Search Documents

By R. W. Mebs, G. W. Geil, D. J. McAdam

As shown in previous papers by the authorsg-17t the resistance of a metal to fracture, like its resistance to plastic deformation, is a function of all three principal stresses. A technical cohesion limit is the technically determined resistance to fracture under a specific stress system. The technical cohesive strength thus comprises an infinite number of technical cohesion limits corresponding to the infinite number Of possible com-binations of the principal stresses. The technical cohesive strength, therefore, may be represented by a surface in a diagram with the three principal stresses as coordinates. As shown in previous papers,'-'' the technical cohesive strength increases with plastic deformation, with decrease in temperature, and with increase in the strain rate. The technical cohesion limit, therefore, is affected by the same factors that affect the flow stress,$ namely, the stress system, plastic deformation, temperature, and the strain rate. More- over, the influence of each of these factors on the technical cohesion limit has been shown to be qualitatively similar to the three of the same factor on the flow stress.9-18 Advance of knowledge about the conditions determining fracture of metals has been retarded by the reluctance of some investigators to abandon preconceived ideas about how metals ''should,, behave. The incorrect idea is still prevalent that the conditions determining resistance to fracture are very different from those determining the flow stress. Attempts are still being made to express resistance to fracture in terms of a single parameter, such as a limiting value of the greatest principal stress, the maximum shearing stress, or the volume stress (one-third the algebraic sum of the three principal stresses). In these attempts, a sharp distinction is sometimes made between a ductile or ,plasticdeformation, fracture,, and a "brittle frat-ture.H In making this distinction, however, the meaning attached to the term "brittle fracture" sometimes is not made clear. The term could mean fracture after very little plastic deformation or it could be used to designate the type of fracture. An ordinary fracture of a ductile metal at room temperature starts as a cleavage, generally transverse to the direction of the greatest principal stress, but eventually changes to a shearing fracture' In some conditions, however, the metal fractures entirely by cleavage, with no evidence of plastic deformation during the fracture; the surface of such a fracture may have a

Jan 1, 1948

By W. A. Hockings, M. E. Volin, A. L. Mular

Batch grinding tests at short times were made in a laboratory rod mill with 10 x 14 mesh quartzite in corn syrup-water mixtures of varying viscosity. The weight fraction broken and size modulus were found to be independent of viscosity up to 20 cp, but at higher viscosities breakage of the feed decreased while the size modulus increased. The mechanisms of the effect of viscosity are discussed on the basis of particle dynamics. The effect of viscosity of the suspending medium on grinding has not been accorded much attention, although both wet and dry grinding are used in bene-ficiation processes and the viscosities of water and air differ greatly. schweyerl investigated the rates of grinding of quartzite in a pebble mill with air, water and glycerol as the suspending media and found the rate in terms of new surface developed per thousand revolutions of the mill to be constant and dependent on viscosity up to 20,000 rev, but to decrease and become independent of viscosity for longer grinding times. Based on considerations of the drag forces exerted on suspended particles and on the grinding media under turbulent and laminar flow conditions, viscosity can be expected to inhibit the rate of grinding in a given system as it changes the flow conditions from turbulent to laminar. The objective of this study was to determine the effect of viscosity of the suspending fluid in the batch grinding of a homogeneous feed of uniform size for short residence times, a region of more practical interest than the long times investigated by Schweyer. In actual grinding operations, the viscosity of the fluid does not change, but the consistency (apparent viscosity) of the pulp increases with additions of fines. In this study the consistency of the pulp was not measured because it was thought that the grinding times were too short to alter the apparent viscosity appreciably.* *Minus 200 mesh quartz at 65% solids has an apparent viscosity of about 25 cp as measured by a simple consistometer. Personal communication from D. F. Kelsall to A. L. Mular. For the purposes of this study, the effect of viscosity on grinding can be shown sufficiently well on the basis of the cumulative weight fraction finer than the feed size at any time, and the size modulus, ku, of the finer than feed sizes. The parameter, ku, is obtained from a form of the Gaudin-Schuhmann equation. METHOD AND MATERIAL The grinding tests were accomplished in a laboratory rod mill 10-1/2 in. long and 8 in. bore with a 20-lb rod charge consisting of two 1-in., eight 3/4-in., eight 1/2-in., and eight 1/4-in. diam rods. The mill speed was 43.2 rpm. Charges of 400 g 10 x 14 mesh Wisconsin quartzite** were ground for times of 60, **Courtesy of Minnesota Mining and Mfg. Co. 120, 180 and 240 sec in 500 cc of fluid made up of corn syrup and water in measured proportions. The temperature of the pulp was measured immediately upon completion of grinding, and the size distribution of the quartzite was determined by a wash-wet-dry screening technique. Corn syrup was chosen because of its high viscosity and ideal viscous behavior, and also because its density is not greatly different from that of water. The viscosity of each fluid mixture was measured with an Ostwald viscometer at 25 C. and a correction was made for the temperature of the pulp according to tabulated values for sucrose solutions. The density differences were so small that they probably did not significantly affect breakage. RESULTS AND DISCUSSION The conditions of the grinding tests, computed viscosities, weight fractions finer than the feed size and values of a and ku are listed in Table I. The values of a and ku were taken from the linear portions of the log-log plots of cumulative weight fraction finer vs size for the various grinding times. The plots for tests in fluids of average viscosity 8.6 cp are shown in Fig. 1. In general all of the sets of curves were linear throughout most of the size

Jan 1, 1965

By Enid C. Plante

To extend our knowledge of the flotation behavior of sulphide minerals, the response of the following minerals to ethyl xanthate as collector was studied by captive bubble and cylinder flotation tests: antimonite (Sb2S3), arsenopyrite (FeAsS), covellite (CuS), rnarcasite (FeS2), orpiment (As&.), pyrrhotite (FeS) and tetrahedrite (4CU2S, Sb2S3). Lollingite (FeAs2) was also exarnined to determine if its behavior could be correlated with that of pyrite or rnarcasite (FeS2. Experimental Method Mineral for Flolation and Contact Tests Mineral was prepared in the manner a1ready described1 and its behavior both freshly ground and "oxidized" was studied. Tests in which the mineral was allowed to oxidize for various periods showed that a uniform response to xanthate was reached in two days or less. Oxidation Products The soluble oxidation products from most of the above minerals were measured and their effect on the flotation of the mineral studied. The mineral samples were wet ground to minus-52 mesh and deslimed, and 20 g of this material placed in 200 ml of distilled water of a measured pH value, and CO2-free air bubbled through each suspension at a constant rate (about I bubble/sec) for 5 days. It has been shown1 that the size of the mineral is unimportant in the rate of formation , oxidation products and that probably the supply of oxygen to the mineral is the rate-determining step. At the end of 5 days the pH value of the 'supernatant liquid was measured again, the mineral filtered off and the soluble products determined. Methods for estimation of sulphur acids, ferrous and ferric iron and copper have already been described.l No satisfactory method was found for antimony. Arsenic was estimated as the arsenate.2 Flotation of "Unoxidized" Minerals with Ethyl Xanthate as Collector Fig I to 3, 4. 6, show the effect of alkali and cyanide as depressants for the minerals with 25 mg potassium ethyl xanthate per liter as collector at 35°C. Wark and Cox8 have shown that with ethyl xanthate as collector, galena, pyrite and chalcopyrite show a greater tolerance to cyanide and hydroxyl ions at room temperature than at 35°C Covellite (Fig I), marcasite (Fig 2) and pyrrhotite (Fig 3) behave similarly. The independence of the curves for pyrrhotite at 35°C with respect to cyanide

Jan 1, 1949

By E. A. Gulbransen, A. Pebler

Pressure-composition isotherms have been determinedfor the systems ZrMo2 -H2 between 0" and 900°C at hydrogen pressures between 10-4 and 760 Torr. Tkese studies plus X-ray diffraction analyses of selected compositions show that these intermetallic compounds form a complete series of hydrogen solid solutions within this temperature and pressure range. The partial molar enthalpies and entropies of solution of hydrogen in the three intermetallic compounds were calculated. The solubility of hydrogen in these Laves phases can be related to their free electron concentration. ThE reaction of hydrogen with inter metallic compounds of zirconium with Laves phase-type structure has both theoretical and practical interest. The in-termetallic compounds have structures different from any of the pure metals. In addition the electron to atom ratio of the intermetallics varies appreciably. In the nuclear materials field, these materials are of interest since intermetallic compounds may exist as precipitates in commercial zirconium alloys with transition metals. From studies on the hydrogen reaction, one can establish the stability of the intermetallic compounds relative to the hydrides of the component metals. The intermetallic compounds may also be used as getters for hydrogen and as materials for hydrogen storage. This paper will present the results of equilibrium and structural investigations of the ZrCr2-H2, the ZrV2-H2, and the ZrMo2-H2 systems for the temperature range of 0" to 900°C and the pressure range of Torr to 1 atm. A complete thermochemical analysis will be made of the measurements. Some of the results have been referred to in a survey paper' covering the types of hydrogen behavior observed in zirconium alloys. LITERATURE ZrCr2 is the only intermetallic phase in the Zr-Cr system.' It exists in two allotropic modifications. Between 900" and 1000°C the hexagonal MgZa (C14) structure transforms into the cubic MgCu2 (C15) structure. Beck4 has previously shown that the intermetallic ZrCrz takes up hydrogen into solid solution up to a composition H/ZrCr2 = 1.14 at room temperature and 1 atm hydrogen. A ZrCr2 hydride was stated to have a fcc structure. The binary Zr-V system has been investigated by williams5 although Rostoker and Yamamoto 6 had given earlier a partial phase diagram. ZrV2 was the only intermediate phase found in the system. wallbaum7 reported earlier that the compound ZrV2 hp the MgZm (CJ4) type structure with a = 5.288A and c = 8.664A. This was not comfirmed by Elliot8 nor by Matthias, Compton, and corenzwit9 who reported that ZrV2 has a cubic MgCua LC15) type structure. The latter authors gave a = 7.429A. Also, several authors do not agree on the temperature of the peri-tectic horizontal. It appears that ZrV2 may exist in several modifications. A high capacity for occluding hydrogen was reported by Beck4 who found H/ZrV2 = 1.38 at room temperature and 1 atm of hydrogen. ZrMoz is the only intermetallic phase in the Zr-Mo system.10 ZrMoa is formed by a peritectic reaction of the melt with a molybdenum-rich solid solution. ZrMo2 has the C15-type structure with a = 7.59A. MATERIALS High-purity chromium, vanadium, and molybdenum were used together with grade 1 crystal bar zirconium to prepare the alloys. Table I lists the chemical analysis and the sources for the metals. Ten-gram alloy compacts were levitated and melted in an inert argon

Jan 1, 1968

By Alfredo O. Del Campo

Copper concentrate smelting has been the subject of significant improvements during the last three decades. Several new processes are being successfully applied at industrial scale, and probably no new copper smelter will be built with the old-fashioned reverberatory furnace. However, because of financial reasons, the existing reverberatory furnaces, which smelt a significant part of the copper produced worldwide, are likely to last at least another decade. Some improvements have been introduced in reverberatory smelting practice, the best known being the use of oxyfuel burners. However, efforts to optimize the reverberatory furnace operation through automatic control have not been reported. The complex and semi-continuous nature of the process makes it dificult to find a suitable strategy for its automatic control. Many factors, like fuel economy, productivity, boiler capacity, refractory wear, converter slag return, copper losses in discard slag, etc. are interconnected. The chosen control strategy should take into account all these factors to achieve good economic results. A detailed discussion of these problems is presented.

Jan 1, 1984

TEE Institute assembled on Wednesday evening at the Western University, and was called to order by President Raymond. Mr. James Park, Jr., of Pittsburgh, made the address of welcome, which was responded to by President Raymond. The Council reported the following names, with approval, for election : Ashburner, William, . . . . . San Francisco, Cal. Asmus, George, . . . . . . New York. Baillie, Nathaniel, . . . . . Uniontown, Pa. Bowie, A. J., Jr., . . . . . San Francisco, Gal. Brown, A. J., . . . . . . Treasure City, Nev. Butler, J. G., Jr., . . . . . Youngstown, Ohio. Chamberlin, J. G., . . . . . Leetonia, Ohio. Clark, R. Neileon, . . . . . Canyon City, Colorado. Cornell, A. B., . , . . . . Youngstown, Ohio. De Crano, E. C., . . . . . San Francisco, Cal. Engelmann, H., . . . . . . Salt Lake City, Utah. Faber du Faur, A., . , . . . New York. Janin, Louie, Jr., . . . . . San Francisco, Cal. Johnson, George J., . . . . . Salt Lake City, Utah., Kent, Joseph C., . . . . . Phillipsburgh, N. J. Kent, William St. G., . . . . Phillipsburgh, N. J. Liebenau, Charles von, . . . . Silver City, Idaho. McClintock, A. H., . . . . . Wilkes-Barre, Pa. Miller, Thomas N., . . . . . Pittsburgh, Pa. Millholland, James A., , . . . Mount Savage, Md. Peters, Ed. D., Jr., . . . . . Dudley, Colorado. Reese, Jacob, . . . . . . Pittsburgh, Pa. Schirmer, J. F. L., . . . . . Denver, Colorado. Smith, W. S., . . . . . . Fairplay, Colorado. Stoelting, Hermann, . . . . . Georgetown, Colorado. Sweet, W. A., . . . . . . Syracuse, N. Y. Tripple, Alexander, . . . . . New York. Van Arsdale, W. H., . . . . . Swansea, Cal. Willard, Dwight D., . . . . . Bordentown, N. J. The following resolution was then offered and passed : Resolved, That gentlemen present, not members, be invited to take part in the discussions of the Institute at the various sessions of the present meeting.

By C. G. Dunn, F. W. Daniels, M. J. Bolton

IN recent papers on interface energies in metals¹,² the concept of an equilibrium of forces has been used in the measurement of interfacial tensions. Mathematically the equilibrium of three forces is given by the relations: where the 2's are the interfacial tensions (interface energies per unit area of interface) of three phases or grains meeting at angles 21 22 and 23 (212 relates to the 1-2 boundary formed by grains 1 and 2;223 to the 2-3 boundary, etc.). If these relationships are valid, one can calculate relative values of the interface energies from measured boundary angles on specimens which have been brought to equilibrium. Since Eq 1 may be derived through a mathematical process of minimizing the grain boundary energy under the restriction that the ?'s be independent of boundary orientation: the concepts of surface tensions and equilibrium of forces are not particularly essential. To deal with the general case involving dependence of boundary energy on boundary orientation, it becomes desirable to drop certain concepts formerly held (namely that energy per unit area is identical with force per unit length or surface tension) and to use the energy concept alone. It is appropriate, therefore, to use E in place of ? in deriving and using the more general equations that express the anisotropic nature of the grain boundary energy. Herring3# ' recently has derived the required general equations using the principle of minimization of energy. Specifying the boundary orientations in terms of angles (4) measured with reference to crystal axes within the grains, Herring's equations take the form E23 + E21 cos?8 + E12 cos?2 — sin ?12 + sin?2-?E12/?12 =O [2] where the partial derivatives are measured in the direction of counterclockwise rotation of the boundaries. Eq 2 implies that an infinitesimal displacement of the triple point along the 2-3 boundary produces no change in the boundary energy. Similar equations apply for infinitesimal displacements along each of the other two boundaries. From such equations Herring obtains the following general relationship (1 + E1 E2) sin?8 + (E2 — E1) cos?3 ________ E38______________ = (1+ E2 E8) sin ?1+ (E3— E2) cos ?1 __________^5____________[3] (1 + E sin ?2, + (E1 — E8,) COS ?2 1 E28 where E1 = 1/E23- E25 and PC and c8 have similar expressions. It is apparent that Eq 3 reduces to Eq 1 when the c's vanish. Eq 3 also reduces to Eq 1 when the E'S are all equal. Shockley and Read' have pointed out one limitation to these equations. When E plotted versus 4 appears as an energy cusp, as their theory requires, for example, for the energy near a twin boundary position, then Eq 3 (and therefore Eq 1 also) no longer applies if one boundary is in the minimum energy position. One of the equations of form Eq 2, however, applies if the infinitesimal displacement is along the boundary associated with the energy cusp. From the foregoing treatment it will be apparent that equilibrium angles alone are not sufficient in general for calculating relative interface energies.

Jan 1, 1951

By I. Javandel, P. A. Witherspoon

The finite element method was originally developed in the aircraft industry to handle problems of stress distribution in complex airframe configurations. This paper describes how the method can be extended to problems of transient flow in porous media. In this approach, the continuum is replaced by a system of finite elements. By employing the variational principle, one can obtain time dependent solutions for the potential at every point in the system by minimizing a potential energy functional. The theory of the method is reviewed. To demonstrate its validity, nonsteady-state results obtained by the finite clement method are compared with those of typical boundary value problems for which rigorous analytical solutions are available. To demonstrate the power of this approach, solutions for the more complex problem of transient flow in layered systems with crossflow are also presented. The generality of this approach with respect to arbitrary boundary conditions and changes in rock properties provides a new method of handling problems of fluid flow in complex systems. INTRODUCTION Problems of transient flow in porous media often can be handled by the methods of analytical mathematics as long as the geometry or properties of the flow system do not become too complex. When the analytical approach becomes intractable, it is customary to resort to numerical methods, and a great variety of problems have been handled in this manner. One such method relies on the finite difference approach wherein the system is divided into a network of elements, and a finite difference equation for the flow into and out of each element is developed. The solution of the resulting set of equations usually requires a high speed computer. When heterogeneous systems of arbitrary geometry must be considered, however, this approach is sometimes difficult to apply and may require large amounts of computer time. The finite element method is a new approach that avoids these difficulties. It was developed originally in the aircraft industry to provide a refined solution for stress distributions in extremely complex airframe configurations. 27 Clough has recently reviewed the application of the finite element method in the field of structural mechanics.6 The technique has been applied successfully in the stress analysis of many complex structures.l, 27, 28 Recognition that this procedure can be interpreted in terms of variational procedures involving minimizing a potential energy functional7 leads naturally to its extension to other boundary value problems. In the field of heat flow, there recently have been introduced several approximate methods of solution that are based on variational principles.2-4, 17 By employing the variational principle in conjunction with the finite element idealization, a powerful solution technique is now available for determining the potential distribution within complex bodies of arbitrary geometry. In the finite element approximation of solids, the continuum is replaced by a system of elements. An approximate solution for the potential field within each element is assumed, and flux equilibrium equations are developed at a discrete number of points within the network of finite elements. For the case of steady-state heat flow, the technique is completely described by Zienkiewicz and Cheung.33 Since the flow of fluids in porous media is analogous to the flow of heat, Zienkiewicz et al. have employed the finite element method in obtaining steady-state solutions to heterogeneous and anisotropic seepage problems. 34 Taylor and Brown have used this method to investigate steady-state flow problems involving a free surface.25 The work of Gurtin has been instrumental in laying the groundwork for the application of finite element methods to linear initial-value problems.12 As a result, Wilson and Nickell have recently

Jan 1, 1969

October 16th, 1872. THE Institute assembled on Wednesday evening at the Western University, and was called to order by President Raymond. Mr. James Park, Jr., of Pittsburgh, made the address of welcome, which was responded to by President Raymond. The Council reported the following names, with approval, for election Ashburner, William, - San Francisco, Cal. Asmus, George, - New York. Baillie, Nathaniel, - Uniontown, Pa. Bowie, A. J., Jr. - San Francisco, Cal. Brown, A. J., - Treasure City, Nev. Butler, J. G., Jr., - Youngstown, Ohio. Chamberlin, J. G., - Leetonia, Ohio. Clark, R. Neilson, - Canyon City, Colorado. Cornell, A. B., - Youngstown, Ohio. De Crano, E. G., - San Francisco, Cal. Engelmann, H., - Salt Lake City, Utah. Faber du Faur, A., - New York. Janin, Louis, Jr., - San Francisco, Cal. Johnson, George J., - Salt Lake City, Utah.. Kent, Joseph C., - Phillipsburgh, N. J. Kent, William St. G., - Phillipsburgh, N. J. Liebenau, Charles von, - Silver City, Idaho. McClintock, A. H., - Wilkes-Barre, Pa. Miller, Thomas N., - Pittsburgh, Pa. Millholland, James A., - Mount Savage, Md. Peters, Ed. D., Jr., - Dudley, Colorado. Reese, Jacob, - Pittsburgh; Pa. Schirmer, J. F. L., - Denver, Colorado. Smith, W. S., - Fairplay, Colorado. Stoelting, Hermann, - Georgetown, Colorado. Sweet, W. A., - Syracuse, N. Y. Tripple, Alexander, - New York. Van Arsdale, W. H., - Swansea, Cal. Willard, Dwight D., - Bordentown, N. J. The following resolution was then offered and passed Resolved, That gentlemen present, not members, be invited to take part in the discussions of the Institute at the various sessions of the present meeting.

Jan 1, 1873

THE Institute conducts jointly with the American Society of Civil Engineers, American Society of Mechanical Engineers and American Institute of Electrical Engineers, certain activities as listed below, and is joint owner with them of certain properties situated at 29 West 39th Street in New York City United Engineering Trustees, Inc. When Mr Carnegie made his gift, "for the erection of a suitable union home" for the engineering societies, United Engineering Trustees, Inc (then United Engineering Society) was chartered under Chapter 703, Laws of the State of New York, 1904, for "the advancement of the engineering arts and sciences in all their branches, and to maintain a free public engineering library" The Corporation was further empowered to acquire real and personal property and to use, maintain and occupy it, with the provision that any building erected by the Corporation shall be used perpetually as a meeting place and headquarters for the Founder Societies Thus the Carnegie gift realized the ideal of bringing the engineering societies together under one roof, and the Corporation through its members nominated in equal numbers by the four Founder Societies had the necessary authority to act for the Founder Societies in their joint interests in owning and operating for them not only Engineering Societies Building, but in the course of time, Engineering Societies Library, and

Jan 1, 1952

By Wm. R. Webster

This is a contribution for the proposed new discussion on the physics of steel. The former discussion on the subject started with the consideration of five papers presented at the Chicago meeting in 1893, and continued for several years. The Suggested Lines of Discussion, prepared by Doctor Howe, covered a wide field and added greatly to the success of the work. Naturally, the first step in a new discussion will be to remodel and bring up to date the old Suggested Lines of Discussion so as to embody all the important advances in the metallurgy of steel that have a bearing on the physics of steel and keep the papers and discussions within the field of work undertaken. This paper will be devoted to the practical application, in rolling steel, of the effects of carbon, phosphorus, and manganese on its tensile strength, with some suggestions on further research work. Dr. J. E. Stead, in his paper Influence of Some Elements on the Mechanical Properties of Steel,' gave a complete review of all that had been done during the past thirty years. He gave full credit to all investigators who worked on these lines, also their results, with his views on same, and in many cases his own results. All of this data and much new valuable information were put in convenient shape for reference and study. To do this required a great deal of work, which is fully appreciated by the steel manufacturers and investigators. The variations in the values given by the different investigators for the increase of the tensile strength of steel for each 0.01 per cent. of carbon, phosphorus, and manganese were largely due to the steels they worked on, the large or small variations in the amount of the elcments present, and the omission to take into consideration all the factors, from the blast furnace through to finished rolled material, that affect the character of the steel. For instance, a poorly made dirty steel requires considerably more carbon to give the same ultimate strength than a well-made clean steel with the same phosphorus and manganese content.

Jan 1, 1922

By Wm. R. Webster

This is a contribution for the proposed new discussion on the physics of steel. The former discussion on the subject started with the consideration of five papers presented at the Chicago meeting in 1893, and continued for several years. The Suggested Lines of Discussion, prepared by Doctor Howe, covered a wide field and added greatly to the success of the work. Naturally, the first step in a new discussion will be to remodel and bring up to date the old Suggested Lines of Discussion so as to embody all the important advances in the metallurgy of steel that have a bearing on the physics of steel and keep the papers and discussions within the field of work undertaken. This paper will be devoted to the practical application, in rolling steel, of the effects of carbon, phosphorus, and manganese on its tensile strength, with some suggestions on further research work. Dr. J. E. Stead, in his paper Influence of Some Elements on the Mechanical Properties of Steel,' gave a complete review of all that had been done during the past thirty years. He gave full credit to all investigators who worked on these lines, also their results, with his views on same, and in many cases his own results. All of this data and much new valuable information were put in convenient shape for reference and study. To do this required a great deal of work, which is fully appreciated by the steel manufacturers and investigators. The variations in the values given by the different investigators for the increase of the tensile strength of steel for each 0.01 per cent. of carbon, phosphorus, and manganese were largely due to the steels they worked on, the large or small variations in the amount of the elcments present, and the omission to take into consideration all the factors, from the blast furnace through to finished rolled material, that affect the character of the steel. For instance, a poorly made dirty steel requires considerably more carbon to give the same ultimate strength than a well-made clean steel with the same phosphorus and manganese content.

Jan 1, 1922

By Wm. R. Webster

THIS is a contribution for the proposed new discussion on the physics of steel. The former discussion on the subject started with the consideration of five papers presented at the Chicago meeting in 1893, and continued for several years. The Suggested Lines of Discussion, prepared by Doctor Howe, covered a wide field and added greatly to the success of the work. Naturally, the first step in a new discussion will be to remodel and bring up to date the old Suggested Lines of Discussion so as to embody all the important advances in the metallurgy of steel that have a bearing on the physics of steel and keep the papers and discussions within the field of work undertaken. This paper will be devoted to the practical application, in rolling steel, of the effects of carbon, phosphorus, and manganese on its tensile strength, with some suggestions on further research work. Dr. J. E. Stead, in his paper Influence of Some Elements on the Mechanical Properties of Steel,1 gave a complete review of all that had been done during the past thirty years. He gave full credit to all investigators who worked on these lines, also their results, with his views on same, and in many cases his own results. All of this data and much new valuable information were put in convenient shape for reference and study. To do this required a great deal of work, which is fully appreciated by the steel manufacturers and investigators. The variations in the values given by the different investigators for the increase of the tensile strength of steel for each 0.01 per cent. of carbon, phosphorus, and manganese were largely due to the steels they worked on, the large or small variations in the amount of the elements present, and the omission to take into consideration all the factors, from the blast furnace through to finished rolled material, that affect the character of the steel. For instance, a poorly made dirty steel requires considerably more carbon to give the same ultimate strength than a well-made clean steel with the same phosphorus and manganese content.

Jan 3, 1921

By Zay Jeffries

AMONG the various metals with low specific gravity, two, aluminum and magnesium, are used in the nearly pure state or as bases for light-weight alloys. Although the production of magnesium is only about one-twenty-fifth that of aluminum, a higher percentage of its output is used in the transportation industry than that of any other metal. The per-centage varies from year to year but, on the average, more than three-fourths of the magnesium production has been used for this purpose. In the United States, about 40 per cent of the aluminum production is used for transportation purposes. It seems obvious that equipment demanding repeated movement with need for rapid acceleration and deceleration should be as light in weight as the economics of engineering materials will permit. There are, however, differences of opinion with reference to both the economics and the engineering aspects of this subject. Tables 1 to 7 inclusive relate to the principal light-metal materials currently used in the transportation industry. These, with the accom-panying titles and footnotes, are in the main self-explanatory. Although the variations in mechanical properties can be easily seen from the tables, it should be kept in mind that the values given are for ordinary tempera-tures and that the changes in properties with temperature are not the same for the different alloys. Also, the corrosion properties cannot be deduced accurately either from the compositions or from the physical properties. Again, certain of these alloys are used because they possess desirable combinations of properties not listed in tine tables, including heat conductivity, coefficient of expansion, machinability, ease of casting or working, light reflectivity, anodic coating characteristics, etc. These, together with variations in prices, must be given careful analysis to effec-tively utilize the light alloys. Some of the alloys listed in the tables are new and some are old, but all are standard. Even the older alloys are available in new shapes and larger sizes than heretofore, and all are used in the transportation industry in structures of new design. Certain of the applications of specific alloys will be touched upon in the following brief history of the use of the light metals in transportation.

Jan 1, 1936

WE the undersigned, being all persons of full age and citizens of the United States, and a majority residents of the State of New York, desiring to form a corporation pursuant to the provisions of the Membership Corporations Law for the purpose of incorporating, as provided in Section 5 of Article I. of said law, the existing unincorporated association known as American Institute of Mining Engineers, do hereby make, acknowledge and file this Certificate for that purpose, and do Certify as follows: I. That the American Institute of Mining Engineers is an unincor¬porated association organized and existing with the object of promoting the arts and sciences connected with the economic production of the useful minerals-and metals and the welfare of those employed in these industries by means of meetings for social intercourse and the reading and discussion of professional papers, and to circulate by means of publi¬cations among its members and associates the information thus obtained. II. That the persons duly appointed or designated to manage the affairs of said association are designated by the rules thereof Members of its Council; that the undersigned are all members of said Council as the same was constituted on the 29th day of December, 1904. III. That on said last-mentioned date a regularly called meeting of said association was held at its office in the Borough of Manhattan, City of New York; that thirty days before such meeting notice of the intention to incorporate said association was given by mail to each member thereof whose residence or post-office address is known; that at said meeting the following resolutions were offered, seconded and duly adopted by the unanimous vote of all its members then present, to wit: "Resolved, That it is the sense of the members and associates of the American Institute of Mining Engineers in general meeting assembled that it is desirable and necessary for the well being of said association and its members and for the furtherance of the objects for which the same has been formed, that said association incorporate under the Membership Corporations Law of the State of New York;

Jan 1, 1923

By Thomas V. Falkie, Robert Stefanko

Much has been said and written recently about the manpower problem in the mining industry. The coal segment of the industry has been scrambling to staff and man its companies and operations in order to accommodate the current boom, and there are some interesting side- lights and developments which deserve further attention from coal mining people. This column will deal with the manpower problem in general and the plight of the professional-the mining engineer-in particular. At this point in the game, it is desirable and perhaps necessary to ask ourselves if there really is a manpower problem and, if so, how serious it is. Suprisingly, there are varying and conflicting answers to this question. If we are talking about warm bodies, then in most mining areas there is no problem. If, however, we are talking about skilled or trained people-at all levels-there are apparently serious shortages, especially in the coal industry and in the U. S. Bureau of Mines. To define quantitatively the present and future need for mining professionals is a formidable task, to say the least. Without pretending that these figures are anything but an educated guess, we feel there is an immediate need for about 1000 mining engineers right now and a continuing need for about 300 mining school graduates per year (double last year's number) for the next ten years in order to take up the slack, provide for attrition and maintain a normal growth rate. Mining companies, large and small, are just now beginning to realize that the industry is undergoing a revolution, It is no longer possible to design, build and operate coal mines by the "seat of the pants." Production demands, the new health and safety law and the inevitable new legislation on surface mining will require more engineering, more planning and new technology. There are mine operators who need mining engineers and don't even know that they need them. This could mean rough going for the small operator. It surely means that there will be a trend toward increasing the ratio of technical to nontechnical employees and the ratio of technical employees to dollars of capital towards levels comparable with other highly mechanized industries.

Jan 1, 1971

AN announcement of the annual meeting to be held in New York, Feb. 14 to 17 inclusive is being mailed to all members. Particular attention is called to the necessity of asking for certificates when you purchase your ticket in order that all may secure reduced return fares.

Jan 1, 1927

By L. Dudley Stamp

In my last report on Petroleum in Burma and India1, details were given of production and development up to 1932. It was pointed nut, that the only statements available for Burma were those published officially by' the Government of India in the Annual Review of the Mineral Production of India (Records of the Geological Survey of India), which are issued about 10 or 11 months after the close of the year. Operations in Burma are almost entirely in the hands of three companies—the Burmah Oil Co., the British Burmah Petroleum Co. (with its subsidiary, the Rangoon Oil Co.) and the Indo-Burma Petroleum Co.—and these companies preserve a policy of secrecy, so that details are not available of new wells, depth, wells abandoned, or of other figures, except in so far as the Government considers it advisable to publish the information in its possession. GeneRal Developments in 1933-1934 As predicted in 1933, there have been no spectacular developments and no new fields have been discovered. Nor are there any new indications of a likelihood of fresh discoveries. The policy of extremely careful exploitation. has been continued and intensified; production is being maintained at an almost steady level and can be so maintained for many years to come—indeed, it is the policy of the leading company to permit refinery and local market requirements to dictate the production required. Contrary to experience in practically every other part of the world, India has shown a slightly decreased demand for petroleum products—especially kerosene, but also for gasoline. The increased use of electricity would explain the lower demand for kerosene, but the falling off in the demand for gasolinc can only be attributed, according to the Chairman of the Burmah Oil Co., to the depression and to the incidence of heavy taxation. In India (including Burma) as a whole, production was 305,018,751 Imperial gallons in 1931 (8,714,822 U. S. barrels); 308,606,031 Imp. gal. in 1932; 306,009,022 in 1933 and is estimated at 308,000,000 in 1934.

Jan 1, 1935

By W. A. Nagel, R. P. Alger, H. Sherman, J. Tittmann

A sidewall epithermal neutron tool has been developed to substantially reduce environmental effects that have previously complicated neutron log interpretation. Designed for operation in uncased wells, the device provides increased accuracy in both liquid-filled and empty holes. A brief discussion of neutron moderation, diffusion and capture shows that logs using epithermal neutron detection depend on a smaller number of formation-characterizing parameters than those using thermal neutron or capture gamma ray detection. Thus, they come closer to providing an unambiguorls determination of hydrogen content. In this new device a directionally sensitive epithertnal neutron detection system has been incorporated in a side-wall source-detector skid to minimize borehole effects. The effects of variations in borehole size and shape, mud type, temperature and salinity are greatly reduced. Small residual borehole effects are then computationally accounted for in the surface control panel to provide a borehole-corrected neutron log. The log presents a direct recording of neutron-derived porosity on a linear scale. With corrections for borehole effects already applied, this direct recording of porosity simplifies log interpretation. Furthermore, comparison with a linear porosity presentation of a formation density log permits sandstones, limestones and dolomites to be readily identified. Thus, in complex or variable lithology, porosity is determined with greater accuracy and reliability than heretofore. Laboratory data and field results demonstrate the improvements in neutron logging afforded by this new side-wall epithermal neutron logging device. INTRODUCTION The new Sidewall Neutron Porosity (SNP) logging system, designed for use in uncased wells, provides reliability and accuracy never before achieved with neutron logs. The effects of variations in borehole diameter and shape, fluid salinity, mud weight and temperature—parameters that have long complicated neutron log interpretation— are suppressed or corrected for by this sidewall epithermal neutron detection system. Furthermore, to simplify interpretation the SNP log presents a direct recording of computed porosity on a linear scale. The performance improvements achieved by this new system arise primarily from the combination of two im- portant design features. First. though not unique to this new tool, an epithermal neutron detection system is used,',' Epithermal neutron detection substantially reduces the perturbing influences of the thermal neutron absorption properties of rock matrices and water salinity. Second, the neutron detection system is mounted in a directionally sensitive sidewall skid to greatly minimize borehole effects. The purpose of this paper is to explain briefy the advantages offered by the detection of epithermal neutrons, to describe the SNP equipment and the log, to present calibration and correction data and to give examples of interpretation methods made especially convenient by this new system. ADVANTAGES OF EPITHERMAL NEUTRON DETECTION Epithermal neutron detection, of all the neutron methods in current commercial use, provides the simplest determination of formation hydrogen content. Advantages of epithermal neutron detectors, as compared with thermal neutron and gamma ray detectors, are probably best explained by a brief review of the life of a source-emitted neutron. A fast neutron from the source will eventually be cap-tured by the nucleus of an atom. However. before capture is likely to occur, the fast neutron (energy of 100,000 electron volts (ev) or more) will be slowed down until it is in thermal equilibrium with its surroundings. The neutron is then considered to be a "thermal" neutron (average energy of 0.025 ev at 25C). The overwhelming majority of the slowing down thus occurs in reaching epithermal energies (energies just above thermal—0.5 to several ev). After reaching thermal energy. the neutron will "diffuse" through the formation with, on the average, no further energy change until capture. Upon the capture of the thermal neutron, relatively high energy gamma rays arc usually emitted. Hydrogen plays a very important role in the process of slowing down fast neutrons. On the other hand, the absorption effects of water salinity and low concentrations of other strong thermal neutron absorbers—relatively unimportant in the moderation process-—are very important in thermal diffusion, capture and the production of gamma rays. Thus, by detecting only epithermal neutrons with the SNP, spurious effects due to these thermal neutron absorbers are greatly minimized as compared to the effects on tools using thermal neutron or gamma ray detectors. The epithermal neutron detection system affords another important advantage. Log response in various litho-

Jan 1, 1967

By A. E. Nehrenberg

THE mechanism by which austenite forms in steels has received a great deal of attention in the literature in past years.'-'* Our present knowledge concerning this mechanism has been recently summarized quite concisely by Bain and Vilella,1 while a few years ago the literature was carefully reviewed by Roberts and Mehl.² The consensus is that any ferrite-carbide interface is a potential site for the nucleation of austenite during heating above the Acl temperature, and that the new austenite generally grows freely to produce approximately equiaxed grains, whether the carbides are initially present in the lamellar or the spheroidal form. In the case of eutectoid steels, growth of the new grains of austenite continues until contact is established with other grains. Then growth stops and an initial austenite grain size is established which does not change until the heating is continued to some high temperature at which grain coarsening begins. In the case of pearlitic steels which are not of eutectoid composition, the proeutectoid ferrite or carbide may interfere with the growth of the austenite if the temperature is not above that designated the A63 or the Acm, respectively. Although a large amount of work has been done to establish the mechanism of austenite formation in steels, it became clear to the present author while he was studying the transformation characteristics of a new 0.25 C Mn-Si-Ni-Mo hypoeutectoid steel" that the manner in which austenite grows in steels depends upon some factor, or factors, not previously considered. This was indicated by the fact that when this steel in the spheroidized condition was heated above the Ae1 temperature the new austenite which was formed did not envelop the carbides and grow in an equiaxed manner as described by Bain³ or spheroidized steels. Instead, in this steel, the austenite was observed to grow much more readily in certain directions than in others with the result that at temperatures within the Ac1-Ac³ ransformation range the austenite grains were acicular in shape. The excess ferrite was also found to be acicular with the distribution of these phases being such that a lamellar pattern was developed. This unusual directional growth of austenite in this new steel initially in the spheroidized condition is illustrated by fig. 1. A search of the literature revealed that this type of growth was not necessarily peculiar to this steel for similar microstructures had been observed by other investigators.4-8 However, the full significance of these microstructures does not appear to have been appreciated, and no work has been done to determine the conditions responsible for this directional growth of austenite or to arrive at an understanding of it. It was for this purpose that the work described in the present paper was carried out. Material: During the course of this investigation a total of 15 steels was studied. They consisted of hypoeutectoid, eutectoid and hypereutectoid carbon steels, and hypoeutectoid and hypereutectoid alloy steels, all of which were obtained in the annealed condition from commercial warehouse stock. As received, the carbon and alloy hypereutectoid steels had microstructures which consisted of spheroidal carbides in ferrite, whereas the eutectoid steel and the hypoeutectoid steels were pearlitic. The grades of steel represented were 1050, 1080, 10110, 3310, 4140, 4340, 4615, 6145, 8620, 9260, 9442,

Jan 1, 1951