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By Paul T. Allsman, E. W. Newman

Trenching, sampling, and core drilling in Stillwater and Sweetgrass Counties, Mont., by the Bureau of Mines have delimited over 5,000,000 tons of chromite ore containing more than 20 per cent chromic oxide. The Benbow and Mouat-Sampson mines have been developed and are fully equipped for mining and milling 500 tons and 2000 tons a day, respectively. Introduction The Montana chromite deposits were the first to be explored under the Strategic Minerals Act of 1939. In June of that year, the Bureau of Mines started exploration by trenching, test pitting, sampling and diamond drilling, and completed the project in March 1943. The U. S. Geological Survey cooperated by mapping the geology and logging the cores. The project was to determine the extent and grade of the chromite ore and to indicate sufficient reserves to justify development and exploitation of the deposits for the national emergency. Exploration has indicated that the district contains the largest and most important reserve of chromite ore in the United States. The Benbow and Mouat-Sampson mines have been developed and a 500-ton concentrating mill has been constructed on the Benhow property and a 2000-ton mill on the Mouat-Sampson property. Concentrates were produced from the Benbow mill three months after the attack on Pearl Harbor, when the nation's major chromite supplies from foreign sources were cut off. History It has been known for 50 to 60 years that some chromite deposits existed in an east-west belt along the north escarpment of the Beartooth Mountains about 25 miles north of Yellowstone Park, but nothing was known of their size and extent until the war demand of 1917 and 1918 stimulated the search. In those years two properties in the Stillwater region were actively developed, but no shipments were made. The Benbow property was located in 1918 by a local group. The property comprised seven claims along the strike at the east end of the belt. An adit was driven several hundred feet on the Eclipse claim. The seven claims were sold to the Chromium Products Corporation of Livingston, Mont., and were subsequently patented. In 1929, an eastern group obtained an option, installed some equipment, and erected several log cabins. The "crash" in the market in 1929 caused the operators to drop their lease, and the property remained inactive until 1939, when the Bureau of Mines began its exploration. Fourteen claims were located on the Boulder River in 1918 and subsequently patented by the U. S. Chrome Corporation.

Jan 1, 1949

By S. R. Goodman, Hsun Hu

The rolling texture transition in copper as a function of deformation temperature is found to be quite similar to that in high-purity silver. The ordinary copper type texture changes gradually to the brass type, accompanied by an increase in the stacking fault frequency, as the temperature of deformation decreases. The rolling textures obtained at low temperatures and the corresponding annealing textures compare remarkably well with the ordinary rolling and annealing textures of low-zinc brasses. Furthermore, it is also found that the observed stacking fault energies of copper specimens deformed at low temperatures correspond closely with those of low-zinc brasses, as deduced from measurements of the dislocation nodes. These results are consistent with the idea that texture transition may be significantly dependent on the stacking fault energy. It was shown in a series of previous publications1"3 that the rolling texture of high-purity silver changes gradually from the common silver type (or the brass type) to the copper type* with increasing temperature *The silver or brass type rolling textures are commonly described as (110)[112],4,5 whereas the copper type rolling textures are mainly (123) [a121 and (146)[211].5 Other ideal orientations have been used by various investigators for the copper type rolling textures, but the actual difference among these ideal orientations is rather small. of deformation, and that such texture transition can be correlated with the change in stacking fault frequency as a function of rolling temperature. Furthermore, it was shown that the formation of annealing textures in high-purity silver from the various rolling textures obtained during the course of texture transition depends entirely upon the deformation texture. From a common silver type or brass type rolling texture (such as produced by rolling at 0" or at 50° C) the recrystallization texture is mainly (120)[211], which is quite different from the recrystallization texture of brass.* However, for both ma- terials the orientation relationship between the rolling texture and the recrystallization texture can be expressed in terms of similar rotations around [Ill.] axes of approximately 30 or 35 deg. They differ in that the [Ill] rotational axes are different. In the case of high-purity silver, the axes of rotation are the two (111) poles near the plane normal of the deformed specimen with a (11l)[112] type rolling texture, whereas in brass, they are the (111) poles near the direction of rolling. For high-purity silver with a predominantly copper type rolling texture (such as produced by rolling at 150° or 200°C) the recrystallization texture is mainly (100)[001], or the cube texture, plus its twin orientations. It was shown previously6 that such reorientation observed in copper or aluminum can be described as [Ill] rotations of 30 to 40 deg. For intermediate cases, i.e., when the rolling textures are composed of a

Jan 1, 1963

THE primary interest in the subject of this chapter lies in the fact that various heats of steel made to the same chemical specification do not always have the same properties. The properties considered here, of course, are those inherent in the ingot immediately after solidification and not qualities imparted by variations in subsequent mechanical or thermal treatment. The expression "made to the same chemical specification" is used because some of the variations in properties are due to variations in chemical analysis within the specified ranges of those elements commonly specified and determined. Other variations in properties are due to variations in those constituents of steel (elements or compounds) that are not ordinarily included among the elements specified, thus not a part of the specified "composition." The term "constitution" is used to include not only the specified composition but also the nature and distribution of every element or compound contained in the steel entering the ingot mold ; also included are items such as aluminum oxides and nitrides, presence of soluble gases, and dispersion of nonmetallic particles. When it is considered that the constitution of steel is determined by the addition or absorption into the bath of all such constituents from whatever source, it follows that constitution is of necessity the final result of steelmaking practice. It is the agency through which steelmaking practice operates to control the properties of the steel. The term steelmaking practice is here used in the broad sense, meaning the control of all the materials entering the steel and of the conditions under which the process is carried out. Steelmaking practice, thus defined, establishes the chemical system within which the reactions between components must proceed in obedience to the laws of chemistry. Thus the chemical constitution of the steel is established and, through constitution, the properties of the metal are established. In the preceding chapters it has been shown how the constitu-

Jan 1, 1964

By C. W. Gennet

Announcement was made in the spring of 1926 that the Boston & Maine R. R. Co. had contracted with the well-known German steelmakers, Messrs. Fried Krupp, for the manufacture of 15,000 tons of basic open-hearth steel rails at the Rheinhausen Works, for delivery to Boston, Mass. The manufacture of rails in the United States has for many years been almost a national pride, and as this feeling is chiefly the result of a long-time liberal and consistent patronage of American rails by American railroads, it is not strange that this somewhat unusual announcement should arouse more than ordinary interest. Since the end of the World War, the importation of foreign rail has been fairly large, principally because the newly created economic conditions have rendered some American competition more difficult, but the tonnage imported, for the most part, has been made up of small orders for miscellaneous use; and the contract referred to constitutes the largest single importation of foreign rail in over ten years. In 1915, the Algoma Steel Co. of Sault Ste. Marie, Canada, supplied the Illinois Central R. R. with 30,000 tons of rails,' and various other American roads with smaller amounts. In 1902, 1903 and 1904, large tonnages of rail from abroad were purchased, the Louisville & Nashville R. R. alone obtaining 30,000 tons from German mills. It is the object of this paper to present, in what is believed to be a new and concise form, figures showing the production and consumption of rails in the United States, and to record some of the testing and inspection results of the recent Krupp rails; also, to direct attention to two quite unique departures from American practice that were regular features of the Krupp process and which are worthy, it is thought, of careful study. Production and Consumption of Rails in the United States Table 1 shows the tonnage of rail produced in the United States and the amount imported, exported, and consumed by years since 1849. That, evidently, was the first year of record, for the statistics of the American Iron and Steel Institute and its predecessor, the American Iron and

By Paul T. Allsman, E. W. Newman

Trenching, sampling, and core drilling in Stillwater and Sweetgrass Counties, Mont., by the Bureau of Mines have delimited over 5,000,000 tons of chromite ore containing more than 20 per cent chromic oxide. The Benbow and Mouat-Sampson mines have been developed and are fully equipped for mining and milling 500 tons and 2000 tons a day, respectively. Introduction The Montana chromite deposits were the first to be explored under the Strategic Minerals Act of 1939. In June of that year, the Bureau of Mines started exploration by trenching, test pitting, sampling and diamond drilling, and completed the project in March 1943. The U. S. Geological Survey cooperated by mapping the geology and logging the cores. The project was to determine the extent and grade of the chromite ore and to indicate sufficient reserves to justify development and exploitation of the deposits for the national emergency. Exploration has indicated that the district contains the largest and most important reserve of chromite ore in the United States. The Benbow and Mouat-Sampson mines have been developed and a 500-ton concentrating mill has been constructed on the Benhow property and a 2000-ton mill on the Mouat-Sampson property. Concentrates were produced from the Benbow mill three months after the attack on Pearl Harbor, when the nation's major chromite supplies from foreign sources were cut off. History It has been known for 50 to 60 years that some chromite deposits existed in an east-west belt along the north escarpment of the Beartooth Mountains about 25 miles north of Yellowstone Park, but nothing was known of their size and extent until the war demand of 1917 and 1918 stimulated the search. In those years two properties in the Stillwater region were actively developed, but no shipments were made. The Benbow property was located in 1918 by a local group. The property comprised seven claims along the strike at the east end of the belt. An adit was driven several hundred feet on the Eclipse claim. The seven claims were sold to the Chromium Products Corporation of Livingston, Mont., and were subsequently patented. In 1929, an eastern group obtained an option, installed some equipment, and erected several log cabins. The "crash" in the market in 1929 caused the operators to drop their lease, and the property remained inactive until 1939, when the Bureau of Mines began its exploration. Fourteen claims were located on the Boulder River in 1918 and subsequently patented by the U. S. Chrome Corporation.

Jan 1, 1949

By H. E. Lee, P. C. Feddersen, D. R. Gittinger, G. W. Dunn, J. B. Schuettenhelm

The new Bunker Hill slag-treatment plant, designed ior, a capacity of 300 to 400 tons of hot slag per day, was "blown in" April 5, 1943. In the ensuing I5-months period, 157,530 tons of slag was processed, with an average recovery of over go per cent of the zinc and practically all of the lead contained. In addition to this high metal recovery, utilization of the waste heat in the gas and fume venting, the process has enabled the generation of 231,376 tons of steam at 250-lb, gauge. Over the first six months opcration the volume of slag treated averaged somewhat under 300 tons per day. Reclaimed dump slag made up only about 1 5 per cent of the plant feed. In October 1943, preparations for the smelting of additional tonnages of dump slag were completed and the plant capacity was increased to an average of about 420 tons of slag per day. During the nine-months interval since that date, monthly averages of 450 toils per operating day have been maintained several times. The new plant (Fig. I) is constructed in close proximity to blast-furnace operations. The fuming furnace and other necessary equipment are housed in an eastward extension of the existing blast-furnace building. Beyond this housed extension the dust-laden gas is conveyed about the perimeter of a large rectangle formed by the flues, cooling towers and baghouses. The course of a 10-ft. balloon flue, which transports the fuming furnace gas, describes the west and south perimeters. This flue connects with a set of cooling towers located at the southeast comer. The flue and cooling-tower system serving the deleading kiln constitute the north side and the two baghouses, serving the kiln and furnace operations, -border the east side. From these baghouses the several discharge gas flows are come biped and conveyed in to the rectangle, being vented to atmosphere by means of a fan through a centrally located zoo-ft. brick stack. In general, the plant design and operation follow quite closely that dictated by experience gained in years of slag-fuming practice by the Anaconda Copper Mining Go., at East Helena, Mont., and the Consolidated Mining and Smelting Co. of Canada, Ltd., at Trail, B.C., and more recently by the International Smelting and Refining Co. at Toocle, Utah. : Fuming operations at the East Helena and the Tooele plants are more or less identical. Trail practice differs chiefly in the methods employed for the storage of the hot feed slag and in the methods utilized for the handling and cooling of the fuming furnace gas. The new Bunker Hill fuming plant closely follows Trail procedure in the treatment of the furnace discharge gas while East Hclcna methods have been adopted for the storage of feed slag.

Jan 1, 1944

By C. G. Dunn

Many investigations have been made concerning the nature of plastic deformation and recrystallization of metals either in the form of polycrystalline materials or in the form of single crystals. However, similar work on strip materials composed of large grains as thick as the strip and having a high degree of preferred crystal oricntation has not been carried out extensively. Such materials are ideal not only for studying changes in single crystals under conditions where neighboring grains exert their influences but also for obtaining the complete change in orientation of a grain or group of grains during the course of plastic deformation and subsequent recrystallization. It is well known that first-order twins in the form of Neumann bands may be produced during the plastic deformation of ferrite crystals, particularly silicon ferrite crystals.l--3 Furthermore, it is believed that high-stress regions exist in the vicinity of these bands4. and it has been said that these banded regions would be active in recrystallization processes.5 Evidence to that effect in silicon ferrite had already been presented with photomicrographs showing recrystallization among Neumann bands during the early stages of recrystallizati~n.5,6 Similar evidence has been published for nonferrous metals5 Merging of fine parallel deformation bands during annealing to form twin bands of ordinary appearance in alpha brass has been offered not only as evidence of an active role being played by mechanical twins but also as evidence that such twins cxisted prior to recrystalli~ation.5 Proof that such new structures are actually first-order twins, or even twins at all, must be considered inadequate except for those cases where X-ray or optical data have been obtained to confirm the necessary oricntation relationship.7,8 A. B. Greninger has obtained excellent iliustrations of annealing twins in alpha iron.9 Since his material was previously deformed by sharp hammering, a process that generally induces Neumann bands, the existence of twins following annealing might suggest that they grew from mechanical twins. In connection with transformation twins in alpha iron, Greninger reported that grains containing three twin orientations occurred rarely and none occurred with three sets of well-developed bands.9 The work at the Pittsfield Works Laboratory on silicon ferrite in the form of large-grained strip steel deformed a small amount and annealed to partially recrystallize the grains indicates that the deformation and recrystallization processes that lead to annealing twins involvc more complex processes than the formation of Neumann bands and the growth of such bands. Some groups of annealing twins are obtained which contain not only three well-developed twin structures, but also contain more than one order of twins. It is also shown, in one case, that an interrelated group of twins did not arise within one single parent grain and, furthermore, orientations of grains in the group

Jan 1, 1944

Following the declaration of a national emergency by the President on Dec. 16, 1950 the Office of Defense Mobilization was established with Charles Wilson as director. It has been obvious since the entry of Red China into the Korean War that the previous defense setup was not adequate for accelerated mobilization.

Jan 2, 1951

The Institute has no available copies of Bulletin No. 7, January, 1906, and Bulletin No. 105, September, 191.5. The sum of 30.50 per copy will be paid for these Bulletins.

Jan 6, 1917

By Elbert Rowland

THE widespread interest in the alloys of beryllium with copper is due principally to the fact that certain compositions show very favorable precipitation-hardening characteristics and are, in fact, the strongest nonferrous alloys known at the present time. Investigations have been conducted by Masing and Dahl and others on the physical characteristics of ternary beryllium alloys, in an attempt to produce precipitation-hardening effects with a smaller amount of beryllium than that required in the binary copper-beryllium alloys (2.0 to 2.5 per cent Be). The results of these investigations show that ternary alloys of beryllium with Cu-Sn, Cu-Al and Cu-Zn, among others, exhibit promising improvements in physical properties after precipitation-hardening treatment and, while the increases in properties obtained are not as high as those realized from the binary copper-beryllium alloys, excellent properties are obtained with beryllium contents averaging about one-half the amount required in the binary alloys. This paper presents the results of an investigation of the equilibrium relations of certain alloys containing copper, tin and beryllium. The alpha-phase boundary of the ternary system is given for alloys containing from 0 to 1 per cent beryllium. The equilibrium conditions beyond the alpha-phase boundary are presented for alloys containing up to 32 per cent tin and 1 per cent beryllium. The data were collected by means of

Jan 1, 1935

By Walter P. Jenney

An investigation, conducted by the author, was begun in September, 1889, by the United States Geological Survey, having for its object the study of the questions bearing upon the occurrence and manner of formation of the deposits of lead- and zinc-ores in Missouri and the adjoining States. The field-work was completed in December, 1891. During the first season the State Geological Survey of Missouri furnished an assistant, and in other ways co-operated in the research within the boundaries of that State. In order that the ore-deposits of the southwest might be compared with those of other sections of the Mississippi valley, an examination was made of the lead- and zinc-mining area of Wisconsin-Iowa, and of the argentiferous lead-mines of the region extending westward from Hot Springs, Arkansas, to Indian Territory. In the discussion of the general geology, and in comparisons between the ore-deposits of the Mississippi valley and those of the Rocky Mountains, the writer has drawn largely from his personal experience, having been engaged for many years in professional work as a geologist and mining engineer in that region. The Director of the U. S. Geological Survey and the Scate Geologist of Missouri have kindly consented to the publication of the present paper. While giving the more important economic results, an endeavor has been made to set forth the unity of plan which appears in the formation of the deposits of lead and zinc of the Mississippi basin, and to show their relation to the argentiferous ores of the Rocky Mountains—that the ores of gold, silver, and mercury, and also of copper, antimony, zinc, and lead, have a universal common origin, irrespective of the geological formations in which they occur.

Jan 1, 1894

By J. H. Nead

The experiments herein described were undertaken with a view to investigating thoroughly the influence of carbon on the tensile and impact physical properties of carbon steel. The original comprehensive plan included investigation of a series of steels with varying carbon contents over a wide range of heat treatments. These were to be studied as to their static tensile qualities, and also their resistance to shock as measured by the Charpy impact bending test. A thorough metallographic examination was likewise included in the schedule. The Charpy tests and the metallographic examination have not been completed to date, and are accordingly withheld for another report. All heat treatments, however, have been made, and the static tensile tests have been completed. A description of the procedure of the experiment and the results thus far obtained are therefore reported herein. Conclusions No attempt is made to draw general conclusions from these experiments, but the curves and the data are submitted as being of general importance and wide applicability. Composition of Materials An attempt was made to secure steels increasing in carbon by increments of 0.1 per cent. from 0.1 per cent. up to 0.8 per cent., and from that composition to 1.6 per cent. by increments of 0.2 per cent. Actually, however, steels of the composition given in Table I were procured, and as the carbon contents were arranged sufficiently well so that satisfactory curves could be drawn showing the relation between carbon content and other properties, these steels were used in the experiments.

Jan 1, 1916

By C. H. Brehaut, W. N. Taylor, R. S. Douglas, H. A. Shannon

THE name for this new method of mining is derived from a composition of Horizontal, Radial, Diamond, and the drilling is from raises. This method, worked out at Copper Mountain, B.C., is believed to be distinct in many features from other known methods. GEOLOGY The ore deposits of Copper Mountain are related to the Copper Mountain stock, which is an ideal example of the magmatic differentiation in that it grades from a basic gabbro at the border to an almost pure orthoclase-pegmatite core. The "contact" ore bodies lie along the contact of the gabbro and an older complex of volcanics and sediment termed the "Wolfe Creek" formation. These older rocks, collectively referred to as greenstone, had been fractured prior to the intrusion of the stock and were highly metamorphosed during the intrusion. The "outlying" ore bodies are somewhat different in character, though a similar structural pattern prevails. It is believed that a deep-seated magma of which the Copper Mountain stock is a part has given off solutions that caused a partial granitization of some of the volcanics. Mining problems are caused further by the presence of a series of soft barren dikes intersecting a great many of the ore bodies, which are about 30 ft. wide, strike north-south, and dip at a high angle to the east; and are further increased by the presence of four major faults, with a great many minor faults running at acute angles from them. Fault zones average 8 ft. in width, and consist of gouge and breccia. They strike northeast and dip steeply to the northwest. The faults cut through the ore zones and the dikes, and continue on into the gabbro. The general mine structure with two types of ore bodies, bounded by weak walls and intersected by several series of soft barren dikes and major faults, indicated that a method of mining should be devised that would remove the ore at low cost with the least disturbance of the waste walls and dikes. THEORETICAL ESTIMATE OF STOPING WITH THE DIAMOND DRILL After consideration of various methods, the most suitable one appeared to be horizontal drilling to break the ore in a manner similar to shrinkage stoping. Drilling vertical holes or rings from a bench and breaking to an open slot was eliminated because the weak walls of ore, dike or waste would not permit this type of opening. It was then decided to drill either horizontal radial holes from a raise or parallel holes from a slot cut across the ore body. After discussion, the latter method was believed unsuitable, for the following reasons:

Jan 1, 1945

By Milton E. Wadsworth, John N. Ong, W. Martin Fassell

The temperature and oxygen concentration dependence on the reaction of sphalerite in oxygen at pressures from 6 to 640 mm Hg have been investigated in the temperature range 700° to 870°C. Sphalerite has been found to oxidize linearly over this entire temperature and pressure range. At higher rates, considerable self-heating was observed. The dependence of the oxidation rate on the oxygen concentration may be expressed by: Rate = k' where k' is the specific rate constant and 0 = K1[O2]/(1 + KI[O2]), where K1 is the equilibrium rate constant for the adsorption of oxygen on sphalerite. Values of the activation energy and the enthalpy of adsorption were found to be 60.3 and —59.6 kcal per mol, respectively. Data have been presented that indicate conditions under which either a sulphatizing or an oxidizing roast may be obtained. ROASTING processes have been employed in the metallurgy of a great number of basic metals in use today. Until recently, however, little attempt has been made to deduce the fundamental mechanism by which oxidation takes place. Structural changes upon oxidation have been investigated1 = and thorough work has been performed with regard to the reaction products and the thermodynamics of the oxidation reactions. The objective of this investigation was to determine the rate of oxidation of sphalerite and to apply the absolute reaction rate theory in the theoretilcal interpretation of the experimental results." "O Description of Apparatus The apparatus contains the following features: 1—a furnace with gas system, 2—an autographic weighing system, and 3—a temperature control system. Furnace With Gas System—The furnace was mounted by a yoke on each end and was free to travel up and down on steel guide rods, permitting the introduction and removal of samples from the apparatus with minimum difficulty. The furnace was heated by three sections of Kanthal wire wound externally on a zirconia tube and insulated with Fiber-frax. Pure gases or mixtures of gases were introduced into the lower end of the furnace through two flowmeters, a mixing chamber, and a gas-tight sparger, Fig. 1. The gaseous products of the reaction and the unused gases were prevented from escaping to the atmosphere by maintaining a small negative pressure on the system. This procedure permitted air from the outside to enter through the small an-nulus around the quartz suspension fiber and prevented the escape of the internal gases. Autographic Weighing System—The autographic weighing system consisted of an adapted gold balance, a photoelectric circuit, and a weight recorder, Fig. 2. The sample was suspended from one end of the balance beam by means of a platinum chain outside the furnace and a long thin quartz fiber on the inside of the furnace. On the other end of the balance beam, the necessary weights were added to counterbalance the sample. In addition, a calibrated chain was added to the balance which was linked directly to the weight recording unit. Control was effected by means of a photoelectric circuit." A parallel beam of light from a strong source was directed onto a small front-surfaced aluminum mirror mounted in the middle of the balance beam and then to a front-surfaced mirror mounted on the ceiling of the room. The beam was then reflected onto a front-surfaced right prism at a distance of 9 ft from the balance

Jan 1, 1957

By D. H. Bacon

Our Transactions contain so many suggestions of apparently trivial, yet really important, contrivances for the saving of time and

Jan 1, 1893

By G. P. Gladis, R. H. Atkinson

Palladium has been used for jewelry for many years, particularly in conjunction with gold. This use increased in amount during the war, as palladium and gold were only moderately used for war purposes while demands for platinum and some of the other members of the platinum group were so great that their use in jewelry was prohibited. Palladium hardened with a small percentage of ruthenium has the necessary technical properties and appearance for good jewelry, and it is sufficiently rare to be desirable for luxury items—at least I00 times as rare as gold. Although both visual and spectro-photometric examination demonstrated that the color of Palladium was almost the same as that of platinum, a few jewelers found the surface of palladium, even after some polishing, rather dark in areas that had been repeatedly heated during the soldering necessary to assemble certain types of handmade ornaments. This phenomenon is not to be confused with the thin, bluish oxide film that can be produced by heating in air over the range 400' to 800°C., as that film is easily reduced by dipping in warm 5 per cent formic acid or in warm methanol. It was suspected that the difficulty arose from heating in atmospheres that were alternately oxidizing and reducing, as Wise and Vines1 had found that this opened the grain boundaries of palladium and palladium-silver alloys in the same manner as in pure silver, as reported by Martin and Parker.2 This damage is caused by the reaction between oxygen in solid solution in the metal, acquired when heated under oxidizing conditions, and hydrogen diffusing in from subsequent heating under reducing conditions; the steam cannot diffuse out and therefore builds up sufficient pressure to disrupt the metal near the surface. Copper and various other metals can be damaged similarly, but platinum is nearly immune; therefore the problem was new to the platinum jeweler. Sulphur in the fuel gas also can cause trouble but did not appear to be dominant in the present instance. Metallographic examination of both pure palladium and ruthenium-palladium showed that the usual torch using oxygen and city gas as normally operated did in fact cause the surface and subsurface damage that had been observed, and also disclosed that a reducing flame caused more damage than an oxidizing flame and was very damaging even in the absence of any intentional swing in atmosphere from oxidizing to reducing (Fig. 7); besides the surface damage, there was serious loss of ductility. A full explanation of the mechanism of attack is not evident at the moment, but may be allied to the attack that occurs on heating catalytically active metals in nonequilibrium atmospheres.

Jan 1, 1946

By B. M. Larsen, W. E. Shenk

This paper describes a method of reversal control of the open-hearth furnace that obtains in practice those effects considered below as essential to a completely automatic control, without appreciable interference with the natural rise and fall in temperature of the regenerative portions of the furnace system. Growing out of some studies of radiation pyrometry in open-hearth regenerators, it was developed during 1934-1938, and has been successfully applied to a number of commercial furnaces. The goal of open-hearth furnace operation is the highest rate of production of steel of proper quality consistent with good refractory life and fuel economy. This requires rapid heat transfer from furnace to charge, which in turn is dependent upon heating the furnace refractories to the highest safe operating temperature. The greater the heat input to the melting chamber, the sooner this limiting temperature will be reached, so that control methods in general that are designed to protect against overheating of refractories should help to maintain maximum fuel input and production rate. For the typical open-hearth system, with fixed regenerator capacity and with rate of fuel input usually restricted in its range of variation, our basic assumption is the idea that the only other important variable —that is, the time interval between successive reversals—should also be held constant or within a small range. The present reversal control was designed therefore so that, under normal operating conditions, no arbitrary limitation is imposed other than to keep the reversal interval within the optimum time range. However, since a near approach to completely automatic operation involves protection of refractories through the balancing of furnace end temperatures as well as emergency protection against temperature peaks above some upper limit, it was also felt essential to employ, as an integral part of the control unit, a temperature-measuring instrument to register the true temperature of the refractory surfaces at some critical region in the hot ends of the regenerative zones. As the basic elements of the control, we thus have one "maximum" and one lLminimum" time relay and a potentiometer recorder-controller, combined with switches and relays to operate as follows: I. Reversal normally occurs within an optimum range limited by the maximum and minimum settings to about 4 to 6 min. variation, but the actual interval usually is less variable and closer to the minimum setting. 2. The margin between minimum and maximum time is utilized, together with a "floating temperature limit" in the potenti-ometric control instrument, to correct any tendency toward temperature unbalance between ends of the furnace. 3. A second "maximum temperature

Jan 1, 1945

By G. P. Gladis, R. H. Atkinson

Palladium has been used for jewelry for many years, particularly in conjunction with gold. This use increased in amount during the war, as palladium and gold were only moderately used for war purposes while demands for platinum and some of the other members of the platinum group were so great that their use in jewelry was prohibited. Palladium hardened with a small percentage of ruthenium has the necessary technical properties and appearance for good jewelry, and it is sufficiently rare to be desirable for luxury items—at least I00 times as rare as gold. Although both visual and spectro-photometric examination demonstrated that the color of Palladium was almost the same as that of platinum, a few jewelers found the surface of palladium, even after some polishing, rather dark in areas that had been repeatedly heated during the soldering necessary to assemble certain types of handmade ornaments. This phenomenon is not to be confused with the thin, bluish oxide film that can be produced by heating in air over the range 400' to 800°C., as that film is easily reduced by dipping in warm 5 per cent formic acid or in warm methanol. It was suspected that the difficulty arose from heating in atmospheres that were alternately oxidizing and reducing, as Wise and Vines1 had found that this opened the grain boundaries of palladium and palladium-silver alloys in the same manner as in pure silver, as reported by Martin and Parker.2 This damage is caused by the reaction between oxygen in solid solution in the metal, acquired when heated under oxidizing conditions, and hydrogen diffusing in from subsequent heating under reducing conditions; the steam cannot diffuse out and therefore builds up sufficient pressure to disrupt the metal near the surface. Copper and various other metals can be damaged similarly, but platinum is nearly immune; therefore the problem was new to the platinum jeweler. Sulphur in the fuel gas also can cause trouble but did not appear to be dominant in the present instance. Metallographic examination of both pure palladium and ruthenium-palladium showed that the usual torch using oxygen and city gas as normally operated did in fact cause the surface and subsurface damage that had been observed, and also disclosed that a reducing flame caused more damage than an oxidizing flame and was very damaging even in the absence of any intentional swing in atmosphere from oxidizing to reducing (Fig. 7); besides the surface damage, there was serious loss of ductility. A full explanation of the mechanism of attack is not evident at the moment, but may be allied to the attack that occurs on heating catalytically active metals in nonequilibrium atmospheres.

Jan 1, 1946

By Erhard Hornbogen

Twins were propagated into large, well-annealed crystals of a, iron-phosphorous and a, iron-molybdenum solid solutions. Strain fields caused by interaction of these twins were made visible by precipitation. These strain fields can be explained by assuming that transmitted and reflected plastic waves are created when a twin strikes an obstacle with high velocity. The twin front itself can be regarded as a shear wave that may be able to develop a one-dimensional shock front. The occurrence of {WO} fracture by the reflected stress is also discussed. The described effects were not found when twins propagated at lout velocity into disturbed crystals, for example, into crystals previously deformed by slip. DEFORMATION twinning leads to shearing of a crystal lattice under external load. The shear appears to be homogeneous over a large number of crystal layers. In a iron, shear occurs on the (112) planes and in the <1ll> directions. The formation of a twin proceeds by the movement of partial dislocations that change the stacking at the twinning plane.l, In the bcc lattice, this partial dislocation can be created by dissociation of a sessile a/2[111] dislocation that lies in the (112) plane: Cottrell and Bilby&apos;s spiral mechanism can explain the homogeneous shear, but has not been proven experimentally. Nevertheless, this mechanism can explain the possible high velocity of formation of a twin. In Cottrell and Bilby&apos;s model, as in other models of twinning or phase transformation, a much higher energy is required to spread the first stacking fault than to add new layers by further movement of the partial dislocations. The dislocations will therefore become accelerated proportional to the difference between the stress, tN, to nucleate and tp to propagate the twin. It has been assumed3,4 that tn is the stress required to make two partial dislocations of apposite sign pass for the first time. After the first layer of new stacking has been formed, the maximum stress is TN=Gb/4pd where G is the shear modulus, b is the Burgers vector of the partial dislocation, and d is their perpendicular spacing so that the amount of shear is S = b/d. From this formula, a value of 25 kg per mm2 has been estimated for twinning in Zn3. The measured values are smaller, but local internal stresses may help to provide the necessary stress. For a iron, a higher value can be expected, mainly due to the higher value of G. That agrees with the observation that "burst" twinning occurs if the yield strength is in-

Jan 1, 1962

By B. M. Larsen, L. S. Darken

SOME years ago we collated all laboratory data then available to us on the distribution at equilibrium of manganese and of sulphur between metal and simple slags, and used the results in setting up an equation, which proved to be in accord with determinations of the distribution ratio of manganese and of sulphur between liquid steel and open-hearth slag, over a wide range of operating conditions. We now present an outline of our calculations and inferences on these two closely related questions, which are of especial importance because of the advisability of conserving manganese wherever possible. In general, our results show that in the open-hearth furnace equilibrium between metal and slag, with respect to both manganese and sulphur, is substantially attained during the finishing period of the heat, or in about a half hour to an hour after any additions were made. This implies that the end result will be identical whether manganese is added as alloy or metal to the liquid steel or as oxide to the slag. The proportion of total manganese retained by the steel is favored: (I) by use of the minimum amount of lime, consistent with other operating limitations, required to give a lime-silica ratio of about 2.4, which usually corresponds to a minimum practical slag volume; (2) by a high concentration in the slag of MnO relative to FeO; (3) by high operating temperature. Absorption of sulphur by the slag from the liquid metal is favored: (I) by large slag volume; (2 by a high concentration of active (or "free") lime and of manganese oxide dis) solved in the slag; (3) by low concentration of silica, iron oxide, and phosphate dissolved in the slag. DISTRIBUTION OF MANGANESE BETWEEN SLAG AND METAL AT EQUILIBRIUM On the basis that the distribution of manganese between liquid steel and slag is controlled by the reaction [FeO + Mn = MnO + Fe [A]slag metal slag metal] the distribution at equilibrium, at a given temperature, is expressed by the equilibrium constant for this reaction, which is defined as [K" aMoO aFeI1 dFec) aMn] where a is the activity of the molecular species denoted by the subscript. The activity of each of the several components, although it is not known precisely, is approximately equal to the concentration of each component expressed as its mol fraction; that is, as the ratio of the number of mols of the given component to the total number of mols of all the molecular species present in the metal or slag, as the case may be. Moreover, since the activity, or concentration, of iron in the liquid metal is in fact substantially constant, the term [afe] may be combined with K" to give a new constant K&apos;. Making these changes,

Jan 1, 1942