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By L. L. Wyman

SINCE the observations of Heyn,1 relative to the embrittlement of copper after having been heated in hydrogen, this subject has received considerable attention from later investigators. The published works of Archbutt2 and of Bengough and Hill3 give the reasons for this embrittlement-the formation of steam by the reaction between cuprous oxide and hydrogen. From Ruder,4 Pilling,5 Moore and Beckinsdale,6 Bassett and Bradley,7 and from Smith8 can be obtained quantitative data concerning the action of hydrogen and other reducing gases on copper samples having various oxygen contents. This problem has been discussed from a practical standpoint by Fuller9 who calls attention to some of the instances of this embrittlement encountered in the manufacturing field. The examples he cites may be considered typical cases of copper embrittlement which were incident to the process of manufacture. In many cases, such difficulties are overcome by changes in the manufacturing process.

Jan 1, 1931

By Klaus Schwerdtfeger

In order to test the performance of ZrO, (CaO) and Tho,(Yz03) electrolytes in the electrochemical determination of oxygen activities in liquid metals at steel-rrzakitng temperatures , electromotive force measurements have been made with the following cells: The oxygen-- activities are calculated from the electmrnotive forces for the investigated systems. The standard free energy of- formation of MnO and the activity of manganese in Fe-Mn melts are derived. Indications are that the Zr 0z(Ca0) electrolyte exhibits little electronic conductivity at oxygen pressures as low as 10'a atnz at 1600°C; however, the partial electronic conductivity may become noticeable at lower oxygen activities. The Tho,(Yz03) electrolyte is found to be an ionic conductor at the oxygen pressure as low as that for the Mn + MnO equilibrium, but exhibits partial electronic conductivity at oxygen pressures higher than 10"1 atm (1500°C). fi. better control of oxidation and deoxidation reactions in steelmaking may be facilitated if the oxygen activity in the steel is known during various stages of the process. In the present work oxygen activities have been measured in liquid iron, manganese, and iron alloys with galvanic cells using ZrOz(CaO) and s solid electrolytes with the object of establishing the range of oxygen pressure in which these materials can be used as electrolytes at steelmaking temperatures. Calcia-stabilized zirconia and Tho2-Y203 solid solutions are oxygen ion conductors. Such electrolytes were first used by Kiukkola and Wagner1 and Peters and ~ann' in galvanic cells for the determination of thermodynamicquantities of oxide systems in the temperature range 700" to 1200°C. At these moderate temperatures calcia-stabilized zirconia has been found to exhibit predominantly ionic conductivity at oxygen pressures as low as those for the Cr + Crz03 equilibrium,394 but at lower oxygen pressures elec- tronic contribution to conductivity becomes significants4 The Th02-Y203 solid solutions are ionic conductors at oxygen pressures lower than those applicable to zirconia base electrolytes.5'6 At high oxygen pressures Thoz base electrolytes exhibit significant p-type semiconduction. At the time the present experiments were carried out several papers1'-* were published on the electrochemical determination of oxygen activities in liquid iron using the ZrOz(CaO) electrolyte. The results of different authors do not agree well. For instance, according to Fischer and ~ckermann" stabilized zirconia can be used to measure oxygen contents in liquid iron larger than 0.02 wt pct, but according to Baker and west1' ZrOz(CaO) cannot be used for the determination of oxygen content in liquid iron because of high electronic contribution to the conductivity. Fig. 1 is a schematic diagram of the apparatus used. About 500 g of liquid metal is contained in a crucible into which a stabilized zirconia or Th02(Y203) tube is immersed. A platinum contact wire is pressed (with a spring mechanism) against the inside bottom wall of the electrolyte tube. The tube is flushed continuously with a stream of air, CO-CO, (or Hz-C02) (at 0.96 atm and at a rate of about 300 cu cm per min), via an alumina tube inserted inside the electrolyte tube. This alumina tube also contains the Pt-Pt/10 pct Rh thermocouple. A capillary alumina tube shielding the other contact wire is immersed in the melt. The molybdenum contact wires were used mostly; in some cases platinum wire was employed. Molybdenum has the advantage that it dissolves more slowly in the melt than platinum. The whole cell was contained in the alumina reaction tube of a resistance furnace with molybdenum winding. The reaction tube was closed gas tight at both ends and flushed continuously with argon. Because of the poor thermal shock resistance of the electrolyte tubes the cell had to be assembled in the cold furnace. The electrolyte tube and alumina sheath

Jan 1, 1968

Discussion of the paper of WALTHER MATHESIUS, presented at the New York meeting, February, 1915, and printed in Bulletin No. 99, March, 1915, pp. 539 to 555. JOSEPH W. RICHARDS, So. Bethlehem, Pa.-This paper answers. partly the difficult questions which have come up as to why it is not economical to use higher blast temperatures in the smelting of Mesaba ores, such as the high temperatures used in European practices, and the answer is very plain that the ores will not stand the higher temperature. But the paper does not go into detail as to what special difficulties were found with the higher temperature of blast, and I would ask the author to kindly specify them. W. A. FORBES, New York, N. Y.-A large part of the troubles that furnace men experienced in using high-blast heats in smelting Mesaba ores in the early days of using Mesaba ores, was clue to the attempt to use these soft ores on furnaces having the same lines as the furnaces used in smelting the hard Old Range ores. As the result of observation and study, the dimensions of the lower part of the blast furnaces have been changed and the difficulties of the blast-furnace men in operating with a large percentage of Mesaba ore and high-blast temperatures have been largely overcome. The changes I refer to in particular are: (1) steepening the angle of the bosh; (2), decreasing the height of the bosh; (3) increasing the diameter of the hearth. JOSEPH W. RICHARDS.-Mr. Forbes's answer is quite satisfactory, and the moral which it points is that when the furnace is run with a higher temperature in the smelting zone, the furnace lines which were adapted for the lower temperatures are not necessarily those best suited for the higher hearth temperatures. If. enriched blast were used in a furnace, and higher temperatures run, it would be found necessary to further modify the lines of the furnace to meet the new conditions and to get the maximum output with economy. J. E. JOHNSON, JR., New York, N. Y.-It seems to me this is one of the few papers which could well have been a little longer. The data which Mr. Mathesius has given us, I think should be considered in connection with the paper which Mr. Brassert read before the American Iron and Steel Institute last spring, in which he described how they had obtained remarkable results with furnaces with steep but very short boshes; the angles have been raised to 80°, and the boshes made so short that they no longer appear as a conspicuous part of the shape of the furnace.

Jan 5, 1915

[Year of Election . 1944 .WALTER HULL ALDRIDGE New York. N. Y 1944 . SELWPN GWILLYM BLAYLOCK Trail. B.C.. Canada]

Jan 1, 1946

By R. W. Heckel, H. P. Cheskis, A. Lawley, M. R. Pinnel

THERE are discrepancies reported in the literature regarding the micro and macro stress-strain behavior of metals and alloys. In particular, Young's modulus and micro yield measurements often show significant variations depending upon the techniques employed.'-" The purpose of this note is to correlate measurements made with four techniques and to indicate where some of these discrepancies might arise. Allied use of these techniques can provide a complete and consistent characterization of micro and macro stress-strain behavior (over the strain range of 10-9 to 10--2 in. in.-') from a minimum number of samples. Techniques. The techniques employed for measuring stress-strain behavior involved the use of a) linear differential transformers, b) SR-4 strain gages, c) longitudinal resonance waves, and d) X-ray diffraction. Specimen geometries and preparations are summarized in Table I for each technique. Differential Transformer and Strain Measurements. An Instron universal testing machine, modified with an alignment device, was used to apply the load via parallel-jaw grips. The signal from the load cell was applied to the Y scale of a Moseley X-Y recorder (sensitivity of 10 lb load per in. chart). The elongation was monitored simultaneously with strain gages mounted on three sides of the rectangular specimen, and with two linear variable differential transformers (LVDT) mounted at 90 deg to one another on faces that also contained the strain gages, Fig. 1. The signal from one of the LVDT's was applied to the X scale of the recorder (sensitivity 40 µ in. elongation per in. chart) in order to trace a continuous load-elonga-tion curve. Concurrently, the strain on the same face (i.e., the face monitored by the LVDT) was recorded by the corresponding strain gage. A stress-strain curve was plotted from the load cell-strain gage data and was compared to the stress-strain curve (converted from load-elongation) plotted from the continuous load cell-LVDT trace. Identical Table I. Description of Specimens Used in the Present Study Material Dimerisions Preparation Condition 99.99 pct A1 tensile 318 by 3/16 by 3 in. as cast ingot; cut annealed specimen on diamond wheel 2024 A1 tensile 318 by 3/20 by 31/2 in. vacuum hot annealed specimen pressed sheets; cut on diamond wheel 99.99 pct Al 3116 by 3/16 by 2 in. cut from tensile prestrained dynamic modulus specimen after 10"* in. specimen test per in. 2024 A1 dynamic 3/20 by 3/20 by 2 in. vacuum hot annealed modulus specimen pressed sheets; cut on diamond wheel 2024 A1 X-ray gage section 112 by vacuum hot annealed specimens 1/4by1/20in. pressed sheets; cut on diamond wheel

Jan 1, 1970

By F. V. Lenel, G. S. Ansell, E. C. Nelson

IRMANN'S' discovery that extrusions of fine alumi-num-flake powders possess remarkable high-temperature strengths has led to the production of a new class of engineering materials whose properties are derived from a fine dispersion of oxide particles in a metallic matrix. A fundamental study of such materials and elucidation of the mechanism whereby the oxide parti-

Jan 1, 1958

By R. Hoffmann

The Waelz process produces oxides of volatilizable metals from ores, metalliferous products and residues. The process was originally used for recovering zinc and lead, where tailings and residues containing those metals had accumulated at mines or smelters, but it is applicable for obtaining tin, arsenic or other volatilizable metals. It is useful when other methods of obtaining the metals from the ores or residues are too difficult or expensive or show too low a recovery. The Waelz process was developed in 1923 for the treatment of large calamine dumps in Upper Silesia, which showed zinc contents of 8 to 10 per cent. and lead contents up to 3 per cent. The rapid development of the process, from the first trials up to the plants now working or in course of erection, is shown in Fig. 1. The first industrial Waelz plant was started in 1925. Within two years the capacity of the working plants reached 700 tons material per day of 24 hr. During the year 1928 the daily capacity of the plants now at work or in course of erection will rise

Jan 1, 1928

By G. R. M. Del Giudice

A survey of the flotation literature of the past 10 years indicates an increasing use of the microscope as a tool for investigation. Thus, the metallurgical microscope has been used by Tucker and Head;' Taggart, Taylor and Ince;2 Ince,3 and del Giudice4 to examine mineral surfaces that had been subjected to the action of various flotation reagents and to the action of slime pulps. It has also been used by Gaudin, Groh and Henderson;5 Martin;6 Morrow and Griswold;7 and others to examine bakelite briquets of mill products. The microscope with transmitted light, both with bright-field and dark-field illuminations, has been used by Taggart, Taylor and Knoll8 and by Ince9 to observe Brownian motrement and flocculation in flotation pulps. The use of the microscope at low-power magnifications with incident illumination for the examination of mill products has been known for years.10 Finally, del Giudice11 has used a relatively new type of illumination, the Ultropak, for the examinntion of slime-coatings.

Jan 1, 1935

By H. H. Power

THE PETROLEUM DIVISION of the A.I.M.E. continued with its diversified activities during 1.935. Sessions at the New York meeting in February were devoted to production engineering, domestic and foreign oil production, and petroleum economics. The symposiums on domestic and foreign production proved their increased usefulness. The data accumulated for 1935 were added to those published during prior years in "Petroleum Development and Technology." A joint session on the use of metals in the petroleum industry was held by the Institute of Metals, Iron and Steel, and Petroleum Divisions. W. S. Farish, chairman of the board of the Standard Oil Co. (N. J.), was the principal speaker at the annual dinner. The October meeting, held in Hous¬ton, was characterized by an excellent program and large attendance. Four sessions were devoted to problems in estimating reserves, reservoir energy, properties of drilling muds, electrical logging, water flooding, and other subsurface studies. Foreign representatives of the Anglo-Persian Oil Co. presented a paper on surface tension and specific gravity of crude oil under reservoir conditions. The address by President Buehler, the dinner at San Jacinto Inn, a trip to various lo

Jan 1, 1936

On the following pages are abstracts of papers published by the Institute during the year 1936 as TECHNICAL PUBLICATIONS and CONTRIBUTIONS, papers in bound volumes appearing for the first time, and papers in MINING AND METALLURGY For abstracts of papers that appeared in bound volumes in 1936 but that were published as TECHNICAL PUBLICATIONS in 1935, see the YEAR BOOK dated January 1936.

Jan 1, 1937

By Maurice L. Pinel, Thomas T. Read, Thomas A. Wright

THE erroneous, but until recently widely prevalent, belief that iron castings were first made in Europe in the fourteenth century has been adequately refuted in a number of earlier papers;1,11,12 but except for an unpublished metallographic study by the late William Campbell, and a phosphorus analysis by T. A. Wright of the metal of the Han dynasty cast-iron stove described by Laufer,2 nothing was known of either the chemical composition or the metallographic structure of the metal of any ancient iron casting, although data on castings of recent manufacture are abundantly available. The metal of the stove, which had been buried in a grave for at least 15 centuries, was so corroded that it seemed inadvisable to publish the results on it until more and better specimens from other ancient castings could be obtained. During a journey through China, extending from Peking in the north to Canton in the south and Cheng-tu, Ssu-chuan, in the west, in the late summer and autumn of 1936, one of us (T. T. Read) was fortunate enough to obtain, and bring home for study, nine castings, all more than 1000 years old, of which the date of manufacture is precisely known because of inscriptions cast in them, another that lacks a dated inscription, but of which the date, as explained below, can be otherwise established, and a specimen from the largest iron casting ever made," which is also dated. The period covered by this suite of specimens extends from 502 to 1093 A.D. In addition, a sample was obtained from a casting of date unknown, but which was certainly cast before 1000 A.D. and possibly as early as the third century A.D. A detailed description of these specimens is as follows: 1. 502 A.D. A pair (right and left) of recumbent lions (Fig. 1). Base 7 ¼ by 14 3/8 in., height over-all 5 ½ in., weight 26 lb. each. The translation of the inscription on the base is: "Made on the twenty-fourth day of the seventh month of the third year of Ching Ming of Great Wei" (Sept. 11, 502 A.D.).

Jan 1, 1938

By J. H. Nead

OBJECT 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.

Jan 12, 1915

By Gregoire Gutzeit

THE development reported in this paper was begun by the author a number of years ago, while he was a lecturer on complex chemistry and metallurgy at the University of Geneva, Switzerland, and in charge of that institution's research laboratory. Completion of the development and reduction to practice did not occur until last year at the Westport mill, laboratories and testing plant of the Dorr Company, where this method is now in general use for identifying and localizing the mineral constituents of both metallic and nonmetallic ores. It has proved to be a practical tool of the metallurgical staff at the Westport mill, devising unusual milling flowsheets for complex and refractory ore bodies. In a number of instances the findings have been successfully used as fundamental factors in the design and specification of complete metallurgical plants. Seven examples of the use of this method in solving practical milling problems are included in this paper. GENERAL OUTLINE The microscopic study of an ore, at first only of scientific interest, has proved extremely useful both in practical geology and in ore dressing. The binocular magnifying lenses for rough observation of the products of an ore-dressing plant have been in use for a long time; but only within the last few years has a systematic microscopical examination of ore samples become a normal tool of any research laboratory dealing with ore-dressing problems. Such an investigation avoids considerable loss of time as well as empirical trials and useless experimentation. It will generally indicate the correct grinding and often will suggest the proper method of treatment. The petrographic determination of transparent minerals in thin sections, or even in grains, has been perfected, and very accurate methods have been devised to meet any requirement, such as Feodorof's rotating stage on the petrographic microscope. Almost all transparent minerals can be positively identified by their optical properties; i.e., isotropism, anisotropism, color, pleochroism, refractory index, cleavage, crystal form, birefringence, and others. The identification of opaque minerals is a much more difficult problem and can be done only by using polished specimens. Unfortunately, most of the valuable metallic ores, and even some of the nonmetallic ones, are not transparent; therefore it has been necessary to develop a special technique for the determination of these minerals. Some optical properties-for instance, isotropism, anisotropism, color, cleavage, reflecting power-are often adequate in roughly classifying the mineral. Only "reflecting power" is a measurable value, provided special photometric equipment (ocular photometer or Orcel's photoelectric cell) is available. The other optical properties mentioned are more or less relative,

Jan 1, 1942

By Sooi P. Chong

Expansion of concentrator capacity at Iron Ore Company of Canada's Carol Lake plant resulted in a dramatic increase in the production of fines. With iron recovery from the fines running only 18%, Carol Lake engineers initiated an extensive test program which resulted in the installation in July 1977, of a full-scale plant utilizing Reichert cone concentrators. Results to date have indicated a 100% increase in iron recovery from the concentrator's fines product. Carol Lake is located near the western boundary of Labrador, Newfoundland, some 960 km (600 mi) northeast of Montreal. Concentrator operations began in 1962 with a design capacity of 7 million t/y (7.7 million stpy). The bulk of the concentrate was pelletized at a 6 million t/y (6.6 million stpy) pelletizing plant completed in 1963. The remaining concentrate was sold in the international market. The concentrator was first expanded in 1966 to 10 million t/y (11 million stpy) capacity. In 1967, the pellet plant was expanded to match the increase in concentrate production. Sales increases led to a further expansion in 1973. By 1977, more than 40 million tons (44 million st) of crude ore were processed to recover in excess of 17.42 million tons (19 million st) of concentrate and 10.4 million tons (11.5 million st) of pellets.

Jan 12, 1978

By E. R. Funk, H. Udin, J. Wulff

The surface tension of solid silver is measured by a refinement of the Udin, Shaler, and Wulff technique. The tests were made in a purified helium atmosphere at four different temperatures and various times. The average of the results is y = 1140 + 90 dynes per cm for the range 875° to 932°C. A SUCCESSFUL measurement of the surface tension of solid copper was reported by Udin, Shaler, and Wulff.' They performed experiments on copper held in vacuum within 100°C of the melting point. At these temperatures, the creep rate in 5 and 3 mil copper wires was sufficient to permit determination of a balance between the contractile force of surface tension and the extending force of small copper weights joined to the end of the wire specimens. By suspending a series of variously weighted specimens and measuring the change in a gage length during the test, the balancing applied load could be found. This point of zero strain is a measure of the surface tension. The mathematical formulation of this gives: w = r y [1] where w is the weight for zero strain; r, the radius of the wire; and y, the surface tension. A subsequent note by Udin pointed out that eq 1 applies only to single-crystal specimens. Since the specimens used revealed a "bamboo" structure upon

Jan 1, 1952

By E. M. Wise, T. E. Kihlgren, N. B. Pilling

SYSTEMATIC data are presented on the relation of composition of nickel silvers to color, tarnish resistance, hardness and liquidus temperatures, for alloys containing up to 30 per cent nickel and 50 per cent zinc, further modified at certain nickel and zinc contents by 0 to 8 per cent of tin and 0 to 10 per cent of lead. Attention has also been directed, using a still more limited range of alloys, toward a study of tensile properties and such casting properties and characteristics as fluidity, shrinkage and pressure tightness. In some of these, rather broad ranges of composition are dealt with; in others, it has been expedient to focus attention on the Federal Specification 20 per cent nickel silver casting alloy, WWP-541.

Jan 1, 1935

By G. L. Oldright

THE upper limit of richness of concentrates that can be smelted by means of the blast furnace without added diluents is fixed by the opera-tion of sintering. A sinter feed with normal gangue constituents, con-taining more than about 50 per cent of lead, tends to fuse; as a result, air does not come sufficiently into contact with the sulphides at roasting temperatures, and sulphur elimination is poor. Since most lead con-centrates now contain 55 to 80 per cent lead, it is necessary to add diluents to lower the grade of such sinter feed to about 50 per cent or less. This not only entails the expense of providing barren diluents when adequate diluents containing precious metals are not available but also appreciably lowers the capacity of the blast furnace to produce lead and increases slag losses. Attempts to desulphurize rich lead concentrates by methods other than sintering have not proved successful. Flash roasting, for example, converts much of the lead sulphide to lead sulphate rather than to oxide. However, this suggested the possibility that deliberate flash roasting of the concentrates to sulphate, followed by sinter roasting of the resulting product, might prove promising, particularly inasmuch as the elimination of sulphur from lead sulphate requires heat alone and not contact with atmospheric oxygen. The sintering of lead sulphate products has additional interest because important amounts of such products are now treated by lead smelters. Considerable quantities of lead sulphate are present in rich lead flue dusts and other by-products; lead-chamber sulphuric acid plants and other

Jan 1, 1940

By H. F. Moore

Jan 1, 1936

By H. F. Moore

Jan 1, 1936

By G. R. Heckman, H. J. Murphy, C. T. Sims

An incestigation has been made of the effects of heat treatment and alloy composition on the long-time stress-rupture properties and structural stability of the similar nickel-base alloys Udimet-500, Lrdimet-520, and Udimet-700. Rupture test data are presented at stresses ranging from 4 to 50 ksi at temperatures from 1450° to 1900°F for times up to 14,000 hr. Ductility response is emphasized. Optical and electron tnicroscopy were complemented by X-ray diffraction analyses of extracted phases to relate microstructural stability to the observed rupture properties. Particular attention is paid to Udimet-520 since structural characteristics of this alloy appear to vary somewhat from its sister alloys. Both cast and wrought performance of Lrdimet-500 are discussed. The computerized PHACOMP calculational technique, based on electron-vacuncy theory, is discussed and related to structural stability where appropriate. Electron microscopy and microprobe techniques were used to conduct evaluation of the oxidation characteristics of Udimet-500 exposed in air for 16,100 hr. The steady advance in strength and reliability of nickel-base superalloys continues to be one of the high points of modern metallurgy. The stress capability of these materials has increased steadily, allowing higher and higher operating temperatures in the highly sophisticated aircraft and industrial gas turbines now on the market. The attendant increase in efficiency, of course, means greatly improved power output. Gas turbines for industrial and marine use have long been designed with these objectives paramount the usual design requirements in terms of time of service being 100,000 hr. High-efficiency, long-life aircraft such as the supersonic transport require superalloy engine materials with high-strength and long-time structural stability. Thus, materials studied for and operating experience from industrial gas turbines provide a good reservoir from which technology of high value to the SST program can be drawn. This study is one such case. Three prominent nickel-base super alloys—Udimet 500, Udimet 520, and Udimet 700 were extensively evaluated for industrial gas turbine bucket use. Particular attention was directed toward structural stability as a requisite property. Within the present context, structural stability is defined as freedom from the propensity to form strength-robbing or embrittling phases such as u,p,x,or Laves, and the ability to maintain useful rupture strength and ductility throughout design life. MATERIALS The three alloys, cast Udimet 500 (U-500C), Udimet 520, and Udimet 700, were chosen for detailed evaluation based on preliminary studies which indicated that U-500C and U-520 possessed comparable rupture strength capabilities, and that U -700 had a greater strength capability but somewhat poorer ductility than wrought U-500. The nominal compositions of the three alloys, along with the compositions of the heats investigated, are presented in Table I. PROCEDURE Dimensionally rejected U-520 buckets from Special Metals Corp. heat 63370 were heat-treated using the four cycles delineated in Table 11. Cycle A was investigated to determine the effects of a shortened 1700°F primary age. Cycle B was considered a "standard" treatment. Cycle C investigated a higher solution temperature in combination with a shortened primary age, while cycle D assessed the effect of the higher solution temperature alone. These heat treatments were designed to produce optimum combinations of rupture strength and ductility through maximum y' development, the development of a y' grain boundary cushion, promotion of MC carbide degeneration reactions, and agglomeration of resultant M23CB. Since one of the premises of the evaluation of U-520 was that rupture strength would be equivalent to U-500, forged U-500 buckets from Special Metals Corp. heat 62916 were heat-treated with cycles A, B, and C to provide comparison. The heat-treated structures of U-520 and U-500 are illustrated in the 8700 times electron micrographs of Fig. l. The U-700 tested was all from 3-in.-diam hot-rolled and centerless-ground rod from Special Metals Corp. heat 2-1426. Two heat-treatment cycles were employed, E and F of Table 11. Cycle E is a standard four-step, triple-age treatment intended to provide an optimum match of strength and ductility through well-developed matrix and grain boundary y', as recommended by U-700 vendors. Treatment F is a shortened , single-age cycle which could provide a significant processing cost reduction should adequate strength and ductility be maintained. Following heat treatment, rupture specimens of U-500 and U-520 were machined from the buckets and tested. Standard rupture bars of U -700 were machined from the heat-treated rod and rupture-tested. Failed and withdrawn rupture bars were prepared and examined by optical and electron microscopy. Select specimens were electrolytically digested, and the residues analyzed for carbide and topologically close-packed phases using CrKa or CoKo radiation. Of the six different U-500C heats evaluated, five were cast by Misco Precision Casting Co. and one was cast by Haynes Stellite Co. Cast-to-size rupture bars

Jan 1, 1968