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By Dorsey Lyon

INTRODUCTION THE electric furnace has always been found to be especially adapted to melting, refining, and finishing processes throughout its gradual acceptance by metallurgists, as a practical apparatus for conducting metallurgical operations. In the steel industry, the electric furnace is firmly established in the manufacture of steel of the highest grade, equal to crucible steel. For the production of the cheaper grades of steel in large tonnage, the electric furnace gives a higher-grade product than the open-hearth or converter, but due to the high cost of power prevailing in steel centers, considered from the electric furnace standpoint, it is not economical to produce tonnage steel in the electric furnace. As a refining and finishing agent for open-hearth or Bessemer steel, the electric furnace has had some degree of success in the production of tonnage steel. After a study of the use of the electric furnace in the steel industry, it appears that there may be a possibility of its use to advantage for the melting of cathode copper. In the case of copper the problem is not one of actual refining, because the copper if refined properly y the electrolytic method needs no further refining; it needs simply to be cast into a marketable shape. The name" refining". is applied to the present finishing process, because in the operation oxygen and other impurities are removed, which the electrolytic copper absorbs in being melted in the reverberatory furnace. Considering that processes may be positive, negative, and neutral; the electrolytic method would be positive; reverberatory melting of cathode copper, negative; and electric furnace melting, neutral. The electrolytic method produces about as pure a copper as is possible, if operated properly and the anodes are not too impure. The final reverberatory melting of this cathode copper lowers the grade of the final product, due to the absorption of gases and impurities.

Jan 8, 1914

By Marcus Grossmann

THIS paper offers for consideration certain somewhat radical modifications in the iron-carbon diagram, these modifications being the result of the presence of notable amounts of alloying elements. When only small amounts of alloys are present, 'the standard iron-carbon diagram (Fig. 1) can be used with but insignificant changes; when larger amounts of Chromium, Per Cent FIG. 1.-IRON-CARBON DIAGRAM. FIG. 2.-IRON-CHROMIUM DIAGRAM. alloys are present, however, it assumes a distinctly altered appearance. No comment is offered for the present except to call attention to the delta area, A4BM, which represents a region of mixtures of austenite and delta iron, just as area A3SP represents mixtures of austenite and alpha iron.

Jan 12, 1926

By R. R. Unterberger

Three different physical techniques have been used to see through or probe into rocks, so miners might know what is ahead or overhead. These are radar, sonar, and a unique type of sonar called nonlinear sonar. Five radar systems have been developed. The highest frequency used is 4300 MHz for detecting small fractures at close range. This gives the best resolution. For longest range (over 2000 m, or 6560 ft) we use the 30 MHz radar for finding faults ahead of mining or ranging to salt dome flanks. Two types of salt, dome and bedded, are recognized. Radar works well in dry (dome) salt, but not in bedded salt which contains small amounts of water. The dipole moment of water absorbs energy from the radar. Thus was born the 30 MHz radar system and sonar probing systems. These can probe to 100 m (328 ft) even into wet salt. All probing systems measure data in time, which are converted to distance by measuring the time of travel of radar or sonar through salt pillars of known thickness. Ranges of probing in salt are from less than 1 m (3.3 ft) to more than 2000 m (6560 ft). Uses of radar and sonar probing in mines include mapping the top of salt above a mine; mapping salt dome flanks; finding impurities in salt such as anhydrite, sandstone, or potash stringers; locating old boreholes in salt pillars; locating fractures in salt; and finding faults or water zones ahead of mining.

Jan 1, 1985

By Clinton M. Young

The experiments herein described were carried on in 1908-9 by- the State Geological Survey of Kansas. Some months before taking up work on black powder the Survey had resumed work on an interrupted investigation of explosions in coalmines, a subject which is engaging the attention of numerous investigators. An unusual number of serious disasters has directed to the subject a study which discloses the disquieting fact that, in the United States, the ratio of lives lost per ton of coal mined has been 011 the increase. Methods of coal-mining have changed to some extent with the great increase of output, attained in comparatively recent years. These changes involve the working of very extensive mines, with increased difficulty of ventilation, increased accumulation of coal-dust, and a very great increase in the amount of explosive used. This last point assumes truly startling proportions when it is carefully observed. In the fields of the Middle West it is not now uncommon for a miner to use six kegs (150 lb.) of black powder in a " pay" of two weeks, while within the memory of men still active, one keg (25 Ib.) would last two men for a " pay." So great has the use of explosives become in some fields that the skilled coal-miner is hard to find, and the coal is not mined, but blasted. A preliminary study of the subject of explosions in coalmines has led to the belief that the use of large quantities of explosives, in some cases by slightly-trained men, had riot been

Jan 1, 1911

By E. V. Potter, E. T. Hayes, H. C. Lukens

Large volumes of hydrogen are liberated at the cathode during electrolytic precipitation of manganese. Most of the gas escapes from the electrolyte, but a considerable amount may be entrapped in the manganese plate. Gas has been observed to escape from manganese melts in puffs that bite at the surface. It has been reported that castings made with electrolytic manganese tend to rise in the molds; for this reason the manganese is often treated to remove hydrogen before the melt is made or it is premelted and used as cast manganese in making the alloys. The effect of hydrogen on the properties of manganese and its alloys is not known, but its effect on iron and iron alloys has been studied extensively.l.2 The close relationship between iron and manganese suggests that hydrogen may have a similar effect on the properties of manganese and its alloys. The purpose of this investigation was to determine the amount of hydrogen or other gases in typical commercial electrolytic manganese sheet and to investigate ways of removing it most conveniently. Apparatus The apparatus used is shown schematically in Fig. I. It consists of a chamber A in which the metal sample is placed, a vacuum or pressure gauge B, volume gauge C, vacuum pump D, hydrogen container E, auxiliary gas chamber F, and furnace G. The specimen chamber was made of two concentric quartz tubes. The outer one, a, connects with the closed gas system and is surrounded by the furnace G. A second tube, b, fits closely inside a and has a small end that projects into the space for the specimen and holds the thermocouple for measuring the temperature of the sample. The inner tube is joined to the outer tube outside the furnace, with rubber tape and sealing wax, to prevent gas leakage into or out of the closed system. This type of specimen container is loaded very easily and can be used several times if molten metal does not come in contact with the quartz. An ordinary mercury manometer B is used to measure the pressure in the system. The volume gauge C is essentially another mercury manometer, but the volume of the column is much larger than normal and the height of the mercury can be varied by raising or lowering the well H. In this apparatus the tube had a volume of IOO C.C. for a 60-cm. length. For larger changes in gas volumes, auxiliary containers F were used to increase the volume of the system by known amounts. Valves were arranged so that these auxiliary containers could be filled from the system and evacuated by the pump as often as necessary to accommodate the increases in the volume of gas in the system. The furnace G, used to heat the samples, was equipped with an automatic temperature controller, which maintained the desired temperatures within ± 5°C.

Jan 1, 1945

By William G. Pariseau

The flexure of geologic strata, a phenomenon of interest to geologists and mining engineers alike, is examined as a sheet bending problem in Coulomb plasticity. Fonnulae for the distribution of stress, strain, and displacement increments; volume change; change in the length of the central surface; and power of dissipation, as well as for the neutral surface shift are given. Strains of any magnitude are considered. The analysis shows that deeply buried strata may bend and develop "tensile" cracks under generally compressive states of stress. It is also shown that bed separation and high capacity props are desirable in mechanized longwall mining, a result in keeping with operating experience. Although speculative at this time, the analysis provides a rational working hypothesis as regards the problem of strata flexure and control. | he purpose of this paper is to present an analysis of the flexure of geologic strata as a problem in the bending of a sheet of material failing in accordance with a Mohr-Coulomb criterion. The flexure of strata has an obvious academic interest to the geologist concerned with the mechanics of folding. It is of interest to the economic geologist as it relates to the structural control of certain types of ore deposits. It has an intimate association with mine subsidence phenomena, and is of concern to the mining engineer. Strata flexure is also the dominant feature of roof behavior about longwall workings. An improved understanding of strata flexure through a rational mechanical analysis thus appears desirable not only from the academic view but from the economic one as well. In the field, the most commonly observed feature of folding, subsidence, and longwall roof behavior is the permanent and therefore inelastic nature of the strata movement. Fig. 1 illustrates the physical disposition of strata in the vicinity of a longwall face. Inasmuch as most rocks (with the possible exception of certain evaporites) do not exhibit significant viscoelastic behavior, at least not over time spans of engineering interest, a plastic analysis is indicated. The analysis is meant to apply to strata whose deformation is dominantly that of bending such as might be expected in the remote roof about a longwall face.

Jan 1, 1970

By J. B. Newkirk, W. G. Martin

Oxidized cobalt powder is known to have a magnetic hysteresis loop which is asymmetric with respect to the magnetization axis. The experiment described herein shows that the orientation relationship between the basal plane of hexagonal cobalt and the oxide which forms upon it at 400°C is {111}ux//{100.1 }co <110>ux//<11.O> This orientation relationship allows a magnetic interaction between the antiferromagnetic oxide and the ferromagnetic substrate which could account for the offset hysteresis loop. Oxidized nickel powder has a symmetrical hysteresis loop and so is apparently not influenced by any magnetic interaction between metal and oxide. The orientation of the oxide (cubic) was found to be identical with that of the nickel substrate when the oxide forms on a polished surface parallel with {111} Ni. IN 1956 W. H. Meiklejohn and C. P. Bean discovered that fine particles of cobalt which had been prepared in a certain way have a magnetic hysteresis loop which in a strong field is asymmetric relative to the magnetization axis.&apos; The cobalt powder exhibited this unusual magnetic property only after it had been oxidized in air or oxygen; it lost the shifted hysteresis loop when the oxide was reduced in hydrogen. X-ray and neutron diffraction&apos; experiments showed the presence of cobaltous oxide (COO) and hexagonal cobalt in samples exhibiting the biased hysteresis loop and specifically showed no indication of any other compound with the exception of mercuric oxide.* The magnetic hysteresis loop becomes symmetrical above the Nee1 temperature (paramagnetic state) of COO. Therefore, it was concluded that the anomalous magnetic behavior is associated with the influence of cobaltous oxide upon the metallic cobalt. It has been proposed that crystallographic coherency may exist between the cobalt and a plane of some antiferromagnetic material which has unbalanced spin distribution and sufficient magnetic anisotropy to hold its spin in the direction which existed when the specimen was cooled. COO has these properties. Therefore, Roth&apos; has suggested that cobaltous oxide may form with a {111} plane parallel and coherent with the basal plane of the hexagonal cobalt metal and proposed that, as consequence of the antiferromagnetic interaction between COO and the underlying cobalt, the magnetization direction in oxidized fine Co particles may be ro-lated from the easy c-direction.2 Such a relationship, he proposed, would explain the observed magnetic effect in oxidized cobalt powder. The main purpose of this study was to determine the orientation relationship, if any, between the basal plane of cobalt and the oxide which forms upon it. Attempts to produce a film of COO which was strong enough to be handled were not successful. However we did succeed in making a film of CoCo2O, which was strong enough to be removed from the cobalt substrate and mounted on an electron-microscope grid. Because of the close structural similarity of COO and CoCo2O, we believe the orientation relation found for CoCo2O, on cobalt probably also holds for COO on cobalt. The epitaxial relationship of NiO and Ni also was investigated. To date no shifted hysteresis loop has been observed with nickel powder. However, the similarity of atomic array in cobalt and nickel leads to the prediction that a {111} of NiO may be parallel with a (111} of nickel. Experimental Method Cobalt-Cobalt Oxide—A coarse-grained specimen of a (hexagonal) cobalt was prepared by allowing a large crystal of fee cobalt to transform slowly at 400°C. The crystal was then cut to expose a surface parallel with the basal plane. A back reflection Laue X-ray photograph showed that the 00.1 plane was within 2" of the cut surface. The surface was mechanically polished and then electro polished in 85 pet orthophosphoric acid after which the crystal was held for 30 min at 400°C in air. During this heat-treatment the surface darkened slightly due to the oxide film which formed. The film was not thick enough to give an X-ray diffraction pattern, even by a glancing-angle technique. Glancing-angle electron diffraction was not possible either, owing to the interference of the electron beam with the high magnetic fields which exist at the 00.1 surface of the cobalt. However, it was possible to make an electron-diffraction photograph of the oxide film by stripping it from the cobalt substrate using the method described later. By maintaining reference marks carefully, it was possible to preserve the orientation relationship between the stripped film and the substrate on which it was formed. The oxidized surface of the crystal was first covered with a 1 pet solution of collodion (cellulose nitrate) in amyl acetate. When the film was dry, small rectangles were scored on the surface with a needle point. The specimen was then repolished

Jan 1, 1959

By Theodor Zuschlag

Electrical prospecting is the art of exploring the structure of the subsoil in regard to conductivity variations and interpreting the results of such exploration as to their geological meaning. Electrical prospecting has been applied during the last few years with outstanding success, not only to prospecting1 for ore but also to structural studies.2 Both applications have proved helpful to the geologist, and the latter application especially promises to become of still greater importance in the future. The mapping of structures is the most important function of the oil geologist. Oil is lighter than water, therefore in water-bearing beds it will migrate upward until the migration is stopped by a bed impermeable to the oil. Geologic structures such as domes, anticlines, faults and terraces, offer good prospects in the search for oil accumulations and can be traced easily by electrical prospecting, provided they are composed of a series of sedimentary layers of which at least one possesses fair electrical conductivity and follows the general trend of the structure. Conditions for Successful Mapping The first condition, fair electrical conductivity, is met in almost any oil-bearing series, because generally the electrical resistance of a sedimentary bed is identical with the resistance of the more or less saline waters, filling partly or entirely the pores of the rocks.3 Briefly, the electrical resistivity of a bed can be expressed for all practical purposes by the product R X P, where R is the specific resistance of the waters in the rock pores and P a factor depending upon the percentage of water by volume in the rock. The specific resistance of any solution can be computed from the chemical analysis, being primarily a function of the

Jan 1, 1932

By M. Cohen, R. T. Howard

It has long been realized among metallurgists that a fast, reliable method for the quantitative determination of the percentage of microconstituents in an alloy would be of great benefit in studies of equilibrium and transformation in the solid state. For example, Polushkinl has shown that the compositions of two coexisting phases in a binary system at a given temperature may be calculated very simply with the aid of two alloys lying in the two-phase field if the relative amounts of the two phases in each alloy can be determined. Recently, Grange and Stewart2 have traced the course of the austenite-martensite reaction in a series of commercial steels by making visual estimates of the percentage of martensite formed as a function of cooling temperature. The correlation of mechanical properties with structure, a subject of wide-spread current interest, is likewise dependent upon quantitative microanaly-sis. Yet, there are very few investigations described in the metallurgical literature, wherein methods of quantitative microscopy are employed. Usually, the relative amounts of the microconstituents are estimated in a qualitative or semiquantita-tive way. The authors were faced with this problem some time ago in studying the kinetics of austenite decomposition. Several aspects of this research could not be treated satisfactorily by other quantitative tools, such as specific volume,&apos; magnetic,6 dila-tometric, electrical resistance7 or x-ray measurements.a It became necessary to find an impersonal quantitative method that could be applied to microstructures. Fortunately, it was noted that geologists and petrographers had coped with quantitative microscopy to a considerable degree in their attempts to evaluate the mineral contents of rocks. A number of excellent articles were found on this subject, and since they appear to be unknown generally to many metallurgists, the first part of the present paper is concerned with a review of the literature in some detail. With this survey as a background, the authors have adapted the so-called methods of point-counting and lineal analysis to metallography, as described in the second part of the paper. Austenite-martensite structures were selected for illustration not only because they are important in many ways, but because such fine intermixtures are notoriously difficult to estimate visually. Literature Survey Perhaps the earliest work on quantitative microscopic analysis goes back to Delesse9 (1848) who proved mathemati-

Jan 1, 1948

By M. Cohen, R. T. Howard

It has long been realized among metallurgists that a fast, reliable method for the quantitative determination of the percentage of microconstituents in an alloy would be of great benefit in studies of equilibrium and transformation in the solid state. For example, Polushkinl has shown that the compositions of two coexisting phases in a binary system at a given temperature may be calculated very simply with the aid of two alloys lying in the two-phase field if the relative amounts of the two phases in each alloy can be determined. Recently, Grange and Stewart2 have traced the course of the austenite-martensite reaction in a series of commercial steels by making visual estimates of the percentage of martensite formed as a function of cooling temperature. The correlation of mechanical properties with structure, a subject of wide-spread current interest, is likewise dependent upon quantitative microanaly-sis. Yet, there are very few investigations described in the metallurgical literature, wherein methods of quantitative microscopy are employed. Usually, the relative amounts of the microconstituents are estimated in a qualitative or semiquantita-tive way. The authors were faced with this problem some time ago in studying the kinetics of austenite decomposition. Several aspects of this research could not be treated satisfactorily by other quantitative tools, such as specific volume,&apos; magnetic,6 dila-tometric, electrical resistance7 or x-ray measurements.a It became necessary to find an impersonal quantitative method that could be applied to microstructures. Fortunately, it was noted that geologists and petrographers had coped with quantitative microscopy to a considerable degree in their attempts to evaluate the mineral contents of rocks. A number of excellent articles were found on this subject, and since they appear to be unknown generally to many metallurgists, the first part of the present paper is concerned with a review of the literature in some detail. With this survey as a background, the authors have adapted the so-called methods of point-counting and lineal analysis to metallography, as described in the second part of the paper. Austenite-martensite structures were selected for illustration not only because they are important in many ways, but because such fine intermixtures are notoriously difficult to estimate visually. Literature Survey Perhaps the earliest work on quantitative microscopic analysis goes back to Delesse9 (1848) who proved mathemati-

Jan 1, 1948

By A. U. Seybolt

The pressure-temperature relations required to maintain the existence of Si3N4 in silicon-iron of 0.44-11.7 pet Si have been partially explored. The critical data obtained have allowed the calculation of some thermodynamic quantities, and have shown evidence of an order-disorder two-phase field extending at 800°C from about l pet to 5.5 pet Si. THE presence of silicon nitride in electrical sheet, nominally about 3 1/4 pet silicon, balance iron, has been described by several authors&apos;" but there has been some discrepancy among them regarding the identity of the nitride. Also, little has been reported on the quantitative thermodynamic prop- erties. In the work to be reported here, the nitride has been found to be more stable than described by Corney and Turkdogan." Several silicon nitrides have been described in the past, including SiN, Si3N4 and Si2N4 (see, for example, Abegg6 and Pascal7). However, the literature on nitrides other than Si,N, is all very old. No recent investigators using the more powerful tools available today have reported the presence of any nitride other than S3,N4. W. B. Hicke and L. R. Brantley8 in 1930 determined the dissociation pressure of Si3N4 which they made by reacting nitrogen

Jan 1, 1959

By J. D. Miller, A. Cortez, J. Hupka

The separation efficiency of the hot water digestion-flotation technique used for bitumen recovery from various domestic tar sands was evaluated. Bitumen viscosity was found to be the most important tar sand property in determining the success of the bitumen separation. Bitumen viscosity of the tar sand war controlled by changes in digestion temperature and/or changes in diluent (kerosene) addition. Complete and uniform dilution of the bitumen phase was achieved by providing a sufficient presoaking, or penetration time, for a given tar sand type. For all the tar sand samples tested, an excellent correlation was obtained between the coefficient of separation and the bitumen viscosity. To achieve a satisfactory coefficient of separation, it was found that the bitumen viscosity must be reduced below 1.5 Pa.s (16 P) at the temperature of digestion. This was the case regardless of the tar sand type, grade, or origin.

Jan 1, 1984

By E. R. Dean

A wire-feed mechanism has been employed to fabricute metal alloy film resistors to various sheet resistivities on oxidized silicon substrates. The effect of several thousand hours storage in air at elevated temperatures on the resistance and temperature coefficient of resistance is presented. Unprotected films of- sheet resistivity between 100 and 500 ohms per sq fabricated at 300°C substrate tenzperatures were unstable when stored at 150°Cfor extended periods. The higher sheet resistivity films exhibited the greatest instability; however, even the 100 ohms per sq films drijted excessively for device application. When stored at still higher temperatures, the normalized resistance increases to maximum, then decreases until a minimum value is obtained, then finally increases in resistance until open. The use of a protective overcoating of SiO has had considerable benejicial effects on the film stability, so that 250 ohms per sq films deposited on 300°C substrates are now stable after 1000 hr storage at 250°C and possess a temperature coefficient of resistance less than 200 ppm per C. The use of a low substrate temperature during depositon (100°C) enables the preparation oj resistors with very low tenperature coefficients of resistance (10 to 20 ppnl per &apos;C). However, these films are less stable than their higher substrate temperatuve counterparts. During extended storage, the resistance of the protected films always decreases with lower substrate films exhibiting larger normalized resistance decreases. This resistance decrease is accompanied by a linearly related increase in the temperature coefficient of resistance. The electrical behavior of these films may be explained by postulating That the structure of the films is in the transition region between thick continuous films and ultrathin island structure films so that the conductivity is the restlt of both electron scattering and tunneling-activated charge carrier creation between neighboring grains. The annealing behavior when thermally aged is the result of defect anneal, grain growth, and selective oxidation. TheRE is a considerable interest in thin metallic films for use as resistor elements in microelectronic circuits.1,2 These resistor films must be stable when exposed to elevated-temperature storage or operating ambient, possess low temperature coefficients of resistance (hereafter referred to as T.C.R.), and be of a high enough sheet resistivity to be useful. The resistivity and T.C.R. of a thin metallic film are determined by the structure and thickness of the film. Hence the stability of the film when exposed to stress would depend on the stability of the structure. The resistivity of a thin film is the result of the electrons&apos; interaction with the lattice vibrations (electron-phonon scattering), scattering of electrons due to impurities, defects, and grain boundaries and specula reflection from the film surfaces.3&apos; All of these effects serve to reduce the electron mean free path and result in a resistivity higher than the ideal bulk. In ultrathin films possessing essentially an island structure consisting of a planar array of aggregates separated by a few to a few tens of angstroms, conduction is dominated by a combination of tunneling and activated charge carrier reation. Thin films would be characterized by relatively low resistivity, positive T.C.R., and reasonable structure stability whereas ultrathin films possess unstable structures, negative T.C.R., and exhibit high resistivity. Feldman6 has investigated films intermediate between the two regions and postulates that the resistivity of a film in the transition region is composed of two linearly additive parts: that due to the resistance of the grains and that due to the gaps. The grain resistivity would represent the scattering of the conduction electrons by defects, surfaces, and phonon interaction while the gap term represents the tunneling contribution. For gold and platinum films, he found as the film structure becomes progressively less continuous, corresponding to thinner films, the absolute value of the T.C.R. becomes progressively smaller until negative values are observed with respective zero T.C.R.&apos;s at about 35 and 150 ohm per sq, respectively. Recently the author7 investigated the behavior of a multicomponent alloy of nickel, chromium, and iron and found the T.C.R.&apos;s of these films decrease with decreasing substrate temperature during deposition. The lower T.C.A. associated with lower substrate temperatures was attributed to an increased contribution to the total resistivity from the negatively temperature-dependent gap tunneling since it is well-known that thin films deposited on low-temperature substrates consist of a higher density of smaller grains than the same sheet resistivity films deposited on higher-temperature substrates. Under conditions of thermal anneal, the author found that, when various sheet resistivity films fabricated at 300°C substrate temperature are exposed to extended storage in air at 300°C, the thinner films increase in resistance until open, while the thicker films

Jan 1, 1967

By R. B. Snow

This paper describes a technique of polishing and etching specimens of open-hearth furnace slags or hearth aggregates for identification of the crystalline constituents —lime (CaO), tricalcium silicate (3CaO.SiO2), dicalcium silicate (2CaO.-SiO2), rnonticellite (CaO.MgO.SiO2), or forsterile (2MgO.SiO2), with especial em-phasis on the mineral merwinite (3CaO.-MgO.2SiO2). With proper standardization, this identification does not require the use of the petrographic microscope. The composition of basic open-hearth slags and furnace bottoms falls, almost without exception, within systems containing CaO, MgO, &apos;IFeO,,, MnO and SiOz, in which the number of basic molecules so greatly exceeds the orthosilicate ratio (two molecules of base to one of silica) that free basic oxides, and combinations between them such as alumi-nates or ferrites, are present in cooled specimens. Orthosilicates of (CaO + NgO) are the most common in such specimens, since in nearly all cases, except premelt slags, the molecular ratio of (CaO + MgO) to SiO, is more than 2 to I. When sufficient lime is available it combines with the silica to form dicalcium silicate (2Ca0.Si02), which contains little, if any, IvfgO, FeO or MnO in solid solution whereas the latter oxides combine to form the oxide solid solution known as periclase. If the lime present is insufficient to form dicalcium silicate (2Ca0.Si02) it combines with Mgo to form either merwillite or moIlticellite (SiOz); these minerals take little if any FeO or MnO into solid solution and the remaining MgO, FeO and hInO combine as periclase. This generalization seems to be valid for basic slags and furnace bottoms, since minerals such as Ca0.MnOSi02 and CaO.FeO.SiOz are found only in slags in which the lime-silica ratio is less than 2 and are not observed in &apos;pecimens from furnace bottoms. The identification of crystalline constituents in such materials, especially of fine crystals in the groundmass, is difficult under the petrographic microscope. They are often masked by their neighbors because of their small size in relation to the thickness of the thin section and because of the presence of Opaque Or colored constituents. The indices of refraction and the optical sign of the mineral are sometimes difficult to determine because of the small size or because Of twinning or of inclusions within the crystal. Moreover, the positive identification of merwinite (3Ca0.Mg0.2Si02) from its optical properties is usually difficult in the presence of dicalcium silicate (zCaO.SiO2). CaO, MgO, jCa0.Si02 and 2Ca0.SiOz in open-hearth &apos;lags have been identified for a number of years in the U.S. Steel Corporation Laboratory by the usual

Jan 1, 1948

By R. B. Snow

This paper describes a technique of polishing and etching specimens of open-hearth furnace slags or hearth aggregates for identification of the crystalline constituents —lime (CaO), tricalcium silicate (3CaO.SiO2), dicalcium silicate (2CaO.-SiO2), rnonticellite (CaO.MgO.SiO2), or forsterile (2MgO.SiO2), with especial em-phasis on the mineral merwinite (3CaO.-MgO.2SiO2). With proper standardization, this identification does not require the use of the petrographic microscope. The composition of basic open-hearth slags and furnace bottoms falls, almost without exception, within systems containing CaO, MgO, &apos;IFeO,,, MnO and SiOz, in which the number of basic molecules so greatly exceeds the orthosilicate ratio (two molecules of base to one of silica) that free basic oxides, and combinations between them such as alumi-nates or ferrites, are present in cooled specimens. Orthosilicates of (CaO + NgO) are the most common in such specimens, since in nearly all cases, except premelt slags, the molecular ratio of (CaO + MgO) to SiO, is more than 2 to I. When sufficient lime is available it combines with the silica to form dicalcium silicate (2Ca0.Si02), which contains little, if any, IvfgO, FeO or MnO in solid solution whereas the latter oxides combine to form the oxide solid solution known as periclase. If the lime present is insufficient to form dicalcium silicate (2Ca0.Si02) it combines with Mgo to form either merwillite or moIlticellite (SiOz); these minerals take little if any FeO or MnO into solid solution and the remaining MgO, FeO and hInO combine as periclase. This generalization seems to be valid for basic slags and furnace bottoms, since minerals such as Ca0.MnOSi02 and CaO.FeO.SiOz are found only in slags in which the lime-silica ratio is less than 2 and are not observed in &apos;pecimens from furnace bottoms. The identification of crystalline constituents in such materials, especially of fine crystals in the groundmass, is difficult under the petrographic microscope. They are often masked by their neighbors because of their small size in relation to the thickness of the thin section and because of the presence of Opaque Or colored constituents. The indices of refraction and the optical sign of the mineral are sometimes difficult to determine because of the small size or because Of twinning or of inclusions within the crystal. Moreover, the positive identification of merwinite (3Ca0.Mg0.2Si02) from its optical properties is usually difficult in the presence of dicalcium silicate (zCaO.SiO2). CaO, MgO, jCa0.Si02 and 2Ca0.SiOz in open-hearth &apos;lags have been identified for a number of years in the U.S. Steel Corporation Laboratory by the usual

Jan 1, 1948

By D. Kramer

HASEN1 has published a phase diagram for the zirconium-nickel system. This phase diagram has been redetermined by Hayes, Roberson, and paasche2 in the range 0 to 50 at. pct Ni. Recently, Smith and Guard3 have published a tentative diagram for the

Jan 1, 1960

By George R. Ensminger, E. Heaton Hemingway

During the past year, the Watertown Arsenal has been interested in the occluded gas and oxide content of certain ordnance steels in order to determine, if possible, whether some of the peculiar failures in their physical properties might not be traced to these causes. For the purpose of best accomplishing a study of this nature, it was decided to heat the various samples of steel in a vacuum for definite periods of time at high temperatures and carefully examine the quantity and composition of the gases evolved. By the use of a fused quartz tube fitted with a water-cooled, ground-glass stopper, it was possible to maintain a vacuum at a temperature of 1000" C. for 10 hr. without perceptible leakage being evidenced as measured by a McLeod gage. The silica tube was connected with an evacuating system so constructed that the volatilized gases could be removed from time to time and a low vacuum of 0.0002 to 0.0010 mm. of mercury continuously maintained. At no time during the period of heating or in the removal of the gases did the evacuated system come in contact with rubber stoppers or any rubber connections, making contamination from such a source, impossible. In other words, the only volatile products that could be: obtained must necessarily have come from the steel itself or from the glass and fused quartz system or from the mercury used as a sealing agent. In the carlier experiments, the steel treated was in the form of turnings, but this practice was discarded because the weight&apos;s of the turnings before and after being heated were widely inconsistent,, even when taken from the same piece of steel. This discrepancy developed largely through variation in the amount of metal volatilized with the gases; this metal could always be seen in the form of a ring where it condensed in the cooler portion of the tube in either the amorphous or crystalline condition. Because of the frequency in occurrence and the variation in the manner of deposition, this material was roughly analyzed and found to consist for the most part of iron. At the same time two samples of steel that had been

Jan 1, 1922

By E. Heaton Hemingway, George R. Ensminger

During the past year, the Watertown Arsenal has been interested in the occluded gas and oxide content of certain ordnance steels in order to determine, if possible, whether some of the peculiar failures in their physical properties might not be traced to these causes. For the purpose of best accomplishing a study of this nature, it was decided to heat the various samples of steel in a vacuum for definite periods of time at high temperatures and carefully examine the quantity and composition of the gases evolved. By the use of a fused quartz tube fitted with a water-cooled, ground-glass stopper, it was possible to maintain a vacuum at a temperature of 1000" C. for 10 hr. without perceptible leakage being evidenced as measured by a McLeod gage. The silica tube was connected with an evacuating system so constructed that the volatilized gases could be removed from time to time and a low vacuum of 0.0002 to 0.0010 mm. of mercury continuously maintained. At no time during the period of heating or in the removal of the gases did the evacuated system come in contact with rubber stoppers or any rubber connections, making contamination from such a source, impossible. In other words, the only volatile products that could be: obtained must necessarily have come from the steel itself or from the glass and fused quartz system or from the mercury used as a sealing agent. In the carlier experiments, the steel treated was in the form of turnings, but this practice was discarded because the weight&apos;s of the turnings before and after being heated were widely inconsistent,, even when taken from the same piece of steel. This discrepancy developed largely through variation in the amount of metal volatilized with the gases; this metal could always be seen in the form of a ring where it condensed in the cooler portion of the tube in either the amorphous or crystalline condition. Because of the frequency in occurrence and the variation in the manner of deposition, this material was roughly analyzed and found to consist for the most part of iron. At the same time two samples of steel that had been

Jan 1, 1922

By R. K. Buhr, H. Thresh, M. Bergeron, F. Weinberg

The microsegregation of nickel and chromium in directionally solidified AISI 4340 steel castings has been measured using electron probe microanalysis. Minimum concentrations were observed to occur at the center of the dendrite stalks, as reported previously. However, the position of the maximum concentrations could not be determined from the dendrite configuration. An etching technique has been developed which shows the position of maximum concentration. Measurements were made of the distribution of nickel and chromium in the dendritic structure. The ratio of maximum to minimum concentration was determined as a function of primary dendrite arm spacing for both as-cast and partially homogenized materials. The results are compared with observations reported in the literatuve. A S part of an investigation of solute segregation in directionally solidified AISI 4340 steel casting, electron probe microanalysis was used to measure the distribution of nickel and chromium in the dendritically segregated material. This complemented the observations on the segregation of radioactive phosphorus obtained by autoradiographic techniques in the same castings.&apos; Kattamis and I?lemings2 have reported similar measurements, using electron probe microanalysis, on dendritically segregated AISI 4340 steels. They found minimum solute concentrations occurred at the center of dendrites, maximum concentrations occurred in the center of interdendritic regions, for symmetrically oriented dendrites, and a regular variation of concentration within dendrite arms. The ratio of maximum to minimum concentration was found to be essentially independent of position in the castings, except near the chill surface where it was somewhat higher. Assuming complete diffusion in the liquid and no diffusion in the solid during freezing, they considered that isoconcentration curves in the steel were homothetic. As a result, isoconcentration curves of the various elements, contour surfaces of dendrites produced by isothermal-transformation studies, and the contour of the solid-liquid interface would all be similar, and could be superimposed by a uniform expansion or contraction of the contours. Preliminary results of the present investigation suggested that isoconcentration curves were not homothetic. It was also evident that points of maximum concentration could not be predicted from the dendrite configuration. Since the ratio of maximum to minimum concentration appeared to be an important parameter in defining the overall segregation in a casting, other techniques for determining the point of maximum concentration were investigated. In addition the overall solute distribution associated with the dendritic structure was examined for both nickel and chromium, and the consistency of the distribution for neighboring dendrites was determined. METHOD Fifty-pound heats of AISI 4340 steel were cast in a manner similar to that used by Flemings et al3 with a water-cooled copper base plate and exothermic sides and top. The nominal composition of the material was C, 0.41 pct; Mn, 0.66; Si, 0.35; S, 0.012; P, 0.010; Ni, 1.88; Cr, 0.95; Mo, 0.28. The steel solidified directionally from the chill surface, with a dendritic structure which increased in dendrite arm spacing with increased distance from the chill. Results of the general investigation of the cast structure and segregation of radioactive phosphorus in these castings have been reported elsewhere.&apos; For the present measurements, sections were cut from the casting at several distances from the chill surface. The sections were subsequently heat-treated, mounted, and then polished on a plane perpendicular to the general freezing direction of the casting. Electron probe microanalysis was carried out with the JEOL-JXA3 microprobe using a voltage of 25 kev and beam current of 0.15 µa. The take-off angle is 22 deg. Quartz crystals were used in the spectrometers and measurements made for Ka radiation from both nickel and chromium simultaneously. A thin layer of carbon was deposited on all specimen surfaces prior to examination in the microprobe. Early measurements were made on polished surfaces, with indentation marks produced by a hardness tester to indicate the area of interest. It was found desirable to use etched surfaces, as opposed to polished surfaces, to reduce sample preparation time and more readily relate the microprobe scan to the structure. To determine if this could be done, without introducing significant errors, a series of measurements were made on polished and etched surfaces of the same specimen. Both polished and etched surfaces produced similar results within normal scatter as shown in the observations. Subsequent measurements were then made on etched surfaces. Measurements with the microprobe analyzer were made by point counting, for periods of 100 sec, at 10-µ intervals. Ten-second counts were made on pure nickel and chromium standards, incorporated in the specimen mount before and after each set of measurements. The results were adjusted for background, then corrected for dead time using the expression:

Jan 1, 1969

By H. J. French

WITHIN the past few years, particularly because of the rapid growth of the airplane industry during the war, considerable attention has been paid to the manufacture of light-wall cold-drawn seamless and welded steel tubing for structural purposes. While the manufacture of such tubing is not, in itself, a difficult matter, some difficulties have. been encountered in producing the same under specifications requiring definite physical properties. It is the purpose of this paper to describe the methods of manufacture and the properties that may be obtained by such methods for tubing coming within about ½ to 2 in. (12.7 to 50.8 mm.) outside diameter and 10 to 22 Birmingham wire gage (0.134 to 0.028 in. wall thickness). Such tubing is largely used as structural material in the aircraft industry, and it is of the utmost importance that the physical and chemical properties should be known, and also that the various factors entering into the manufacture should be under such control as to allow these properties to be varied and held within definite limits. In general, tubing may be divided into four classes: namely, specialty tubing, such as riveted-sheet or plate, lock jointed, etc.; brazed tubing; welded tubing; and seamless tubing. Welded tubing may be divided into hot product, such as lap welded and butt, welded, and cold product, such as acetylene and electric welded. Seamless tubing may be hot rolled or cold drawn.

Jan 9, 1919