearing in the literature. EXPERIMENTAL PROCEDURE Material Preparation. Tantalum carbide specimens of various carbon content were prepared by statically carburizing high-purity tantalum filaments in measured quantities of pure hydrocarbon gas. The filaments, which were 10 mil in diameter and 20 or 40 cm long, were heated by their own resistance at temperatures from 1800" to 2200°C using alternating current in some cases and direct current in others. Tantalum wire from two sources was used. One had a reported purity of 99.96 wt pct Ta. The ingot from which this wire was drawn had been electron beam-melted as the final step in its purification. The reported purity of the other wire, which was prepared by a powder metallurgical process, was 99.88 wt pct Ta. The impurities of both tantalum sources are listed in Table I. Spec-trographic-grade toluene or research-grade propane was used as the source of carbon. The apparatus for the carburization of the filaments is shown schematically in Fig. 1. The system was evacuated to 1 x l0-' mm of Hg when using the electron beam-melted tantalum and to less than 1 p when using the less-pure tantalum. Neither the difference in the base vacuum, nor in the hydrocarbon gas, nor in the tantalum filaments resulted in any detectable difference in the properties studied in this work. However, only the carbides prepared from the higher-purity tantalum were used in the magnetic-susceptibility determinations. Once the base vacuum had been reached, the system was flushed with the hydrocarbon and re-evacuated. For any desired composition of the carbide, hydrocarbon gas was allowed to leak into a constant-volume flask to a predetermined pressure. These pressures were measured by a Cartesian diver-type mercury gage with a range from 0 to 20 mm and with a scale expanded to nine times. The hydrocarbon gas was allowed into the reaction tube and the filament was quickly raised to the reaction temperature. The slack in the filament due to thermal expansion was taken up by drawing out the movable electrode with a screw mechanism. The filaments were kept at temperature from a few minutes to 200 hr. In the majority of cases the heating time was 6 hr. The reaction tube was cooled by cascading water on its outer surface. By means of an ammeter and a voltmeter the electrical resistance at the reaction

Jan 1, 1963

By I. R. Kramer, H. Shen, S. E. Podlaseck

The tensile and creep properties of aluminum in vacuum have been investigated. It was found that the general effect of a vacuum environment was to reduce the rate of work hardening. Results obtained from creep tests showed that lowering the test pressure from 2 x 10-4 to 10-7 torr produced a decrease in the activation energy as much as 500 cal per mole. An attempt is made to explain these effects in terms of how the surface-stress field of a specimen may be affected by a vacuum environment during plastic deformation. In a previous paper,' the results were reported of some of our early work on the effect of vacuum environment on the stress-strain curve of aluminum single crystals. This effort has been extended to the studies of the tensile and creep properties in vacuum as a function of various metallurgical parameters. Some of the recent surface-effect studies2'3 have revealed that a region of high dislocation density, the so-called "debris" layer, is formed near the surface of the specimen as a result of plastic deformation. This layer acts as a surface barrier to oppose dislocation movement. The strength of this barrier depends on the surface condition such as oxidation or surface removal. Experimental results obtained from surface-removal work2, 3 indicate that such a surface barrier, which may be characterized by a stress field, affects the applied stress and the rate of work hardening. In the case of aluminum, this stress field was found to be directly proportional to the strain and the strain rate; however, the slope of this curve is independent of orientation of the crystal and may be altered by using different surface treatment. Since the escape of dislocations may be retarded by the presence of an oxide on the surface of a specimen, it is expected that a change in the rate of oxidation in vacuum will affect the process of dislocation accumulation in the debris layer. Consequently, it also affects the plastic behavior of a metal. This paper reports the changes in some of the creep and tensile properties of aluminum in vacuum and discussions of the observed effects in terms of the concept of the "debris" layer. EXPERIMENTAL PROCEDURE Tensile Tests. A sketch of the tensile apparatus is given in Fig. 1. This apparatus was contained in a bell jar (14 in. diam by 24 in. high) connected to a 10-in. vacuum system. The load was applied to the specimen by means of a gear train which was driven by a magnetic clutch located outside the vacuum chamber. The specimen, held by a pair of square shoulder grips, was attached to the load cell at the top and the drive gear at the bottom. A displacement transducer was placed between the two grips as shown in the figure to measure the elongation. Signals of elongation and load were amplified and recorded on an X-Y recorder. The system was capable of detecting loads as small as 0.025 lb and displacements of 0.0002 in. Shoulder-grip specimens of aluminum single crystals, having a nominal square cross section of 1/8 by 1/8 in. and a 3-1/2-in, gage length, were grown by the Bridgeman techniques. The original purity was 99.997 pet. The orientations of the crystals investigated are shown in Fig. 4(a). The crystals were annealed at 600°C for 2-1/2 hr, electropolished, and placed in the vacuum test chamber without any delay. All the crystals were deformed at a strain rate of 4 x 10-5 sec-1 at 24o ± 3°C. A study was made to find whether a chemically passive surface film would give the same effect as a vacuum environment. Specimens of aluminum 1100 (0.187 in. diam with a grain size of 0.1 mm)

Jan 1, 1965

By T. J. Smolik, Harman, D. W. Fuerstenau

By means of electrokinetic measurements, the surface properties of the aluminosilicate polymorphs (sillimanite, andalusite, and kyanite) and also mullite have been found to depend on the ratio of A10 bonds to SiO bonds in the surface. The Al-toSi ratio in the surface is dependent upon the crystal lographic properties of the mineral, which in turn determine coordination numbers of A1 and of Si, cleavage characteristics, and density of the various solids. Mullite with a greater bulk Al-toSi ratio has the highest zpc of the aluminosilicates. By treatment in dilute acids or by cycling between acidic and basic solutions, alumina is selectively dissolved from the surface of these orthosilicates. This shifts the apparent zpc to lower pH values as the fraction of SiO groups in the surface increases. Thus, surface properties can be altered by procedures that alter the A l-to-Si ratio in the surface. Flotation of these aluminosilicates results from electrostatic interaction of the collector ions with the mineral surfaces. As a result, flotation response shifts in accord with any shift in apparent zpc by pretreatment. Separation of minerals by flotation is based on differences in the physicochemical properties of their surfaces.'-3 For many minerals, adsorption of flotation collectors results from their functioning as counter ions in the electrical double layer at solid-water interface. In such systems, separation depends on differences in the zero point of charge (zpc) of the various minerals. The zpc is defined as the concentration of potential determining ions in solution at which the surface is uncharged. The potential determining ions for inorganic oxide-water interfaces are hydrogen and hydroxyl.4,5 This work is concerned with the effects of crystal structure, composition, and surface preparation on the surface properties and flotation behavior of aluminosilicates. Differences resulting from crystal structure were studied by measuring electrokinetic potentials and determining the flotation behavior of three different aluminosilicate materials having the same chemical composition (Al2O3 SiO2), namely andalusite, kyanite, and sillimanite. Furthermore, the effect of the Al2O3-to-SiO2 ratio on flotation behavior and surface properties was investigated by including synthetic mullite, 3A12O3 .2SiO2. Gaudin and co-workers 6,7 have clearly shown how crystal structure determines the native floatability of certain minerals. Those solids in which the surface is comprised mainly of broken residual bonds possess naturally hydrophobic surfaces. It was found by Bakakin8 that for a number of oxidized lead minerals, differences in floatability were due to the distance of Pb atom from the surface. Only limited work has been done on relating electrical properties of surfaces to crystal structure and composition. Healy et. a1.9 found that the zero points of charge of various manganese dioxides ranged from about pH 1.5 to pH 7.5, and these differences in the zpc's were interpreted in terms of the atomic packing in the various crystals. The research presented here clearly shows that crystal structure and chemical composition do affect the surface properties of aluminosilicates and, in addition, that these effects can be altered by changing conditions under which the surfaces are prepared. CRYSTAL STRUCTURE OF THE ALUMINOSILICATES Sillimanite, andalusite, and kyanite are composed of regionally metamorphosed rocks differing mainly in degree of metamorphism. All three minerals have the same chemical composition, Al2O3 - SiO2, of which sillimanite is the high temperature polymorph and kyanite and andalusite the lower temperature polymorphs. Andalusite and sillimanite crystallize in the orthorhombic system while kyanite crystallizes in the triclinic system. The structure of these three minerals is essentially chains of aluminum-oxygen octahedra linked laterally by silicon and aluminum. The arrangement of these chains in the three minerals is shown in Fig. 1.l4

Jan 1, 1967

By Milton E. Wadsworth, W. Martin Fassell, William H. Dresher

A study of the rate of dissolution of molybdenite (MoS2) in alkaline solution was carried out under carefully controlled conditions. Effects of temperature, oxygen over-pressure, and KOH concentration were evaluated. Studies were made in the temperature range 100°C to 175°C and in the pressure range 0 to 700 psia of oxygen. Under these conditions molybdenite was found to leach according to a linear mechanism. Both oxygen over-pressure and KOH concentration were found to control the rate of leaching. The mechanism has been explained in terms of adsorption of oxygen at the molybdenite surface followed by configurational rearrangement of the adsorbed molecules. The hydroxyl ion dependency is believed to be diffusion-controlled. Laboratory batch studies have shown that molybdenite can be readily dissolved in alkaline solutions under moderate conditions of temperature and pressure. Commercial application of this process to the production of ferro-molybdenum and molybdenum chemicals is promising in view of the ease of dissolution of molybdenite and the relatively noncorrosive conditions involved in the process. HIGH temperature-high pressure techniques have long been used to great advantage in the organic chemical industry, the petroleum industry, and the paper industry. Only recently, however, have these methods been used to extract metals from their ores on a commercial scale. The Chemical Construction Corp., together with interested producers of nickel and cobalt, has done much to develop methods of producing nickel and cobalt powders by the use of high temperature-high pressure techniques.' The Howe Sound Co. is currently operating a plant near Salt Lake City in which the new Chemical Construction Corp. technique is applied to cobalt-arsenic sulfide concentrates. In this method the concentrates are leached in a dilute solution of sulfuric acid under air pressure at a high temperature. Near Edmonton, in Alberta, Canada, the Sherritt Gordon Co. is also using the new method in conjunction with its ammoniacal leach process.' National Lead Co., at Fredricktown, Mo., is operating a process similar to that of Howe Sound. In spite of the rapid growth of high temperature-high pressure hydrometallurgical processes, there has been very little work done on fundamental principles involved in this type of process. Conse- quently the literature lacks any significant data in this field. Oxidation of pyrite,3 phalerite,4 galena,5 and recently molybdenite" in alkaline solutions has been reported to some extent. This investigation was initiated, therefore, to broaden the application of high temperature-high pressure hydrometallurgy and also to contribute some insight into the basic mechanisms of oxidation in an aqueous medium under these conditions. In addition to the immediate consequences of these processes much valuable information remains to be learned about fundamental reactions when they are carried out at temperatures and pressures slightly higher than those normally encountered. Leaching of molybdenite by alkaline solutions under oxygen pressure has recently been reported in the Russian literature by E. S. Usataya,8 who found that leaching rate increased with an increase in the pH of the solution—the strongest effects being observed at a pH of 10—and also with an increase in temperature. Usataya also has reported the formation of a protective film on the surface of the molybdenite when the leaching solution was weakly alkaline, neutral, or acidic. He believes that this oxidation process explains the migration of Mo+ + in the oxidation zones of molybdenite ore deposits and the subsequent impoverishment of the ores. Equipment: The high temperature-high pressure reaction unit used in this work was especially designed for kinetic studies of this nature, emphasis being placed on accuracy of measurement and precision of control. As details of the unit's construction and operation have been discussed elsewhere,7 Only basic features and principles of operation will be discussed at this point.

Jan 1, 1957

By D. A. Koss, R. O. Gordon

Changes in the ultrasonic attenuation in steel specimens have been observed during tensile tests. Samples of AISI 1020, 1045, and 1095 steel quenched and tempered to a spheroidized condition have been used. Both attenuation and microstrain measurements fail to reveal preyield dislocation motion in the as-tempered specimens. Upon reapplication of the load to samples in the strain-aged condition there is a large preyield attenuation increase but no observable micvostrain up to 90 pct of the flow stress. These and other observed changes can be related to changes in the free disloca-tion density and the average dislocation segment length. The results show that the increase inflow stress in the strain-aged condition is caused by increased fric-tional stresses rather than by dislocation pinning. Strain aging is found to proceed through three distinct stages. The second of these follows the t2,3 law and is characterized by an activation energy of 20 kcal per mole. RECENT years have seen substantial progress in the understanding of the sharp yield-point phenomenon in metals; the influence of solute atom pinning of dislocations, of dislocation multiplication, and of the stress dependence of dislocation velocity on the stress-strain curve has been investigated. Evaluation of the relative importance of these factors in the various metals and alloys is not complete, however, because observation of the stress-strain curve alone is not sufficient to determine the yield mechanism. In the experimental study of the sharp yield point it would be desirable to be able to directly observe the dislocations in a bulk specimen. Ideally, the observations should be made during deformation because of the rapidity of recovery processes in lightly strained metals. While direct observation of dislocations under these conditions is not possible, certain physical properties sensitive to the dislocation structure can be observed while a test specimen is undergoing deformation. Of these properties, one of the most useful is the ultrasonic attenuation. The total observed attenuation, a, is due to a number of causes: acoustic diffraction, scattering by inhomogeneities in the structure, heat flow, magnetostriction, and dislocation damping. Satisfactory measurements of the absolute a are difficult to make because all of these factors cannot be evaluated in any given specimen, but changes in a due to changes in the dislocation contribution alone can be reliably observed by appropriate technique. Because dislocation damping is sensitive to small concentrations of long, free dislocation segments, observation of acoustic attenuation due to dislocations is particularly useful in the study of the early stages of plastic deformation. In the experiments to be described, acoustic-attenuation measurements have been made on steel samples as these were pulled through their yield in tension. While many details of dislocation-damping phenomena in the bee metals remain obscure, the main characteristics of this type of internal friction are established. At low strain amplitudes and at frequencies well below that of dislocation resonance (the conditions of these experiments) the dislocation contribution to a is given by1 where A is the density of freely oscillating dislocation segments, L is the average segment length, B is the damping constant for a moving dislocation, w is the frequency, O is an orientation factor, C is the dislocation line tension, and t is a numerical factor relating average segment length to the distribution of lengths. Because of its fourth-power dependence on L, a is highly sensitive to changes in dislocation free segment length such as might arise from unpinning, recovery, jog formation, or dislocation intersection. The above equation is not valid near the resonant frequency of dislocations, but the segment length in steel is believed to be much too short to cause over-damped resonance near 10 Mc; this will be discussed later. In the present experiments plastic-strain measurements with a sensitivity of 2 x 10-5 were also made during the early stages of loading in order to detect preyield strain. The general plan of the experiments is to observe

Jan 1, 1967

By R. E. Reed-Hill

The shear continuity conditions under which one mechanical twin may cross another are considered. Twin intersections usually involve various types of slip deformation in addition to twinning. Because the shear of the crossing twin may be partly transmitted through the crossed twin by slip mechanisms, continuity of the twinning shear vectors is not required at a twin intersection. It is concluded that analyses based on twin intersections should not he used as an independent method for deducing twinning elements in newly observed twinning modes. WHEN one mechanical twin passes through another, a twin intersection is said to occur. In the simplest form of intersection, Fig. 1, the crossing of one twin by another is accomplished with the aid of a second-order twin induced, in the twin that is crossed, by the crossing twin. The subject of twin intersections is significant to the field of deformation studies because it has been postulated by cahn1 that twin intersections should occur only under the following continuity conditions: 1) the traces of the primary and second-order twin must be parallel to each other in the plane of the crossed twin; 2) the direction 771 and magnitude, S, of the twinning shear must be identical in the crossing and second-order twins; also, the sense of shear must be the same. If these postulates are valid they constitute a valuable tool for determining twinning elements of newly observed twinning modes in metals. In his classic paper in 1953 on the plastic deformation of a uranium, Cahn1 used these continuity conditions to deduce twinning elements for several uranium modes. However, in the same year, pratt2 showed that both of Cahn's continuity equations were violated for (1012) twin intersections in zinc. Later, Kiho and Maruyama3, 4 showed that Cahn's second postulate was violated in {301) and (101) twinning in tin and (101) twinning in bismuth. In spite of this documentation that Cahn's second postulate is often violated, several recent papers5'6 have been published which have attempted to use the condition of continuity of twinning shear vectors for the evaluation of twinning elements. The primary purpose of this paper is to call attention to the possible ambiguity inherent in applications of Cahn's postulate, and to present additional information concerning the nature of twin intersections.

Jan 1, 1964

By F. J. Martin, W. G. Hubler

The Beattie mine is at about the center of Duparquet township in the Province of Quebec, Canada. It is 22 miles northwest of the town of Noranda. The elevation is approximately 1200 ft. above sea level. This locality, long considered a favorable one from the geological point of view, has been prospected for over 20 years, but no discoveries of economic importance were made until the present orebody was found by John Beattie in 1930. The specific gravity of the ore is 2.77. The gold occurs in intimate association with the sulfides, pyrite and arsenopyrite, which in turn are very finely disseminated in a silicified porphyry. The bulk of the gold is associated with the pyrite, only a small proportion being with the arsenopyrite. There are small amounts of magnetite, ilmenite and chalcopyrite present in the ore. There is also some hematite in the ore that is mined from near the surface in the open pit. Metallurgical Problems and Methods or Attack 1. The ore is extremely hard and resistant to grinding. 2. The sulfide minerals are finely disseminated in the gangue. 3. The gold, in turn, is so intimately associated with the sulfides that grinding to even 5 microns will not release all of the values for cyanidation. 4. It is necessary to make a high ratio of concentration in order to obtain a product sufficiently high in gold to meet high shipping and treatment charges. Hardness of the Ore.—Owing to the extreme resistance of the ore to grinding, it was recognized that grinding costs would be high. Microscopic tests showed that grinding to 95 per cent minus 325 mesh would be necessary to liberate a sufficient amount of the values in order to obtain a tailing assaying 0.02 oz. gold per ton, which is considered to have the economical minimum gold content that can be obtained. It is not feasible to grind this hard low-grade ore (0.18 to 0.20 oz.) to 95 per cent minus 325 mesh, so it was necessary to overcome the problem in another way. The following method was decided upon: (1) Fine crushing to minus 1/4 in.; (2) relatively coarse primary grinding; flotation of low-grade concentrates in the primary and rougher circuits and discarding the

Jan 1, 1935

By G. Derge, M. Bourgon, G. M. Pound

A STUDY of electrical conductance in molten Cu-Fe sulfide mattes' has shown that pure molten Cu,S behaves like a semi-conductor in that it is an electronic conductor and its specific conductance, of the order of 100 ohm-' cm-', increases with increase in temperature. On the other hand, pure molten FeS, another electronic conductor, behaves like a metallic conductor in that its specific conductance, about 1500 ohm-' cm-', decreases with increase in temperature. Molten solutions of Cu,S and FeS follow a roughly additive rule of mixtures with respect to both specific conductance and temperature coefficient. The behavior of molten Cu,S may be understood, by analogy to the situation in solids, in terms of semiconductor theory.' It is thought that, although the melt consists of cuprous and sulfide ions, the bond between these atoms has a certain degree of cova-lency. According to the simplest concept the electrons in the partially covalent bonds are thermally promoted to a conduction band. In another concept, small amounts of impurities (undetermined) provide donor or acceptor levels in the forbidden zone between the valence and conduction bands and thus facilitate semi-conduction in the usual way. However, the metallic behavior of molten FeS is difficult to explain, because one might expect from similar reasoning that it too should act like a semi-conductor. It was suggested that the apparent metallic behavior of molten FeS might be explained by a large negative temperature coefficient of density. Thus if molar conductance instead of specific conductance were plotted versus temperature, the slope might prove to be positive, indicating semi-conduction instead of apparent metallic conduction. Accordingly, density measurements were made in order to answer this question in regard to molten FeS and also to provide data for conversion of specific conductance to molar conductance for molten Cu,S and a molten 50-50 wt pct Cu-Fe sulfide matte. Experimental Diagrams of the apparatus are given in Figs. 1 and 2. A 3 x 8-cm dense alundum crucible containing the prefused specimen is positioned in the uniform temperature zone of an induction furnace tube and melted under a helium atmosphere. Then the cell assembly, consisting of two 3-mm spectro-graphite rods, one of which is in a 1-cm ID open

Jan 1, 1959

By W. M. Weigel

Salt production in Louisiana and Texas at the present time is entirely from salt domes of the interior and coastal groups. Before and during the Civil War salt was recovered from numerous salines and salt springs by evaporation in open kettles. The location of these in nearly every instance was near what is now known to be a salt dome, and the source of the salt in the salines and spring waters was that in the salt core. The tops of many of the shallower domes have been subjected to erosion1. The discovery that the salt occurred as large masses of rock salt in the form of domes was made in May, 1802, at Avery Island, La., by John Marsh Avery, grandson of the original owner, John C. Marsh, who built the old salt works in 18122. The first shaft for mining was sunk on the Avery dome in 1867 by Chouteau and Price. It was 90 ft. deep, about 58 ft. being in solid salt. It was abandoned in 1870. There are three general groups or fields of salt domes; interior Louisiana in northern Louisiana, interior Texas in northeastern Texas, and the coastal domes nearer the Gulf Coast and extending from the Mississippi River to the Rio Grande. This last group contains by far the greatest number of domes. As many of the coastal domes especially are prolific producers of petroleum and a few of sulfur, their geology has been intensively studied and fully covered in the literature. The depth to the top of the salt varies from near the surface, where shallow ground waters have dissolved the salt to just below recent deposits, to several thousand feet, where the depth has been cstimated only by geophysical methods. The diameter of the salt core varies from less than 1/2 mile to over 2 miles. Only domes where the salt is comparatively near the surface have been developed for commercial salt. Three deeper domes, which will be described later, have recently been developed or are in process of development, as a source of brine for chemical use. Fig. 1 shows the location of the domes so far developed for commercial salt and brine. Nos. 1, 2, 4, 7, 8, 9 and 10 are in the Gulf Coastal field,

Jan 1, 1938

By W. M. Weigel

Salt production in Louisiana and Texas at the present time is entirely from salt domes of the interior and coastal groups. Before and during the Civil War salt was recovered from numerous salines and salt springs by evaporation in open kettles. The location of these in nearly every instance was near what is now known to be a salt dome, and the source of the salt in the salines and spring waters was that in the salt core. The tops of many of the shallower domes have been subjected to erosion1. The discovery that the salt occurred as large masses of rock salt in the form of domes was made in May, 1802, at Avery Island, La., by John Marsh Avery, grandson of the original owner, John C. Marsh, who built the old salt works in 18122. The first shaft for mining was sunk on the Avery dome in 1867 by Chouteau and Price. It was 90 ft. deep, about 58 ft. being in solid salt. It was abandoned in 1870. There are three general groups or fields of salt domes; interior Louisiana in northern Louisiana, interior Texas in northeastern Texas, and the coastal domes nearer the Gulf Coast and extending from the Mississippi River to the Rio Grande. This last group contains by far the greatest number of domes. As many of the coastal domes especially are prolific producers of petroleum and a few of sulfur, their geology has been intensively studied and fully covered in the literature. The depth to the top of the salt varies from near the surface, where shallow ground waters have dissolved the salt to just below recent deposits, to several thousand feet, where the depth has been cstimated only by geophysical methods. The diameter of the salt core varies from less than 1/2 mile to over 2 miles. Only domes where the salt is comparatively near the surface have been developed for commercial salt. Three deeper domes, which will be described later, have recently been developed or are in process of development, as a source of brine for chemical use. Fig. 1 shows the location of the domes so far developed for commercial salt and brine. Nos. 1, 2, 4, 7, 8, 9 and 10 are in the Gulf Coastal field,

Jan 1, 1938

By R. C. Craze

This paper discusses the characteristics of the velocity logs now available to the petroleum industry, and some of their advantages and limitations. The velocity log was designed as an aid to the geophysicist to determine velocity layering in the earth and to provide fast, accurate and economical vertical travel time data. After a number of logs had been made, studies were carried out on their use ia correlating strata in adjacent wells. It was found that adjacent strata usually show sufficient velocity contrast to make it possible to correlate these from well to well, even in areas where electric or radioactive logs fail.' In addition, velocity logs have been useful in the determination of porosity and thickness of reservoir rock.' These uses for velocity logs require an understanding of the characteristics of the log in response to the changes in velocity and in borehole conditions encountered normally in logging. GENERAL DISCUSSION OF INSTRUMENTATION The measurement made in velocity logging is more accurately described as a measurement of time rather than velocity. Ideally the log is obtained by measuring the length of time required for compressional sound waves to travel through a fixed distance in the formation. In practice, the time measurement may be made accurately but the distance through which the waves have traveled may vary slightly. Changes in borehole diameter are responsible largely for the difficulty in maintaining a fixed distance, especially if the diameter variations are so abrupt and frequent that the borehole instrument cannot follow contours of the hole. Several service companies have velocity logging equipment available or under development which have different transmitters, receivers, and measuring systems. While these differences are important, there are actually only two systems in use at the present time (Fig. I)."' The first system initiates a pulse at a trans-mitter and detects it at a single receiver. The transmitter and receiver are separated by a fixed distance, called the spacing. The time measured is that between the initiation of the pulse and the first arrival of acoustical energy at the receiver. The second system uses two receivers and a transmitter. The receivers are separated by a fixed distance and the time between arrivals of energy at the two receivers is measured. Here, the spacing is the distance between receivers. The two systems have much in common for it is possible to record both logs simultaneously. Usually the transmitter is an electro-mechanical transducer which produces discrete

The eastern part of the state of Rhode Island on both sides of Narragansett Bay, including the island of Rhode Island, is underlaid with carboniferous rocks which carry veins of anthracite. This formation extends into the neighboring portion of Massachusetts, including the area from the state line, the towns of Mansfield, Brockton and Bridgewater,: and extending probably ten miles east of the latter two towns, to Middlesboro, and to Fall River. In Massachusetts the coal formation extends over nearly the whole of Bristol, and parts of Plymouth and Norfolk Counties. In Rhode Island and Massachusetts the area covered is about 400 square miles. In both states the exact limits of the coal measures cannot be determined on account of a thick layer of drift which overlays it. Along parts of Narragansett Bay, the coal measures outcrop in the cliffs on the west side of Rhode Island, and the presence of coal here seems to have been noted as early as 1760, and in 1768 a patent was granted to parties who "were about to dig after pit, coal or sea coal" at the back of the town of Providence. In 1807-08 Benjamin Silliman, later a geologist, visited some openings,' and in 1808 a mine was opened near Portsmouth, in the northeast part of Rhode Island. Work was done here until about 1814 when the mine was abandoned. No anthracite had been used in New England at that time, all coal used came from Nova Scotia, Virginia or England, and was high volatile bituminous; neither experience nor the means of firing favored the use of the local fuel? This mine was again working in 1827, was again abandoned and operations were resumed in 1847. In 1837 a note in a magazine mentions, "the immense coal mine in Cumberland-about six miles from the city of Providence" as having a shaft 14 ft. in diameter and 80 ft. deep, that the horses then used for hoisting the coal were to be superseded by a steam engine and another shaft was to be sunk. With these improvements 30,000 to 50,000 tons were to be produced the following year at a cost of $1 per ton and a sales realization of $6.1 Hitchcock's report refers to a number of localities in both states where definite knowledge of coal existed. These are:

Jan 1, 1942

By K. Leutwyler

The authors present an interesting review of various applications of rather well known theories. Their rearrangement of the original working equations is strictly computer oriented and serves well to that effect; however, the new appearance will be confusing to the slide rule-wielding members of the profession. In reviewing discrepancies existing between calculations made by Baker Oil Tools, Inc. field engineering staff members and computer output submitted based on the authors' program, the following error in concept was discovered in Eq. 4. The authors quote the length change due to helical buckling in the following form We appreciate Kurt Leutwyler's awareness of Archimedes' principle, and concur that the final term in the denominator of Eq. 4 results in a small error. Examples checked revealed less than I ft error, and corrective expressions for the four possibilities of displacement follow. The portion of the denominator within extra large brackets represents the original term W,, = weight of outside fluid displaced per unit length. The authors interpreted the expression "displaced" in general oilfield terminology as a fluid displacement, such as "mud displaced with water, etc." A review of the theory forming the basis for these helical buckling calculations discloses that this displacement is meant to be interpreted in the Archimedean sense, i.e., fluid displaced by the solid body. here the tubing and the seal nipple. Lubinski* illustrated the point by summing moments due to mechanical and hydraulic forces acting on a free body immersed in fluid. This moment summation, always in the Archi,medean sense, yields effects of the real forces, including W,, and the fictitious force on the bending mechanism. I would be interested to hear the authors' comments regarding this theoretical point, which nevertheless is not mute since its lack of recognition seems to result in erroneous calculations. We must not remain mute to Leutwyler's suggestion that these equations, although computer oriented, are confusing to the slide rule engineers. Such input information as density in pounds per gallon, pipe diameters in inches, pumping rate in barrels per minute and pipe length in feet is not confusing to most of us. Yet there may be some rugged individuals in field positions who carry tables of conversion constants and have committed to memory such items as coefficients of thermal expansion and Poisson's ratio; however, even this type of individual would welcome a simplified equation occasionally. M

JOHN ALEXANDER MATHEWS, who has been awarded the Hunt Gold Medal for his paper "Austenite and Austenitic Steels," which was pre-sented before the Institute as the Howe Memorial Lec-ture for 1925, was born at Washington, Pa., on May 20, 1872. His interest in metallurgy may be said to be hereditary, as three generations of his Colonial forbears were gold and silversmiths. After graduating from Washington and Jefferson College in 1893, he entered Columbia University where he was successively assistant in assaying and tutor in chemistry and at the same time continued his work for the Ph. D. degree, which he received in 1898. He was at one time awarded a fellowship in chemistry, and for 1900, 1901 and 1902 re- ceived the award of the Ear- nard Fellowship for the En- couragement of Scientific Re- search, spending one year at the Royal School of Mines, in London, studying alloys un- der Sir William Roberts- Austen, another at Columbia under Henry M. Howe, and the third at Sanderson Bros. works, Syracuse. While in England, he was one of the first three, recipients of an Andrew Carnegie Scholarship of the Iron and Steel Institute of Great Britain, which later awarded him the first Car- negie Gold Medal for Re-search. He entered the employ of the Crucible Steel Company of America, at its Sanderson works, in 1902, as metal- lurgist and soon became as- sistant manager. In 1908 he ent to the Halcomb Steel JOHN A. Co., Syracuse, N. Y., as superintendent, later becoming general manager and president in 1915. In 1920 he returned to Crucible Steel Co. of America, first as vice-president and later became president from 1921 to 1924. He retired from the presidency in 1924, made a metal-lurgical trip to Europe, and returned as vice-president to resume his "favorite pastime" of directing research and development work in the production of special tool and alloy steels. He has taken a particular interest in the development of austenitic steels which, in addition to an extraordinary resistance to corrosive attack, show under fatigue, torsion, and tension tests superior qualities as compared with the ordinary engineering steels, and at elevated temperatures show remarkable resistance to oxidation and scaling and several times the strength of many of the complex alloys that are not of the natural austenitic variety.

Jan 2, 1928

FROM the first to the last meeting of t h e Rocky Mountain Club John Hays Hammond served as president. He guided its deliberations when there were any, but that always y o u n g organization was never particularly deliberate. Youth never is. And the Club was the embodiment of the youthful spirit of the West, which considers any- thing can be done if there be but the will to do it. Ham- mond and the others came out of the West, but they, brought the West with them P and in all the far countries in which he has served his profession and in all the honorable offices in which he has served his country, he lived true to the ideals under which he was raised. A Californian, born in San Francisco in 1855, the son of an army officer, Major Richard Pindell Hammond, educated in the public schools of his native city, at Yale, and at Freiburg, he turned early and quickly to mining. He served his apprenticeship as all successful mining men do, as assayer, surveyor, as assistant in ex-aminations and later as principal, and finally as mine manager. Even in those days of beginnings, his future world-wide career was foreshadowed in that Mexico as well as California served as his training school. His first major step up the ladder was in connection with the Bunker Hill and Sullivan mine, where he served in various positions finishing as president and considerable owner. It was from this great lead mine that he was called to South Africa, where he remained a number of years and was the technical expert who guided the great enterprises of Barnato Brothers and Cecil Rhodes. The story of his activity in developing the "deeps" of the Rand and in opening Rhodesia has been often told but is always an alluring one of adventure and accomplish-ment. After his famous escape from death at Johannes-burg as a member of the Reform Committee, he went first to London and later returned to the United States representing both British and American capital in the purchase and development of great mines in all parts of the world. For some years he was general man-ager, consulting engineer, and director of the Guggen-heim Exploration Co., but of recent years he has oper-ated entirely on his own account and with marked success.

Jan 4, 1928

GENTLEMAN: The year 1928 was another in the history of the Institute which was marked by quiet growth and steady progress. The total membership as of December 31, 1928, was 8703 as compared with 8438 on December 31, in 1927. Again the main increase has been in Members and the number of Junior Associates is less. As will be seen also by the Treasurer's report, the increase is reflected in larger receipts for dues indicating that fewer have had to be dropped for non-payment. There has been a gratifying increase in the number applying for reinstatement and it seems clear that interest in and attachment to the Institute has notably increased. The year was signalized by the merging of the Rocky Mountain Club with the Institute which brought to our roll one hundred and forty who were not previously members from among the men who have made the West. It also brought to the Institute a strong tradition of good fellowship and a fund of over $100,000, the interest from which is to be expended so far as may be, for purposes beneficial to the Western states. The Endowment Committee expects to see other and similar funds entrusted to the Institute and the Board has already appointed a special committee to consider all projects for expenditure of the revenue from them. It is felt that with the organization and personnel available in the Institute even modest revenues can be made to yield large returns in the way of scientific and technical knowledge. Within the year also, a third great Division has been organized within the Institute, building on the foundation of the old Iron and Steel Committee. The new Division signalized its independence by joining the Lake Superior Mining Institute in a visit to the Menominee Range in September and by furnishing material for a special volume of 353 pages, "Iron and Steel" Technology in 1928," printed and distributed in December. The Institute of Metals Division held its fall meeting with good attendance as one feature of National Metal Week at Philadelphia in October, and published its volume of Proceedings, running to 836 pages, in August. "Petroleum Development and Technology in 1927," 844 pages, came out in June and recorded the work of the Petroleum Division. A most interesting Fall meeting was also held by the Division at Tulsa,

Jan 1, 1929

By R. H. Wightman, G. H. Adams

In order to secure good results in the prevention of accidents, it is generally recognized that the desire for such accomplishment, as well as the aggressive and constructive action to achieve it, must emanate from the Top Management and permeate successively down through the "Chart of Authority" to the workmen. Several years ago, with the above as a basis and with full support of the Top Management, the Mining Department started a program of selling the foremen and bosses the idea that safety could be achieved and that it was desired and required. Using psychology, persistence and numerous other methods, the foremen and bosses were finally impressed with the idea that "It can be done" and "It will be done." With this in mind, new ideas were brought forth by the foremen and bosses regarding the caving operation and the specific jobs in the operation. These new ideas were taken up in round-table discussions and resulted in certain changes in the undercutting method and the actual drawing of the blocks. These changes resulted in increasing fragmentation of the blocks which prevented the usual hang-up areas in the blocks. With the rock smaller in size and within reasonable reach from the tapping drifts, accidents were prevented in the tapping section. At the same time, an enforced campaign of housekeeping throughout the mine was undertaken with very beneficial results. The foremen and bosses then, in turn, educated and trained the workers themselves to become safety conscious. In so doing, a constant reminder was given on all jobs assigned that the job was to be done safely as well as efficiently. No man is assigned a job who is not qualified for the type of work required. Efficiency and safety go hand in hand. Safety Rules To supplement and aid this safety conscious attitude, certain safety rules applicable to our operation, a modified block caving system of mining limestone, in addition to the established state regulations, were put into effect and enforced. The specific rules referred to above and which will be mentioned below are in most cases simply a means of applying and complying with the very adequate "Mine Safety Orders" issued by the Industrial Accident Commission of the State of California. Some of the safety rules and policies are as follows: All men are required to wear safety

Jan 1, 1950