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By A. L. Holley

THE general usage of engineers, manufacturers, and merchants, is gradually, but surely, fixing the answer to this question. In every country rails, boiler-plates, and machinery bars, whether hard or soft, are almost universally called steel, when they are made from cast ingots. Other names for the softer steels, such as " homogeneous metal," " Bessemer iron," " Martin iron," and the like, have failed to obtain general recognition. The meaning of the term steel, before it was enlarged to cover newly developing varieties, has been traced, by a recent writer, down through Percy, Shakspeare, and the Bible, in a most interesting manner, from an archaeological point of view. Undoubtedly, it did characterize hardness and other qualities imparted by carbon. It is within the memory of most of us, that all steels were tool steels, and that the soft, structural varieties were introduced-varieties which harden but little, which bend cold, and which, in many physical properties, are akin rather to wrought-iron than to tool-steel. But, since both the hard and the soft steels are made by the same processes, and have their great, distinguishing structural feature in common, viz., homogeneity resulting from fluidity, it has come to pass, despite every other proposed nomenclature, that all the compounds of iron which have been cast in malleable masses, are called steel, the term wrought-iron being still confined to malleable iron made from pasty masses, and hence laminated in structure. No inconvenience has been found, so far, in distinguishing between the more or less carburized products, in general, by the terms " high-steel," " low-steel," " tool-steel," etc., and, in particular, by prefixing the percentage of carbon and other ingredients, to the terra steel. Steels which contain distinguishing ingredients other than carbon, are called "chrome-steel," " titanium-steel," and the like, just as variously compounded bronzes are called "phosphor bronze," "alu¬minium bronze," etc. Thus the combination of several words or symbols, and figures, may completely disclose the characters of the metal, in terms that are subject to no misunderstanding. But inasmuch as several high metallurgical authorities and clever writers have of late proposed to disturb this natural and somewhat settled nomenclature, it seems important to consider the claims of the various classifications. I shall attempt, in this paper, to show

Jan 1, 1876

By A. L. Holley

The general usage of engineers, manufacturers, and merchants, is gradually, bat surely, fixing the answer to this question. In every country rails, boiler-plates, and machinery bars, whether hard or soft, are almost universally called steel, when they are made from cast ingots. Other names for the softer steels, such as " homogeneous metal,'' "Bessemer iron," " Martin iron," and the like, have failed to obtain general recognition. The meaning of the term steel, before it was enlarged to cover newly developing varieties, has been traced, by a recent writer, down through Percy, Shakspeare, and the Bible, in a most interesting manner, from an archœological point of view. Undoubtedly, it did characterize hardness arid other qualities imparted by carbon. It is within the memory of most of us, that all steels were tool steels, and that the soft, structural varieties were introduced—varieties which harden but little, which bend cold, and which, in many physical properties, are akin rather to wrought-iron than to tool-steel. But, since both the hard and the soft steels are made by the same processes, and have their great, distinguishing structural feature in common, viz., homogeneity resulting from fluidity, it has come to pass, despite every other proposed nomenclature, that all the compounds of iron which have been cast in malleable masses, are called steel, the term wrought-iron being still confined to malleable iron made from pasty masses, and hence laminated in structure. No inconvenience has been found, so far, in distinguishing between the more or less carburized products, in general, by the terms " highsteel," "low-steel," "tool-steel," etc., and, in particular, by prefixing the percentage of carbon and other ingredients, to the terra steel. Steels which contain distinguishing ingredients other than carbon, are called "chrome-steel," "titanium-steel," and the like, just as variously compounded bronzes are called " phosphor bronze," " aluminium bronze," etc. Thus the combination of several words or symbols, and figures, may completely disclose the characters of the metal, in terms that are subject to no misunderstanding. But inasmuch as several high metallurgical authorities and clever writers have of late proposed to disturb this natural and somewhat settled nomenclature, it seems important to consider the claims of the various classifications. I shall attempt, in this paper, to show

By C. Zener, H. Nielsen, D. Van Winkle

THE internal friction of metals has been studied frequently at elevated temperatures.1-4 In most cases it rises rapidly with increasing temperature. The notable exceptions are ferromagnetic materials, and lead.2 This paper describes an investigation of the general features of the high-temperature internal friction of 70-30 alpha brass. EXPERIMENTAL METHOD The internal friction of a metal is a measure of the rate at which it dissipates energy of vibration. The measure adopted here, I/Q, is (I/2p) times the specific damping capacity, a measure commonly used by engineers. In the measurements of this investigation, the stress level was kept so low that the observations were independent of the stress. The general method of making such measurements, and of observing the temperature of the specimen during a measurement, has been described elsewhere.5,6 The driver and detector coils were wound with wire insulated with glass thread, in order to withstand the high temperatures used. In previous work electrical eddy currents in the specimen served as the coupling between the mechanical vibration of the specimen and the electrical circuits of the driver and detector. The high values of the internal friction in the present investigation rendered this coupling insufficient. In order to increase this coupling, pole pieces cut from ordinary telephone diaphragms were attached to the specimen. A mixture of French chalk and water glass proved a satisfactory cement. All measurements were made at the fundamental frequency for transverse vibration, which lay between 600 and 900 cycles per second. SPECIMENS The measurements described herein were made upon a single cylindrical rod of brass, kindly furnished by Dr. Cyril Stanley Smith, of the American Brass Co. This rod was the specimen E of the set of alphabrass rods described in an earlier paper.6 Successively larger grain sizes were obtained by annealing at successively higher temperatures. A slice was cut off one end after each set of measurements. Grain counts were made on each slice by W. E. Lindlief, of the American Brass Co. Nine fields were viewed on each piece, located as shown in Fig. I. Results are given in Table I. The grain size is defined in the usual way; namely, Grain size = I/n ½ where n is the mean number of grains per square millimeter. EXPERIMENTAL RESULTS This paper is concerned exclusively with the part of the internal friction that becomes dominant at high temperatures. It is thus desirable to separate this part of the internal friction from the part that is

Jan 1, 1942

By J. W. Hickman, E. A Gulbransen

The physical and chemical structure of the oxide films formed on metals and alloys is of interest in our understanding of their protective properties. According to Pilling and Bedworth,¹ if the specific volume of the oxide is equal to or greater than that of the metal, a compact or continuous structure results; if the volume of the oxide is less, a cellular or porous structure forms. With the cellular type of coating the surface layer of oxide offers no impedance to oxidation; at a given temperature the rate of oxidation is quite constant. On the other hand, the compact type of coating acts as an effective barrier to oxygen and the rate of oxidation will follow a parabolic law. The recent work of Gulbransen2 and of Leontis and Rhines3 on the oxidation of magnesium indicates that it is not necessary for the volume of the oxide to be greater than that of the metal in order that the oxidation may follow a parabolic rate law. One exception to the rule of Pilling and Bedworth¹ is noted by Scheil;4 namely, tungsten. At 500° and 700°C long-time oxidations indicate a linear rate law with time. However, Dunn's6 0xidation measurements from 700°to 1000°C indicate that a parabolic rate law is followed. The oxide is mainly yellow WO a with a thin layer of the blue oxide. Preliminary results on the oxidation of tungsten6 in the temperature range 400° to 500°C indicate that the oxidation does proceed according to a parabolic rate law. Irrespective of the actual rate law that tungsten may obey, it is of interest to compare the results obtained on the oxidation of tungsten in the thin film region with those found when the metal is scaling. A time-temperature study of the oxides formed on both molybdenum and tungsten may indicate whether there exist any peculiarities in the oxide structures of the thin film region compared with those of the scaling region of oxidation. In a recent paper the authors7 presented an investigation of the structures of the oxide films formed on the metals iron, cobalt, nickel, chromium and copper. The results of these studies are presented in graphical form as existence diagrams of the oxides on a time-temperature scale. The existence diagrams of the oxides occurring on some of the metals are simple and show few chemical transitions, but there are many cases in which the physical state of the oxide surface changes as a function of time and temperature, as evidenced by the appearance or disappearance of orientation effects and sharpness of patterns. In general an increase in temperature results in an increase in

Jan 1, 1947

By E. A. Gulbransen, J. W. Hickman

THE physical and chemical structure of the oxide films formed on metals and alloys is of interest in our understanding of their protective properties. According to Pilling and Bedworth,1 if the specific volume of the oxide is equal to or greater than that of the metal, a compact or continuous structure results; if the volume of the oxide is less, a cellular or porous structure forms. With the cellular type of coating the surface layer of oxide offers no impedance to oxidation; at a given temperature the rate of oxidation is quite constant. On the other hand, the compact type of coating acts as an effective barrier to oxygen and the rate of oxidation will follow a parabolic law. The recent work of Gulbransen2 and of Leontis and Rhines3 on the oxidation of magnesium indicates that it is not necessary for the volume of the oxide to be greater than that of the metal in order that the oxidation may follow a parabolic rate law. One exception to the rule of Pilling and Bedworth' is noted by Scheil;4 namely, tungsten. At 500° and 700°C long-time oxidations indicate a linear rate law with time. However, Dunn's5 oxidation measurements from 700° to 1000°C indicate that a parabolic rate law is followed. The oxide is mainly yellow W03 with a thin layer of the blue oxide. Preliminary results on the oxidation of tungsten6 in the temperature range 400° to 500°C indicate that the oxidation does proceed according to a parabolic rate law. Irrespective of the actual rate law that tungsten may obey, it is of interest to compare the results obtained on the oxidation of tungsten in the thin film region with those found when the metal is scaling. A time-temperature study of the oxides formed on both molybdenum and tungsten may indicate whether there exist any peculiarities in the oxide structures of the thin film region compared with those of the scaling region of oxidation. In a recent paper the authors' presented an investigation of the structures of the oxide films formed on the metals iron, cobalt, nickel, chromium and copper. The results of these studies are presented in graphical form as existence diagrams of the oxides on a time-temperature scale. The existence diagrams of the oxides occurring on some of the metals are simple and show few chemical transitions, but there are many cases in which the physical state of the oxide surface changes as a function of time and temperature, as evidenced by the appearance or disappearance of orientation effects and sharpness of patterns. In general an increase in temperature results in an increase in

Jan 1, 1947

By E. A. Gulbransen, J. W. Hickman

The physical and chemical structure of the oxide films formed on metals and alloys is of interest in our understanding of their protective properties. According to Pilling and Bedworth,¹ if the specific volume of the oxide is equal to or greater than that of the metal, a compact or continuous structure results; if the volume of the oxide is less, a cellular or porous structure forms. With the cellular type of coating the surface layer of oxide offers no impedance to oxidation; at a given temperature the rate of oxidation is quite constant. On the other hand, the compact type of coating acts as an effective barrier to oxygen and the rate of oxidation will follow a parabolic law. The recent work of Gulbransen2 and of Leontis and Rhines3 on the oxidation of magnesium indicates that it is not necessary for the volume of the oxide to be greater than that of the metal in order that the oxidation may follow a parabolic rate law. One exception to the rule of Pilling and Bedworth¹ is noted by Scheil;4 namely, tungsten. At 500° and 700°C long-time oxidations indicate a linear rate law with time. However, Dunn's6 0xidation measurements from 700°to 1000°C indicate that a parabolic rate law is followed. The oxide is mainly yellow WO a with a thin layer of the blue oxide. Preliminary results on the oxidation of tungsten6 in the temperature range 400° to 500°C indicate that the oxidation does proceed according to a parabolic rate law. Irrespective of the actual rate law that tungsten may obey, it is of interest to compare the results obtained on the oxidation of tungsten in the thin film region with those found when the metal is scaling. A time-temperature study of the oxides formed on both molybdenum and tungsten may indicate whether there exist any peculiarities in the oxide structures of the thin film region compared with those of the scaling region of oxidation. In a recent paper the authors7 presented an investigation of the structures of the oxide films formed on the metals iron, cobalt, nickel, chromium and copper. The results of these studies are presented in graphical form as existence diagrams of the oxides on a time-temperature scale. The existence diagrams of the oxides occurring on some of the metals are simple and show few chemical transitions, but there are many cases in which the physical state of the oxide surface changes as a function of time and temperature, as evidenced by the appearance or disappearance of orientation effects and sharpness of patterns. In general an increase in temperature results in an increase in

Jan 1, 1947

By J. W. Cloud

years ago upon the effect of having the rails always rolled in the same direction, and also of having them rolled backwards and forwards, and showed that under the latter course there were of necesshy weak spots somewhere near the centre of the rail, yet in all this discussion the methods of rolling have been passed by almost in silence. Mr.. Sandberg in his paper mentions the idea of using a regietering dynamometer attached to the punching machines, and of det.erminit~g the quality of the metal by the resistance which is shown. I think the' first idea of this kind was published by Professor Langley, then of Pittsburgh, who, while making some investigations for Mesrs. Miller, Metcalf and Parkin, announceti as tile result of a series of dynamometric experiments that abrasive resistance was the term which should be wed in regard to steels of different wearing qualities. I have had extremely delicate dynamometers attached to the instruments of precision with which I am making the iuvestigation on the fatigue of metals, and hope soon to communicate the results of the iovegtigation- made with them to the Institute. I wish again to call attention to the fact that we are wing the words " hardener " and " hardness " without any real idea of the meaning of these words. When we say hard and soft, as we have hen constantly doing during this discussion, is it quite sure that every one has exactly the same meaning in his mind ? Certainly, when hard is used in distinction from soft*, we mean not the capacity of wear, but the capacity of resistance to peuetration, to fracture, or some other resistance, and do not always meau the capacity of resistance to abrasion or crushing, which the discussion would sometimes seem to imply were the only qualitiw requisite to constitute a god rail. J. W. Cloud, Altoona, Pa. : I would call the attention of the Institute to the title of Dr. Dudley's interesting and valuable paper, —" The Wearing Capacity of Steel Rails in relation to their Chemical Composition and Physical Properties." Here are two separate and distinct questions: lst, The wearing capacity of steel rails in relation to their chemical content; and 2d, the wearing capacity of steel rails in relation to their physical properties. The discussion has been almost exclusively confined to the former question, on which there may be many differences of opinion in matters of detail without greatig affecting the result. The latter

Jan 1, 1881

By Walter J. Karplus

By means of a finite difference expansion a fluid flow field in cylindrical coordinates with axial symmetry, is simulated by a network of electrical resistors. A series of DC analog computing units, connected to the network bounrlary corresponding to the free surface effectively adjust the network parameterr to satisfy simultaneously Laplace's equation and the borrndary conditions. The system automatica1ly "re1axes" to the correct boundary shape in a fraction of a second. A detailed application of the method to the water coning problem in oil wells is presented. INTRODUCTION The water coning problem in petroleum production is a prime example of a class of problems known as free surface problems. A free surface arises in fluid flow regions when the shape of the boundary of a single phase flow region is affected in some manner by the pressure or potential gradients within the region. When there exists an interface of two fluids of different densities, the shape of this interface will be determined by the relative velocities of the two fluids and will therefore comprise a free surface. Other free surface problems of interest to petroleum engineers include the gas coning, water injection, and gravity drainage probIcms. In each case it is desired to predict the shape of the boundary of the oil zone as a function of the flow rate, the well penetration and the physical parameters and dimensions of the system. Such problems do not lend themselves to the classical analytical treatments of boundary value problems because in this case the boundary of the potential field and the potential distribution within the field are interdependent and must be calculated simultaneously. A further difficulty arises from geometric considerations. Since the fluid flow is of the radial type in most cases, such effective methods as conformal transformation and the hodograph are not applicable. It is the purpose of this paper to present a method whereby free surface problems of this type may be solved rapidly to the desired order of accuracy by means of a combination of a network of electrical resistors and conventional analog computer units. The water coning problem is treated in some detail. Then the procedure for extending the technique to other free surface problems is indicated. FORMULATION Most commercial oil reservoirs consist of an oil-saturated sand, bounded above by an impermeable strata and below by a water-saturated sand. Gravimetric separation results in a horizontal oil-water interface. When an oil well is drilled so that it partially penetrates the oil zone, and production is initiated at a constant rate, the oil-water interface will assume a new shape as a result of the pressure gradients in the oil zone. It should be emphasized that this is a steady phenomenon. After an initial transient period the water phase will be completely static and only the oil will be in motion. The new steady-state shape of the interface, as shown in Fig. 1, depends upon the depth of penetration, d, the thickness of the oil zone, I, the production rate, q, the hydraulic permeability zone of the sand, k, the viscosity of the oil, µ, and the densities of the oil and water, p.,. and pw.. The problem is to determine this relationship. Darcy's law + = - (P f g p z).....(1) it.

Jan 1, 1957

By Jr. J. L. Ryon.

Experimentation with ammonium nitrate-fuel oil mixtures at three underground salt mines revealed its excellent applications at those properties. The author relates the present blasting practice used at these mines by the Intemzational Salt Co. The International Salt Company is presently performing blasting operations with a pneumatically -placed ammonium nitrate-fuel oil mixture at three rock salt mines, and plans its use in the near future at its new Cleveland mine. Use of ammonium nitrate is saving the company approximately $250,000 annually. With rapidly increasing operating expenses and increasing competitive pressure resulting in lower prices, savings such as those realized through the use of ammonium nitrate are vitally important. ORIGINAL INVESTIGATION AND EXPERIMENTAL ACTIVITIES The three mines presently involved are located at Detroit, Mich.; Avery Island, La.; and Retsof, N. Y. Initial experiments were conducted at the Detroit mine where a detailed investigation was carried on to determine the significance of the static electricity factor when blowing ammonium nitrate into drill holes in which millisecond delay electric blasting caps had been placed. Although the information developed at the Detroit mine was passed along to the other mines, each mine independently pursued its own course of inves- tigation. This fact, plus the differing mining conditions, resulted in slightly different operational procedures at each mine. Some of the varying statistical data are shown in Table I, and data common to all three International Salt Company mines are shown in Table 11. BLASTING PROCEDURE AT THE DETROIT MINE This mine has been using the ammonium nitrate-fuel oil mixture for more than two years on a full time production basis and represents the successful detonation of several hundred thousand holes. Results have been excellent and the blasting cost has been reduced many times. The actual operation at Detroit consists of adding the fuel oil to the bags of ammonium nitrate by means of a portable fuel oil tank complete with hose, nozzle, and metering device. The bags of the ammonium nitrate-fuel oil mixture are transported to the working face from the oiling area by means of a jeep-drawn trailer. At the face, the ammonium nitrate is placed on the elevating platform of a powder-load ing rig which consists of a pneumatically-tired, large fork-lift truck with a fully insulated elevating platform constructed on the forks. The placement of the dynamite primer and the pneumatic placement of the ammonium nitrate is a two-man operation. First, one cartridge of the primer is placed in each hole on the line of holes which can be reached from the loading rig platform. The plastic hose is then inserted into the hole and pushes the primer to the back of the hole. The proper charge of ammonium nitrate is then placed in the pneumatic placement machine and,

Jan 1, 1961

By Colin Fink

THE important developments within the past few years in electrochemistry, in particular in the electric furnace art, in electrometallurgy and in the methods of combatting corrosion are to be the subjects of my discussion. Fig.1 shows the rise of the electric steel furnace industry in this country and Canada. Many prophesied that the electric furnace was largely a war baby and that the sudden rise in the industry, due to the outbreak of the great war, would be fol-lowed by an equally sudden drop after the armistice. However, the curve shows that this, prophecy was not correct; the number of furnaces in operation in this country and Canada has continued to increase steadily, so that at the end of 1925 there were over 525 electric steel furnaces in successful operation. What does this mean? It has a big significance, namely that the en-tire steel industry has been revolutionized, to a certain extent, that we have been able to introduce certain alloys and steel products that we were unable to pro-duce before. On the table is. a sample of metallic chro-mium, analyzing more than 98 per cent chromium, made in the electric furnace. Before the war, the only commercial method of producing chromium was that by the Goldschmidt process. If chromium oxide is mixed with granulated aluminum, a violent reaction occurs, resulting in the production of metallic chro-mium. However, the price of chromium so made will always be above that of the raw material, which at the present time is about 27 cents a pound.. Furthermore, the chromium metal could only be turned out in small quantities, whereas in the electric furnace, large quan-tities, ton masses, can be produced today. The advent of chromium produced in the electric furnace has brought about an entire new phase in the alloy indus-try. The fuel-fired furnaces can turn out a low-carbon chromium steel that runs about 3 per cent chromium, whereas in the electric furnace, 60 per cent ferro-chromium is daily produced in large masses with almost entire elimination of carbon. It is difficult indeed to turn out ferrochrome very low in carbon. New steels are being produced today, for example the steel with which everyone has become familiar within the 'last few years, "stainless steel,". and which would have been impossible without the low-carbon ferrochrome. The elimination of most of the carbon made it possible to roll the chromium steels into thin sheets and manu-facture them into knife blades.

Jan 2, 1927

By A. D. Smigelskas, E. O. Kirkendall

THIS is the third paper in a series on the diffusion of zinc in alpha brass.1 At the time of the first-paper it was accepted that diffusion in a substitutional type of solid solution depended upon an equal interchange of solute and solvent atoms across the diffusion interface (or past a given lattice reference point). Discrepancies in the size of the areas under the diffusion curves on each side of the interface, if observed, were explained on some other basis than the fact that the solute atoms might cross the diffusion interface without an equal number of solvent atoms diffusing across the interface in the opposite direction. The second paper presented evidence indicating that zinc atoms in alpha brass diffuse across the interface more rapidly in one direction than the copper atoms diffuse across the interface in the opposite direction. This phenomenon forced the interface to move in the opposite direction of the diffusion of zinc atoms to provide space for the additional zinc atoms dissolved in the alpha brass. That the interface and columnar grain structure on one side would remain intact during this mass movement was not expected; however, it is gratifying that they did. While the evidence was sufficiently satisfying to the author, it was decided that additional experiments were in order to prove that zinc diffuses more rapidly than copper in alpha brass. It is the purpose of this paper to present the results of these experiments. PROCEDURE A bar of 70-30 wrought brass was selected, to avoid the relatively large volume change in going from beta to alpha brass as in the previous investigation. A bar 7 in. (18-cm.)* long and about ¾ in. (1.9 cm.) wide was surface ground and polished with abrasive paper on plate glass to 0.4184 ± .0002 in. (1.0625 ± 0.0005 cm.) thick. Six 0.005-in. (0.013-cm.) diameter molybdenum wires, chosen because of their very low solubility in copper and alpha brass, were stretched lengthwise along each of the two plane surfaces. Glass tubes placed at right angles to the wires every ½ in. held the wires tightly against the brass. The sample was then emersed in an acid copper sulphate plating bath and electroplated to a depth of about 0.020 in. (0.050 cm.) copper on all sides. The glass tubes were no longer necessary to hold the molybdenum wires in place and were removed. The sample was then electroplated to a depth of

Jan 1, 1946

By A. J. Miles, A. D. Topping

in this paper, the theory of elasticity has been applied to the rock about a deep well, It is assumed that the rock has a modulus of . elasticity and a Poisson's ratio and that the theory of elasticity applies. It is necessary to know or assume the state of stress existing in the rock before it is penetrated by the well drill. The application of this theory indicates that stress concentration of shear, tensions, and compressions about the bore hole are of a high order. This is particularly true when a horizontal compressive stress exists in one direction only in the formation before drilling. If such an initial state of stress exists before drilling, then the rock will have stress concentrations of both tension and compression at the same elevation and of such magnitude that failure of the rock is likely. Accompanying these is a shearing stress of large proportion which is likely to produce spalling of the well walls. Internal pressure applied to the well bore will relieve the extreme compression but not the tension and has little effect upon the shear. Plastic deformation of the rock through a geological time tends to mitigate the stress concentrations. IntroductioN It has long been known that the stresses about holes and re-entrant corners of elastic solids under the influence of loads are different and generally more intense than those imposed upon the body else- where. Stress concentration at a re-entrant corner can be reduced by increasing the radius of the fillet at the corner. Stress concentration at the end of a crack in a plate undergoing either tension or compression Can be relieved appreciably by drilling a hole at the very end of the crack. Also, stresses can be increased in an elastic body in tension or compression by making a hole in it. The stress concentration is greatest at the edge of the hole. Considerable knowledge of the stresses which exist about the bore hole of a deep well may be had by applying our knowledge of engineering mechanics; or more particularly the theory of elasticity. It is, of course, necessary to make the assumption that the rock is elastic and behaves as an elastic solid, that is, that it obeys Hooke's law, has a modulus of elasticity, and a Poisson's ratio. It is also necessary to know, Or assume, the state of stress which exists in the rock prior to the penetration of the drill. With this knowledge it is possible to compute the stresses about the bore hole. The problem can be simplified by considering several simple cases separately and then by applying the principle of superposition to solve the more complex cases which are made up of the simpler ones. Case i—Rock Strata in Compression Penetrated by a Hole This case was first worked out by G. Kirsch* for structural material, but applies equally well to a horizontal rock strata in a state of in in one direction

Jan 1, 1949

By J. T. Peters, N. Schapiro, R. J. Gray

Petrographic studies of coal have resulted in a better understanding of the origin and composition of coal and have added to the knowledge of how and why coals differ in their response to various prepamtion and utilization processes. Petrographic methods can now be used in scientific economic exploitation of coals. Because the United States Steel Corp. is one of the largest consumers of coal and coke, there is a continuing interest in the corporation in perfecting a better understanding of coal so that it can be utilized more effectively. Coal is a heterogeneous substance composed principally of plant material that has been altered by a complex geochemical process to form rock. The science of coal is anthracology. The ultimate aim of anthracology is determining the relationships and differences among coals. The fundamental aim is finding out why coals differ. The practical application is determining how the differences in coals affect their utilization properties. Coal, like other sedimentary rocks, consists of more than one material. Fig. 1, a photograph of a natural fracture and a polished surface of a lump of coal, displays heterogeneity in terms of the banded ingredients present. The earliest attempts to describe coal were based on its hardness and appearance. ' Thus, coal has been described as hard or soft, bright or dull, and banded or nonbanded. The variations in the hardness and physical appearance of the coal reflect differences in materials that constitute the coal. The banded nature, lustre, and texture depend upon the relative proportions of the various constituent materials. Even the earliest petrographic investigations of coal produced evidence of of the heterogeneity of the coal substance and shoul have destroyed the concept of the unit coal molecule. Coals (Fig. 2) that appear the same frequently consist of different microscopic materials and may behave differently during mining, pulverization, washing, or coking. In Fig. 3, the upper photograph shows a bright at-trital medium-volatile coal, and the micrograph at the right shows some of the materials that constitute the coal. The lower photograph shows a bright attrital low-volatile coal and the corresponding micrograph shows material of similar origin to those from the medium-volatile coal. Any petrographic description of a coal that has meaning in terms of its utilization begins with a microscopic examination. Numerous attempts have been made to describe coal on the basis of the materials that constitute the coal.2*3 Initial petrographic studies were directed towards the question of the origin of coals without any true basis for studying the metamorphic changes in the

Jan 1, 1962

By L. G. Truby

DISCUSSION By Rhrt G. Nisle, Phillips Petroleum Co., Barthesville, Okla. The subject paper presents the results of a reservoir behavior analyzer study of the pressure-production performance of five Ellenburger pools in West Texas. These five pools are Wheeler, TXL, Andector, Embar, and Martin. This laboratory has also made reservoir behavior analyzer studies in this area and arrived at substantially the same conclusions. Although the principal results of the studies made in this laboratory are confirmed by the results in the subject paper, there are certain points of difference. The points of difference are (1) the subject paper includes the Martin pool in the common aquifer, whereas our studies indicate that it is not, and (2) the subject paper concludes that the effective aquifer is considerably smaller than that derived from studies made in this laboratory. In terms of reservoir analyzer data, our rejection of Martin is based on the inability to obtain a satisfactory match of the pressure curve when Martin is considered as lying within the common aquifer. A satisfactory match was possible, however, when Martin was run as an isolated pool. This indicates that the pressure disturbance resulting from production at Martin had not reached Embar, Andector, TXL, or Wheeler at the time of our study. A similar situation exists relative to Dollarhide. In tern of geological data, our rejection of Martin is based on the presence of a faulted zone between Martin and Embar. This condition is indicated in Fig. 4 and again in Fig. 10 of the subject report. If a permeable connection between Martin and the other fields does exist, it is probably by way of a detour around this fault. The second point of difference between the two studies is illustrated by a comparison of Fig. 4 of the subject paper with Eg. A. Fig. A is obtained from an internal report on one of the studies made by this laboratory. It will be noted that the area indicated in Fig. 4 is roughly that marked "Pool Unit" in Fig. A. The additional portion of the aquifer shown in Fig. A was simulated on the reservoir analyzer by means of the water drive network. A satisfactory pressure match could not be obtained without this additional network. The differences involved here stem from a more fundamental consideration concerning reservoir analyzer operating techniques. The true source of these differences in reported results cannot at this time be determined because of the incompleteness of the subject paper. It is not stated, for instance, whether the pressure match was induced by altering the field resistance or the field capacitance, or both. Changing analyzer

Jan 1, 1953

By D. J. McAdam

In a recent survey of the literature, the author has found evidence incompatible with prevalent views regarding the technical cohesive strength and yield strength of metals. Some of the evidence regarding the technical cohesive strength was presented in a previous paper,21 and views were presented that are believed to be in better accord with the evidence. In that paper, it was shown that the technical cohesion limit (contrary to prevalent views) varies with the combination of principal stresses,t and that the influence of plastic deformation on the technical cohesive strength is not in accordance with prevalent views. In this paper, consideration will be given to both the technical cohesion limit and the yield stress as affected by the combination of principal stresses. Evidence will be presented that the variations of the yield stress and the technical cohesion limit with the combination of principal stresses are not in accordance with prevalent views. Consideration will also be given to ductility and work-hardening capacity, which depend on the initial difference between the technical cohesion limit and the yield stress. By the "technical cohesion limit" is meant the mean stress at actual or poten- tial* fracture. An example of a rechnlcal cohesion limit is the "true" breaking stress of a tension-test specimen, the breaking load divided by the sectional area at fracture. The cohesion limit thus obtained for a ductile metal, however, has been greatly altered by the plastic deformation. It is important to consider the cohesion limit of the metal prior to this deformation, and the variation of the cohesive strength with plastic deformation. The relation between the cohesion limit and the corresponding flow stresst determines the ductility of a metal and the energy that it will absorb before fracture. In this paper, as in the previous paper,21 tensile stresses will be viewed as positive and compressive stresses as negative. The algebraically greatest principal stress will be designated S1, the least principal stress will be designated S3, and the intermediate principal stress will be designated Sz In the previous paper, attention was confined to stress combinations with two of the principal stresses equal (with the intermediate principal stress S2 equal eithel to S3 or 31). In this paper, consideration will also be given to the effect of stress combinations with all three principal stresses unequal. In the earlier sections of the paper (pp. 3I I to 324), attention will be confined to stress combinations with

Jan 1, 1942

By D. J. McAdam

In a recent survey of the literature, the author has found evidence incompatible with prevalent views regarding the technical cohesive strength and yield strength of metals. Some of the evidence regarding the technical cohesive strength was presented in a previous paper,21 and views were presented that are believed to be in better accord with the evidence. In that paper, it was shown that the technical cohesion limit (contrary to prevalent views) varies with the combination of principal stresses,t and that the influence of plastic deformation on the technical cohesive strength is not in accordance with prevalent views. In this paper, consideration will be given to both the technical cohesion limit and the yield stress as affected by the combination of principal stresses. Evidence will be presented that the variations of the yield stress and the technical cohesion limit with the combination of principal stresses are not in accordance with prevalent views. Consideration will also be given to ductility and work-hardening capacity, which depend on the initial difference between the technical cohesion limit and the yield stress. By the "technical cohesion limit" is meant the mean stress at actual or poten- tial* fracture. An example of a rechnlcal cohesion limit is the "true" breaking stress of a tension-test specimen, the breaking load divided by the sectional area at fracture. The cohesion limit thus obtained for a ductile metal, however, has been greatly altered by the plastic deformation. It is important to consider the cohesion limit of the metal prior to this deformation, and the variation of the cohesive strength with plastic deformation. The relation between the cohesion limit and the corresponding flow stresst determines the ductility of a metal and the energy that it will absorb before fracture. In this paper, as in the previous paper,21 tensile stresses will be viewed as positive and compressive stresses as negative. The algebraically greatest principal stress will be designated S1, the least principal stress will be designated S3, and the intermediate principal stress will be designated Sz In the previous paper, attention was confined to stress combinations with two of the principal stresses equal (with the intermediate principal stress S2 equal eithel to S3 or 31). In this paper, consideration will also be given to the effect of stress combinations with all three principal stresses unequal. In the earlier sections of the paper (pp. 3I I to 324), attention will be confined to stress combinations with

Jan 1, 1942

By E. C. Carris

The loading of bituminous coal mechanically was recognized about the year 1900, but during the following 28 years less than 5 per cent of the bituminous production in the United States was loaded by mechanical means. During the past 16 years, however, the usage of some form of mechanical loader has had a very rapid and accelerated growth, until at present production of bituminous coal by mechanical means has reached an all-time high of approximately 46 per cent, and is still increasing. This rapid growth in the use of the mechanical loader has been supplemented by an increase. in mechanical cleaning. The importance of mechanical cleaning of coal was recogniaed many years before the mechanical loader was introduced. because of the impossibility of cleaning manually the sizes below 2 in.. and the increasing competition from other fuels. Utilization of mechanical loaders without nleclianical cleaning 011 the surface for at least one or more sizes is the exception, rather than the rule. One exception is a mine that employs caterpillar-mounted mobile loaders exclusively, and mines the entire seam without any selectivity, and yet loads and ships six grades of coal of the very highest quality without mechanical cleaning. Such a fortunate situation can exist only where mining conditions are ideal, where top and bottom are exceptional and there are no impurity partings, and where there is loader height. The conversion from hand loading to mechanical loading has definitely introduced many problems in the preparation plant of yesterday and in the modern streamline plant as well. Many of these problenis have been solved by good, sound, conscientious initiative on the part of the plant personnel, with minor expenditures; the solution taking the pattern of rearranging 2nd improving the equipment at hand. Other problems have caused, and are causing, considerable concern and difficulty. Large Impurities The removal of large quantities of large impurities from the lump coal, and their handling and disposal, is definitely a troublesome and costly problem. The cost of manually removing the impurities from the picking table alone, based on the actual recovered lump coal, can reach a cost of 42 cents per ton or more. In the design of future plants it would be wise to give this phase of preparation considerably more time and thought, particularly if the seam of coal contains one or more heavy partings and the mining procedure is all seam. This same caution applies to seams that may not contain heavy partings but have poor and heavy draw-slate top, which falls with the coal during the mining cycle. One of the more recent of the modern preparation plants has answered this problem by installing a rock crusher under the picking table in such a manner that the impurities can be diverted by gravity directly to the crusher. This reduces the

Jan 1, 1947

By E. C. Carris

The loading of bituminous coal mechanically was recognized about the year 1900, but during the following 28 years less than 5 per cent of the bituminous production in the United States was loaded by mechanical means. During the past 16 years, however, the usage of some form of mechanical loader has had a very rapid and accelerated growth, until at present production of bituminous coal by mechanical means has reached an all-time high of approximately 46 per cent, and is still increasing. This rapid growth in the use of the mechanical loader has been supplemented by an increase. in mechanical cleaning. The importance of mechanical cleaning of coal was recogniaed many years before the mechanical loader was introduced. because of the impossibility of cleaning manually the sizes below 2 in.. and the increasing competition from other fuels. Utilization of mechanical loaders without nleclianical cleaning 011 the surface for at least one or more sizes is the exception, rather than the rule. One exception is a mine that employs caterpillar-mounted mobile loaders exclusively, and mines the entire seam without any selectivity, and yet loads and ships six grades of coal of the very highest quality without mechanical cleaning. Such a fortunate situation can exist only where mining conditions are ideal, where top and bottom are exceptional and there are no impurity partings, and where there is loader height. The conversion from hand loading to mechanical loading has definitely introduced many problems in the preparation plant of yesterday and in the modern streamline plant as well. Many of these problenis have been solved by good, sound, conscientious initiative on the part of the plant personnel, with minor expenditures; the solution taking the pattern of rearranging 2nd improving the equipment at hand. Other problems have caused, and are causing, considerable concern and difficulty. Large Impurities The removal of large quantities of large impurities from the lump coal, and their handling and disposal, is definitely a troublesome and costly problem. The cost of manually removing the impurities from the picking table alone, based on the actual recovered lump coal, can reach a cost of 42 cents per ton or more. In the design of future plants it would be wise to give this phase of preparation considerably more time and thought, particularly if the seam of coal contains one or more heavy partings and the mining procedure is all seam. This same caution applies to seams that may not contain heavy partings but have poor and heavy draw-slate top, which falls with the coal during the mining cycle. One of the more recent of the modern preparation plants has answered this problem by installing a rock crusher under the picking table in such a manner that the impurities can be diverted by gravity directly to the crusher. This reduces the

Jan 1, 1947

By R. E. Robbins, H. R. Brager

THIS note describes an unusual result obtained in an electron microscope investigation of cavities produced in commercial type 304 stainless steel irradiated in a thermal reactor (ETR) at 290°C to a high neutron flu-ence, 6 x loz1 n per sq cm. The analysis of the steel used is given in Table I. The unusual result is that the calculated quantity of helium gas produced by transmutation during the irradiation, 12 ppm, is less than one-tenth the amount of gas necessary to balance the surface tension of the observed cavities produced in the steel during ETR irradiation. Therefore, the cavities would be expected to behave like voids; however, they behave like "gas filled" bubbles. The maximum quantity of helium produced in the steel by B" transmutation was 8 ppm. In addition, the amount of helium formed by (n, (1) fast neutron reactions with the major alloy constituents and nitrogen was calculated to be 4 ppm based on the tabulated differential or effective fission-averaged cross sections of elements in type 304 stainless steel irradiated in typical thermal reactors.', In previous investigations concerning commercial austenitic stainless steel irradiated in a thermal reactor, the amount of helium gas calculated to be produced by transmutation has always been significantly greater than the amount calculated on the basis that the bubbles were gas filled, PPs= 2y/R. The balance of the gas was assumed to be in bubbles smaller than could be detected on the electron micrographs. Accordingly, the bubbles were attributed to helium produced from transmutation of impurity boron by thermal neutrons. These bubbles were not uniformly dispersed in the matrix but were located principally at grain boundaries, or were radially positioned around a few precipitates located in the matrix and at the grain bundaries., 4 Voids have also been observed in austenitic stainless steel irradiated at high temperature to high neutron fluences in the EBR-I1 and Dounreay Fast Reactors. The voids were uniformly distributed throughout the matrix. The amounts of helium gas produced by transmutation during these irradiations were less than one-tenth the amounts needed to balance the surface tension of the voids formed by the fast reactor irradiation. The fast reactor results are quite analogous to those reported here for the ETR irradiated steel. Electron microscope examination of the fast reactor irradiated material after a 1 hr postirradiation annealing at 900°C disclosed that essentially all the voids had been eliminated. The authors stated that the voids had developed due to the high concentration of vacancies produced during irradiatin., 6, ' The microstructure of the ETR irradiated material as-tested at 75O°C, Fig. 1, contained about 2 X lot5 cavities per cm3 with an average diameter of 110A. With the Van der Waals b correction and y = 1500 ergs per cm2, 300 ppm He would balance the surface tension of the observed cavities. Stereoscopic examination of the electron micrographs showed that the cavities were neither preferentially located near the grain boundaries nor highly concentrated at specific regions or precipitates. The cavities were nearly uniformly distributed throughout the matrix, on dislocations and at grain boundaries. These observations imply that the cavities were not the sole results of B'O

Jan 1, 1969

By U. F. Kocks

SINGLE slip and a single parallel array of edge dislocations have been obtained in silicon single crystals by homogeneously bending them in a four-point dead-loading device at 1000°C around the [211] axis with [253.] as the tensile axis which encloses an angle of 40° with the glide plane. Other orientations or lower temperatures proved unsuitable. The homogeneity of the bending was checked by the method shown in Fig. 1. The chemically polished specimen was exposed to parallel light from a microscope-stage lamp. The sharpness of the focus of the reflected light is an approximate measure of the circularity of the sample. This method permitted the determination of the actual radius of bent specimens within 10 pct accuracy. The etching solution developed to show up dislocations consisted of the following volume parts: 2 HF, 1 HNO,, 2 CH,COOH, 1 a solution of 5 wt pct of CuNO, in water (Rosi'). The acetic-acid content was adjusted to produce fine well-defined etch-pits in about 2 min at room temperature. The effectiveness of the etch did not depend on the crystal-lographic orientation of the face etched. The number of etch pits produced after a given deformation was checked in the usual way against the Cahn formula' and showed good agreement. As it is to be expected from the orientation of the primary system there are slip steps on the top and bottom faces but not on the side faces (perpendicular to the bending axis), whereas etch pits appear on the side faces but not on the top and bottom faces. This is different only for occasional dislocations of a secondary glide system. All the micrographs included have been taken in places where the most of secondary glide could be seen. From this it is evident that in the homegeneously deformed region the number of secondary dislocations was less than 1 in 1000 of the primary type. Dislocation Distribution—A series of tests with varying amounts of deformation is shown in Figs. 2(a-c). An observation that can readily be made from these pictures is that the linear density of dislocations within slip lines is relatively constant and independent of the amount of deformation. "Slip line" in this context is understood to mean a line that is a straight connection of individual etch pits. The heavily pitted bands which can be seen in each of these three pictures may be resolved fairly definitely, at higher magnifications, into many "slip lines" the distance between them being of the order of 0.5p The distance between dislocations in slip lines is of the order of 2p and it is also fairly constant in going from the neutral zone outward. The higher over-all dislocation density in the outer regions of any sample and the higher total number in a more heavily deformed sample, are effected by a larger number of "slip lines." The relative constancy of the dislocation distance within an individual slip line is surprising. The absence of pile-ups" may imply, if there is no rear- rangement on unloading," that there are no substantial obstacles to slip in this case. It seems that the equilibrium distribution of the dislocations in each active slip plane under the higher external stress on

Jan 1, 1959