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By H. M. Day, C. H. Mathewson

THE constitution of the system silver-mercury has attracted the attention of many investigators during the last two decades, but since their results are for the most part in poor agreement, there is little need for a review of their individual contributions. It remained for the very careful thermal and microscopic investigation of Murphy' in 1931 to give the constitutional diagram in its present and unquestioned form, which is shown in Fig. 1. He devised methods for taking cooling curves on alloys under high pressures and for the microscopic observation of alloys which contained liquid mercury as a structural constituent at ordinary temperatures. The compositions of the intermediate phases were confirmed and supplemented through X-ray analyses by Preston2 and Stenbeck.3 According to Murphy, at 276° C. silver is able to dissolve 44 to 45 weight per cent of mercury, which may increase at lower temperatures to about 50 per cent. Preston concluded that the saturation boundary occurred at 46 ± 2 per cent at 100° C. From the values reported in the literature, these are the only ones that may be accepted as lying even in. the right region. PREPARATION OF ALLOYS The silver used in the present investigation was supplied by the United States Metals Refining Co. through the courtesy of the Committee on Industrial Uses of Silver and, since a complete spectrographic and chemical analysis was furnished, no attempt was made to purify it or to further establish the impurities present. The analyses reported by the company are shown in Table 1. Milligan4 has found that the magnesium content is probably less than 0.0005 per cent.

Jan 1, 1938

[ ] DISCUSSION F A LORIA*-The method of testing gun steel for resistance to surface cracking described in this paper was restricted to the examination of small, rod-shaped specimens The writer would like to point out the importance of other factors in producing defects in forged and bored gun tubes which would not be apparent in this investigation because of the nature of )he test Actual section size would accentuate the possibility of internal wall (bore) defects arising from unequal expansion between the internal and external wall surfaces on firing, resulting in internal tearing Checks and tears on the inside walls arise from internal tensions and nonuniformity on cooling, but the internal tearing can be reduced by using alloys of low expansion and of good thermal conductivity so as to reduce the difference between the outer and inner wall surfaces Also, the possibility of the location of inclusion segregates within a machined gun tube becomes more likely than in a small test specimen The effect of these nonmetallics on gun life and performance is evident when one realizes that the inclusions are soft yet brittle They reduce the amount of plastic deformation which can take place before cohesive failure occurs Once localized fracture has occurred at the position of a chain of these inclusions, a sharp notch (crack) is formed which produces stress conditions more favorable to cohesive failure than to plastic deformation These cracks aid erosion by providing channelways for the explosive gases, eventually leading to the tearing out or spalling of blocks of metal Oxidation of the surface may be partly responsible for the change in the surface of gun steel during firing observed by the author The appearance of burn on the surface is an indication that high temperatures were reached on firing, resulting in a slight oxidation of the surface Since the color of the oxidized film depends on both temperature and time, a higher temperature is required for a given color to form when it is caused by explosive heat, which acts for only an extremely short time at a given spot, than when it is caused by ordinary tempering The cross section of the gun steel specimen, Fig 16, illustrates that the repeated firing temperatures were high enough to cause

Jan 1, 1948

By E. B. Spice

Although much may be learned about the economics of cold weather operations by studying successful mining ventures in southern and central Canada, it is the purpose of this article to extend the study by considering only permafrost areas. Geographically this means most of the country north of the 60th parallel. In this area, at the present time, only five Canadian companies are carrying on routine and successful mining operations on a year-round basis. However, there have been some score of unsuccessful ventures, and a number of properties in the development stage show promise of being producers. Problems of cold weather are worthy of study. It may be pointed out that successful mines in this area face problems of isolation and costly transportation as well as cold weather. To reach valid conclusions, consider the development of a mythical mineral deposit located on the 65th parallel in the heart of the barren lands; problems of isolation and transportation will be ignored.

Jul 1, 1956

By Carl Swartz

METALLURGISTS differ considerably in their opinions regarding the effect, if any, of small amounts of iron pyrites, or other iron compounds on zinc sulfide ores during the roasting operation. As a result, the literature on this subject expresses many conflicting ideas. The ore, previously crushed to pass through a one-millimeter screen, dries in the roasting kiln, losing water up to 200° to 300° C. At 150° C. iron pyrites begin to lose sulfur. As the temperature increases, while the ore is passing to the hotter part of the furnace, the sulfur burns to sulfur dioxide, leaving the metals as zinc oxide and ferric oxide. These two substances then interact to form zinc ferrite, a compound, yellow brown in, color, having the general characteristics of a spinet Like magnetite, another spinel, zinc ferrite is insoluble in alkalis and dilute acids. As a result, when leached with 10 per cent. sulfuric acid solution zinc values tied up in this compound remain behind. HISTORY In the electrolytic recovery of zinc from its ores, the roasted ores are usually leached with a 10 per cent. sulfuric acid solution. When the zinc ore contains iron pyrites as an impurity in an appreciable amount, the actual yield of metallic zinc is much lower than a theoretical calculation would indicate. Further, losses of zinc are, in a rough way, directly proportional to the amount of iron pyrites or other iron compounds present. When the iron is present in the ore in an isomorphous relation to the zinc, as in the case of a marmatite, a greater amount of zinc remains insoluble than when present as a true pyrite or marcasite. Work on the insoluble residues obtained from leaching of the calcines shows that the zinc lost is intimately tied up in this residue. Some investigators have suggested a definite compound, such as zinc ferrite, others merely a mixture of zinc and iron compounds.

Jan 1, 1927

By C. K. Donoho

SILICON is used in almost all commercial steels; up to about 0.20 pct in killed wrought steels and 0.50 pct in steel castings. Above about 0.50 pct in wrought steels and 0.70 pct in cast steels, silicon is considered an alloy. As an alloy, silicon is useful for several purposes: (I) for its effect on magnetic properties of parts for electrical apparatus; (2) for increasing the yield strength of carbon and low-alloy steels without too much sacrifice of ductility and weldability; (3) for adding hardness and toughness to spring and chisel steels; (4) for adding resistance to scaling and carburization to heat-resistant steels; and (5) for its graphitizing effect in graphitic steels. In acid electric steels for casting we are principally interested in the effect listed second; i.e., increase of strength with minimum sacrifice of ductility.

Jan 1, 1947

By Dennis K. Mortensen

Startup of the 9000 tpd Sacaton concentrator is expected to increase Asarco's domestic copper concentrate capacity by 21%. The plant site is located due west of the mining operations, consisting of both crushing and concentrating facilities. Arthur G. McKee & Co. served as the prime contractor for the project. The Sacaton mineralization contains both sulfide and oxide ores. Primary mineral constituents are chalcocite, azurite, malachite, chrysocolla, and minor amounts of silver and occasional gold. Sulfides are distinguished from oxides when more than half the total copper content is in the form of a sulfide copper mineral. While non-sulfide copper minerals are considerably less prevalent throughout the orebody, they tend to occur quite intimately with the sulfide minerals, particularly in the upper zones of the mineralization. For this reason the decision was made to treat all the ore in a flotation circuit using existing sulfidizing methods.

Jan 11, 1974

By J. W. Hickman, E. A. Gulbransen

In a previous paper' the authors have investigated the structure of the oxide films formed on most of the metals that make up the alloys of this study. The metals were studied in order to provide basic information on the structures, both physical and chemical, of the oxide films and to determine how these structures are effected by the temperature, time of oxidation, and surface preparation. It was felt that an understanding of the physical and chemical structure as well as the stability of the oxide film might furnish clues as to the nature of the reaction process and the protective quality of the film. The oxidation of the metals was studied over the temperature range 300' to 7o0°C. except for copper, wherc the range selected was 100' to 500°C. The results of these studies were presented in graphical form as existence diagrams of the oxides on a time-temperature scale. For some of the metals the existence diagrams were simple and showed few chemical transitions, but there were numerous cases where the physical state of the oxide surface was a function of time and temperature. In general the physical state of the oxide surface changed with increasing temperature so as to increase the sharpness of the diffraction patterns and to cause orientation effects to be more pronounced. Deviatiois in lattice Darameters from X-ray values were noted. In general these deviations were of positive nature and may be due to solid solution of the metal in the oxide lattice. This effect might be expected in thin oxide films. In a study of the oxidation of alloys containing two or more metals, there may arise the complicating factor of identification of the oxides formed. A thorough understanding of the oxides formed on the pure metals, therefore, was, essential before investigation of the oxidation of alloys. In this paper it is our purpose to present a study of the following problems: 1. The existence diagrams of various alloys. 2. The effect of the structure of the alloying metal on the existence diagram of iron. 3. The effect of the percentage of chromium on the oxides formed on Fe-Cr alloys. 4. The relationships, if any, between the oxides formed and the protective quality of the oxides. The following alloys are included in this study: alloys of iron with body-centered cubic, face-centered cubic and other metals, 13 Cr-Fe, 18-8 stainless steel, K4²B, Nichrome V, Hipernik, Inconel, Stellite "²I," Refractaloy, Kovar, mild steel, a series of Cr-Fe alloys and a series of Co-Fe alloys. Since many of the commercial alloys in this list contain more than two metals, various complicating factors in the identification of the oxides formed may arise.

Jan 1, 1947

By E. A. Gulbransen, J. W. Hickman

In a previous paper' the authors have investigated the structure of the oxide films formed on most of the metals that make up the alloys of this study. The metals were studied in order to provide basic information on the structures, both physical and chemical, of the oxide films and to determine how these structures are effected by the temperature, time of oxidation, and surface preparation. It was felt that an understanding of the physical and chemical structure as well as the stability of the oxide film might furnish clues as to the nature of the reaction process and the protective quality of the film. The oxidation of the metals was studied over the temperature range 300' to 7o0°C. except for copper, wherc the range selected was 100' to 500°C. The results of these studies were presented in graphical form as existence diagrams of the oxides on a time-temperature scale. For some of the metals the existence diagrams were simple and showed few chemical transitions, but there were numerous cases where the physical state of the oxide surface was a function of time and temperature. In general the physical state of the oxide surface changed with increasing temperature so as to increase the sharpness of the diffraction patterns and to cause orientation effects to be more pronounced. Deviatiois in lattice Darameters from X-ray values were noted. In general these deviations were of positive nature and may be due to solid solution of the metal in the oxide lattice. This effect might be expected in thin oxide films. In a study of the oxidation of alloys containing two or more metals, there may arise the complicating factor of identification of the oxides formed. A thorough understanding of the oxides formed on the pure metals, therefore, was, essential before investigation of the oxidation of alloys. In this paper it is our purpose to present a study of the following problems: 1. The existence diagrams of various alloys. 2. The effect of the structure of the alloying metal on the existence diagram of iron. 3. The effect of the percentage of chromium on the oxides formed on Fe-Cr alloys. 4. The relationships, if any, between the oxides formed and the protective quality of the oxides. The following alloys are included in this study: alloys of iron with body-centered cubic, face-centered cubic and other metals, 13 Cr-Fe, 18-8 stainless steel, K4²B, Nichrome V, Hipernik, Inconel, Stellite "²I," Refractaloy, Kovar, mild steel, a series of Cr-Fe alloys and a series of Co-Fe alloys. Since many of the commercial alloys in this list contain more than two metals, various complicating factors in the identification of the oxides formed may arise.

Jan 1, 1947

By M. C. Manderson

Abstract-The sharp drop in world phosphate demand that took place in 1975, due to temporarily high prices, now seems to be reversing itself. And prices for both phosphate rock and phosphate fertilizers, which declined dramatically from their 1975 highs, now appear to be bottoming out. This recent price weakness has delayed new mining ventures that had previously been planned for completion by around 1980. While there is ample capacity to supply near-term rock needs, the stage seems to be emerging for a better supply-demand and price environment in the late 1970's and early 1980's.

Jan 1, 1978

By Ralph M. Roosevelt

IN AS MUCH as our Institute, by tradition, never adopts any official view of matters upon which difference of opinion exists, it may be taken for granted that the duty of its Production Control Committee does' not embrace the formulation of any general policy on that much-discussed subject. During the first years of its existence the Committee confined its activities to making arrangements for an annual general session at which the broader aspects of the general problem were discussed by men both within and outside the mineral industry. These general sessions, although interesting, did not indicate any definite path of progress, so during the last year the Committee has held a number of luncheon meetings at which the members might discuss in detail problems existing in the specific industries with which they are most closely acquainted, in the hope that discussions dealing with conditions rather than theories might result in the bringing to light of some general truths. Most of these truths have been fairly obvious from the beginning but they are of such basic importance that a periodic restatement of them seems worth while,

Jan 1, 1932

By C. Stansfield Hitchen

THE introduction of the logarithmic sector method of quantitative spectrography by Scheibe and Neuhäusser in 1928, and the subsequent .modification and improvement of the method by Twyman and Simeon, would seem to have marked yet a further advance in quantitative spec-trum analysis and its industrial application, inasmuch as it offers a simple means of eliminating some of the uncertainties inherent in the older methods based upon mere visual comparison of line intensities. In their recent admirable review of the position and capabilities of industrial spectroscopy, Brownsdon and van Someren1 say: Ways and means of facilitating the comparison of line-intensities so as to give them numerical values are helpful, and of these a logarithmic sector rotating in front of the slit appears to he one of the most promising; . . . the success recently experienced by the author in using this method for the examination of steels and solutions of metallic salts prompted him ,to investigate its possible use in estimating the impurities commonly present in crude and refined tin. The results of this investigation are submitted in the present paper. Details of a number of spectrographic analyses of tin for various impurities have already been published. Thus, Schweitzer2 describes the spectrographic examination of tin for lead, bismuth and cadmium, and was able to distinguish between such atomic percentages as 0.01, 0.05, 0.10, 0.30, 0.60, 1.20, 3.00 and 10.00. Negresco3 investigated the bismuth content of tin over a range of from 0.0005 to 35 per cent. Meggers, Kiess and Stimson4 compare spectrographic and chemical analyses of tin metal for copper, lead, iron, zinc, silver, nickel and bismuth. They stress also the value of spectrum analysis in the examination of tin used for boiler plugs, where the requirements that only minute quantities of impurities shall be present render the chemical analysis both tedious and difficult.

Jan 1, 1933

The following letter was received from Prof. Kemp in reply to a telegram expressing the greetings of the members attending the Annual Meeting in New York. "Melbourne Beach, Fla. Feb. 17, 1916. Dear Mr. Stoughton: The welcome telgram from the members of the Institute, which you kindly trans-mitted to me, came safely yesterday and I catch the next available mail with a heart-felt acknowledgment. I cannot express to you how greatly the remembrance cheers and braces me during the days of patient waiting for the feeling of over-strain to fully pass, and for the time when I can again be back among the friends in the Institute who are very clear to me. While I cannot reach all the members who joined in the telegram I will ask you to say to such as are available that I am profoundly sensible of the thoughtfulness which prompted the message. I write from a little bungalow on the ocean. side of the half mile or more of sand dunes, thickly grown with palmetto, which separate the ocean from the Indian River. Two miles or more of Indian River still intervene between the little colony of Melbourne Beach and Melbourne on the mainland and on the Florida East Coast R. R. where the telegraph station is. I was thus unable to respond at once by wire. Sincerely yours, (Signed) J. F. Kemp."

Jan 4, 1916

By T. M. Girdler

INDUSTRIAL progress and development in this country from the earliest daps to the present has proceeded at an ever-quickening pace. Yet during recent decades the nature of our industrial progress and development has undergone a change of great significance. The earlier days were a period of tremendous expansion. Population was increasing by leaps and bounds. Vast areas of new land were being .2 opened to settlement. And almost boundless new sources of timber, coal, oil, ores, and power were being opened to ever-expanding markets. Today, however, that picture has al- most completely changed. Today, with population increase tapered way off and the opportunity for free expansion into western frontiers gone, the great industrial development of our country continues on a vastly different front. Industrial progress and development today rest on a foundation of technology. The key- stone is research. Our frontiers to- day are frontiers of sciencec

Jan 1, 1939

SLAG composition, slag constitution, reactions in slag, and reactions between slag and metal-in other words, the physical chemistry of slags-are matters of great importance to the open-hearth operator, whether or not he makes use of any detailed knowledge of them. Although this is a relatively young branch of the science of steel- making, much progress has been made; however, much remains to be learned, and many of the statements that can be made at present are probably--or even certainly-subject to future change. Nevertheless, the physical chemistry of slags is sufficiently developed to provide a reasonably secure basis for real understanding of steelmaking reactions. FUNDAMENTALS OF SLAG CONTROL By way of introduction, some time is spent in this chapter on effecting an easy transition from some of the more "practical" manifestations of slag to discussions couched in the more formal language of physical chemistry. This necessitates a certain amount of repetition, but it is felt that the purpose of the chapter is best served in this way. Reactions in the metal phase have products that find their way into the slag and are important components thereof; they are discussed in detail in the preceding chapter. Some substances distribute themselves Between slag and metal in definite fashion, and others are found only in the slag. Their reactions are a large reason for this chapter. Limitations of Slag Control. The open-hearth process is essentially oxidizing and cannot be otherwise operated. (Oxygen gradients in the furnace, the mechanism of oxygen inflow, and similar subjects are discussed in Chapter XIX.) As shown in the calculations of material and heat balances for the charge (see Chapter XV), from 25 to 50 lb. of oxygen will flow from air or combustion gases into the charge or molten bath during the heat for each ton of liquid steel

Jan 1, 1944

ALTHOUGH the refining period of the heat is generally defined as starting after the charge has been completely melted, it may more properly be considered as beginning with the first efforts to facilitate the shaping up of the slag and the making of corrective additions for the control of slag or metal composition. Such actions may be initiated during the latter half of the lime boil. The early part of the refining period may, then, in essence overlap the latter part of the melting period. The primary aims of the refining period are: (1) to reduce phosphorus and sulfur from the steel bath to levels safely below the maximum contents specified; (2) to eliminate carbon to a specified level as rapidly as possible and still allow time for proper conditioning of the slag and attainment of the necessary bath temperature; and (3) to have the heat ready for tapping or furnace deoxidation, with slag in the proper physical and chemical condition, and with carbon and oxygen contents and the temperature of the steel at the proper levels for the composition and grade of steel being produced. The particular conditions that fulfill these aims are distinctly different, depending upon whether the steel is to be finished according to fully killed. semikilled, or rimming practice and also depending upon the carbon range specified. Regardless of the type of charging practice employed, the object of the refining period is to produce repeatedly the desired finishing and tapping conditions for the grade of steel being produced. The variations and proportions of raw materials used in the charge may cause some variations in the degree of control required during refining, but not in the method of control. The refining period can therefore be discussed from a viewpoint largely independent of charging and melting practice. SHAPING UP THE SLAG In the first helper's vocabulary, refining practice consists in

Jan 1, 1951

By Jack A. Simon, M. E. Hopkins

GENERAL GEOLOGY Coal is defined as a combustible rock that had its origin in the accumulation and physical and chemical alteration of vegetation. Coal can be ignited and burned like the wood that was man's earliest fuel, but coal gives more heat than the same amount of wood and has many industrial uses. Unlike wood, coal is not generally found on the surface of the ground but is mined from the solid rock of the earth. Before taking up the occurrence, formation, and the somewhat unique character of coal in the rock sequence, let us briefly consider the general character of all rocks in the crust of the earth. Relatively little is known about the very earliest history of the earth, although a number of logical theories have been developed. Manned exploration of the moon and the rocks being returned to earth will, we hope, provide some answers to questions concerning the earth's origin and history. The period of earth history with which we concern ourselves here begins after great areas of water had evolved on earth and substantial land areas of once molten (igneous) rock existed. Weathering and other processes that attacked the surface of the rocks reduced them to small particles. Water provided by rainfall transported this material, ultimately, to large bodies of water where it was deposited. Thus was initiated the geologic sequence of sedimentary rocks that lie above the once molten igneous rocks. The crust of the earth is not completely stable, and throughout the geologic past portions of the crust have moved laterally and vertically. Even today, many coastal areas are slowly rising or sinking. More sudden earth movements are recognized by the earthquakes they cause. Throughout geologic history, rises in sea level or the sinking of the land areas have many times permitted the oceans to cover much of what are now the areas of the continents. Only relatively small parts of the present continents appear to have been above sea level throughout geologic time. Great

Jan 1, 1973

By Arthur Taggart

THE major portion of the work described in this paper was performed by R. W. Young,+ a graduate student in the department of Mining and Metallurgy, Sheffield Scientific School, Yale University, working under a cooperative agreement between the Hardinge Conical Mill Co., the Sheffield Scientific School, and himself. Since this cooperative scheme is at present in effect in the case of a considerable number of other students in the department and since it is the hope of the school that the privilege thus extended may be utilized even more freely in the future by mining and manufacturing companies, it may not be amiss at this point to give a summary of the general plan. Briefly it is as follows: A graduate student, whose undergraduate work in this or other universities shows promise of ability to handle research work, is chosen by conference between the company and instructor involved. The aim of the company in the agreement then entered into is to obtain the solution of one or more of the technical problems with which it may be confronted, or, at the end of 1 or 2 years, to obtain as an employee a man especially trained in its work. As. a means to accomplish one or both of these ends, the company furnishes the machine, apparatus, or material to be tested and pays the student during his graduate work a small salary, usually just sufficient to cover his living expenses, tuition and fees. The aim of the student is special training along a line in which he is particularly interested, the attainment of his advanced degree, and the chance to show to his future employer ability to handle such problems as may be presented to him. In return for the financial aid which he receives he agrees to devote at least half of his working time to the special problem submitted by his company. The other half is devoted to study of the collateral subjects required by the department for the granting of the degree which the student seeks. The student further agrees to enter the employ of the company in question at a wage not greater than that paid in like positions to recent graduates not specially trained and to remain with his employer at such wage for at least 1 year. If the student is to obtain a degree, the special work forming the basis of his investigation must be such as will involve real research and not mere routine manipulation. The subject is chosen by conference between the three parties to the agreement. The work is carried on under the direct supervision of the instructor involved. The school furnishes the general laboratory and library equipment essential to the pursuit of any extended investigation, In

Jan 4, 1917

By J. Handin

Triaxial compression tests with independently applied external confining pressures and internal pore pressures show that the ultimate compressive strengths of representative oil well cements are nearly linear functions of effective pressure — the difference between external and internal pressures on the jacketed cylindrical specimens (to 15,000 psi). The strengths are little affected by the test temperature to 350F (not to be confused with the curing temperature). At an effective pressure of 15,000 psi, strengths are in the rage of 30,000 to 50,000 psi, comparable to those of sedimentary rocks under similar conditions. The cements become very ductile even under low effective pressures; permanent shortenings of 30 per cent or more are attainable without rupture. INTRODUCTION Since the pioneering work of Richart, Brandtzaeg and Brown1 on the failure of cement under combined compressive stresses, it has been recognized that ultimate compressive strength is greatly enhanced by the application of confining pressure. More recently, Mc Henry2 showed that the strength of concrete was a linear function of the effective pressure (the difference between the external confining pressure on a jacketed specimen and the internal fluid pore pressure), at least for a range of 0 to 1,500 psi. The effect of temperature had not been investigated, and no previous systematic triaxial compression testing of naterials used for oilwell cementing seems to have been done. The present work was suggested by the late J. hi. Bugbee3 who stated that "consideration of the common application of high-pressure hydraulic fracturing to the initial completion or recompletion of wells, and the large pressure drawdowns in some producing wells, particularly those in abnormally high-pressure gas-condensate reservoirs, raises the question of what is a suitable cement strength for various completions. The intuitive belief exists that cement strength need be no greater than formation strength. Tests should, however, be conducted at downhole conditions." The ultimate compressive strengths of rocks penetrated by the borehole must rise several fold with increasing depth.4 This marked enhancement of strength is due to the influence of the effective pressure, the total weight per unit area of the overburden less the hydrostatic pore pressure. (The effect of temperature due to the geothermal gradients is relatively small for depths to 30,000 ft.) .A significant comparison of the strengths of rocks and cements at downhole conditions requires knowledge of the confined compressive strengths of cements as well. EXPERIMENTAL PROCEDURES The theory and technique of triaxial compression testing are fully discussed in earlier reports.4-6 Briefly, cylindrical specimens 1-in. long and 0.5-in. in diameter are jacketed in thin copper tubes of negligible strength, placed in the test chamber and subjected to an external confining pressure of kerosene and loaded axially by the piston at a strain rate of 1 per cent per minute. Pore pressures of water (or kerosene) are applied independently through the hollow piston and are maintained constant during the shortening of the specimen, Tests at sensibly 0 pore pressure are arranged so that any free water in the cement can escape to the atmosphere. (If egress of water were denied, pore pressure would rapidly attain the value of the external confining pressure because of reduction of pore space.) The test chamber can be heated for high-temperature experiments. Unless otherwise noted, the cement samples were air dried for about a week. Recorded during a test are pore and confining pressures, shortening and axial differential force (total force less the product of the confining pressure and the area of the piston). True stress-strain curves are constructed by dividing the measured differential force by the actual cross-sectional area of the specimen at a given

Jan 1, 1966

By J. E. Steiner, J. M. Hodge, M. A. Orehoski

Ingots of four steels (1045, 1080, Ni-Mo-V, and Ni-Cr-Mo-V) were cast at pressures varying from about 1 to 760 mm of mercury, so as to obtain a range of hydrogen contents in each steel. The susceptibility of these steels to flaking was evaluated by cooling hot-rolled blooms at a range of cooling rates, varying from water quenching to slag cooling, and studying the occurrence of flaking as a function of cooling rate. The steels exhibited differences in susceptibility to flaking, and a tlzreshold value for hydrogen content for each steel was found, below which the susceptibility was very low and above which the susceptibility increased markedly with increasing hydrogen content. Mechanical property evaluations, metallogvaplzic exantinations, and X-my diffraction determinations o,t retained austenite were made on samples from the blooms. A mechanism of flaking which is consistent with the observed behaviors, the effects of hvdrogen content, and the differences in susceptibility among the steels investigated is postulated, based on the results of mechanical property evaluations and metallographic and X-ray diffraction studies. ThE important role of hydrogen as a factor in the occurrence of "flakes" or "hair-line cracks" in steel has now been established by many investigations. These have included investigations by steel producers and forging manufacturers, to whom the prevention of flaking is a very real and serious problem, and many research studies aimed primarily at establishing the mechanism of this behavior Several investigators3 have reported that steels cast at reduced pressures (absolute pressures of about 1 mm) not only are low in hydrogen content but are essentially insensitive to the formation of flakes. These investigations have shown that a general relationship exists between hydrogen content and susceptibility to flaking. The difficulty of obtaining suitable samples of steels of a given composition with the desired range of hydrogen contents, particularly in the relatively large sections in which flaking most commonly occurs, has been the principal obstacle to quantitative evaluations of these relationships. Steels with intermediate hydrogen contents between 1 ppm, and the 4ppm or higher of air-cast steels are generally not available in commercially produced steels. Laboratory procedures, in which the hydrogen is introduced into solid steel samples by heating in a hydrogen atmosphere under pressure, generally involve a limitation in the size of the sample which can be treated, and thus are not representative of the behaviors in large sections. The availability of a facility at the South Chicago Works of U.S. Steel, in which several ingots could be cast from a single heat of steel at total air pressures ranging from 0.25 to 760 mm of Hg, has made it possible to overcome this obstacle and to obtain ingots of a given steel covering the intermediate range of hydrogen contents desired. These ingots, furthermore, are of a size suitable for the production of product with section sizes large enough to be representative of the products in which flaking most commonly occurs in commercial production. In these experiments, this facility was used to study the relationships between hydrogen content and the susceptibility to flaking of four steels, two plain carbon steels at 0.45 and 0.80 pct C and two low-carbon alloy steels representing a medium and a rather high hardenability level. These flaking studies were supplemented by evaluations of mechanical properties and by metallographic studies on samples from the blooms, in order to obtain pertinent information on the factors other than hydrogen content which influence the susceptibilities of these steels to flaking. Based on the results of these tests, a mechanism for the initiation and propagation of the flaking cracks, which is consistent with the observed behaviors, is postulated. MATERIALS AND EXPERIMENTAL WORK Steelmaking and Conversion. To provide material for the investigation, five 29- by 35-in., hot-topped, big-end-up ingots were cast from each of four 80-ton, basic electric-furnace heats of four different steels (a 1045 steel, a 1080 steel, a Ni-Mo-V steel, and a Ni-Cr-Mo-V steel). A double-slag practice was used on all steels and the two plain carbon steels were Si-A1 deoxidized with an addition of 2 lb of A1 per ton, while the Ni-Mo-V and Ni-Cr-Mo-V steels were deoxidized only with silicon and

Jan 1, 1964

By P. Payson

INTERGRANULAR corrosion in corrosion-resistant chromium-nickel steels has been widely discussed in the last few years. So far as the author knows, nothing has been published which definitely shows that this tendency can be eliminated, although suggestions have been made that a remedy is possible if certain specifications are satisfied. Strauss, Schottky and Hinueber1 suggested an increase in chromium content to an extent that would prevent the impoverishment of chromium on carbide precipitation sufficient to cause impaired corrosion resistance in the matrix. Pilling2 suggested an increase in nickel, so that the stability of the austenite matrix would be increased. Aborn and Bain,3 say that "intergranular attack-may be eliminated by preventing carbide precipitation (e. g., by lowering the carbon content or somehow raising its solubility) or by precipitating it permanently under conditions which will not remove chromium from solid solution so drastically at any points." In a later paper Aborn and Bain4 state that many different metallic elements, tungsten, vanadium, copper, aluminum, molybdenum, titanium and zirconium, have been added in small per-centages to increase the stability of these alloys, but that it has been reported that according to the copper sulfate test these added elements act only to retard the intergranular corrosion, and that increased nickel and chromium contents have similar effects. Newell5 showed that the lower the quenching temperature before reheating, the less severe was the intergranular attack.

Jan 1, 1932