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By D. Dever, E. S. Fisher

Measurements of the temperature dependence of the elastic moduli in single crystals of hep ruthenium, rhenium, cobalt, dysprosium, and erbium were carried out for various temperature ranges so as to investigate the correlation, suggested by prior work, between the shear anisotropy ratio, A = C44/C66, and the occurrence of the hcp — bee phase transformation. These measurements confirm the suggestion that A has a positive temperature dependence in that group of hcp metals that undergo thermally induced transfornzations to the bee structure and a negative or zero temperature dependence in the other hcp metals. It appears, from indirect evidence, that the hcp -fee transformation in cobalt is preceded by a highly negative temperature dependence of A. These results indicate that elastic anisotropy is an important factor in determining the temperatures at which martensitic phase transformations occur. Two possible roles for elastic anisotropy are proposed: 1) the shear-modulus ratio within the habit planes must be nearly similar for the two phases and 2) a large anisotropy decreases the stress necessary for the movement of the transfornzation dislocations. FUCHS' calculations of the elastic moduli in the alkali metals have shown that the high shear-anisotropy ratios, c/c', in certain bee metals and alloys are the result of large negative contributions to c' = (c11 - c12)/2 arising from the nearest-neighbor repulsive forces.' On this basis, and following Zener,2 the association between high c/c' ratios and the martensitic phase transformations that occur upon cooling certain bee metals is explained as a unique characteristic of the bee structure. Recent measurements of the elastic moduli in hcp titanium and zirconium show, however, that a high elastic anisotropy also exists in these hcp structures at the temperatures at which they transform to bee upon heating3. If there exists a direct and consistent correlation between the elastic anisotropy in close-packed structures and the occurrence of transformations to the bee phases then there is evidently a need to re-examine the conclusions of Zener theory. Elastic anisotropy may also be the result of the effects of temperature on the stability of the low-temperature close-packed structures or it may play an important role in the mech- anism of the martensitic transformations. The present measurements were aimed at establishing the phenomenological correlation between elastic shear anisotropy in hcp structures and the thermally induced hcp —bee transformations that occur in the majority of the twenty-three hcp metals, as shown in Table I. Prior to the present work the temperature dependence of the anisotropy ratio, A = c44/c66, was known at various temperatures for nine of the metals listed. The data showed a negative temperature dependence of A for cadmium, zinc, magnesium, and cobalt, which do not transform to bee, and a positive temperature dependence of A for thallium, zirconium, titanium, hafnium, and yttrium. The correlation was, however, ambiguous in that these two groups of metals are also separated with respect to the c/a ratios as noted in Table I. There remained the possibility that the temperature dependence of A is a function of c/a and not consistently associated with the transformation. The measurements of the elastic moduli in rhenium and ruthenium, in which hcp —bee transformations do not occur, were needed to help decide this question. The studies of dysprosium and erbium were undertaken to determine whether the correlation holds for the heavy rare earth metals.

Jan 1, 1968

By William Johnson

IT is now recognized that several important types of reactions in metallic systems proceed by the formation of nuclei and the growth of these nuclei. The process of freezing is a simple example of this, as Tammann pointed out years ago.1 Tammann held that ' the rate, of freezing is determined by a rate of nucleation, expressed as the number of nuclei formed per unit volume of unfrozen liquid per second, and a rate of growth of these nuclei, expressed as the linear rate of radial growth in units of length per second. For isothermal freezing the conception is simple; for ordinary freezing, extending over a range of temperature, it is not as simple, for the values of the two constants must change with change in temperature. There is ample evidence that the postulated mechanism is correct even though a quantitative derivation of the rate of isothermal or of ordinary freezing in terms of the two constants has been lacking. In recent years other reactions have been found to proceed in a similar fashion. It has been well established, particularly by Bain,2-8 that. the formation of pearlite from the eutectoid decomposition of the solid solu-tion austenite proceeds in such a way, and Polanyi and Schmid, Tammann and Crone, Karnop and Sachs, and others9-11 have shown that the process of recrystallization proceeds in a similar way. Isothermal reaction rates have been determined for eutectoid decom-position by a number of investigators. Bain's2-8 work on the formation of pearlite from austenite is especially valuable in this respect-the type of isothermal reaction curve obtained, as illustrated in Fig. 13, showed an initial slow rate, accelerating to an intermediate maximum rate which then decelerated to the completion of the reaction; similar curves have been obtained by Wever and his collaborators.12 Other eutectoid decompositions show similar behavior: for example, the decomposition of the beta eutectoid in the copper-aluminum system, studied by Smith

Jan 1, 1939

By G. D. Van Arsdale

This paper describes a series of experiments leading to the development of a method for leaching the mixed ores of the Inspiration Consolidated Copper Co., containing chalcocite and silicates of copper, by the use of solutions acidified with sulfuric acid and carrying ferric sulfate. Iron is added to the solutions and ferric iron is regenerated electrolytically to a percentage high enough to act as an effcient solvent. The decreased yield is partly compensated for by a higher current density. An important problem in modern copper metallurgy, particularly in the Southwest, has been to obtain good recoveries from what are commonly known as mixed ores; that is ores in which the copper occurs partly as oxide and partly as sulfide compounds. The dividing line between mixed ores and ores commonly accepted as concentrating is not definite. In other words, much ore now being concentrated carries considerable copper in non-sulfide form, on which recoveries are not so good as on ores carrying less of these constituents. While treatment by concentration may be commercially profitable on ores carrying oxide copper within certain limits, there are large deposits for which the application of concentration could not be considered, and yet which have not been considered amenable to leaching because they carried too much sulfide. The Inspiration Consolidated Copper Co. has large amounts of such mixed ores, and this paper is an account of the experimental work by which a method was developed for their treatment, and for which a large plant is now being erected by the Inspiration Co. It is not claimed that the method is a general solution of the problem of mixed-ore treatment but it is apparently well adapted for leaching the ores of the Inspiration Co., for which it was designed. The work done has covered preliminary laboratory and test-plant investigation, and a pilot-plant run, extending from March to the middle of December, 1923. Thoroughly consistent and satisfactory results were obtained continuously for more than six months in the pilot plant; and it is believed that the results and probable costs that can be had on a large scale have been definitely proved. The method, however, was designed for local conditions; and while the basic principles are general, there are ores on which it will not work and other ores for which considerable modification may be required.

Jan 1, 1926

By J. Geertsma

In order to obtain a better insight into the pressure-volume relationship of reservoir rocks a theory of pore and rock bulk volume variations is presented. The theory is independent of the shape of the pores but is restricted to isotropic porous media built up of continuous homogeneous matrix material. The main conclusion obtained from this theory is that only three elastic constants and three viscous constants are required for describing pore and rock bulk volume variations if the porosity is explicitly introduced into the treatment. In addition, reasonable approximations are introduced for various types of reservoir rock, e.g., sandstones, limestones, and shales, which lead to further simplifications of the basic formulas. In consequence there is then a further reduction in the number of deformation constants which have to be determined experimentally. It is shown how measurements of these remaining deformation constants can be performed most conveniently. Finally the application of the theory to reservoir studies is discussed and the translation of experimental results obtained in the laboratory into reservoir behavior is considered. INTRODUCTION The decline of fluid pressure in connection with the withdrawal of fluid from an underground reservoir gives rise to a change in volume of both reservoir fluids and reservoir rock. The volume variation of the reservoir rock results in a decrease of both the pore volume and the total volume of the fluid-filled formation. Whereas the variation in volume of the reservoir fluids with pressure is usually known from PVT analysis, that in the volume of the porous medium is rarely measured, as it is considered of minor importance in reservoir engineering. Nevertheless, certain experimental results' suggest that in a number of cases the neglection of the variation in pore volume may introduce errors into material balance calculations of reservoirs producing above the bubble point. Only a few experimental results on the compressibility of porous rocks have been published. The compressibility of pure quartz and of calcite can be found in a paper by Adams and Williamson'. Botset and Reed' carried out some experiments on the compressibility of loose sands, while Carpenter and Spencer' measured the compressibility of a number of consolidated sandstones, which data were supplemented by Hughes and Cooke5. Hall' finally reported a number of experiments designed to study the influence of the porosity on the compressibility of oil-bearing formations, from which it appeared that, particularly in the low porosity range, the compressibility of the pore volume is important enough to be taken into account. Difficulties, however, arise in applying these experimental results to field cases. This is partly due to the fragmentary nature of the published data. Yet even if more complete data were available, the need for a theoretical background would be strongly felt. Such a background can be partially found in studies carried out by Biot,6,7 who published a theory of elastic deformations of porous materials and their influence on fluid displacement within the pores, by Lubinski8, who studied the stress distribution in an elastic porous medium neglecting pore compressibility, and by Gass-mann" who mathematically analysed the elasticity of packings of spheres. The contributions of Biot intro-duce a number of deformation constants which are impractical for reservoir rocks from an aspect of experi-mental determination. The theory developed by dass-mann is correct but difficult to read. It appeared, how-

Jan 1, 1958

By John E. Dorn, Oscar E. Harder

The phenomenon of diffusion, according to the most prevalent conceptions at the present time, undoubtedly played an important part in the formation and distribution of metals and minerals in the earth's crust. Apparently there is good evidence that in the geological rate of cooling diffusion caused numerous materials to separate into individual masses or into duplex structures. As is well known, the early steels were made by cementation; that is, by heating wrought ferrous metal in contact with carburizing materials so as to produce a relatively high carbon content on the surface. If the process was continued long enough, the carbon diffused throughout the piece. A more homogeneous product depended upon further heating and forging, so that the carbon diffused to a fairly uniform concentration throughout the metal. In the modern metallurgical industry, diffusion is the basis for many operations; for example, the production of hard surfaces on steels by carburizing, nitriding, cementing with chromium, silicon, boron and beryllium. Castings or ingots as they solidify do not have homogeneous structures, but these structures are made largely homogeneous by suitable process of heat-treating and the resulting diffusion. It is in modern physical metallurgy, however, that we become greatly concerned about the mechanism of the phenomenon of diffusion. The rates of diffusion, effect of temperature and time on diffusion, and the relation of diffusion to the many properties of the parent metal and the diffusing metal have become important; also, we are concerned with the diffusion of a single metal into a complex alloy. For example, what is the mechanism whereby carbon and nitrogen travel into steel? What is the effect of alloying elements in the ferrous material on the rates of diffusions? What is the effect of simultaneous diffusion of carbon and nitrogen? How does chromium, beryllium, boron, or the like, diffuse into the steel, and what are the effects of alloying elements in the steel previous to the cementation process? These inquiries are by no means limited

Jan 1, 1938

By Oscar E. Harder, John E. Dorn

The phenomenon of diffusion, according to the most prevalent conceptions at the present time, undoubtedly played an important part in the formation and distribution of metals and minerals in the earth's crust. Apparently there is good evidence that in the geological rate of cooling diffusion caused numerous materials to separate into individual masses or into duplex structures. As is well known, the early steels were made by cementation; that is, by heating wrought ferrous metal in contact with carburizing materials so as to produce a relatively high carbon content on the surface. If the process was continued long enough, the carbon diffused throughout the piece. A more homogeneous product depended upon further heating and forging, so that the carbon diffused to a fairly uniform concentration throughout the metal. In the modern metallurgical industry, diffusion is the basis for many operations; for example, the production of hard surfaces on steels by carburizing, nitriding, cementing with chromium, silicon, boron and beryllium. Castings or ingots as they solidify do not have homogeneous structures, but these structures are made largely homogeneous by suitable process of heat-treating and the resulting diffusion. It is in modern physical metallurgy, however, that we become greatly concerned about the mechanism of the phenomenon of diffusion. The rates of diffusion, effect of temperature and time on diffusion, and the relation of diffusion to the many properties of the parent metal and the diffusing metal have become important; also, we are concerned with the diffusion of a single metal into a complex alloy. For example, what is the mechanism whereby carbon and nitrogen travel into steel? What is the effect of alloying elements in the ferrous material on the rates of diffusions? What is the effect of simultaneous diffusion of carbon and nitrogen? How does chromium, beryllium, boron, or the like, diffuse into the steel, and what are the effects of alloying elements in the steel previous to the cementation process? These inquiries are by no means limited

Jan 1, 1938

By Walter H. Munk

Generation of Waves by storms, and the transformation of waves in shallow water by local bottom topography are briefly reviewed. A detailed description of water motion in waves explains the nature and distribution of wave forces. A numerical example dealing with forces and moments against vertical piles summarizes the principles involved. Introduction The oil industry is moving into the open waters of the Gulf of Mexico. The design and construction of offshore drilling rigs present a number of difficult problems, among them problems involving the action of waves on fixed and floating structures. This paper deals with our present knowledge of ocean waves as it pertains to these problems, and the principles involved in computing wave forces against fixed structures. It is hoped that the more difficult case pertaining to floating structures can be discussed at a later time. None of the engincering aspects of the problem are entered upon in this paper, yet an understanding of the principles presented here should be helpful in the solution of practical problems. Waves are capable of exerting almost unbelievable forces. During a gale, waves at the harbor entrance of Amsterdam Canal in Holland lifted a 20-ton concrete block, which was resting on the bottom in 12ft of water, and deposited it on top of a pier which was 5 ft above the high water mark. At Wick Breakwater in Scotland, a mass of large stones in cement and bound together with iron rods, weighing 1350 tons, was broken loose and moved bodily! But one need not go to Holland or Scotland to find evidence of damage that waves are capable of inflicting (Fig I and 2). What is the mechanism by which waves are capable of exerting such enormous forces? To answer this, we must consider briefly the nature of wave motion. When a wind blows over a wheat field, waves appear to travel across the field, whereas the wheat itself remains rooted, slowly swinging back and forth. Similarly, in the case of water waves, the waveform travels swiftly over the water surface, whereas the water particles oscillate back and forth, but scarcely advance. The speed of the wave form is called wave velocity, the speed of the water particles is called orbital velocity. This fundamental difference between wave velocity and orbital velocity was already recognized by Leonardo da Vinci. Orbital velocity is generally much slower than wave velocity except for a breaking wave, a case which is of particular importance in the application to engineering problems. Forces exerted by the waves on obstacles

Jan 1, 1949

By J. W. Galpin, V. L. Minear, F. C. Sturges, B. H. Mott, R. H. Allen, W. W. Weigel, Wm. D. Owsley, R. E. Moeller

By definition the word "grout" means a thin mortar, or a kind of plaster or ce¬ment, and "grouting" means to fill up or finish with grout. The words "cement," "plaster" and "mortar" mean a substance that is used in a soft state which subsequently hardens. Thus, grouting is the filling of void space with a substance that hardens. Construction cements are the most common substances used, either by themselves or in mixtures, but the term grouting is applied quite correctly when other substances such as plastics and certain chemicals are used. Also, the use of the term grouting to cover the filling of voids with materials that do not actually become hard, such as the-flotation tailings used in grouting in the southeast Missouri lead district, should be considered correct, as some stiffening does take place and, anyway, it is a better descriptive term than any substitute. Engineers are interested in grouting because some of the materials with which they must work contain voids, and certain conditions can be improved if these voids can be filled with something solid and permanent. Grouting is done to accomplish several purposes: I. To stop the passage of fluids and gases, 2. To cement materials together to make them stronger, and 3. To prevent consolidation of materials by filling void space with something solid as a replacement for the air and water that could be forced out under load. The construction industry uses grouting extensively for all three purposes. Grouting is used to stop water percolation under and around dams. It is used to control water flow in tunnel driving and in shaft sinking. It is used to improve foundation conditions under civil engineering structures by permanently filling void space and thereby reducing settlement, or by cementing broken rock together and increasing its supporting strength. The oil and gas industry does a lot of grouting, primarily to stop the passage of gases and fluids. The search for oil at increasingly greater depths has meant greater investment per well, and the oil industry has spent large sums on development of improved drilling methods. This

Jan 1, 1948

By W. F. Domis, F. von Gemmingen, R. W. Whitmore, F. Garofalo

Constant-load creep-rupture tests at 1100°, 1300° and 1500°F were made on a Type-316, 18 Cr-8 Ni-ZMo, austenitic stainless steel to determine the relationship between ruptzire life and other aspects of creep behavior, The test program was designed on a statistical basis to check the variability of various creep properties and to determine emprically the dependence of minimutn creep rate and ruptzire life on initial stress, The dependence of the rupture life, tn, on the initial stress, a,, is found to be related to the stress dependence of the wrinimum creep rate, i,, and secondary creep strain, The instabilities or breaks found in the conventionual log - logt, plots can be traced to either a change in the linear dependence of log i, on log a, or to a change in secondary creep strain. In the alloy tested, rupture is found to be predowmanantly of the inter crystalline type, For this material, the secondary creep strain is -found to depend on the nature of the grain boundary precipitate, which affects grain boundary migration. It has been shown for a variety of metals and al tested at elevated temperatures under creep conditions that the empirical relationship exists between rupture life, tr, and minimum creep rate, i,. This relationship, in which C and a are in some cases independent of stress or temperature, shows in a general way that creep rupture depends on creep behavior prior to tertiary creep stage. To determine more fully the factors which control creep rupture requires, therefore, more knowledge of the relationship between rupture and creep behavior. To obtain such information, constant-load creep-rupture tests have been made on a Type-316, 18 Cr-8 Ni-2 Mo, austenitic stainless steel at 11000, 1300°, and 1500°F. These tests were designed on a statistical basis to determine the variability of the various creep properties measured and to determine empirically the stress dependence of minimum creep rate and rupture life. As a result of this work, various empirical relations have been established defining more closely the factor, C, in the relation between rupture life and minimum creep rate. This factor is found to be proportional to the amount of strain during secondary creep. The variation of secondary creep strain with rupture life and temperature is determined and its effect on rupture behavior discussed. The variability in minimum creep rate and rupture life is also dis- cussed and the dependence of these quantities on initial stress is interpreted. TEST MATERIAL AND TEST PROCEDURES The material tested is an austenitic stainless steel, AISI Type 316, of the following composition: C, 0.07 pct; Mn, 1.94 pct; P, 0.01 pct; S, 0.021 pct; Si, 0.38 pct; Cr, 18 pct; Ni, 11.4 pct; Mo, 2.15 pct; All 0.003 pct and N, 0.043 pct. The material was received as a hot-rolled 0.5-in. diam bar which was sectioned into 3.25 in. long blanks. Each blank was heat treated by holding 1/2 hr at 2000° F followed by water quenching. A 3/8-in. coupon was removed from each heat-treated blank and the microstructure was examined, the grain size determined, and the hardness measured. The microstructure was found to be uniform from blank to blank and the grain size was found to range from 4 to 6 ASTM numbers. Hardness, measured using a 20-kg load, varied between 127 and 148 Vpn. Tensile creep-rupture specimens having a 0.25 in. diam within a 1.5-in. reduced section were machined from the heat-treated blanks. Constant-load tests were made on these specimens at 1100°, 1300°, and 1500 F. Six specimens were tested at each stress level. Three creep-rupture machines were employed for tests at each temperature, two specimens being tested in each machine for each stress level. To minimize any effect due to local inhomogeneities along the length of the as-received bar the specimens were randomized before test. Each specimen was tested to rupture and in most cases an autographic extension-time curve was obtained. For very low stress levels at 1500°F no auto-

Jan 1, 1962

By Richard R. Zupp, David A. Stevenson

An experimental method to determine the carbon activity in various solid solutions was developed. Samples of the solid solutions and an Fe-C reference sample were equilibrated with respect to carbon content by annealing them in a Hz-CHI gas mixture in a closed cell. The carbon content of each sample was determined, and the carbon activity was obtained from the carbon content of' the reference sample and well-established data for the dependence of the carbon activity on the carbon content in Fe-C alloys. The influence of vanadium on the activity of carbon in austenitic Fe-C-V alloys at 1000°C was determined by this technique. A general semiempirical correlation was developed to describe the dependence of the activity coefficient of- carbon on the composition of ternary austenitic iron-base alloys containing interstitial carbon and a substitutional solute. The correlation is particularly useful in predicting the partitioning of- carbon between various alloys. THE influence of substitutional solutes on the activity of interstitial solutes in metallic solid solutions is important in the theory of alloy phases. Solid solutions of particular interest are the fcc austenite phases of ternary Fe-C-Z systems, in which carbon is the interstitial solute and Z represents any substitutional solute. Carbon-activity data are also needed in these solid solutions to solve practical problems; the quantitative treatment of diffusion-controlled transformations' is an examvle. Experimental information is available for ternary austenitic solid solutions containing Mn,2 Si,2 and A16 as the substitutional solute. Because qualitative preliminary studies indicated that vanadium appreciably decreases the carbon activity,14 the present investigation was undertaken to determine the influence of vanadium on the activity of carbon in austenite. Although Flender and ever" measured carbon activity over a range of compositions in the Fe-C-V system, they were primarily interested in determining phase boundaries in the ternary system, so most of their measurements were outside the composition range for stability of single-phase austenite. Petrova and Shvartsman' also made limited measurements of the carbon activity in Fe-C-V alloys. The dependence of the carbon activity on the carbon content of an alloy may be determined by passing COCOz or H2-CH4 gas mixtures of carefully measured composition over the alloys, determining their equilibrium carbon content, and utilizing the relevant equilibrium relationships. smith16 used this technique with both CO-COZ and HZ-CH4 gas mixtures to determine the dependence of carbon activity on carbon content in pure Fe-C alloys. His data, which are in good agreement with those of some previous and subsequent investigators,6'17 but not with those of others,lfl'ao are usually considered to be the most reliable. Although the same method can be applied to Fe-C-Z alloys, it is difficult experimentally, because the appropriate gas mixtures are almost pure CO or Hz. A simpler technique is to simultaneously equilibrate the Fe-C-Z alloys and pure Fe-C alloys with the gas mixtures, and then use Smith's data to determine the carbon activity in the pure Fe-C alloy. A number of investigators have employed this technique. others Have used the partitioning of carbon at the interface of a diffusion couple prepared from an Fe-C alloy and a Fe-C-Z alloy. In the present study, a closed-cell method was developed by which carbon was selectively transferred via a gas medium between pure Fe-C alloys and Fe-C-V alloys which were not in physical contact. A similar method was developed independently by Heckler and winchel14 and used to study the Fe-C-Ni system. EXPERIMENTAL METHOD A schematic diagram of the experimental arrangement is shown in Fig. 1. In a typical experiment, a 5-g Fe-C sample was placed in one compartment of a quartz cell, and a 5-g Fe-V sample was placed in each of the other compartments. The cell was evacuated, outgassed, backfilled with approximately 125 Torr of hydrogen, and sealed. After being placed in a fur-

Jan 1, 1967

By K. T. Aust

It is proposed that the intergranular corrosion of austenitic stainless steels is associated with the presence of continuous grain houndary paths of either second phase, or solute segregate resulting from solute-vacancy interactions. Experimental observations of structural changes and crrosion behavior of different types of austenitic stainless steel provide support for this poposal. On the basis of this model, it is shown that the intergranular -corrosion susceptibility of austenitic stainless steels in nitric-dic hromate solution may be substantially reduced either by suitable heat treatments or by impurity control. AUSTENITIC stainless steels, such as Type 304, generally have excellent corrosion resistant properties when properly solution heat-treated and used at temperatures where carbide precipitation is slow. However, several corrosion environments have been found which produce intergranular corrosion of solu-tion-treated stainless steels, that is, those steels with no detectable carbide precipitation.''2 Of the various corrosion environments, the most widely used test solution has been the boiling nitric-dichromate solution. In these acid solutions, stainless steels have been found to be susceptible to intergranular attack despite the addition of carbide-forming elements such as titanium or columbium, or despite lowering of the carbon content or use of high-temperature solution treatments. Studies of the electrochemical mechanism of corrosion attack have been made by several worke1s3'4 who found that oxidizing ions such as crt6 depolarize the cathodic reactions and consequently raise the open-circuit potential of stainless steel immersed in nitric acids. As a result of this, the anodic reaction is accelerated. The reason for the localization of anodic activity at the grain boundaries, and resulting intergranular corrosion, has not been conclusively determined. Several workers, e.g., Streicher,3 and Coriou et al.,4 have suggested that the strain energy associated with grain boundaries provides the driving force for the accelerated intergranular corrosion. This argument would predict that alloys of high purity would still be susceptible to intergranular attack. However, work by chaudron5 and by ArmijO,6 has shown that high-purity alloys are immune to attack, in disagreement with this argument. An alternative suggestion is that chemical concentration differences exist between grains and grain boundaries, that is, impurity segregation at boundaries, and that these chemical differences provide the driving force for localized attack. It is this impurity segregation which can lead to accelerated dissolution of grain boundaries when the alloy is exposed to a suitable corrodant. This mechanism would predict the immunity of high-purity alloys to inter-granular attack, which is in agreement with experi-mental observations. In the present paper, some recent studies on inter-granular corrosion of austenitic stainless steels which were conducted by coworkers and myself will be re-tibility A simple model will be described in which it is proposed that the intergranular corrosion of aus-tenitic stainless steel is associated with the presence of continuous grain boundary paths of either second phase or solute-segregated regions.* On the basis of this model, it is suggested that the intergranular corrosion rate can be markedly reduced by the formation of a discontinuous second phase at the grain boundaries if the discontinuous second phase incorporates the major part of the segregating solute, drained from the grain boundary region. Results are presented of corrosion tests and electron microscopic studies of different types of austenitic stainless steel after various heat treatments which provide experimental support for this model. Finally, a solute clustering mechanism, based on a solute-vacancy interaction, is shown to be consistent with the results obtained for inter-granular corrosion of solution-treated austenitic stainless steels. EXPERIMENTAL Corrosion tests using weight loss measurements were made on sheet specimens, which were lightly electropolished, washed, and immersed in boiling (115°C) 5 N HN03 containing 4 g crt+6 per liter added as potassium dichromate. Studies in which the inter-granular penetration depth was measured both by electrical resistance and metallographic methods have shown an empirical correlation between the rate of intergranular penetration and the weight loss per unit time for identically treated specimens of stainless steel." As a result, although all the corrosion data reported here are in terms of simple weight loss measurements, these data are considered to reflect primarily the rate of intergranular dissolution. Fig. 1 shows a typical result of intergranular attack of a solution-treated Type 304 stainless steel after 4 hr in a boiling nitric-dichromate solution. The wide grain boundary grooving at the surface, and the attack at incoherent twin boundaries, are evident; very little corrosion attack is seen at the coherent twin boundaries. INTERGRANULAR CORROSION MODEL

Jan 1, 1970

By John D. Sullivan

Leaching of copper ores is a comparatively old art, probably dating back to medieval times. The leaching of mixed oxidized-sulfide ores, however, is modern. The first modern plant leaching mixed ores was at Ajo, Ariz., where commercial operations commenced in 1917. While the ore at Ajo was primarily oxidized there was always some sulfide present. The Inspiration leaching plant, which was put in operation in 1926, may be considered the first plant constructed for the extraction of both sulfide and oxidized copper. The pioneers in leaching mixed ores had a difficult task before them since they had very little fundamental data on the chemical and physical factors of leaching. For the very large amount of painstaking experimental work that was done before building the Ajo and Inspiration leaching plants the reader is referred to the original articles.' For a period of several years the writer worked on problems connected with the chemistry and physics of leaching mixed oxidized-sulfide ores. This paper summarizes the experimental work and discusses various factors involved in leaching ores. It also presents many data heretofore unpublished. Among the new data are those on chrysocolla, pages 518 to 519, inclusive; dioptase, page 519; covellite, page 529; virtually all those on chalcopyrite, pages 531 to 533, inclusive; enargite, page 533; and tetrahedrite and tennantite, pages 534 and 533. The oxidized copper minerals of commercial importance in American ores are azurite, Cu3(OH)2(CO3)2; malachite, Cu2(OH)2CO3; chrysocolla, CuSi03.2H2O; tenorite (or melaconite), CuO; and cuprite, Cu2O. Dioptase, CuSiO3.H2O is less common. Brochantite, CuSO4.3Cu(OH)2, while the chief mineral in the ore at Chuquicamata, is not of major importance in the United States. Metallic copper, while chemically not so, is frequently classed as an oxidized mineral of copper. The most important sulfide minerals are chalcocite, Cu2s; covellite, CuS; bornite, Cu5FeS4; and chalcopyrite, CuFeS2. Less important complex sulfides are enargite,

Jan 1, 1934

By H. C. Theuerer

GeC14 may be purified by extraction with HCI and chlorine. The process is as effective for the removal of AsCI:, as the more cumbersome distillation methods usually used for this purpose. GERMANIUM for semiconductor use contains impurities at levels no higher than a few parts in ten million. Material of this quality is obtained from highly purified GeC1, by hydrolysis to the oxide and reduction of the oxide in hydrogen. When purifying GeCl,, AsC1, is the most difficult impurity to remove. This is usually accomplished by multiple distillation procedures.1-3 AsC1, may also be removed from GeC1, by extraction with HC1.1-4 Reducing the arsenic to low concentrations is not practicable, however, because of the large number of extractions needed. This paper discusses a new method for the removal of arsenic from GeC1, by extraction with HC1 and chlorine. The method is rapid, leads to little loss of germanium and is at least as efficient as the distillation procedures currently being used. Theory of Extraction Procedures In the simple extraction of GeC1, with HC1, the following reaction occurs ASCl8G8C1 D AsCl3rc1 at equilibrium CA/Cn= K, where K is the distribution coefficient, and C, and C,, are the molar concentrations of AsC13 in HC1 and GeCl,, respectively. The materials balance equation for this reaction is VACA + vncn = VnC,, where V, and Vn are the volumes of HC1 and GeCl4, respectively, and C, is the initial concentration of AsC13 in GeC1,. From this it can be shown that for multiple extractions where C,, is the concentration of AsC13 in GeC14 after n extractions, and r is the ratio of V, to V,,. It is assumed that r is maintained constant, that equilibrium is established during each extraction, and that K is independent of the AsCl3 concentration. By saturating the system with chlorine, the following reaction occurs in the aqueous phase AsCl3 + 4H2O + Cl2 D H5AsO4 + 5HC1 at equilibrium K' = ------------ ai - a4 h2u - aet2 where a is the activity of the various components. The effect of this reaction is to reduce the concentration of the AsC1, in the aqueous layer and, therefore, to promote further extraction of this component from the GeC1, layer. If the arsenic acid remains entirely in the aqueous phase, the net effect of this reaction is to promote the removal of arsenic from the GeC11. The materials balance equation for extraction with HC1 and chlorine with the foregoing reaction is, then, VaCC + VACA + VACn = VnCo where C,. is the molar concentration of H3AsO, in the HC1. With the added assumptions that the activities of AsC13 and H8ASO4 in the aqueous phase are equal to their molar concentrations, it can be shown that for n extractions Cn/Cu = (1/rkK + rK + 1) n where k - K1 a4h2o - acl2/aoncl. It can be seen by comparing Eqs. 1 and 2 that if k is large, the removal of AsC1, by HC1 extraction will be greatly improved by the addition of chlorine. Dilution of the HCI used in the extraction with chlorine would also favor the separation. This, however, would increase the loss of GeCl,, which is undesirable. Experimental Procedure Germanium prepared from oxide of semiconductor purity is n-type with resistivities greater than one ohm-cm. The resistivity is controlled by the donor concentration, which is —lo-: mol pct. Germanium prepared from material with added arsenic will have lower resistivity commensurate with the arsenic concentration. With such material, at arsenic concentrations above 10-1 mol pct the resistivity is controlled by the added arsenic, and effects due to other impurities initially in the oxide are negligible. In this investigation GeO, of semiconductor purity was converted to GeCl,, and -0.01 mol pct As was added. This material was used for the extraction experiments and the purification attained determined by a comparison of the resistivity data for samples of germanium prepared from the initial and purified GeC1,. A method for calculating the arsenic concentration from the resistivity data is discussed later. The details of the experimental procedures used are as follows: Two hundred and thirty cu cm GeC1, were prepared by the solution of GeO, in HC1, followed by

Jan 1, 1957

By P. G. Shewmon

THIS paper is concerned with the redistribution of a second phase when a 2-phase solid alloy is annealed in a temperature gradient. An examplewhich is discussed in detail is the redistribution of carbides in a low-carbon steel annealed in a temperature gradient below the A, temperature. As a result of such a treatment, the carbides at the cooler side disappear, while those at the hotter side grow in size. In a 2-phase zirconium-hydrogen alloy, the amount of hydride will tend to be increased at the cold end and decreased at the hot end. That such an effect can occur in solid metals is not generally appreciated. However, with the trend toward higher operating temperatures in several fields, this phenomenon will become more important in the future. Actually, such effects should be rather common in the core of nuclear power reactors where the op- erating temperatures are high and temperature gradients are an order of magnitude higher than in previous high-temperature applications of alloys. The purpose of this paper is to point out the existence of such an effect, to discuss the manner in which one predicts whether a redistribution of the second phase will occur in a given system, whether the second phase will go to the hot or cold face, and how rapidly the redistribution will occur. One aspect of this problem has been discussed by pfam and Wernick2who considered the migration of a small liquid region through a solid. In their case, the diffusivity in the liquid is much larger than in the solid and they have interpreted their results successfully by using Fick's first law as the flux equation in the liquid, and taking the concentration gradient from the phase diagram. For all the cases they have studied, this type of analysis predicts that the liquid region migrates from the cold end to the hot end, and this is what was found ex-

Jan 1, 1959

THE primary interest in the subject of this chapter lies in the fact that various heats of steel made to the same chemical specification do not always-have the same properties. The properties considered here, of course, are those inherent in the ingot immediately after solidification and not qualities imparted by variations in subsequent mechanical or thermal treatment. The expression "made to the same chemical specification" is used because some of the variations in properties are due to variations in chemical analysis within the specified ranges of those elements commonly specified and determined. Other variations in properties are due to variations in those constituents of steel (elements or compounds) that are not ordinarily included among the elements specified, thus not a part of the specified "composition." The term "constitution" is used to include not only the specified composition but also the nature and distribution of every element or compound contained in the steel entering the ingot mold; also included are items such as aluminum oxides and nitrides, presence of soluble gases, and dispersion of nonmetallic particles. When it is considered that the constitution of steel is determined by the addition or absorption into the bath of all such constituents from whatever source, it follows that constitution is of necessity the final result of steelmaking practice. It is the agency through which steelmaking practice operates to control the properties of the steel. The term steelmaking practice is here used in the broad sense, meaning the control of all the materials entering the steel and of the conditions under which the process is carried out. Steelmaking practice, thus defined, establishes the chemical system within which the reactions between components must proceed in obedience to the laws of chemistry. Thus the chemical constitution of the steel is established and, through constitution, the properties of the metal are established. In the preceding chapters it has been shown how the constitu-

Jan 1, 1951

By Everett M. White

Numerous articles have been written in regard to the man who mines coal and he has been likened to brave men in all ages who have gone out to conquer some unknown hazard. Now, however, modern mining is no longer something to be avoided but is a vocation that anyone can well be proud of, with remuneration equal to or above that of almost any industry. A concerted effort is being made each day by both the operator of most mines as well as the state and Federal inspectors to see that coal mines are as safe or safer than any other industry. However, it is true that mine fires and explosions have occurred in the mining industry since its earliest inception. One of the earliest accurate references to such an occurrence is found in the transactions of the Royal Society of London. In the Colliery Managers' Handbook, 1898, Caleb Pamely writes of an explosion that occurred at Fatfield, England, which resulted in the death of 69 persons in August 1708. It is interesting to note that he states, "Three of them, viz, two men and a woman, were blown quite up from the bottom of the shaft, fifty-seven fathoms deep, into the air, to a considerable distance from the mouth of the pit." From this statement it is noted that women were employed as miners in England during that period. Numerous mine fires and explosions have occurred in mines in this and other countries. Several of them claimed more than 100 lives. Among the greatest losses was a mine explosion in West Virginia that claimed 361 and a mine fire in Illinois that claimed 259. Although no one would minimize the seriousness of a mine fire or an explosion, yet in too many cases they have been publicized out of proportion. This especially is so when compared with the accident rate of other industries or on our highways. It should be remembered that of these general classifications of hazards in mining, mine fires and explosions rank very low in the accident rate in any given year. In modern times the coal industry has completed two years or more, at various times, without a single major disaster. The

Jan 1, 1973

By Philip E. LaMoreaux

Fluoride, generally less than 0.5 ppm, is present in ground water from rocks of Paleozoic age and older, in northern and eastern Alabama. Some of the water-bearing formations in the Coastal Plain area of the State yield water with as much as 6.8 ppm fluoride.

Jan 1, 1950

By T. E. Schmieman, J. E. Miller, M. L. Rizzone

Both centrifugal and reciprocating-type pumps have been widely used in the transport of slurries. Although with some limitations, centrifugal pumps may be used, especially for short-haul systems, however, for the long pipelines the reciprocating pumps are better suited. A state-of-the-art review is presented in which a discussion of applications is made and some of the problems associated with meeting the proper design conditions for satisfactory service are discussed. Several developments underway give considerable promise of better pumps in the future, although the current level of development provides for an economical means to move slurries. The movement of liquids in pipelines necessarily occasions the use of pumps. The petroleum industry is familiar with the transport of solids through mud pumps and cementing and fracturing pumps where the movement of slurries is an everyday matter. In the drilling of an oil well, the circulating fluid utilized to remove drill cuttings is called drilling mud. This substance is usually a fairly sophisticated material designed to develop certain characteristics desirable in the drilling process. The cuttings are suspended in a moving column of this fluid and brought to the surface. The separation of the cuttings from the drilling fluids is accomplished by the use of shaker screens and settling pits; however, it is impractical to remove the cuttings completely and as a result they are pumped through the mud pumps back into the circulating stream. Over the years, mud pumps have been improved so that rather long life can be obtained from liquid end parts subject to the attritional effects of the abrasive-laden fluid. It is from this background that reciprocating-type slurry pumps have been developed. Centrifugal Pumps Centrifugal pumps have also been used to transport solids, where low heads are required, typically up to 200 ft or so, and for short hauls. The centrifugal pump is a hydrokinetic device wherein the increase in velocity of a fluid stream is converted to head, and to achieve high heads a large change in velocity is necessary. Abrasive laden fluids cause wear on impellers and casings as a result of erosion by the fluid and the suspended particles. Centrifugal pumps, therefore, can only be used where the internal velocity of flow is rela- tively low. The advantage of centrifugal pumps is their high capacity at relatively low capital cost and usually relatively small space requirement. One of the disadvantages of the centrifugal pump when used in slurry pipelining can be seen in its typical pressure-volume performance relationship, which tends to work against the application (see Fig. I). If an increase in pressure (head) is occasioned by flow restrictions in the pipeline, say by the dropping out of solids, a desirable characteristic of a slurry pump would be that it develop increased pressure to overcome the restriction. The centrifugal pump provides the increased pressure only at the expense of considerably reduced volume which then results in a lower flow velocity. With the reduced flow rate, adequate velocity to hold the material in suspension and keep it flowing in the line might not be achieved. If centrifugal pumps are considerd for the movement of solids in a long line, a series of pumps must be staged in order to provide the necessary motivating force. A large number of pumps in the line would be required, since each of the pumps could provide only a small pressure increment. An equal number of standby pumps

Jan 1, 1971

By Arthur Winslow

Introductory.—The following paper is based upon a report on the lead- and zinc- deposits of Missouri, prepared for the State Geological Survey, which is now being printed. This report is the outcome of work prosecuted by the writer, assisted by Mr. J. D. Robertson, during the past five years. The studies in the State were supplemented by examinations of the similar ore deposits in Wisconsin and Arkan- sas. The report will contain in all about 800 pages, and the aim has been to make it complete and exhaustive, especially in descriptive matter. Naturally, only a brief outline can be presented here, and the reader is referred to the report itself for further details. Contents. I.—History and Statistics, . . 636 II.—Topography of the Region, . 639 III.—General Geology, . . .639 The Archean, . . .639 The Algonkian, . . 640 The Silurian, . . .640 The Devonian, . . 640 The Lower Carboniferous, 641 Tie Coal Measures, . 641 The Tertiary, . . .641 Structural Geology,. . 642 IV.—The Ore-Deposits, . . .643 Geologic Distribution, . 643 The Forms of the Ore-Bodies, . . .641 The Composition if the Ore-Bodies, . . .645 Gangues, . . . 645 Minerals, . . .618 Paragenesis of Minerals, . . . 651 The Structure of the Ore-Bodies, .... 651 V.—Descriptions of Types, . . 652 The Eagle Mines, . . 652 Shaft No. 23, . . 652 The Western Zinc Company or Oswego Lands, 651 The Gobar and Tomlinson Shaft, . 655 The Alba Company's Mine, 656 The Victor Mine, . . 658 The Bonne Terre Mines, . 660 General Geology, . 660 The Ore-Bodies, . 661 The Vallé Mines, . . 664 The Garatee Mines, . 664 The Corn-Stalk Diggings, . . .665 The Virginia Mine, . 666 The Conlogue Mine, . 667 VI.—The Mode of Formation of the Ore-Bodies, . . 670 The Formation of the Cavities. . . . 670 The Filling of the Cavities, . . . .675 The Formation of the Breccia Deposits, . . 673 The Formation of Circle Deposits, . . .674 The Impregnated Deposits of the Southeast, . 676 VII.—The Origin of the Metalliferous and Other Minerals, 676 1. Originally Deposited in Concentrated Condition, 676 2. Derived from Great Depths, . . .677 3. Original Diffusion, Supplemented by Lateral Secretion, . . . 678 4. Concentrated Through Surface Decomposition, 681

Jan 1, 1895

By Welton Crook

UNLESS present in considerable proportion, metals of the precious-metal group-other than gold and silver-are not readily detected by the methods of fire assaying usually applied to ores and metallurgical products. Platinum, when present in small quantity, will ordinarily be reported as silver unless special methods of parting are used. Other elements occurring in the gold itself are all fluxed and slagged in the assay operation and if analyses are made on bullions the melting and slagging operations to which the bullion has been subjected may eliminate most of the associated elements. On the other hand, the analysis of precipi-tate from the cyanide treatment of gold ores may reveal the presence of many unexpected elements, such as tungsten and molybdenum. It is uncertain, however, whether many of the elements present in the pre-cipitate are derived from the ore gangue or from the gold itself. No very general survey of the distribution of metallic elements in gold seems to have been made. Rose and Newman,1 in connection with the composition of native gold, say in part as follows: Gold is occasionally found alloyed with copper and sometimes also with iron, bis-muth, lead, mercury, tin, antimony, palladium or rhodium. Rhodium gold from Mexico was found to be of the specific gravity 15.5 to 16.8 and contained 34 to 43 per cent of rhodium. The native alloy of palladium, gold, and silver from Porpez con-tains 85.98 per cent of gold, 9.85 per cent palladium and 4.17 per cent silver. Mal-donite, from Victoria, contains gold 64.5 per cent, bismuth 35.5 per cent (Louis). Dana' says that native gold is usually alloyed with silver in varying amounts, and that sometimes it also contains traces of copper and iron. Rare varieties contain palladium, rhodium and bismuth. Other authors, for instance Zeigler3 and Clark,4 give similar information. Most refer-ences on the subject agree that ordinary native golds contain, in common, the elements silver, copper and iron. After completion of the work of which this paper is a record, the conclusion is reached that all ordinary native gold probably does contain these elements and, although in certain cases other elements may be found to be present, that it is difficult to

Jan 1, 1939