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By C. S. Barrett, P. Coheur

AXnealing twins are common in the microstructure of copper that has been rolled and recrystallized. In such samples it follows that a twin relationship should exist between components of the re-crystallization texture,' and several examples of this have been reported. For example, twin relationships have been found in recrystallized electrolytic copper sheet, as indicated in Fig. I, from a paper by Coheur and Lejeune.2 In this pole figure the cube texture (100) [001] is indicated by the hollow squares in the lower half of the figure (the pole figure for 200 reflections) and in the upper, (III), part of the figure. The texture contains, in addition to this orientation, the first-order twins of it, shown in the figure by the filled triangles. This orientation relation has been suggested by others also, under certain annealing conditions,3'4 although pole figures have not been published to confirm it. Some orientations in recrystallized sheets are identical with their twins, because of the symmetry elements of the texture— this is true, for example, with the (113) [ZII] texture so commonly reported for brass—hence it appears impossible in such samples to decide whether the twin relationships result from twinning or merely from the symmetry of the deformation process. The present investigation of a commercial copper strip seems to yield an example in which annealing twins account unambiguously for the principal orientations present. It proves to be a case, also, for which the recrystallization texture cannot be viewed as derived from the deformation texture by a first or second-order twinning mechanism. Materials and Methods The samples investigated were of secondary copper (melted in belgium) to which 0.19 per cent iron had been added to raise the recrystallization temperature. How much the orientation characteristics of this metal can be ascribed to the iron content and how much to other impurities or to melting and pouring practice have not been investigated.* The rolling was done in one direction only, on a mill with rolls of about 20-cm diameter. A strip I. cm wide was reduced from 5 mm thickness to 0.05 mm by several cold passes at commercial speeds. The samples cut from this 99 per cent reduced strip were X-rayed throughout their entire thickness. A pole figure made soon after rolling and annealing was identical, within experimental error, with one that was made when a two-year interval occurred between rolling and annealing. X-ray patterns were made on a camera2 that traversed

Jan 1, 1947

By M. Cohen, W. J. Harris

The recent application of lineal analysislt2 to the austenite-martensite reaction has made possible a quantitative study of the kinetics of this transformation during rapid cooling. Martensite range curves can thus be constructed to portray the onset of the reaction at Ma and its subsequent progress as a function of temperature down to and below the ambient. It now seems in order to investigate other aspects of the martensite transformation, using this quantitative method of approach. One of the least understood characteristics of the austenite-martensite reaction is that of stabilization which has been defined by Troiano and Greninger3 as 'la lowering of Ma, resulting from aging, without change in chemical composition of the parent solid solution." In other words, if the hardening quench is arrested at a predetermined subcritical temperature (TA) for a sufficient period of time, more austenite may be retained at a given lower Or reference temperature (Tr) than if the steel had been cooled directly and rapidly to Tr in the first place. For the purposes of the work at hand, the extent of stabilization produced by the isothermal treatment at Th is measured explicitly in terms of the excess austenite (6) that exists in the steel at T,, over and above the amount that is normally present after direct quenching to T,. T, is conveniently taken to be room temperature, but this choice is not essential and is sometimes undesirable. The holding temperature (TA) may be above or below M,, and still cause stabilization depending upon the themistry of the austenite. stabilization has been found to occur in the presence of bainite4 and of martensite6,6,7,8 as well as in the absence of either,g The phe-nomenon of stabilization is not concerned with (and may even be obscured by) ferrite formation or any other type of phase change occurring at T~ that alters the chemistry of the remaining austenite. Such a structural change would obviously influence the martensite transformation during subscquent cooling. Stabilization, however, is more subtle; it appears to manifest itself without detectable variation of the austenite composition, whether in the presence or absence of transformation products. There are relatively few direct references to stabilization in the literature. The stabilizing effect of room temperature aging and tempering on the subzero transformation of retained austenite has been clearly shown in plain carbon,6,8 low alloy6s7.8 and high alloy tool steels.10'5 ssa- with the as-hardened steel, the degree of stabilization increases with tempering time and temperature through

Jan 1, 1949

By N. J. Grant, D. S. Bloom

THE development of high temperature, high stress alloys had proceeded with such rapidity during the war, and for a short time afterward, that our knowledge of the constitution of the alloys had become seriously inadequate. To interpret correctly alloy behavior it is not only necessary to recognize the phases present, but also to know the properties of the phases under all varieties of conditions and treatments. Chromium in these high temperature alloys holds the unique distinction of being the only one element which must be present when an oxidizing or generally corrosive atmosphere is present and when a long life is desired in service. Carbon and nitrogen must also be considered where chromium is present. Carbon is always present, either as an impurity in the raw alloying elements, or as a deliberate addition agent to increase the strength. Nitrogen is generally picked up from the atmosphere during melting or may be added as an alloying element. The effect of nitrogen additions is not too dissimilar to that of carbon additions. As such, chromium carbides and nitrides become of great interest since they are present in a very large number of alloys, including alloy steels, stainless steels, super alloys, and the like. In the chromium-carbon system there are three accepted, carbides: Cr,C, Cr7C8, and Cr3C2. The existence of one more carbide, a still higher carbon form CrC, has been advanced. The phase diagrams of chromium and carbon as published by Friemann and Sauerwald² and by Tofaute, Kuttner and But- tinghaus³ -do not extend beyond the carbide Cr3C2, which contains 13.3 pct carbon; but Hatsuta has extended the diagram up to 20 pct carbon, and in doing so hypothesized, with the use of some questionable experimental results, the compound CrC. This carbide would contain 18.75 pct carbon, 81.25 pct chromium, by weight. It is further known that as the chromium carbides increase in carbon the acid resistance increases but the oxidation resistance decreases4,5 This is of great importance in high temperature alloys where time-temperature stability, as well as oxidation resistance, is of prime importance. The possible existence of a carbide of the formula CrC thus becomes of prime importance and it was considered important to recheck the chromium-carbon binary constitutional diagram for such a compound. In view of the wide spread of values listed for the melting point of chromium (1500° to 1850°C) and 1930°C8, it was considered .that the liquidus temperatures might well be redetermined more ac-

Jan 1, 1951

By C. S. Smith, E. W. Palmer

IN 1934, when Gregg and Daniloffl wrote their excellent monograph on the alloys of iron and copper, the most recent literature on the constitution of the alloys indicated a narrow single-liquid area for 20" above the liquidus with a closed liquid mis-cibility gap above this. Since that time, however, a number of investigators have confirmed the much earlier studies of Mushet2 and Stead3 who, among others in the nineteenth century, had described the true state of affairs. Liquid copper and iron are completely miscible in the absence of carbon, but small amounts of carbon cause liquid segregation. In 1934, one of the writers' mentioned evidence for the absence of liquid separation in carbon-free alloys at temperatures up to 1700°C. Two years later, Mad-docks and Claussen5 unequivocally established the absence of liquid segregation and published a revised diagram, reproduced in fig. 1. They also studied the limits of the two-liquid area in ternary alloys of iron, copper, and carbon as a function of carbon and iron content. In the same year Simpson and Bannister" and Schumacher and Souden7 described in some detail the properties of alloys containing 50 to 75 pct Cu. More recently Hodges et al.16 have developed the copper-rich alloys for use as high-strength conductors. In 1937, Iwase, Okamoto, and Ameniya8 published data on the miscibility gap in ternary alloys of iron, copper, and carbon that supported the conclusions of Maddocks and Claussen, and definitely located the two-liquid area at temperatures of 1450" and 1540°C. They also reported that additions of 1 pct Al, Ni, Pb, Sn, or Zn caused no segregation in 50 pct Cu alloys at 1540°C. The use of copper in amounts approximating 1 pct has found industrial employment to an increasing degree in both wrought and cast steels, for such steels are capable of being precipitation-hardened following normalizing, and have high yield strengths. This is summarized by Gregg and Daniloff,1 Sallitt,9 and Lorig and Adams,10 while Alexander" gives additional information on the heat treatment of copper-steel castings. Lippert12 has described Digby's two-phase steels containing copper and chromium. The work described in the present paper was done in the years 1932 to 1934, at which time much of the information was new. The excellent work subsequently done in other laboratories but more promptly published makes the present paper in part only a confirmation of what is now well known. There has not, however, been published any unified study of

Jan 1, 1951

By Charles S. Barrett, F. W. Steadman

DEFORMATION bands of surprising regularity are found in large-grained polycrystalline copper after cold-rolling (Fig. I). Individual bands frequently are large enough to permit a determination of their orientation by means of etch pits and an optical goniometer. Measurements have been made on 21 areas in seven different grains, and these, combined with X-ray studies of nine single crystals that had been cold-rolled after mounting in a polycrystal-line block, have contributed to a better understanding of the preferred orientations in rolled copper just as similar studies have for rolled iron' and brass.2.3 Particular attention was given to determining orientations that are stable during rolling and to the manner of fragmentation and rotation of unstable grains. The possible role of twinning was also carefully investigated. The texture of polycrystalline copper after cold-rolling is well established by the pole figures that have been plotted by Schmid and Staffelbach,4 Iweronowa and Schdanow,5 and Brick and Williamson,3 all of which are in substantial agreement. There has been some divergence in the list of individual "ideal" orientations that have been used to describe the texture by these observers and others,6 although the orientation (110) [112]-that is, (110) parallel to the rolling plane and [112] parallel to the rolling direction-is generally recognized as the most prominent orientation and (I12) [111] one of the lesser orientations. Other orientations have been given by some observers as (236) [533], (100) [001], and (I 10) [001]. The texture of copper has also been described as (135) [533].6.1 The sum of these orientations provides a reasonable approximation to the complete pole figure, but it does not follow that these specific orientations are necessarily of fundamental significance, for the choice of indices is arbitrary, within limits. Furthermore, a detailed investigation of the ideal orientations in cold-rolled iron discloses continuous ranges of equally favored positions rather than definite positions of high stability,1 and similarly Brick's observations in a single crystal of a brass2 suggest that all orientations in the range between (110) [113] and (110) [117] are about equally stable. MATERIALS AND METHODS The material used was vacuum-cast electrolytic copper kindly supplied by L. L. Wyman, of the General Electric Co.* Slices 1/2 in. thick and 2 1/2 in. square, cut from the ingot, were rolled with 50 per cent reduction per pass to final thicknesses between 0.02 and 0.04 in., and etched to develop cube-face etch pits suitable for goniometric work.8 The etch was light on some strips and deep in others.

Jan 1, 1942

By B. R. Coil, C. A. Ross

NEW demands for underground power in the Miami mine of the Miami Copper Co., Miami, Ariz. has brought about expansion of the distribution system for both ac and dc power. Progress in mining equipment and the normal changes in the mine were responsible for this increased demand. Early power requirements were for pumping and haulage. A 440 v ac power line down No. 5 shaft took care of a small pumping load and shaft station lighting, 275 v dc power was generated by motor generator sets on the surface, with a churn drill hole from surface to the 570 haulage level serving as a cableway. Electric lights were installed where power was available, and thus were confined to the haulage level and shaft stations. All industrial power in the Miami area is 25-cycle, which dates back to the hydroelectric generator installation at Roosevelt Dam in 1908-10. The Problem The main haulage level was moved to the 720 level and later, to the 1000 level, requiring a longer feeder line with the resultant voltage drop. Also, as mining progressed to the east, the churn drill hole for the power cable would have been subjected to subsidence cracks. The first extension in the use of electricity was in electric blasting. About 1935 the mine went to electric blasting, using the dc haulage current. Bringing electric current to the working levels of the mine for blasting greatly expanded the use of electric lights. Lights were used in tool rooms, powder and cap magazines, stairways, and other semi-permanent installations. Like all mines, Miami Copper began to study and experiment with mechanical mucking and transportation of ore by slushers, shakers, and belts during the late 1930's and early 1940's. At the beginning of the program, power was supplied from the haulage level 275 v dc system. Later it became necessary to run a cable, carrying 440 v ac power, down the No. 7 ventilation shaft. The increased use of power came about gradually, and many new problems were added, not the least being the introduction of switch boards and power cables into the working areas of the mine, where drifts and crosscuts take weight, and require repairs. The 25-cycle current presented special problems, in that 25-cycle transformers are twice as large and about 2V2 times as heavy as 60-cycle transformers of the same power output. The 25-cycle transformers were considered too large for installation in the mining areas. In 1947 the distribution system was revised and standards were adopted, governed by the following

Jan 1, 1952

By A. A. Collins

OF widespread interest to all lead metal¬lurgists is a dross smelting process that will consistently give mattes and speiss of low lead and high copper contents. It is -a problem that has intrigued operators through the years. In the past few years, with increased amounts of copper and overcrowded metallurgical furnaces, it has been almost imperative to evolve some method. Experience at El Paso has shown that high copper-to-lead ratios can be consistently attained by use of the new soda process.* OLDER METHODS Three older methods; i.e., I. Dross plus siliceous ore and limestone, 2. Dross plus one fourth blast-furnace speiss and siliceous ore, 3. Dross plus sulphides and siliceous ore and scrap iron, do not give consistent results and the products are higher in lead and lower in copper than those produced with the soda process. Any radical changes in the blast-furnace drosses will throw any of these older methods into a tailspin. For almost ten years, El Paso used the third method, with varying results. It was noted that as the arsenic and antimony contents of the dross increased, the speiss and matte steadily increased in lead and decreased in copper. A dross containing four parts of copper to one part of arsenic was considered to be ideal. At times this balance of copper to arsenic was almost impossible to obtain, especially when handling copper Cottrell dusts, which vary so greatly in copper and arsenic. Custom smelters like El Paso, handling a great variety of dusts, concentrates and ores, are apt to have anywhere from 1 to 15 pct copper on charge, with a variable in arsenic of from 0.5 to 2 pct. With such conditions, and drosses varying from 12 to 40 pct copper, an operator using the older dross reverberatory practices would find it just about im¬possible to control the reverberatory operations and to produce a good product low in lead and high in copper. These conditions prevailed at El Paso from the year 1940 to the present. In May 1942 it, was decided to experiment with the soda process. THE SODA PROCESS After considerable work the soda method was finally evolved to the present state. It has never failed to produce a good product even under the most adverse conditions. It might be well to remember that many men of thought in the smelting industry have at one time or other suggested the removal of all copper, arsenic and antimony from the lead blast-furnace charge as an aid to better metallurgy.

Jan 1, 1947

By C. S. Barrett, P. Coheur

ANNEALING twins are common in the microstructure of copper that has been rolled and recrystallized. In such samples it follows that a twin relationship should exist between components of the recrystallization texture,1 and several examples of this have been reported. For example, twin relationships have been found in recrystallized electrolytic copper sheet, as indicated in Fig. I, from a paper by Coheur and Lejeune.2 In this pole figure the cube texture (100) [001] is indicated by the hollow squares in the lower half of the figure (the pole figure for 200 reflections) and in the upper, (111), part of the figure. The texture contains, in addition to this orientation, the first-order twins of it, shown in the figure by the filled triangles. This orientation relation has been suggested by others also, under certain annealing conditions,3,4 although pole figures have not been published to confirm it. Some orientations in recrystallized sheets are identical with their twins, because of the symmetry elements of the texture this is true, for example, with the (113) [211] texture so commonly reported for brass-hence it appears impossible in such samples to decide whether the twin relationships result from twinning or merely from the symmetry of the deformation process. The present investigation of a commercial copper strip seems to yield an example in which annealing twins account unambiguously for the principal orientations present. It proves to be a case, also, for which the recrystallization texture cannot be viewed as derived from the deformation texture by a first or second-order twinning mechanism . MATERIALS AND METHODS The samples investigated were of secondary copper (melted in Belgium) to which 0.19 per cent iron had been added to raise the recrystallization temperature. How much the orientation characteristics of this metal can be ascribed to the iron content and how much to other impurities or to melting and pouring practice has not been investigated.* The rolling was done in one direction only, on a mill with rolls of about 20-cm diameter. A strip 10 cm wide was reduced from 5 mm thickness to 0.05 mm by several cold passes at commercial speeds. The samples cut from this 99 per cent reduced strip were X-rayed throughout their entire thickness. A pole figure made soon after rolling and annealing was identical, within experimental error, with one that was made when a two-year interval occurred between rolling and annealing. X-ray patterns were made on a cameral that traversed

Jan 1, 1946

By Henry J. Joesting

During the past year and a half, the Territorial Department of Mines in Alaska has conducted a modest experimental program for the purpose of determining the extent to which magnetic and resistivity methods can be used in interior Alaska in connection with prospecting, mining and geological studies. Since little information is available concerning previous work,l,2 and since conditions differ considerably from those in most other regions, it was considered advisable to make a general study of the possibilities and limitations of the two methods, rather than a detailed study of any single problem. Problems One of the most serious handicaps to prospecting and geological study in interior Alaska, especially in the mature regions, is a cover of unconsolidated deposits ranging in thickness from a few feet to several hundred feet. These deposits, some of which are permanently frozen, consist of silt with varying proportions of vegetation and windblown material in the valleys and of residual deposits on the hills.3'4 The problems treated here are caused by the existence of this overburden: I. Location of buried placers. 2. Determination of depth and areal distribution of permanently frozen and of thawed unconsolidated deposits. 3. Location of water-bearing beds under unconsolidated deposits. Instruments and Methods Magnetic and direct-current resistivity methods were used because they are relatively simple, rapid and inexpensive and because generally they are well suited to the study of the problems indicated. The instruments used were a vertical Schmidt-type magnetometer and a direct-current resistivity instrument similar to those used by the Geophysical Branch of the U. S. Geological Survey. For placer surveys with the magnetometer, a sensitivity of about 25 gammas per scale division was found suitable. For resistivity studies of frozen and thawed overburden and of underground water, the Lee partitioning method6 was found to be most generally suitable. In the Lee method a central potential electrode is placed midway between the two potential electrodes of the Wenner four-electrode configuration.7 Nonpolarizable electrodes were made from unglazed porcelain pots about 10 cm. high and 5 cm. in diameter. In order to retard evaporation of the electrolyte the sides of the pots were glazed, inside and out, with clear Duco lacquer. For resistivity work in cold weather, a nonfreezing electrolyte consisting of equal parts of ethylene glycol and a saturated water solution of copper sulphate proved satisfactory. Stainless steel rods of 3/4-in. diameter made excellent current electrodes because their bright finish enabled good ground contacts to be made.

Jan 1, 1946

By Gerhard Derge

METALLURGISTS have used borax as a fluxing agent traditionally, but until recently elemental boron has played an insignificant role as an alloying element. Neither the metal nor its compounds have been regarded as important metallurgical materials and there is a surprising lack of knowledge concerning their metallurgical behavior. The new applications to steelmaking of both boron and borates, which arose in part from wartime incentives and restrictions, have been seriously handicapped by this lack of data. For example, rasorite, a naturally occurring sodium borate, has been shown to be an effective substitute for aluminum as a ladle deoxidizer in rimming steels.1 Likewise, the effectiveness of boron as an alloying agent has been demonstrated, 2,3 giving deep hardening when used in restricted amounts. The exploitation of both of these uses has been retarded by the difficulty of attaining suitable metallurgical control. Recognizing that the most important information required was a knowledge of the equilibrium between boron and oxygen dissolved in liquid iron, Gurry4 calculated this relation from the best thermal data available. However, estimates of the entropy of melting of boron, the activity coefficient of boron in liquid iron and the activity coefficient of B203 in slag were involved, and experimental work on this problem was obviously desirable. The experiments to be described were planned to establish the boron-oxygen relations in liquid iron and to demonstrate at the same time the ferroborate slag compositions in equilibrium with various amounts of oxygen in liquid iron. Accordingly, slags containing varying proportions of iron and boron oxides were held in contact with molten iron, and samples of both slag and metal were analyzed. The limitations upon the accuracy of the data will be considered, but in a practical sense the oxygen levels that can be attained in iron by iron borate slags, and the amounts of boron in iron at these oxygen levels were established. EXPERIMENTAL PROCEDURE No entirely suitable refractory was found for the mixtures of iron oxide and boron oxide used as slags. Crucibles of silica, magnesia, Ramix, beryllia, and zirconia were all tried unsuccessfully. The most satisfactory method discovered for handling them was the rotating-crucible technique, which creates a parabolic crucible of liquid iron 5,6 Even this was not entirely successful, for at steelmaking temperatures (1600°C.) the slags had such a low surface tension that they crept up to the refractory and slowly dissolved it. These difficulties made it impossible to maintain a constant slag composition for an unlimited period of time. However, by using the rotating

Jan 1, 1946

By C. R. McEwen

The displacement equations of Buckley and Lever-ett' have been successfully applied to the prediction of oil recovery in frontal drives for a number of years. Commonly, the capillary pressure term is omitted from Leverett's fractional flow formula. The resulting satura-tion-vs-distance curves become multi-valued, however. Buckley and Leverett, recognizing that the neglect of capillarity was most likely the cause, proposed that this part of the solution he ignored. An ingenious method of propagating a discontinuity in place of the multi-valued portlon of the curve was devised by Cardwell using "non-capillary displacement theory". However, it would seem that a completc description of the displacement pracess would require the inclusion of capillary forces. Three publications on displacement theory have appeared in which capillary pressure was included. Ter-williger. et al', calculated saturation profiles which matched those which they observed when gas displaced water vertically downward. Based on their study, Jones-Parra and Calhoun5 roposed a method of computing saturation distributions sufficiently removed in time from the initial conditions so that all saturations in the flood front region were assumed to move with the same velocity. This latter assumption corresponds to the tangent construction on the flowing fraction-vs-satura-tion curve proposed by Welge." A numerical solution to the problem of water displacing oil from a water-wet porous medium was recently presented by Blair, ef at'. The initial conditions included a uniform saturation slightly above interstitial water saturation. that is, the permeability to water ahead of the front was not zero. This appeared to result in a region of slowly rising water saturation ahead of the front, at least for the particular set of relative permeability and capillary pressure data used to illustrate the computation. The authors also postulated an "end-effect" at the outflow face of the system, whereby no water could pass out of the system until the water saturation had built up to a high value. The saturation profiles computed under these assumptions show water accumulating at the downstream end of the system while the flood front proper is still traveling toward the outlet. The purpose of this paper is to present the results of a numerical solution to the one-dimensional water-flooding equation in which no outlet end-effect is considered and where there is no flow of water ahead of the flood front. It should be noted that the contemporary paper of Fayers and Sheldon8 deals with the problem under discussion. For a thorough treatment including both capillarity and gravity the reader is referred to their paper.

By Henry J. Joesting

During the past year and a half, the Territorial Department of Mines in Alaska has conducted a modest experimental program for the purpose of determining the extent to which magnetic and resistivity methods can be used in interior Alaska in connection with prospecting, mining and geological studies. Since little information is available concerning previous work,l,2 and since conditions differ considerably from those in most other regions, it was considered advisable to make a general study of the possibilities and limitations of the two methods, rather than a detailed study of any single problem. Problems One of the most serious handicaps to prospecting and geological study in interior Alaska, especially in the mature regions, is a cover of unconsolidated deposits ranging in thickness from a few feet to several hundred feet. These deposits, some of which are permanently frozen, consist of silt with varying proportions of vegetation and windblown material in the valleys and of residual deposits on the hills.3'4 The problems treated here are caused by the existence of this overburden: I. Location of buried placers. 2. Determination of depth and areal distribution of permanently frozen and of thawed unconsolidated deposits. 3. Location of water-bearing beds under unconsolidated deposits. Instruments and Methods Magnetic and direct-current resistivity methods were used because they are relatively simple, rapid and inexpensive and because generally they are well suited to the study of the problems indicated. The instruments used were a vertical Schmidt-type magnetometer and a direct-current resistivity instrument similar to those used by the Geophysical Branch of the U. S. Geological Survey. For placer surveys with the magnetometer, a sensitivity of about 25 gammas per scale division was found suitable. For resistivity studies of frozen and thawed overburden and of underground water, the Lee partitioning method6 was found to be most generally suitable. In the Lee method a central potential electrode is placed midway between the two potential electrodes of the Wenner four-electrode configuration.7 Nonpolarizable electrodes were made from unglazed porcelain pots about 10 cm. high and 5 cm. in diameter. In order to retard evaporation of the electrolyte the sides of the pots were glazed, inside and out, with clear Duco lacquer. For resistivity work in cold weather, a nonfreezing electrolyte consisting of equal parts of ethylene glycol and a saturated water solution of copper sulphate proved satisfactory. Stainless steel rods of 3/4-in. diameter made excellent current electrodes because their bright finish enabled good ground contacts to be made.

Jan 1, 1946

By George H. Found

DURING recent years considerable interest has been focused on the energy-absorption characteristics of metal when it is cyclically stressed in vibration. The most familiar manifestation of this phenomenon, which is called the "damping capacity" or "internal friction" of a material, is involved in the dissipation of mechanical energy of vibration, which otherwise would build up to stress levels where the problems of noise and fatigue are involved. In addition to its engineering importance in structures, the damping behavior of metals, particularly at low stress amplitudes, has also been used as a unique metallurgical research tool with which to provide sensitive means for indicating certain structural changes within metals. Important contributions toward understanding the energy-dissipating mechanisms that are responsible for internal friction in metals have been made in the last few years. The information is not yet sufficiently extensive, however, to provide a useful metallurgical concept describing exactly how the structure affects the internal friction, or to encourage more general use of this technique among metallurgists. Three fundamental mechanisms have been proposed, as a result of recent experimental investigations, to account for the internal friction in nonferrous metals in low-stress amplitude tests. These include damping due to internal thermal currents that are created and flow in metal because of differential vibratory stress effects,1 damping due to localized inelastic stress relaxation at inhomogeneities within the metal,2,3 and damping related to plastic flow of a localized type for which an explanation has been sought in terms of the dislocation theory.4 How each of these mechanisms functions as a result of structural changes in the metal is, in general, not well understood because of insufficient experimental data for which the controlling variables have been segregated and because of uncertainties in regard to the nature of the structural changes themselves. In several investigations the effects of cold-working on the internal friction of polycrystalline brass and aluminum have been described. As reported by Köster and Rosenthal,5 and by Förster and Breitfield,6 there is an initial large increase in the damping when the metal is worked. The initial high value is not stable, but declines rapidly, at first, in a hyperbolic manner. About 100 hr, after straining, a stable value is reached of magnitude proportional to the amount of strain.7 In Fig. I is shown the relationship found by Zener and his collaborators between the internal friction due to cold-working of alpha brass and the amount of cold-working.8 Several investigators have made internal-friction measurements on worked poly-

Jan 1, 1945

By E. P. Klier

The work of Klier and Lyman1 on the bainite reaction has led to the full description of this reaction for medium-carbon low-alloy steels. Certain experimental data reported by Klier and Lyman appear, however, to be improbable of obtaining in very high-carbon steels. The study herein reported consists of an analysis of the transformation characteristics of a 3 per cent chromium, I per cent carbon steel by means of X-ray and metallographic methods. From the results obtained it is concluded that the bainite reaction in this steel is more complicated than that reported by Klier and Lyman for the low-carbon low-alloy steels. Henever, the mechanism of bainite formation in this steel appears to be essentially the same as proposed for the low-carbon low-alloy steels with the modification that the first volumes to transform are carbon-rich rather than carbon-poor. Experimental Procedure The analysis of the steel studied was: Cr, 2.89; C, 1.02; Mn, 0.33; Si, o.35; S, 0.012; P, 0.020. The stock was received from the Carpenter Steel Co. in rolled bars. Specimen Preparation Specimens were austenitized at 1200°C. (2192°F.) for 25 min. in purified nitrogen. The resultant A.S.T.M. austenite grain size was 0-1. Isothermal transformation was allowed by quenching the specimens into liquid metal baths controlled to 5°C. at 540°C. (1004°F.) and above, and to 2°C. at 490°C. (914°f.) and below. Following the desired degree of transformation all specimens were water quenched. Metallographic Examination Specimens 1/4 in. round by 1/4 in. were used for nietallographic examination. Etch-ants used were Vilella's reagent (I gram picric acid, 10 ml. hydrochloric acid to make 100 ml. ethyl alcohol solution) and alkalinc sodium picratc (electrolytic). Vilella's reagent was effective in revealing all microconstitucnts, while the alkaline sodium picrate developed the carbon-rich structures or carbides only. X-ray Examination Two X-ray techniques were used—the Debye-Scherrer method and a back-reflection method. 'The small specimens necessary for the Debye-Scherrer method were austenitized and then allowed to transform, or were cut from the larger metallographic specimens. The metallographic specimens were used for the back-reflection X-ray analysis. When it was desirable to determine the structure of the carbide present, sliver specimens were electrolytically etched to develop a carbide coating, then were exposed in the cameras. This technique was frequently necessary to allow positive identification of the carbide.

Jan 1, 1945

By D. C. Hilty, W. Crafts

The solubility of oxygen in iron containing aluminum has been determined at 1550°, 1600°, and 1650°C and found to be much higher than predicted from theoretical considerations, possibly due to equilibria with an iron-aluminum spinel phase rather than pure AI,O.. The presence of manganese greatly increased the deoxidizing power of aluminum. DEOXIDATION and inclusion formation in steel have proved to be elusive phenomena that are difficult to control in spite of much effort to understand and evaluate the reactions. Study of the problem indicated that more accurate data on the solubility of oxygen in iron containing deoxidizers were essential to further progress, and an empirical determination of oxygen solubilities has been initiated at the Union Carbide and Carbon Research Laboratories, Inc. The investigation has included the effects of aluminum, silicon, manganese, and combinations of these elements at 1550°, 1600°, and 1650°C. The equipment and experimental procedure as well as the results of a study of the effects of aluminum are described below. In general, it was found that the solubility of oxygen in iron containing aluminum is much higher than predicted, possibly because of the formation of complex nonmetallic phases, and that manganese greatly increases the deoxidizing power of aluminum. The generally accepted deoxidation curves for 1600°C are summarized in fig. 1, from "Basic Open Hearth Steelmaking"'. These curves are assumed to represent the solubility of oxygen in the presence of deoxidizers and should indicate the limits of mis-cibility gaps in the phase diagrams of the systems that control the formation and character of non-metallic inclusions as described by Benedicks and Lofquist'. They were derived mainly by application of the methods of thermodynamics to the available experimental observations, and by calculations based on the thermal constants of the pure substances when experimental data were lacking. Among the more notable researches contributing to the development of knowledge of oxygen solubilities are those of Korber and Oelsen8, 4, C. H. Herty, Jr. and associates5,6, Krings and Schackmann7, Went-rup and Hieber8 Schenck and Briiggeman9, Vacher and Hamilton'" and Chipman and co-authors 1,11,12,13 Practically, the deoxidation curves are of limited value in predicting oxygen content and rationalizing deoxidation practices. The reasons for this inadequacy appear to be error from inaccurate data, oversimplifying assumptions, interacting effects of combined deoxidizers, and possibly unknown extra-equilibrium and side reactions. Although inclusion formation is a very complex reaction it must be re-

Jan 1, 1951

By G. Sachs, E. J. Ripling, S. I. Liu, J. J. Lynch

It is a generally recognized fact that by repeated straining the fracture stress of any metal is reduced to a fraction of its value for static loading. The value of this fatigue strength depends upon numerous factors, such as the states of strain and stress, the limits of straining, and the number of repeated loadings or cycles The large volume of previous investigations on fatigue is concerned entirely with large numbers of cycles, say exceeding 10,000 and up to 500,000,000. However, the changes in fracture stress and fracture strain occurring after a small number of repeated loadings have attracted little attention. Apparently the only investigations of this type are those byLudwik4.5 who subjected steel, copper, and aluminum wire to repeated torsion. In each test the torque was varied between identical values in the two directions of twisting. Depending upon the magnitude of the moment, fracturing occurred after a number of cycles, up to 10,000. The results of Ludwik's tests will be discussed later Such torsion does not readily yield actual stress and strain values. Therefore a pre- liminary study was made of the effects of repeated direct stresses, that is, tension and compression stresses. Because such tests are considerably more tedious than torsion tests, only high stresses were used in the preliminary work, yielding definite changes in metal properties after a few cycles. It was found in these tests that strains could be controlled more readily than stresses in the investigated range of high stresses. This paper, consequently, deals with the effects of strains of equal magnitude but different signs. The metal was first prestrained in static tension by a certain amount then subjected to compression to yield the same amount of strain after unloading. This loading cycle was repeated up to a maximum of seven times. After various cycles, the stress-strain curves in tension were determined, up to fracturing. As material for these tests, the aluniinum alloy 24ST was selected because it exhibits a comparatively small amount of necking in the tension rest This alloy permitted, therefore rather accurate cont.rol at the high strains necessary to produce fatigue failures at less than seven cycles. The results of this invest~gation appear sufliciently interesting to extend the method of attack in various directions It is intended to study (11 the effects of cycles up to a tew thousands and (2) the effects of strains of different magnitude in tension and compression respectively 'The latter variable also includes a. a special case the effects of compressive strains.

Jan 1, 1949

By W. L. Fink, M. S. Hunter, R. H. Brown

Early workers attempted to study the structure of alloys by measurement of equilibrium electrode potentials in aqueous solutions containing ions of the metals from which the alloy was made.' The method was subject to such limitations (e.g., the difficulty in attaining electrochemical equilibrium at low temperatures) that it has not been widely used by metallurgists. Recently, Seltz and co-workers have introduced a greatly improved method for studying alloys by measurement of equilibrium electrode potentials in molten salts.2"4 The mathematical treatment is the same, of course, as for equilibrium potentials of amalgams in aqueous solutions.5 This method will probably find extensive use, since it makes possible not only the determination of phase fields of equilibrium diagrams but also the determination of certain thermodynamic quantities which can be used advantageously in metallurgical calculations. However, the method presents difficulties. With many metallic and alloy electrodes, reversibility is not readily obtainable. Also, the difficulty of obtaining suitable material from which to make the cells is increased as the temperature is increased. Moreover, the necessity of carrying out measurements in a vacuum requires additional apparatus and introduces considerable difficulty, especially at the higher temperatures. Apparently, no consideration has been given heretofore to the metallurgical use of irreversible electrode potentials that exist when a specimen is immersed in a suitable aqueous solution at room temperature. The apparatus and the method required for such measurements are very simple, and if the results of such measurements could be demonstrated to be reproducible they might be very valuable in studying the structure of alloys. The method would not have the scope of that developed by Seltz and his co-workers because no thermodynamic quantities could be calculated from the data. However, the utility and the simplicity of the method might warrant extensive use for the determination of phase fields and similar applications. Theory of Irreversible Potentials A brief review of the theory of irreversible potentials will be given before showing how to interpret the potential readings in terms of alloy structure. It is known that heterogeneity of a metal surface in an electrolyte will produce points of different potentials, with the result that current flows between these points and electrochemical reactions occur. The points at which oxidation reactions are localized are known as anodes, and those at which reduction reactions are localized are known as cathodes.6, 7, 8 For the benefit of those who are not familiar with the terms anode and cathode as applied to a primary cell, the potential difference between anode and cathode of such a cell can be measured when

Jan 1, 1941

By John Chipman, Eric R. Jette, O. B. Ellis

IN the study of the chemical reactions occurring in the open-hearth furnace, it is frequently assumed that a condition of equilibrium between slag and metal is attained. In order to test this assumption it is necessary to have dependable operating data as well as an exact knowledge of the equilibrium state. Considerable progress has already been made in the study of slag-metal equilibria, notably in the earlier work of Herty1 and of Oberhoffer and Schenck2 and in the more recent researches of Krings and Schackmann3 and of Koerber and Oelsen.4 None of these investigators, however, have employed basic slags comparable to those encountered in basic open-hearth practice, so that up to the present time our only information regarding the equilibria of these slags is based upon observations drawn from steelmaking practice in which there is little assurance that actual equilibrium was attained. The original plan of this investigation was to secure simultaneous slag and metal samples at intervals during the making of an open-hearth heat, recording the heat history in detail and obtaining complete analyses of slag and metal, then to bring these slag samples into equilibrium with liquid iron in the laboratory induction furnace and thus to determine directly whether or not the observed relationships in the open hearth represent conditions approaching equilibrium. This plan was only partly successful. While slags were obtained from the open hearth under satisfactorily recorded conditions and these were remelted in the laboratory under equilibrium conditions, changes in slag composition, which accompanied the remelting operation, were so great that the final slag from the induction furnace bore little resemblance to its open-hearth parent and the direct comparison was therefore abandoned. The results, however, lie within a range of slag composition that is of interest in the making of low-carbon steel. As far as we are aware, they represent the first published laboratory study of equilibria involving slags that contain all the constituents of basic open-hearth slag. EXPERIMENTAL HEATS The first set of measurements on slagmetal equilibrium was made in the Research Laboratories of the American Rolling Mill Co. at Middletown, Ohio. This will be known as series A. The second set was made in the Metallurgical Research Laboratories at Massachusetts Institute of Technology, and will be referred to as series B. Series A.-The induction furnace used has been described.5 Approximately I kg. of a special ingot iron containing less than

Jan 1, 1941

By M. S. Hunter, W. L. Fink, R. H. Brown

Early workers attempted to study the structure of alloys by measurement of equilibrium electrode potentials in aqueous solutions containing ions of the metals from which the alloy was made.' The method was subject to such limitations (e.g., the difficulty in attaining electrochemical equilibrium at low temperatures) that it has not been widely used by metallurgists. Recently, Seltz and co-workers have introduced a greatly improved method for studying alloys by measurement of equilibrium electrode potentials in molten salts.2"4 The mathematical treatment is the same, of course, as for equilibrium potentials of amalgams in aqueous solutions.5 This method will probably find extensive use, since it makes possible not only the determination of phase fields of equilibrium diagrams but also the determination of certain thermodynamic quantities which can be used advantageously in metallurgical calculations. However, the method presents difficulties. With many metallic and alloy electrodes, reversibility is not readily obtainable. Also, the difficulty of obtaining suitable material from which to make the cells is increased as the temperature is increased. Moreover, the necessity of carrying out measurements in a vacuum requires additional apparatus and introduces considerable difficulty, especially at the higher temperatures. Apparently, no consideration has been given heretofore to the metallurgical use of irreversible electrode potentials that exist when a specimen is immersed in a suitable aqueous solution at room temperature. The apparatus and the method required for such measurements are very simple, and if the results of such measurements could be demonstrated to be reproducible they might be very valuable in studying the structure of alloys. The method would not have the scope of that developed by Seltz and his co-workers because no thermodynamic quantities could be calculated from the data. However, the utility and the simplicity of the method might warrant extensive use for the determination of phase fields and similar applications. Theory of Irreversible Potentials A brief review of the theory of irreversible potentials will be given before showing how to interpret the potential readings in terms of alloy structure. It is known that heterogeneity of a metal surface in an electrolyte will produce points of different potentials, with the result that current flows between these points and electrochemical reactions occur. The points at which oxidation reactions are localized are known as anodes, and those at which reduction reactions are localized are known as cathodes.6, 7, 8 For the benefit of those who are not familiar with the terms anode and cathode as applied to a primary cell, the potential difference between anode and cathode of such a cell can be measured when

Jan 1, 1941

By Walter R. Hibbard, Ming-Kao Yen

VARIOUS rationalizations of preferred orientations in cold worked polycrystalline metals have been based on the operation of at least two,1 three,2 five,4 an indefinite number,5 and all,6 slip systems of the type occurring in single crystals. Pickus and Mathewson3 suggested that the cold rolling texture in face-centered cubic metals could be rationalized on the basis of two or more operating slip directions symmetrically disposed about the direction of flow in such a manner that the resolved shear stress factor is equal for all operating slip systems and lattice rotations cancel each other. The importance of the direction of flow, † the necessity for the operation of slip systems capable of producing the required, changes in external dimensions, the maintenance of a common surface between adjacent grains and a symmetrical arrangement of the operating slip systems in order to produce an end orientation which is stable under additional deformation lead to the following rationalization of textures based on the type of slip systems operative in single crystals. The rationalization is intended to explain why certain orientations are suitable for deformational flow without a change in orientation and thus are stable end orientations or ideal texture orientations. It does not attempt to explain how the grains of a randomly oriented polycrystalline aggregate will reach this orientation. The rationalization is based on the following four postulates: I. The ideal textures for polycrystalline aggregates are the result of reorientations of individual crystals toward the same stable end orientation at which no further reorientation will occur even during additional deformation. Since, in simple slip, - the relative orientations of the stress axis and the active slip system determine the change in orientation during slip, it is considered that the orientation of the stress axis with respect to the ideal texture determines what slip systems must be active to retain the stable end orientation. Therefore the stable end orientation should be a symmetrical one around the stress axis with respect to the active slip systems such that lattice rotations resulting from slip will cancel each other and prevent a resultant change in orientation. (Rotational symmetry only-not translation, inversion, nor others-is considered here.) Thus a metal under a pure stress should develop a texture consisting of one or more of the crystallographically symmetrical directions, <100>, <110> or <111> for cubic metals or <0001>, <1010> or <1120> for hexagonal dose-packed metals, parallel to the stress axis. 2. Since the active slip direction is the direction of glide during simple slip and thus the direction of maximum shear movement, in the ideal texture the active slip

Jan 1, 1948