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By Grover J. Holt

A detailed description of the many variations in iron mining and transportation practice in Minnesota would require much space. Since a fairly detailed description of the practices then in use was published in the guidebook issued in connection with the meeting of the Institute on the iron ranges in 1920, and subsequent developments have been described by E. E. Hunner, M. H. Barber,2 and A. E. Anderson, J. M. Riddell and G. J. Holt,³ it will not be necessary here to do more than review the highlights of current practice. Details on any points of interest can be obtained through correspondence with the operators involved. † The iron ores of Minnesota, which have been formed through enrichment of the iron formation in which they occur, largely by the removal of silica, are usually covered by a blanket of glacial drift known locally as "surface." Surface material, including sand, clay, hardpan and boulders, makes up the greater portion of the stripping in open-pit operations. In some instances, stripping also includes taconite and paint rock," directly below the surface material and overlying the ore. Tacenite is the iron formation, a ferruginous chert with inter-bedded slate layers. :'paint rock" is a local term for oxidized slate layers inter- bedded in the iron formation, high in phosphorus, alumina and moisture. The iron ores fall into two classes: (I) direct shipping (merchantable ores or ores requiring no treatment except possibly crushing or screening to make an acceptable sized product), and (2) ores requiring beneficiation (such as sintering, drying, washing, jigging, high-density treatment, or magnetic separation in the case of magnetite). The Mesabi Range produces chiefly soft Bessemer and non-Bessemer ores. The Cuyuna Range produces mainly low-manganese brown ore and high-manganese black ores, with some iron ore. The Vermilion Range yields mainly Bessemer and non-Bessemer iron ore, with some hard or lump ore that finds use in the open hearth. Open-pit mining is limited to the Mesabi and Cuyuna Ranges but underground mining is done on all three. The choice of mining methods is determined by the relative economics of overburden-removal and shaft-mining costs. Stripping Practice Common practice has been to remove the bulk of the overburden during the winter season and to mine during the summer, In- the present emergency many operators are forced to forego the economies attained by year-round utilization of paper. and to equip for, and carry on, stripping and mining simultaneously. In the normal years or lean years to come, most properties probably will be overequipped and high depreciation charges Will have to be absorbed.

Jan 1, 1943

By Norman Brown

It is suggested that the difference in ease of cross-slip among the fcc metals determines the relative amounts of [111] and [100] wire texture which occur in each metal. Since the ease of cross-slip is controlled by the stacking fault energy, it turns out that the amount of [111] texture should increase as the stacking fault energy increases. Arguments and existing data are presented to support the above suggestion. THE fcc metals generally have a dual texture, [11 and [loo], after wire drawing. As yet no fundament explanation exists concerning the variation of the amounts of each texture among the metals. Barrett&apos; has compiled data which show how the relative amounts of each texture vary from 100 pct [Ill] in the case of aluminum to 25 pct [l1] for silver. In this paper it is suggested that the value of stacking fault energy plays a major part in determining the amount of each type of texture. The double texture has its origin in the classical rotation of a single crystal under tension. An equilibrium position of the crystal is one in which three or more equivalent slip systems are operating simu taneously. Most crystals, initially, tend to rotate toward the [1ll] or the [l00] pole depending upon its initial orientation. This single-crystal behavior is essentially the same as the rotational behavior of the polycrystalline metal as worked out by Taylor.2 The next point to consider is whether the [Ill] or [100] orientation is more stable. There have been many discussions of this question3&apos;" which, in general, have lead to the conclusion that 11111 is most stable. For example, Pickus and Mathewson 4 suggested that a [Ill] texture produces more effective flow becake the [ 110] slip direction makes a smaller angle with the [111] than with the [loo]. A crude statistical argument will be presented which again favors the (1111 orientation. In order to maintain a pure [loo] wire texure, slip must occur in equal proportions in four of the six possible <110>slip directions. In order to maintain a pure [Ill] texture, slip must occur in equal proportions in only three of the six <110>directions. Since the <110> directions are the only slip directions in a fcc metal and if it is assumed that each of these six directions is equally probable, then the relative probability of a [1ll] texture vs a [l00] texture may be calculated. The statistical weight of a particular texture is the multiplicity of a texture times the probability of obtaining any one. The statistical weight for [Ill] is

Jan 1, 1962

By William Lodding

Muscovite was the crystalline material used in the experiments discussed in this paper. It was both wet and dry ground for various periods of time. The effects (physical and chemical changes) produced in grinding are analyzed by use of thermal analysis. That grinding may change a crystalline material both in a physical and in a chemical sense has been shown by a number of authors in recent years. Mackenziel and Bartha2 reported the effects of careful grinding on muscovite, quartz, gypsum, dolomite, etc. Increase in specific surface produced by grinding implies increase in total energy of a system. Newly produced surfaces are chemically more reactive; dislocations may be introduced during grinding and, on the other hand, existing strain may be released by the same process, as shown by Holt, et a1.3 All these changes are easily detected by thermal analysis, but it is not easy to separate the multiplicity of effects registered and to arrive at quantitative interpretations. This paper is an attempt to analyze, by the use of thermal analysis, some effects produced in grinding. In differential thermal analysis (DTA) one measures the sum of all thermal changes occurring in a substance during heating or cooling; e.g., chemical changes, such as decompositions, synthesis, oxidation, reduction, etc., and physical changes such as phase transformations, changes in specific surface and thermal conductivity, strain release, etc. By thermogravimetric analysis (TGA), on the other hand, only chemical changes involving weight loss or gain are recorded. Similarly, gas evolution analysis (GEA) will register only reactions involving gas evolution. By performing two or all three of these methods of thermal analysis simultaneously and on the same specimen, one can separate the different effects registered and, by difference, evaluate their magnitude. The results of TGA are usually plotted as percent weight against furnace temp. When one differentiates weight against furnace temp, a rate of weight-change curve is obtained, and the resulting differential thermogravimetric (DTG) plots are similar in appearance to DTA thermograms for the same reaction. While the integrated area under a DTA peak represents enthalpy and can be expressed in calories per gram the area under the corresponding DTG peak represents the weight change which took place during a reaction. The similarity of DTA and DTG thermograms obtained from one material can be seen in Figs. 1 and 2. EXPERIMENTAL A Fisher mortar grinder and a porcelain mill with burundum balls were used for both dry and wet grinding. Muscovite was first carefully hand-filed and screened on 20 and 100 mesh. The middle fraction was considered essentially unaltered muscovite.

Jan 1, 1968

By Grover J. Holt

A detailed description of the many variations in iron mining and transportation practice in Minnesota would require much space. Since a fairly detailed description of the practices then in use was published in the guidebook issued in connection with the meeting of the Institute on the iron ranges in 1920, and subsequent developments have been described by E. E. Hunner, M. H. Barber,2 and A. E. Anderson, J. M. Riddell and G. J. Holt,³ it will not be necessary here to do more than review the highlights of current practice. Details on any points of interest can be obtained through correspondence with the operators involved. † The iron ores of Minnesota, which have been formed through enrichment of the iron formation in which they occur, largely by the removal of silica, are usually covered by a blanket of glacial drift known locally as "surface." Surface material, including sand, clay, hardpan and boulders, makes up the greater portion of the stripping in open-pit operations. In some instances, stripping also includes taconite and paint rock," directly below the surface material and overlying the ore. Tacenite is the iron formation, a ferruginous chert with inter-bedded slate layers. :&apos;paint rock" is a local term for oxidized slate layers inter- bedded in the iron formation, high in phosphorus, alumina and moisture. The iron ores fall into two classes: (I) direct shipping (merchantable ores or ores requiring no treatment except possibly crushing or screening to make an acceptable sized product), and (2) ores requiring beneficiation (such as sintering, drying, washing, jigging, high-density treatment, or magnetic separation in the case of magnetite). The Mesabi Range produces chiefly soft Bessemer and non-Bessemer ores. The Cuyuna Range produces mainly low-manganese brown ore and high-manganese black ores, with some iron ore. The Vermilion Range yields mainly Bessemer and non-Bessemer iron ore, with some hard or lump ore that finds use in the open hearth. Open-pit mining is limited to the Mesabi and Cuyuna Ranges but underground mining is done on all three. The choice of mining methods is determined by the relative economics of overburden-removal and shaft-mining costs. Stripping Practice Common practice has been to remove the bulk of the overburden during the winter season and to mine during the summer, In- the present emergency many operators are forced to forego the economies attained by year-round utilization of paper. and to equip for, and carry on, stripping and mining simultaneously. In the normal years or lean years to come, most properties probably will be overequipped and high depreciation charges Will have to be absorbed.

Jan 1, 1943

By W. R. Opie

The object of this paper is to show the manner in which typical electrodeposits of hexagonal-close-packed metals—zinc, titanium, and zirconium—tend to form. The conditions of electrodeposi-tion markedly affect the nature of the deposits in regard to crystal size, orientation, and appearance. No attempt is made to correlate cell conditions with deposit quality but, rather, characteristic types of deposits were selected and a study made to show the relationship between outward appearance and crystal structure. The zinc deposits were made in aqueous electrolytes and the titanium and zirconium deposited from fused salt baths. ZINC deposits studied were made in the American Smelting and Refining Co.&apos;s Central Research Laboratories. They were representative of bright, shiny, smooth deposits, which can be obtained by using proper current densities and electrolyte addition agents, and of deposits which are dull and tend to be nodular. Four deposits were selected which ranged from smooth and bright to very nodular and dull, and their classifications are shown in Table I. These were examined microscopically and were found to differ quite markedly in outward surface structure and in microstructure. The outward surface variation is illustrated in Figs. 1 to 4. At X50 the texture could be seen to progress from granular to platelike to smooth. The microstructures of the deposits&apos; cross sections from starting sheet to outer surface are shown in Figs. 5 through 8. The dull nodular deposits (sample Nos. 1 and 2) show some tendency for acicular growth. The platelike sample (No. 3) shows tendency for columnar growth development and the smooth deposit (No. 4) has a well developed columnar structure. Back-reflection X-ray patterns of the deposit surfaces revealed some interesting information. The crystal orientation was random in all deposits except the smooth deposit. Fig. 9 is a typical back-reflection pattern of a nodular deposit. All planes are reflecting in the proper relative intensity. The pattern of the smooth deposit is shown in Fig. 10. The only planes which reflect are the (10.4). This series of planes is in the right position, with the FeKa radiation used, to satisfy the Bragg equation if the basal planes {00.1) are at right angles to the X-ray beam. The results were interpreted to mean that in the bright smooth deposit preferred orientation has occurred with the basal hexagonal planes oriented in the plane of the sheet but with all other planes randomly oriented around the c-axis.

Jan 1, 1957

By A. H. Geisler, R. F. Mehl, C. S. Barrett

The complicated nature of the property changes that accompany age-hardening has made it necessary to reconsider and to elaborate the simple dispersion theory.l It has been apparent for some time that more direct information is needed concerning the atomic mechanism of precipitation from solid solution if the theory of age-hardening is to be developed past a purely qualitative stage.‡ Fortunately, in recent years information has been developed which allows us to trace in detail the lattice changes accompanying the process of precipitation from solid solution. This information relates chiefly to the sequence of the several stages of lattice alteration by which the matrix lattice is transformed to the equilibrium precipitate lattice, and permits reasonable inferences to he drawn concerning the states of internal strain that accompany these stages. This information is most complete for the solid solution of copper in aluminum. The equilibrium precipitate is the 0 phase, "CuAl2." This forms in plates, parallel to the {100} matrix planes. The atom pattern and atom spacing on the plane in 0 lying parallel to this plane are roughly similar to those opposite it in the matrix.3 The formation of 0, however, is preceded by the formation of a transition lattice 0&apos;: which again lies parallel to the matrix {100} plane, but in this case the matching of atom pattern and spacing across the matrix-precipitate interface is nearly periect; thus there is lattice coherency across the interface and the interface is a plane of separation in only a very limited sense.&apos;8 Particles of 0&apos; may be recognized microscopically and form a well-defined Wid-manstatten figure.* The 0&apos; lattice is recognized by the occurrence of diffraction lines on powder photo-grams or of spots on Laue photograms which may be analyzed in the usual ways to determine the lattice type and the lattice spacings. Very recent research 6, 7, 1 has shown, however, that streaks occur on the Laue photogram at an earlier point in time during the aging process. These streaks have been attributed to a preferential clustering of copper atoms into small platelike elements of only a few atoms in thickness and a lew hundred atoms in diameter, probably of the composition of " CuA12," which may be designated as Guinier-Preston zones or aggregates.1 It is difficult if not impossible to determine the lattice type and lattice spacing in these aggregates. It is possible1 that these aggregates are in fact ?&apos; in a high State of dispersion; the inclination to argue this is strong, as we shall see later. Never-

Jan 1, 1941

By R. F. Mehl, C. S. Barrett, A. H. Geisler

The complicated nature of the property changes that accompany age-hardening has made it necessary to reconsider and to elaborate the simple dispersion theory.l It has been apparent for some time that more direct information is needed concerning the atomic mechanism of precipitation from solid solution if the theory of age-hardening is to be developed past a purely qualitative stage.‡ Fortunately, in recent years information has been developed which allows us to trace in detail the lattice changes accompanying the process of precipitation from solid solution. This information relates chiefly to the sequence of the several stages of lattice alteration by which the matrix lattice is transformed to the equilibrium precipitate lattice, and permits reasonable inferences to he drawn concerning the states of internal strain that accompany these stages. This information is most complete for the solid solution of copper in aluminum. The equilibrium precipitate is the 0 phase, "CuAl2." This forms in plates, parallel to the {100} matrix planes. The atom pattern and atom spacing on the plane in 0 lying parallel to this plane are roughly similar to those opposite it in the matrix.3 The formation of 0, however, is preceded by the formation of a transition lattice 0&apos;: which again lies parallel to the matrix {100} plane, but in this case the matching of atom pattern and spacing across the matrix-precipitate interface is nearly periect; thus there is lattice coherency across the interface and the interface is a plane of separation in only a very limited sense.&apos;8 Particles of 0&apos; may be recognized microscopically and form a well-defined Wid-manstatten figure.* The 0&apos; lattice is recognized by the occurrence of diffraction lines on powder photo-grams or of spots on Laue photograms which may be analyzed in the usual ways to determine the lattice type and the lattice spacings. Very recent research 6, 7, 1 has shown, however, that streaks occur on the Laue photogram at an earlier point in time during the aging process. These streaks have been attributed to a preferential clustering of copper atoms into small platelike elements of only a few atoms in thickness and a lew hundred atoms in diameter, probably of the composition of " CuA12," which may be designated as Guinier-Preston zones or aggregates.1 It is difficult if not impossible to determine the lattice type and lattice spacing in these aggregates. It is possible1 that these aggregates are in fact ?&apos; in a high State of dispersion; the inclination to argue this is strong, as we shall see later. Never-

Jan 1, 1941

By S. C. Lindsay, D. J. I. Evans

With each year that passes hydrometallurgical processes are being more widely used to recover base metals from ores and concentrates. Generally these processes involve liquid-solid separation of metal-bearing liquors from barren residues. This may be done by countercurrent decantation, thickening and filtration, or filtration or centrifuging only. Choice of method is governed by chemical and physical characteristics of the pulps; cost of labor, power, materials, and waste disposal; and even by the amount of capital available when building plans are under way. Since all these controlling factors change with time and location and with technological advances, the separation method must be re-evaluated when new plants or expansion programs are contemplated. At the Sherritt Gordon refinery in Fort Saskatchewan, Alberta, an ammonia pressure leaching process recovers nickel, copper, and cobalt from the nickel concentrate produced at Lynn Lake, Manitoba.&apos; Pregnant liquors are separated from the barren leach residues in a thickener-filter liquid-solids circuit. The decision to use this type of separation was based on a summation of economic factors during the pilot plant and design stages. Although countercurrent decantation was not incorporated in the refinery flowsheet, the problems solved in thickening the leach residues and the experience gained in operating the commercial plant are pertinent to countercurrent decantation, particularly where it is applied to slow-settling leach slurries or slurries having a relatively high vapor pressure of a valuable, obnoxious, or poisonous vapor. The nickel sulfide concentrate is leached under pressure with air and ammonia to dissolve the nickel, copper, and cobalt and most of the sulfur, leaving a residue of iron and siliceous material to be discarded.2,3 During a subsequent distillation stage to recirculate part of the ammonia used for leaching, copper is recovered from the solution as a high-grade sulfide. After further purification to remove traces of copper and undesirable sulfur compounds, the nickel is precipitated by hydrogen under pressure at an elevated temperature. The cobalt, together with unreduced nickel, is precipitated as a mixed metal sulfide by hydrogen sulfide for eventual cobalt recovery. The end solution is then evaporated to produce a crystalline ammonium sulfate byproduct. As shown in Fig. 1, the nickel concentrate is leached in a continuous, two-stage, countercurrent circuit. In the first stage, or adjustment leach, the fresh concentrate is partially leached (60 pct) in the liquor produced in the second stage, or final leach. This system is necessary to produce a solution suitable for treatment in the copper sulfide precipitation step. Both stages are carried out at 170" to 180°F under a total pressure, with air, of 100 to 120 psig in large, horizontal, water-cooled autoclaves. The autoclaves are divided by overflow weirs into four compartments to give a certain amount of staging during leaching. In each compartment a relatively slow-speed (100 to 150 rpm) agitator maintains the nickel concentrate in suspension. Adjustment leaching, carried out in two autoclaves in parallel, is followed by a thickener-filter liquid-solids separation. Final leaching is done in two parallel trains of three autoclaves using aqueous ammonia to extract metal values from the adjustment leach residues. This too is followed by a thickener-filter circuit. Here the residues are repulped once with aqueous ammonia and twice with process water and refiltered after each repulping stage, to insure a maximum recovery of soluble metal, before being discarded to the tailings pond. The adjustment leach is followed by a seven-disk Dorr-Oliver American filter, with an agitator in the filter boot to keep the residues in suspension. Agitators have also been installed beneath the four ten-disk filters following the final leach thickener. Slurry Characteristics: A typical analysis of the Lynn Lake nickel concentrate, produced by differential flotation,&apos; is given in Table I. The concentrate comprises 35 to 49 pct pentlandite, (Fe, Ni)S; 3 to 6 pct chalcopyrite, CuFeS,; 1 to 4 pct pyrite, FeS2; and 24 to 42 pct pyrrhotite, Fe1-2S (where x varies between 0 and 0.2) together with various siliceous minerals such as actinolite, hornblende, and talc. During leaching, the sulfur in the pentlandite, chalcopyrite, and part of the pyrrhotite is successively oxidized through the thiosulfate and poly-thionate radicals to sulfate and sulfamate." Simultaneously the nickel, copper, and cobalt are converted to soluble ammine complexes and the iron in the pentlandite, chalcopyrite, and part of the pyrrhotite is oxidized to a spongy hydrated iron oxide. The hydrated iron oxide is readily broken down by the agitation needed to sustain the concentrate in suspension and to maintain a satisfactory mass transfer of the oxygen from the air to the slurry. Table I shows typical chemical, screen, and

Jan 1, 1961

By R. F. Lynch, J. D. Wood

The Al-1.0 pct Mg alloy 565 7 was studied using optical microscopy and electron microprobe X-ray analysis. Constituent particles were found to exist inter-dendritically in the as-cast material in a region of precipitate free a -aluminum. Five phases besides a fine precipitate and a-Al were identified in the cast structure: Fel3, Fe2Al7, Mg2Al3, CUMgAl2, and Cu2FeAl7. Thermal treatments conducted for 100 hr at 1180°, 1130°, 1080°, 1030°, 980°, and 880° F revealed a general dissolution and spheroidization of the in-terdendritic constituent network observed in the cast structure. The principal constituents present in the thermally treated structures were FeAl3 and Fe2Al7 with the relative amount of Fe2A17 to FeAl3 increasing with a decrease in the treatment temperature. The phases Present in the wrought structure were identical to those observed after the thermal treatments, with the constituent particles strung out in the direction of rolling. ALLOY 5657 is a nonheat-treatable commercial purity Al-1.0 pct Mg alloy utilized extensively because of its bright finishing characteristics. This investigation was conducted to determine the constituents present in 5657 alloy, and to study the effect of extended thermal treatments on morphology. Numerous studies have been carried out to establish the equilibrium diagrams for various aluminum systems,1-3 with phase identification based on X-ray analysis, morphology, and the etching response of relatively large particles. Phragmen4 conducted a study of the phases in aluminum eutectic systems and compiled a "corrected" table of etching responses, drawing on his work plus that of Schrader,5 Keller and Wilcox,6 and Mondolfo.7 A review of the original work of Keller and Wilcox, and Mondolfo, which was concerned with the constituents found in commercial alloys, reveals that in numerous cases their etching responses differ from those reported by Phragmen and from each other. These inconsistencies may occur because a specific constituent will react to a given etch in a varying manner depending upon its size, the elements dissolved in the phase, the other constituents surrounding a phase, and the solute content of the matrix. Work with a commercial orientation was conducted on alloys 2024 and 3003 by Sperry8,9 and on alloy 3003 by Barker,10 where the relationship between the phase diagram and the nonequilibrium structure of an alloy was examined. Backerud11 investigated the A1-Fe binary system and found that at high cooling rates the equilibrium eutectic reaction forming a-A1 and FeA13 is replaced by another lower temperature eutectic reaction forming a-A1 and metastable FeAl6, a constituent first identified by Hollingsworth et al.12 Most of the above mentioned studies were conducted on materials having a significantly greater alloy content than 5657 alloy, where the relatively small size and sparse distribution of second phase particles hinders the process of identifying constituents. EXPERIMENTAL PROCEDURE Material with a composition as given in Table I was examined in the as-direct chill cast, hot rolled and cold rolled conditions, and after thermal treatment of the cast structure. Thermal treatments were terminated by a water quench. Microscopic examination was conducted under various lighting conditions following the application of standard etchants as specified in Table 11. A semi-quantitative electron microprobe X-ray analysis was conducted for Al, Mg, Fe, Cu, Si, Zn, and Ti. RESULTS AND DISCUSSION Microstructure of the As-Cast Material. Particles of second phase material were found to exist inter-dendritically, principally in regions of precipitate free a-Al, as illustrated in Fig. 1. Adjacent to the ingot edge was a region of inverse segregation, resulting in an increased amount of second phase material containing large sized particles which aided in phase identification. Phase Identification. Cast Structure. Five phases besides a-Al and a fine precipitate were identified using optical microscopy and electron microprobe X-ray analysis, as presented in Tables II and III, respectively. FeA13 and Fe2A17 are often found with Fe2A17 forming a sheath around the core of FeAl3, resulting from an incomplete peritectoid reaction. These phases have a nearly identical appearance under white light, although they are easily differentiated under crossed polarizers, as characteristically illustrated in Figs. 2(a) and 2(b), respectively. Microprobe analysis con-

Jan 1, 1970

By W. L. Korbee, P. Hazebroek, M. Prats, E. E. Allen, C. A. 225-000-000-017 Verbraak, H. C. van Elst

In a recent paper,&apos; one of us has presented some experimental evidence on the relationship between twinning and brittle fracture in steel. From metallographic examinations of brittle fracture it could be derived that mechanical twins and microcracks are formed already in front of a running brittle fracture. A tentative explanation based on the evaluation of the statistical distribution of mechanical twins vs various angles to the fracture was given in the above mentioned paper. It was suggested that these twins are caused by stress waves emitted by a running brittle fracture. With the aid of high-speed photography and the use of photo-stress sheet we are now able to study in more detail the propagation of a brittle fracture and the emittance of stress waves connected with fracture. A typical example is given in Fig. 1. In this figure a running brittle fracture in an ordinary Thomas steel is shown. The experiment was performed on a Robertson apparatus and the stress waves caused by the fracture were made visible with photo-stress

Jan 1, 1962

By R. Rocca, M. B. Bever

THE adiabatic elastic deformation of a body is accompanied by a change in temperature. This phenomenon is known as the thermoelastic effect. Under adiabatic conditions the temperature of a metal bar is decreased by an elastic elongation and is increased by an elastic compression. All materials which elongate on heating behave in this manner. The sign of the thermoelastic temperature change is reversed for the few materials which have a negative coefficient of thermal expansion. The following equation for the thermoelastic effect can be derived from fundamental thermody-namic theorems, as shown in the Appendix: dT8 =-a1/cs T dss [1] Cs In this equation, T is the absolute temperature, S is the entropy, a, is the coefficient of linear thermal expansion, cs&apos; is the heat capacity per unit volume at constant stress and s is the stress (positive in tension). Eq 1 can be applied to small, but finite changes in stress in the following form: ?Ts =- a1/cs T?ss [2] The sign of the temperature change AT is opposite to that of the change in stress s for materials which have a positive coefficient of thermal expansion. Eq 2 has been verified for many different materials and stresses at room temperature. No previous publication appears to have been devoted to an in- vestigation of the thermoelastic effect over a range of temperatures. Review of Literature Lord Kelvin (W. Thomson) presented a general theory of the thermoelastic effect in 1851&apos; and later applied it to a solid, subject to an arbitrary system of stresses&apos;. His analysis was based on a cycle of isothermal and constant-strain transformations and led to Eq 2 above. Even today, one of the clearest expositions of the thermoelastic effect is found in Lord Kelvin&apos;s article on elasticity in the Ninth Edition of the Encyclopedia Britannica (1878). R. ROCCA, Junior Member, and M. B. BEVER, Member AIME, are Research Assistant in Metallurgy and Associate Professor of Metallurgy, respectiuely, Massachusetts Institute of Technology, Cambridge, Mass. AIME New York Meeting, Feb. 1950. TP 2760 E. Discussion (2 copies) may be sent to Transactions AIME before APT. 1, 1950, and is scheduled for publication Nov. 1950. Manuscript received Oct. 15, 1949.

Jan 1, 1951

By D. Roberts

SUMMARY In order to accommodate a new plant in a limestone quarry in the Mendip Hills, it became necessary to excavate a potentially unstable disused face of the quarry. A simple two-dimensional graphical method was used to analyse a failure, which occurred during a period of exceptionally heavy rain in 1968, and the results of this analysis were used in estimating the stability of the proposed excavation. The presence of water in vertical fissures and tension cracks was found to be a dominant factor in determining the stability of these faces. The results of this approximate analysis were used as a guide in deciding upon the final slope design and the purpose of presenting this example is to illustrate how the various factors involved in arriving at this design were weighed to arrive at a compromise between theoretical recommendations and practical considerations. INTRODUCTION The successful outcome of a geological and geochemical survey to prove adequate re- serves of high quality limestone, suitable for producing burnt lime, led to planning for the installation of the necessary plant at Amalgamated Roadstone Corporation&apos;s Batts Combe Quarry at Cheddar in Somerset. Topographic and property boundary limits added to restrictions which were likely to be imposed by any forthcoming planning consents and restricted the choice of plant location to one site. The particular site is, in fact, the main floor area of the original quarry which, like many hillside quarries, had been worked with just one face. Before a benching scheme had been introduced on higher ground, the original face had attained a height of 230 ft. and sloped at angles of 58º to 64º. Fig. I shows the present configuration of the disused quarry face and the present working area above. The floor area below the disused face accommodates the existing crushing, conveying, and screening plant. The new facilities for lime burning are to be in addition to the existing main line business of producing roadstone and concrete aggregates and, although a new aggregate production plant would be included in the new installation, no disturbance of current production was to be contemplated.

Jan 1, 1972

By A. Lawley, H. W. Schadler

TWINNING has long been recognized as a possible mode of deformation in crystalline solids and has been studied in a wide variety of crystals.&apos; Recently, deformation markings which have the topographical characteristics of twins have been seen in tungsten" and the body-centered cubic alloys of tungsten and molybdenum with rhenium.3-7 These markings have been identified as twins because: 1) they are visible after polishing and etching;2,3 2) their formation is accompanied by an audible click and a drop in load;4 and 3) the habit plane is {112}, the plane which has been identified as the twinning plane for several body-centered cubic metals.&apos; However, there has been no published evidence for the specific determination of the twinning direction in rhenium alloys of tungsten and molybdenum, because usually the deformation twins were not broad enough to be detected with a conventional X-ray beam. Consequently, [111] is inferred as the twinning direction since the latter must lie in a plane of symmetry perpendicular to the twinning plane (112). As Sims and Jaffee3 and Lawley and Maddin4 have shown, the addition of rhenium to molybdenum and tungsten increases the ductility of the alloy over that of the pure metal, but twinning is much more profuse in these alloys than in the pure elements, particularly at Mo-35 pct Re*and W-30 pct Re. Since twinning is often associated with brittle fracture in iron8 and the silicon-irons,9 direct experimental proof that the deformation markings in tungsten and molybdenum alloys of rhenium are twins seemed to be needed. Using the Laue back-reflection technique, the deformation markings in a Mo-35 pct Re alloy are shown to be deformation twins. The twins have a (112) habit plane and the twinning direction is <111>. The Mo-35 pct Re specimen used was taken from a 0.060-in. zone-refined single crystal deformed 6 pct in tension at 78°K. The Laue back-reflection technique, with a film to specimen distance of 2 cm, and white radiation from a copper target were used.

Jan 1, 1962

By L. H. Levenson, Charles S. Barrett

Plastic flow in metal crystals and the changes in orientation resulting from it are generally understood to take place by the following fundamental mechanisms: (1) slip on crystallographic planes, (2) homogeneous crystal rotation resulting from the slip, (3) bending of the 1attice between the planes of slip, and, under certain circumstances, (4) twinning. This paper and a preceding one on iron subjected to uniaxial compression1 concern two additional processes that must now be added to this list: (5) the formation of deformation bands, and (6) the bending and rotation of these bands. The present investigation yields a new understanding and definiteness to the common terms so loosely used when speaking of cold-worked metals —(&apos;grain fragmentation," "elongated grains," and "deformation twins," "deformation bands," "etch bands," or "X-bands." Bands have been noted on the polished and etched surfaces of cold-worked metals by various investigators for more than 25 years, ‡ yet their nature and their significance have been so little understood that they are not treated in the most comprehensive modern texts on the deformation of crystals. The experiments in this series show that they are one of the fundamental processes in the deformation of metals, of importance in the development of preferred orientations, in work-hardening (since they have the effect of reducing the effective grain size and interfering with slip), and in the recrystallization process. The present experiments were performed on the same stock of material that was used in the earlier compression experiments1—hydrogen-purified mild steel in which the carbon content had been reduced to the limit detectable under the microscope and in which single crystals could be grown by a strain-anneal treatment.2

Jan 1, 1939

By Charles S. Barrett, L. H. Levenson

Plastic flow in metal crystals and the changes in orientation resulting from it are generally understood to take place by the following fundamental mechanisms: (1) slip on crystallographic planes, (2) homogeneous crystal rotation resulting from the slip, (3) bending of the 1attice between the planes of slip, and, under certain circumstances, (4) twinning. This paper and a preceding one on iron subjected to uniaxial compression1 concern two additional processes that must now be added to this list: (5) the formation of deformation bands, and (6) the bending and rotation of these bands. The present investigation yields a new understanding and definiteness to the common terms so loosely used when speaking of cold-worked metals —(&apos;grain fragmentation," "elongated grains," and "deformation twins," "deformation bands," "etch bands," or "X-bands." Bands have been noted on the polished and etched surfaces of cold-worked metals by various investigators for more than 25 years, ‡ yet their nature and their significance have been so little understood that they are not treated in the most comprehensive modern texts on the deformation of crystals. The experiments in this series show that they are one of the fundamental processes in the deformation of metals, of importance in the development of preferred orientations, in work-hardening (since they have the effect of reducing the effective grain size and interfering with slip), and in the recrystallization process. The present experiments were performed on the same stock of material that was used in the earlier compression experiments1—hydrogen-purified mild steel in which the carbon content had been reduced to the limit detectable under the microscope and in which single crystals could be grown by a strain-anneal treatment.2

Jan 1, 1939

By Daniel M. MacNeil, Carle R. Hayward, Raymond L. Presbrey

At the February, 1916, meeting of the Institute, a paper presented by Hayward and Raymond gave the results of a study on the effect of time in tempering medium-carbon steel, when the following conclusions were reached: It is not fair to consider the question settled when only three specimens were used for each treatment, but the results obtained indicate that for reheating quenched medium-carbon steel to temperatures below 500" it is only necessary to heat it through. Longer heating has little or no effect on the tensile strength, ductility, or hardness. At temperatures above 500°, increasing the time of treatment causes a slight falling off in hardness and tensile strength with a corresponding increase in ductility. In the discussion of the paper these conclusions were attacked and evidence was presented that seemed to throw doubt on their accuracy. The authors, however, showed that this evidence was based on high-carbon or alloy steels and no facts regarding medium-carbon steel were presented. During this study the heat treatment was carried out in a small electric resistance furnace. It held nine specimens, but when these were placed in the furnace the temperature was lowered to such an extent that 30 to 40 min. were required to reach the desired heat. The authors pointed to this as a weak point in the investigation and it seemed wise to supplement the research by work on similar steel but using a different method of heating. This has been done and the results are given in the present paper. The Rhode Island Tool Co. coöperated by furnishing the steel and turning the tensile specimens. The steel used in this investigation came in three bars 3/4 in. in diameter; analyses are as follows: Carbon. MaNGanese, Phosphorus, Sulfur Bar NUmber PeR Cent. Per Cent. Per Cent. Per Cent. 1 0.46 0.56 0.010 0.055 2 0.44 0.58 0.007 0.042 3 0.48 0.58 0.007 0.048

Jan 1, 1922

By B. E. Thompson, H. B. Fuqua

For a very brief description of the North Texas area, and the general geological features with which it is associated, the reader is referred to the opening paragraph of last year&apos;s summary1. A more complete discussion of the structure of the area, together with other interesting data concerning it, has been published recently by the Bureau of Economic Geology at the University of Texas2. It has been impossible for the authors to isolate the statistics for production for each of the many small pools of this district, as such statistics are not kept by operators except by counties or arbitrary divisions of counties. The total number of wells drilled in Archer, Wichita and Clay counties also has been subject to some estimate, as many of the shallower holes are not reported. While both routine development in proven or semiproven areas and exploratory drilling during 1935 showed an increase over the year 1934, the discovery of new producing areas of importance did not show improvement over that period. Several extremely local productive spots within semiproven areas were found in Archer, Cooke and Wilbarger counties; and extensions to older producing areas were developed in Archer, Baylor, Cooke, Montague, Wichita and Wilbarger counties. In Archer County, the Grace and Woods No. 1 Archer County (Fee), 4 miles northwest of Archer City, in the Thomas Glass survey, encountered a sand from 2836 to 2845 ft. of Pennsylvanian (lower Canyon) age, which showed an initial yield of 75 bbl. daily. While its production is of negligible importance, it is given special mention in this review because of the fact that it is producing from a new and deeper horizon than has been previously exploited in the county. Little deep development occurred in the district during the year. The Walter Gant No. 2 C. M. Worsham in J. M. Swisher survey, about 14 miles east of Henrietta, in Clay County, was abandoned at 5127 ft. in

Jan 1, 1936

By Daniel M. MacNeil, Raymond L. Presbrey, Carle R. Hayward

At the February, 1916, meeting of the Institute, a paper presented by Hayward and Raymond gave the results of a study on the effect of time in tempering medium-carbon steel, when the following conclusions were reached: It is not fair to consider the question settled when only three specimens were used for each treatment, but the results obtained indicate that for reheating quenched medium-carbon steel to temperatures below 500" it is only necessary to heat it through. Longer heating has little or no effect on the tensile strength, ductility, or hardness. At temperatures above 500°, increasing the time of treatment causes a slight falling off in hardness and tensile strength with a corresponding increase in ductility. In the discussion of the paper these conclusions were attacked and evidence was presented that seemed to throw doubt on their accuracy. The authors, however, showed that this evidence was based on high-carbon or alloy steels and no facts regarding medium-carbon steel were presented. During this study the heat treatment was carried out in a small electric resistance furnace. It held nine specimens, but when these were placed in the furnace the temperature was lowered to such an extent that 30 to 40 min. were required to reach the desired heat. The authors pointed to this as a weak point in the investigation and it seemed wise to supplement the research by work on similar steel but using a different method of heating. This has been done and the results are given in the present paper. The Rhode Island Tool Co. coöperated by furnishing the steel and turning the tensile specimens. The steel used in this investigation came in three bars 3/4 in. in diameter; analyses are as follows: Carbon. MaNGanese, Phosphorus, Sulfur Bar NUmber PeR Cent. Per Cent. Per Cent. Per Cent. 1 0.46 0.56 0.010 0.055 2 0.44 0.58 0.007 0.042 3 0.48 0.58 0.007 0.048

Jan 1, 1922

By G. S. Farnham, D. A. Scott

Partition of certain elements, particularly nickel, was determined for slowly cooled steels, the greater number containing from 0.30 to 0.35 pct C. Approximately 3 pct of the nickel, 18 pct of the manganese, 33 pct of the molybdenum, and 35 pct of the chromium occur in the carbide phase. Partition of one element is not much affected by the presence of another. THE object of this investigation was: 1—to determine the partition of nickel between cemen-tite and ferrite in a medium and high carbon series of annealed steels; 2—to evaluate the effect of chromium and/or molybdenum or both on the partition of nickel in medium carbon annealed steels; 3— to determine the partition of chromium between ferrite and carbide in a series of medium carbon annealed steels; and 4—to study the chemistry of the carbides formed in an AISI 2330 steel during both isothermal transformation, and quench and draw experiments at 1150°F (620°C). The partition of alloying elements between ce-mentite and ferrite in annealed steels has been the subject of many investigations, a summary of which has been given by Austin1. However, there is no satisfactory data available concerning the partition of nickel. It has generally been assumed that virtu- ally all of the nickel concentrates in the ferrite phase in annealed steels. Two investigators"." have reported the finding of nickel in extracted carbide residues. Recently, it has been shown4 that nickel substitutes up to 40 pct for iron in the lattice of cementite produced by the low temperature carburization of iron-nickel powders. In addition to the lack of data on nickel partition, the literature also fails to make reference to the effect of other elements on the nickel content of the carbide in nickel-bearing steels. The partition of molybdenum between ferrite and carbide has been reported"-&apos; for hypoeutectoid steels, isothermally transformed at 1300°F (705°C) and

Jan 1, 1954

By H. B. Fuqua, B. E. Thompson

For a very brief description of the North Texas area, and the general geological features with which it is associated, the reader is referred to the opening paragraph of last year&apos;s summary1. A more complete discussion of the structure of the area, together with other interesting data concerning it, has been published recently by the Bureau of Economic Geology at the University of Texas2. It has been impossible for the authors to isolate the statistics for production for each of the many small pools of this district, as such statistics are not kept by operators except by counties or arbitrary divisions of counties. The total number of wells drilled in Archer, Wichita and Clay counties also has been subject to some estimate, as many of the shallower holes are not reported. While both routine development in proven or semiproven areas and exploratory drilling during 1935 showed an increase over the year 1934, the discovery of new producing areas of importance did not show improvement over that period. Several extremely local productive spots within semiproven areas were found in Archer, Cooke and Wilbarger counties; and extensions to older producing areas were developed in Archer, Baylor, Cooke, Montague, Wichita and Wilbarger counties. In Archer County, the Grace and Woods No. 1 Archer County (Fee), 4 miles northwest of Archer City, in the Thomas Glass survey, encountered a sand from 2836 to 2845 ft. of Pennsylvanian (lower Canyon) age, which showed an initial yield of 75 bbl. daily. While its production is of negligible importance, it is given special mention in this review because of the fact that it is producing from a new and deeper horizon than has been previously exploited in the county. Little deep development occurred in the district during the year. The Walter Gant No. 2 C. M. Worsham in J. M. Swisher survey, about 14 miles east of Henrietta, in Clay County, was abandoned at 5127 ft. in

Jan 1, 1936