Search Documents

By R. H. Richman, F. Borik

A 0.3 pct C-12 pct Cr-6 pct Ni steel was rolled to 93 pct reduclion in area as austenite at 510°C, and then partially transformed as desired to ~rlartensite by qnenching to - 196°C. Pole figures for the austenitic matrix and for the martensitic product were separately determined by an X-ray transmission method. The deforitration texture of' the warm-worked austenite is characlerized by (110)(225) components, and is thus closely similar to those produced in a brasses. The pole jigure of the martensite in partially transformed material agrees well with that which can be constructed by transfortnation of the {110)(225) orientations according to either the Kuvdjuniov- Sacks or the Nishi-yatuu relatiotship. Howeuer, an important result of this construction is that me-third of the predicted orientations are missing. A graphical analysis can then be used to show that in deformed austenite certain crystallographic variants of martensite (related to the most probable austenite slip systems) are suppressed, resulting in this preferred transformation. The evidence for preferred transformation is corroborated by the measured elastic anisotropy of warm-rolled and fully transformed H-11 steel. EXTENSIVE plastic deformation of a polycrystal-line aggregate in a manner that causes flow predominantly in one direction results in a preferred orientation of the constituent crystallites. The particular orientations that are produced depend upon the crystal structure and composition of the material, as well as upon the temperature, mode, and degree of deformation; in any case, the preferred crystallo-graphic orientations, or textures, are reflected in directionality of mechanical properties. Although such anisotropy may be exploited in certain specialized applications, it is more commonly diminished or eliminated by heat treatment lest it interfere undesirably in subsequent forming operations or in structural design. In the recently developed thermomechanical treatments that significantly enhance the strength of some steels,1,2 considerable deformation of the metastable austenite prior to the martensite transformation is essential to the strengthening process. If the austenite is textured by the deformation, and if the transformation to martensite proceeds according to one of the relationships established for transformation in annealed austenite, then it must be expected that the martensite will also possess a preferred orientation even though the multiplicity of martensite orientations possible in a given austen- ite crystal will tend to restore some degree of randomness. The existence of a residual anisotropy, both mechanical 3-6 and crystallographic,' has been substantiated. In the latter crystallographic investigation, preferred orientations were determined for the martensitic structure of an SAE 4340 steel rolled 72 pct as austenite at 833°C and then quenched. However, the choice of a composition that transformed almost completely to martensite during the quench to room temperature did not permit direct measurement of the prior austenitic texture. In fact, when the "ideal orientations'' associated with well-known fcc rolling textures were converted, alone or in combination, to martensite according to the Kur-djumov-Sachs (K-s)' or Nishiyama8 relations, the agreement obtained with the observed martensite texture was only fair at best. Recently a pertinent aspect of the austenite to martensite transformation was reported by Bokros and parker,10 who found that certain habit-plane variants of martensite were suppressed by tensile deformation of Fe-31.7 Ni single crystals prior to the necessary subzero cooling. It might be anticipated that the consequences of such preferred transformation are sustained during the formation of martensite in warm-worked austenite that has a well-developed deformation texture. The present investigation was undertaken first to establish more firmly the relation between preferred orientations in plastically deformed austenite and in the resulting martensite, and second to examine the textures for evidence of deformation-induced preferred transformation. EXPERIMENTAL PROCEDURES An alloy containing 0.3 pct C, 12 pct Cr, 6 pct Ni, and the balance iron, was selected because the mar-tensite-start temperature (M,) of about -100°C allowed convenient experimental manipulation of either austenite or martensite at room temperature. Furthermore, this composition can be readily deformed as metastable austenite at moderately elevated temperatures without intervention of appreciable isothermal or athermal decomposition products. The alloy was austenitized at 1150°C, aircooled to 510°C, rolled unidirectionally at this temperature to 93 pct reduction of cross-sectional area, and finally oil-quenched to room temperature. Partial transformation to martensite was accomplished by quenching to -196°C as needed. The rolled stock was reduced in thickness from 0.067 to 0.010 in. by etching in a solution of 5 pct HC1, 45 pct HNO3, and 50 pct water, and further thinned by careful mechanical polishing to maintain the two sides of the sheet parallel within 0.0003 in. After mechanical polishing to 0.005 in., electropolishing in 1:9 perchloric-acetic acid solution produced a final thickness of 0.002 in. The preferred orientations were determined from

Jan 1, 1968

By J. D. Livingston, H. E. Cline

Cu-Pb alloys in the vicinity of the monotectic composition have been directionally solidified under a high temperature gradient at rates up to 2 X l0-' cm per sec. Over a wide range of compositions, high growth rates yield a composite structure consisting of continuous rods of lead in a copper matrix. This range of compositions increases with increasing growth rate, in agreement with arguments based on the relative velocities of composite growth and the growth of copper dendrites or lead drops. The breakdown of the composite structure at slow growth rates is explained in terms of the relative interphase surface energies. The observed interrod spacings of the composite structure are large compared with the predictions of the Jackson-Hunt equations of eutectic growth. ThE directional solidification of many eutectic alloys produces fine composite structures of parallel lamellae or rods. There has been considerable interest not only in the fundamentals of this two-phase solidification process,'-3 but also in the interesting physical properties produced by such regular and aniso-tropic microstructures. Composite structures can be grown only over a limited range of composition, beyond which coarse primary dendrites of one phase appear. In organic eutec-tics, this composition range of composite structures has been shown to increase with increasing growth rate.7"10 These results were explained in terms of the relative velocities of composite (coupled) growth and dendritic growth. Although similar arguments should apply to metallic eutectics,11-13 suitable experimental results are lacking. In contrast to the work on eutectics, the directional solidification of monotectic alloys has received little attention. (The monotectic reaction is similar to the eutectic reaction, except that one of the resulting phases is a liquid, which subsequently solidifies in a separate reaction at a lower temperature.) Directional solidification of some monotectic alloys'4715 yields regular rodlike microstructures, whereas in other cases macroscopic separation of solid and liquid phases occurs.16 chadwick17 rationalized these results in terms of the probable relative magnitudes of the various interphase surface energies. A recent study of chill-cast Cu-Pb alloys18 revealed a fine rodlike microstructure in alloys near the monotectic composition. It was decided to investigate the directional solidification of such alloys, and to determine the range of composition and growth conditions yielding composite structures. The Cu-Pb system is convenient for such a study, both because it is simple metallurgically, with no compound formation and negligible solid solubilities, and because its basic properties are well-documented. Recent literature on the Cu-Pb system includes studies of bulk thermo-dynamic properties,'g surface energies,20"21 densi-ties,25 and diffusion constants.a6 A similar study of the directional solidification of Cu-Pb alloys was recently undertaken, independently, by Kamio and Oya." EXPERIMENTAL Alloys were prepared by melting 99.999 pct Cu and 99.999 pct Pb in a graphite crucible, stirring well, and pouring into a cold graphite mold. Rods 0.175 in. in diam were machined from the ingots. Alloy compositions studied ranged from 25 to 55 wt pct Pb. Samples were placed in graphite crucibles 5 in. long with 4 in. OD and 0.035-in. walls. They were melted under flowing argon in a vertical, two-zone. platinum -wound furnace. A voltage stabilizer was used to minimize fluctuations in input power. The narrow specimen diameter minimized convection. Directional solidification was achieved by driving the crucible downward into a +-in. hole in a water-cooled copper toroid. The toroid was located immediately below the narrow end zone of the furnace. The end zone was separately powered to maintain high local temperature. Therefore a high temperature gradient (approximately 300 deg per cm) was maintained in the specimen throughout the run. The crucible motion was screw-driven. and a wide range of drive speeds were available. The limited rate of heat removal caused a thermal lag in the specimens at high drive rates. However. temperature-time curves from thermocouples imbedded in a representative sample indicated that the average growth rate still approximately equaled the drive rate. Although the specimens were initially homogeneous, melting and re solidification redistributed the lead. producing composition variations of several percent along the specimen length. (During melting. lead melted first and ran down the sample surface. Rapid freezing tended to reproduce the resulting composition gr~dient, but slow freezing did not because a slow-moving interface tended to reject lead. as discussed later.) To determine local composition. ;-g samples were cut from regions exhibiting various microstructures and were chemically analyzed for lead content. Micrographs were taken on as-polished or lightly etched surfaces. Three-dimensional structure of the lead network was viewed with a scanning electron microscope after removal of some of the copper matrix with nitric acid. RESULTS Several different microstructures are observed, depending on composition and drive rate. Because melting and resolidification produced composition gradients, results are best presented in t&ms of final local composition, rather than initial or average composition. The ranges of local compositions and drive

Jan 1, 1970

By R. V. Ramani, R. Stefanko, P. C. Thakur

The effects of diesel exhaust on mine ventilation systems are discussed. Mathematical models for emission of gaseous pollutants from diesel engines and their dispersion into mine air have been developed. Situations likely to prevail in mines were originally modeled using partial differential equations, but only simplified solutions are presented here. Validity of these models has been established by field observation of the growth of carbon monoxide concentrations in mine air environment. Consequently, these models can be used for air requirement calculations for diesel engines in underground mines.

Jan 1, 1977

By V. M. Frey

IN 1936 the foreman at one of the oldest limestone quarries in northern Virginia discovered the remains of three old well-drill holes that contained dynamite. As consulting engineer for the property, I was then called upon to devise a method for removing the explosive. As no exact formula for the handling of unexploded dynamite exists, the proper steps for removing it must always be dictated by local conditions. A description of the procedure in this case may, therefore, be of interest to others faced with a similar problem.

Jan 1, 1939

By P. L. Allsman

A method of analyzing blasting action indicates that major cost savings are possible by revising practice and bringing the classical blasting formulas up to date; difficult problems such as taconite and throw-breakup can be attacked by engineering Denonation pressure — the peak pressure developed by the explosive reaction; "shatter blasting." Average detonation pressure — the average pressure over the time the reaction continues; "heave blasting." Radial presswe — the stress in a radially expanding sphere about the detonation. Corresponds to the diminishing peak pressure. Lateral stress - the stress in a circumferential direction, induced by outward movement of the rock away from the detonation. Limiting stress or Slim— the rock property at which failure will occur in the case at hand; may be tensile or compressive strength, or combinations. Recent developments in explosives technology, following the advent of nuclear explosions, have led to a rather complete understanding of their action. A survey was made for the purpose of uncovering any knowledge which might be applicable in the mining and quarrying industries, the principal users of explosives. Although no revolutionary techniques have become apparent, much basic data pertaining to blasting — fortunately not classified — have been developed by recent research, from which a good general understanding of the process can be derived. It is hoped this explanation of the scientific principles governing explosive action, together with a proposed analysis of blasting practice, will further the development of mining engineering. NATURE OF THE REACTION: The phenomenon of explosion, termed detonation, is in reality a rather complex chemical reaction, and as such is completely explainable by physical and chemical laws. Detonation is characterized by high temperature and pressure, extreme rapidity — often being complete within one microsecond — and most importantly by formation of a shock pulse which accompanies the reaction zone. As with any chemical reaction, there is a critical value of temperature and pressure below which detonation can not occur; this is termed the "critical point". Whereas an explosive substance will decompose slowly at ordinary temperature, with the formation of gases which readily dissipate; at elevated temperature the reaction is considerably speeded. If pressure is suddenly applied at some point in an explosive medium, adiabatic compression results, and the temperature is locally raised. When the temperature becomes high enough the decomposition will be so rapid that the gaseous products do not have time to dissipate, but contribute to a further build-up of pressure. This, in turn, furthers adiabatic temperature rise over a widening area, and with any heat generated by an exothermic reaction, causes a rapid increase in temperature. Both temperature and pressure are spontaneously built up in this manner until the critical point is reached, resulting in detonation. The values of pressure and temperature necessary to create detonation are established by the unusual nature of the process. If temperature alone is raised above the critical point, without sufficient increase in pressure, deflagration or "low-order detonation" occurs. In the true, or "high-order detonation", the shock pulse resulting from the violent decomposition becomes an integral part of the reaction, and itself aids in increasing the detonation

Jan 1, 1961

By M. J. Pool

The partial molar heats of solution in liquid tin of cadmium, silver, tellurium, and zinc have been measured at 655°. 700°, and 750°K by liquid-metal solution calorimetry. Silver, cadmium, and zinc are endothermic at these temperatures while tellurium is exothermic. Only the heat of solution of silver depends on composition while all four elements show a temperature-de pendent heat of solution. The heat of solution of tellurium is constant up to 0.6 g-at. pct, becomes increasingly more exothermic, and reaches a limiting value at 1 g-at. pct Te. The limiting value has been used to calculate the heat of formation of SnTe at 750°K. The heat effects associated with the dissolution of the compounds Ag2 Te, CdTe, and ZnTe in liquid tin were measured at 750°K. These values are cotnOined with the measured hat effects at 750°Kfor silver, cadmium, tellurium, and zinc to detertrline the heats of formation of the telluride compounds. Cadmium lelluride exhibits a heat of dissolution which has a compositional dependence. THERE is a considerable amount of interest in the compounds of tellurium because of their electronic properties. Both cadmium and zinc tellurides are thermoelectric materials and considerable work has been done on their electronic properties but a limited amount of data is available on their ther-modynamic properties. This work was undertaken to elucidate the heat of formation data on cadmium and zinc telluride. Since both cadmium and zinc are in Group II it seemed to be of interest to compare the values obtained for them with the heat of formation of a Group I telluride. Silver telluride was selected for this comparison. In the course of the work it was also possible to determine the heat of formation of tin telluride and therefore to make a comparison of some of the Group I, 11, and lV tellurides with the metallic elements silver, cadmium, and tin being in the same period. There is also a great deal of interest in the energetic changes which occur upon addition of solute elements to a common solvent. This investigation provided an opportunity to study the partial molar heats of solution of silver, cadmium, tellurium, and zinc in liquid tin. The partial molar heats of solution are of theoretical interest because solute-solute interactions are a minimum in dilute solutions and application of solution models is simpli- fied. In order to complete the analysis of solute-solute and solute-solvent interactions the temperature dependence of the partial molar heats of solution was also measured. MATERIALS AND EXPERIMENTAL PROCEDURE All materials were of the highest purity available. The silver, zinc, cadmium, and tellurium were obtained from American Smelting and Refining Co. and were reported to be 99.999 pct pure. The silver telluride, zinc telluride, and cadmium telluride were obtained from Atomergic Chemetals Co., a division of Gallard-Schlesinger Chemical Manufacturing Corp., and were electronic-grade material of 99.999 pct purity. Tin used for the solvent bath and for calibration was obtained from the Vulcan Manufacturing Co. and was reported as being 99.99 pct pure. The liquid-tin solution calorimeter used in this work is similar in principle to the differential twin-type calorimeter described by K1eppa.l Two of three identical calorimeter wells are used together during any set of experiments, one well being active and the other being passive. The wells are positioned 120 deg apart in an aluminum calorimeter block. Each well contains a multijunction thermopile and a Pyrex test tube to hold the liquid metal bath. Forty-eight of the thermopile junctions are distributed over the surface of each calorimeter well adjacent to the test tube and serve to integrate the heat effects occurring. The other forty-eight are next to the aluminum calorimeter block. The thermopiles for the three wells are connected differentially so that any change in temperature at the outer junctions (which will be the same for both wells because of the high conductivity of the aluminum block) will oppose for the two wells and result in no shift of the zero. The electrical output represents the true temperature difference between the two reaction vessels. A reaction occurring in the active well gives a comparison with another body of very similar thermal properties. In this way, any spurious heat effects due to slight temperature drifts within the entire calorimeter block are eliminated. The output of the differential thermopile goes to a dc amplifier with multiple ranges of from * 10 pv to 1 30 mv. The output of the amplifier is then fed into a Leeds and Northrup strip-chart recorder. The adiabatic temperature change is then calculated using the technique of Howlett, Leach, Ticknor, and ever.' The aluminum calorimeter block is contained in a cylindrical furnace with main and control heaters

Jan 1, 1965

By J. C. METCALF

MORE than 80 per cent. of the iron produced in the United States and over 30 per cent. of the world's annual production is obtained in the Lake Superior district. Though iron ore was discovered on the Marquette range in 1844, the poor transportation facilities retarded the development of this region for many years. The structure of the Lake Superior basin is essentially an east-west synclinorium with steep dips on the south side of the lake and considerably flatter ones on the north and west. The Upper Huronian series, which -is the iron-bearing one of the formation, on the south side of the lake dips north from 55' to 80°, and on the north side dips south from 8" to 200. The series has been subjected to local folding and faulting, which have influenced the development of the mining systems used.

Jan 1, 1921

By Donald H. McLaughlin

PRICES paid for goods and services in paper currencies are undoubtedly determined by many interrelated factors, but among them none is more specific in pushing prices toward higher and higher levels than the vast increase in debts and monetary obligations of our own and practically all major governments. There is nothing unorthodox in the situation in which the gold miners find themselves today. With wages and the prices of all materials required in the production of gold at the high levels characteristic of a period of prosperity, phony or otherwise, and with shortages of both men and machinery to contend with as well, the spread between the returns in paper dollars that must be accepted for gold in the United States and the cost of producing it is rather painfully small for most producers. Technical

Jan 1, 1948

By Pradeep K. Rohatgi, David N. French, Surendar M. Jain, Clyde M. Adams

The effect of solute concentration and diffussivity on dendritic solidification of dilute binary aqueous solutions has been investigated; chlorides of sodium, potassium, lithiurn, and hydrogen were used as solutes. Dendrite spacings were measured in spherical droplets and in unidirectionally solidified specimens. In the droplets, the freezing rate is uniform over the entire specimen and remains constant from the beginning to the end of solidification. In the unidirec-tionally frozen specimens the freezing rate varies within a given volume of liquid during the solidification cycle; in addition, it varies with location uithin the specimen. Mass transport analysis has been used to calculate the supersaturation, AC, supercooling, AT, and transcerse growth velocity, V , of ice dendrites during solidijication from the dendrite spacings measured in the droplels. The ice dendrite spacing in a given solute increases lineary with the solule concentralion at a fixed freezing rate. The ualues of AC, AT, and V increase with an increase in solule concentration. The value of AT in the aqueous solution is of the same order of magnitude as in Al-Cu alloys of the same concentration; the dendrite spacings in Al-Cu alloys also increase with an increase in solute concentralion. For the jamily of aqueozrs solulions incestigaled, the dendrite spacing increases linearly with solute diffusivity at fixed values of concertralion and freezing ,rate. The values of ?C and ?T decrease, whereas the value of V increases with an increase in solule diffusicity. The measured dendrite spacings , L, can be expressed by the relatiun: L = K;(dfa/db) 4 K2C +K3D - K4 where dfs/d? is-change in fraction solid with time (freezing rate), C is solute concentration, D is solute diffusivit K1 = (14 * 4)pmin1'2, K2 = (70 ± 10) pl (moles)- K3 = (24 r 3) . l05 psec (cm)-~. K. = -132 ± 10) 1. FREEZING of solutions is almost always an ehunmix-ing" process because the composition of crystallizing solid generally differs from that of the parent liquid. " Solute concentration and transport are therefore in]portant considerations in solidification of solutions. The influence of these factors on the dendritic solutions produced from metallic solutions is of practical significance since the properties of the solid aggre-gate are often strongly influenced by dendrite spacing.''' Alexander and Fthines3 found that dendrite spac- ings generally increase with solute concentration in several metallic systems. Michael and Bever1 have observed an increase in a aluminum dendrite spacings in dilute A1-Cu alloys. Rohatgi and AdamsJ have reported a linear increase in a aluminum dendrite spacings with increasing copper contents up to 28 pct in A1-Cu alloys. Bolling and Tiller"' have theoretically examined the effects of solute concentration and diffusivity on the growth of cells and dendrites. Their analysis of dendritic growth assumes a steady-state growth and the maximum possible velocity for dendrite propagation. In addition, the quantitative analysis is restricted to dendrites of rotational symmetry and is therefore not directly applicable to the plate-shaped dendrites of ice obtained in the present study. There are practically no experimental observations of the effect of solute diffusivity on dendrite spacings in metallic systems. The reason appears to be the lack of experimental data on solute diffusion coefficients in liquid metallic solutions. The present work is concerned with the effect of solute concentration and diffusivity on dendritic solidification of dilute aqueous solutions: the solutes examined are potassium chloride. sodium chloride, lithium chloride. and hydrogen chloride. There were several reasons for selecting these solutes. The variation of dendrite spacing with freezing rate in these solutiolls is similar to that observed in A1-Cu alloys.8 These aqueous solutions have almost identical phase diagrams at dilute concentrations. Fig. 1. and the diffusion coefficients show very little variation with solute Concentration.9,10 Dendrite spacings were measured as a function of freezing rate. solute concentration. and solute diffusivity. Dendrite spacings were measured in two different types of freezing systems. droplet and unidirectional, respectively. In the droplet freezing system

Jan 1, 1970

By W. C. Phalen

The production of salt in the United States divides itself at the outset into two distinct classes…

Jan 1, 1915

Rutile – Zircon Mining on East Coast Surfing Beaches – Rutile-Zirconium Producing Companies in Australia

Jan 10, 1964

By T. C. Mendenhall

All persons, actively engaged in your profession, must have a natural interest in the subject of weights and measures. All members of the engineering profession have to do with operations of weighing and measuring—some with measuring more than weighing, and some with weighing more than measuring—but all with both of these processes to a greater or less degree. Methods of weighing and measuring have improved constantly from the earliest times and have kept pace with the advance of other technical processes. It is, therefore, believed that you will be interested in a few remarks concerning some of the more recent advances in relation to the establishment of decimal standards of length and mass in this country. Before speaking of this, I will refer very briefly to some facts which may not be very generally known regarding our customary system of weights and measures. Although the yard is universally accepted as the unit of length, and the pound as the unit of mass, it is not generally understood, I believe, just in what respect the yard is the unit of length, or the pound the unit of mass. That is to say, it is not generally known in what degree these units have been legalized by Acts of congress. Doubtless, many of you are familiar with the facts which I will briefly recapitulate. The Constitution of the United States authorizes Congress to establish a system of weights, measures and coinage. The establishment of a system of coinage, as you know, was one of the first acts of the government, and the system then adopted is certainly one of the most perfect, if not the most perfect, that the world has yet seen. But, although Congress had the power to establish a system of weights and measures, it has never yet seen fit to exercise this power; that is to say, Congress has never yet

Jan 1, 1890

JESSE L. JONES,* Pittsburgh, Pa.-I would like to ask Miss Erskine if down-draft has been used in any of the foundries where heavy fumes have to be removed, instead of the overhead draft.? L. -ERSKINE.-The system of overhead draft to remove heavy fumes has been very much more successful. The entire efforts of the New Jersey Department of Labor in regard to stabilizing conditions in the foundry are the result of the physical examination of the foundryman himself on first-hand information as to the prevalence of the minor ailments and the bad timekeeping that naturally accompanies them. These ailments are a factor in not only increasing the labor turnover but in increasing the percentage of bad work as well. The physical exertion of the foundryman himself is of course an important factor. In certain standard shops the amount of energy expended runs from 11 to 13 tons of foot-pounds of energy a day. In certain shops on piece work, I found a record of the energy expended per day to run as high as 22 tons. In one shop, during the war period, the management established a bonus system, and the men increased their output from 60 to 100 molds a day. The result was an increase of some 60 per cent. in output, and an increase of 400 per cent. in defective castings. The question of the physical exertion in the unsanitary foundries, of course, is very much complicated by other factors, for which reason the department has devoted a good deal of attention to estimating what is a reasonable exertion in a sanitary, well ventilated foundry. We have met certain physical difficulties in the brass foundries that the iron foundries did not have. All that information is available through our Bureau of Industrial Information. The question of the physical energy exerted by the molder is found to have a very distinct bearing on the question of contracts, for the possibility of increasing production is balanced by the extra overhead involved. JESSE L. JONES.-I would like to ask if any evidence has been noticed of carbon-monoxid poisoning among the employees of the foundries.

Jan 4, 1919

By Daniel T. O’Brian

Mineral exploration activities are benefiting from new interpretive techniques which have become economically practical with computers. Government agencies, educational institutions, and industry have each contributed research and development efforts for improving the mathematical analysis and graphical display of exploration data, resulting in operational aids not foreseeable a decade ago. Progress has been worldwide and is expanding rapidly. Books 1-10 are supplementing the periodic literature, at least one abstracting service is now active, 11 and an association has recently been formed to encourage and publicize advances in this field. 12 With the diversity of applications, only partial coverage of the subject can be made at any single symposium. Four of the six papers in this section report on the current state-of-the-art in selected areas of interest: graphics, time-sharing, mathematics, and economic analysis. The remaining two papers are descriptions of advanced statistical techniques for gaining additional information during exploration, and illustrate methods which will become more commonly applied in the future. "Computer Graphics: A New Tool for Exploration and Mining" describes the use of a computer and accessory equipment as an information retrieval device, graphically merging and displaying pertinent information for visual inspection and interpretation. This is a rapid means of studying information which has been pre-stored in a form accessible to the computer. Time-sharing is a means of achieving a comparable rapid response when calculations are being performed. The paper, "Some Applications of Time-Sharing in Mining Geophysics," describes the experience of one company using a time-sharing facility for geophysical computations. Another paper on this subject, stressing mining applications, has recently been published. 13

Jan 1, 1969

By Alexander N. Mitinsky

UP to a certain limit, the increase of pressure on the diamond-drill increases the rate of progress in drilling. That limit is set by the resistance of the diamonds to compression; and beyond it, the destruction of the stones will involve an. economic loss, both in time and in money. It is, therefore, important to all diamond-drillers to know what is the resistance mentioned. In Europe, operators usually follow an empirical rule, which directs the maintenance of a pressure, on the area-of the bottom of the drilling-tool, of 12 kg. per sq. 4m. For the tools in ordinary use, this is equivalent to 1 kg. per sq. mm. of the diamonds set in the tool So far as I know, American drillers are using pressures as high as 50 to 60 kg. per sq. cm. of the total area of the drill, and the consumption of diamonds (on Denny's authority, 0.2 carats per meter bored) is greater in America than in Europe. But the reason for this difference may be the comparatively larger size of the diamonds commonly used by American drillers. With the assistance of my friend, the late S. Woisslaw, who was the pioneer of diamond-drilling in Russia, I selected from his stock a number of black diamonds, which I subjected in my laboratory to compression-tests. To prepare regular cubes for such tests, as is generally done with other stones, would have been not only costly, but, what is more important, practically useless. I therefore determined, in order to assimilate as nearly as possible the conditions of actual use, to place each sample between a hard plate (corresponding to the rock) and a softer plate (corresponding to the bottom of the tool), into which it would be pressed during the test.

Jan 1, 1906

By L., Ormsby

DRILLING and blasting practices in the Morenci open pit have undergone considerable modification in recent years. Changes in the character of the ground being mined, modifications of working conditions, and continuous experimentation have been the contributing factors.

Jan 1, 1950

By P. N. Richards, M. K. Ormay

Commercially hot-rolled low-carbon steel strip may have one of two basic types of orientation texture, depending upon the amount of a iron which was present during the finishing passes. The changes in these textures with varying amounts of cold reduction up to 95 pct have been determined for the sheet surface plane and for parallel planes down to the mid-plane. The development of cold reduction textures has been reassessed on the basis of (200), (222). and (110) stereographic pole figures and pole density or inverse pole figure values. In agreement with the literature, it is shown that the textures can be described in terms of partial fiber textures but alternative descriptions are given for one of the fiber textures, in order to more closely correlate with experimental data. One partial fiber texture consists of orientations of the type (hkk)[011] extending from (100)[011] to {322}(011) in agreement with the literature. At moderate amounts of cold reduction, a second partial fiber texture forms with a <331> fiber axis inclined 20 deg to the sheet normal and a range of orientations centered on one close to (1 11)[112] and reaching to (232)[101] or (322)[011]. An alternative description involves a (111) fiber axis parallel to the sheet normal but capable of rotation about the rolling direction with rotation about the fiber axis. ORIENTATIONS developed in low-carbon steel strip after cold reduction are of commercial importance because they control, in part, the final preferred orientations after subsequent annealing. The method of control however is not understood completely. Some preliminary work indicated that the cold-reduced orientations and the subsequent annealing textures of commercial low-carbon steel were dependent on the orientations present in the material before cold reduction, that is, those present in the hot-rolled strip but, to date, the effects of initial orientations have not been extensively investigated. For this reason, much of the information given in the literature on development of preferred orientation is difficult to assess as details of initial texture and processing conditions are often inadequate or are altered by a subsequent heat treatment such as normalizing.&apos; It is known2 that anomalous results for near surface orientations may be obtained if lubrication during cold rolling is not adequate but whether lubricant was used during the experiments has not always been given, nor has the exact depth below the surface at which determinations have been made. A comprehensive review of cold rolling textures has been made recently by Dillamore and Roberts&apos; and more restricted recent reviews are due to stickels4 and Abe.5 Based largely on the experimental work of Bennewitz,1 reviewers have accepted that the preferred orientations produced on cold reducing low-carbon steel can be described in terms of two partial fiber textures as follows: Partial Fiber Texture A which has a (011) direction in the rolling direction and includes orientations within the spread from (211)[011] through (100)[Oll] to (211)[011.]; there is some controversy as to whether it extends as far as the orientation (111)[011]. As Dillamore6 has observed, the extent of this partial fiber texture depends on the intensity levels selected. Partial Fiber -texture B which has a (011) direction located 60 den from the rolling direction in the plane containing the rolling direction and the sheet normal. There are two directions which satisfy these conditions and orientations in this partial fiber texture extend from (21l)[0ll] through (554)[225] to (121)[101]. The orientations {211}(011) are members of both partial fiber textures A and B and it can be noted that a variant of {554)<225> is within 6 deg of a variant of {111}(112). Barrett7 had postulated earlier that, in addition to orientations which would fall into partial fiber texture A, a true fiber texture with a (111) direction in the sheet normal was present after heavy cold reduction. This fiber texture would include orientations such as {111}(011) and {111}(112). Later investigators, notably Bennewitz,&apos; have discounted this, mostly on the ground that the partial fiber textures A and B, as described above, contain all the strong orientations that have been observed. However in other work it has been reported2 that (222) pole density or inverse pole figure values show a continuing increase with increasing reduction by cold rolling and give values considerably greater than for any other low indices plane. Thus it could be inferred that a (111) fiber texture as described by Barrett would be one which becomes more dominant with increasing cold reduction, whereas Bennewitz&apos; concluded that components such as {554)(225) in partial fiber texture B began to decrease in intensity at high reductions. Following Bennewitz, one would expect a decreasing (222) pole density value (parallel to the sheet normal) with increasing cold reduction. Because fiber textures consist of grains with a range of orientations that have one axis in common, it has been inferred that during deformation the crystal orientations rotate about the fiber axis&apos;74 and that the orientations of crystals that at one stage belong to one fiber texture can rotate on further cold reduction into the other fiber texture through an orientation in which the two fiber textures intersect.&apos; For example,

Jan 1, 1970

By W. J. Reagan

All of the material described in the following paper is within the following specifications: carbon, 0.50 to 0.85 per cent; phosphorus and sulfur, 0.04 per cent max.; manganese, 0.60 to 0.85 per cent; silicon, 0.20 to 0.30 per cent. Steels with much lower carbon contents can be handled in exactly the same manner. One of the first things necessary to basic open-hearth slag control is uniformity of charge, particularly as to the silicon content and the percentage of lime charged. Our past work has shown that the silicon content of the charge is more important than the carbon content in determining the carbon at which a heat will melt. We have found that by keeping the silicon content of the charge about 0.60 to 0.65 per cent, and with a lime charge of about 7 per cent (limestone equivalent), our heats melt sufficiently high in carbon to allow a moderate feed of ore and the slag will be of low iron oxide content. In making a heat of 0.75 carbon steel we endeavor to have the heat melt at about 1.20 per cent carbon. The iron oxide content of the finishing slag depends upon the final phosphorus desired; for a given ratio of lime-silica in the slag, the lower the phosphorus desired in the final steel, the higher the iron oxide content of the finishing slag must be. By reducing the lime charge to a minimum, the heats melt faster, and by keeping the silicon content at the desired figure the heats melt with a high SiO2 slag, which has been shown in previous work to give a low iron oxide slag. In most of our work, using a 180,000-lb. charge and with basic pig containing about 1.20 per cent silicon, we use a lime charge of 8500 lb. of limestone and 2000 lb. of burnt lime. The pig charge is about 48 per cent of cold pig, and the charge contains a large percentage of works scrap. This causes a heat to melt with about 1.20 to 1.30 per cent carbon, for a heat that will finish about 0.75 per cent carbon. This gives a heat that will need a feed of about 2000 lb. of ore, and also a slag with an FeO content of about 4 to 5 per cent at melting. The additional FeO obtained from the ore addition will bring the FeO in the slag at tapping to about 6 to 7 per cent. It is necessary to carry quite a fluid slag to prevent pickup of FeO, as a too heavy slag causes FeO to build up in it, giving a finishing slag with a greater FeO than is desired. By adjusting the lime charge of a basic open-hearth heat, a very sensitive adjustment of the slag may be obtained. The figures in Table 1

Jan 1, 1935

By W. J. Reagan

All of the material described in the following paper is within the following specifications: carbon, 0.50 to 0.85 per cent; phosphorus and sulfur, 0.04 per cent max.; manganese, 0.60 to 0.85 per cent; silicon, 0.20 to 0.30 per cent. Steels with much lower carbon contents can be handled in exactly the same manner. One of the first things necessary to basic open-hearth slag control is uniformity of charge, particularly as to the silicon content and the percentage of lime charged. Our past work has shown that the silicon content of the charge is more important than the carbon content in determining the carbon at which a heat will melt. We have found that by keeping the silicon content of the charge about 0.60 to 0.65 per cent, and with a lime charge of about 7 per cent (limestone equivalent), our heats melt sufficiently high in carbon to allow a moderate feed of ore and the slag will be of low iron oxide content. In making a heat of 0.75 carbon steel we endeavor to have the heat melt at about 1.20 per cent carbon. The iron oxide content of the finishing slag depends upon the final phosphorus desired; for a given ratio of lime-silica in the slag, the lower the phosphorus desired in the final steel, the higher the iron oxide content of the finishing slag must be. By reducing the lime charge to a minimum, the heats melt faster, and by keeping the silicon content at the desired figure the heats melt with a high SiO2 slag, which has been shown in previous work to give a low iron oxide slag. In most of our work, using a 180,000-lb. charge and with basic pig containing about 1.20 per cent silicon, we use a lime charge of 8500 lb. of limestone and 2000 lb. of burnt lime. The pig charge is about 48 per cent of cold pig, and the charge contains a large percentage of works scrap. This causes a heat to melt with about 1.20 to 1.30 per cent carbon, for a heat that will finish about 0.75 per cent carbon. This gives a heat that will need a feed of about 2000 lb. of ore, and also a slag with an FeO content of about 4 to 5 per cent at melting. The additional FeO obtained from the ore addition will bring the FeO in the slag at tapping to about 6 to 7 per cent. It is necessary to carry quite a fluid slag to prevent pickup of FeO, as a too heavy slag causes FeO to build up in it, giving a finishing slag with a greater FeO than is desired. By adjusting the lime charge of a basic open-hearth heat, a very sensitive adjustment of the slag may be obtained. The figures in Table 1

Jan 1, 1935

By N. J. Grant, B. C. Giessen, M. Morris

The slvuclures of alloys in the system In-Bi have been investigated after (levy vapid queuching from the mell (splat cooling) to -190°C. Tuo-phase fields could be suppressed over most of the tota1 concentvalion range; five melastable phases a1, a2, ?, ?1. and ß exisl, of which four have simple elementtike structures. For example, ß has the A5 struclure of white till. Crystal-tographic data and coordination numbers for these phases aye given, as well as addilional information on the equilibrium diagram, where a new phase In5Bi3 teas found. THE phase diagrams of binary combinations of B elements from the groups B2, B3, B4, and B5 are usually of a simple type and show considerably fewer intermediate phases than combinations of these elements with A metals, transition metals, or the B1 noble metals. Aside from phases such as the typical B3-B5 compounds with the ZnS-B3 structure type, few stoichiometric phases are known; among them are In2Bi and 1nBi.l Nonstoichiometric phases include ß (In-Sn), a1, (In-Pb), and the tin-rich ? phases in the In-Sn, Cd-Sn, and Hg-Sn systems.&apos; The first two phases have a close relationship to indium, while the latter group are known to be structurally related to a Sn. Thus, there are generally no immediate experimental data for the correlation of the crystal structures of B metals and B metal combinations with certain monotonously varying parameters, such as the valence electron concentration (VEC), or the average atomic size. Such parameters have been recognized as structure determining, e.g., for the transition 4 Sn — y phase,2,3 where nonintegral valence electron concentrations are encountered. It should be possible to extend such correlations to other binary systems, if nonequilibrium single-phase alloys could be produced over broad valence electron concentration ranges, and if their crystal structures could be regarded as being imposed by their electronic states. It has been shown in the case of the tin-rich 7 phases3 that alloy phases with typical crystal structures can be produced in B metal alloys rapidly quenched from the liquid to -190°C by the splat cooling technique due to Duwez,3-8 and reviewed in Refs. 5 and 6. The In-Bi system was selected because it extends over a valence electron concentration range in which several metastable, nonstoichiometrir phases could be expected to occur. Further, the low melting points of the known intermediate phases, In2Bi and InBi, Fig. 1(a), indicated low binding energies and thus possibly low driving forces for the formation Of the equilibrium structures. EXPERIMENTAL TECHNIQUES AND RESULTS The preparation of the quenched foils followed the practice described in Ref. 3. Master alloys were produced by melting of indium (99.97+) and bismuth (99.99+) in evacuated Vycor capsules or in an inert gas arc furnace; quantities of 20 mg were splat-cooled onto copper and silver substrates held at - 190°C; and crystal structures and lattice parameters were determined on a GE XRD-5 diffractometer using Cu Ka, radiation at -190°C and at room temperature. The duplication of each run with both substrates permitted the elimination of overlap of the substrate diffraction pattern and that of the investigated substance. The XRD patterns were usually taken from sin2 " = 0.03 to 0.35; the substrate was used as a means of internal calibration. The fractional accuracy of the lattice parameters of metastable phases is approximately 10-3 In the following, all percentages are in atomic percent. The stable and metastable phases found after rapid quenching to -190°C are listed in Table I, together with estimated concentration ranges and crystallographic data. The investigated alloys and phases present in them are given in Table 11. Except for the region between indium with 33 and 50 pct Bi, where a revision of the equilibrium phase diagram became necessary to include a new stoichiometric phase In5Bi3, the diffraction patterns taken after heating to room temperature agreed with those expected from the phase diagram, Fig. l(a). This suggests that the new nonstoichiometric phases are not stable at room temperature, thus following the observations made for the y phases based on tin.3 Results concerning the equilibrium phases In2Bi and In5Bi3 and the revision of the equilibrium phase diagram which is made necessary by the inclusion of In5Bi3 will be treated first. The Crystal Structure of In2Bi. Makarov7 had identified In2Bi as belonging to the AlB2-C32 type ; however, in a later paper the structure was revised.8 In2Bio was found to be of the Ni21n-B8ß type,21 with a = 5.496A, c = 6.57.9A, and N = 6 atoms per unit cell.9 This crystal structure was confirmed in the present work; definite evidence for the doubling of the c axis, as compared to the A1B2-C32 type, and for the proposed order structure, was found in the powder pattern. The observed lattice parameters agree well with those of Ref. 8; those measured at -190°C are given- in Table I. The Crystal Structure of In5Bi3. A new, equilibrium, intermediate phase was identified in slow-cooled, as-cast alloys; it was identified as In5Bi3. The structure has been worked out by Giessen and Grant;" lattice parameters at -190°C are given in Table I. This phase is probably identical with "In3Bi2", produced by vapor deposition techniques, but not recognized as an equilibrium phase by Palatnik et a1.11 After completion of the present work, the existence of In5Bi3 has also been demonstrated by superconductivity measurements on In-Bi alloys.20

Jan 1, 1968