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By H. M. Day

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 Murphy1 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 con-firmed and supplemented through X-ray analyses by Preston 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 tempera-tures 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.

Jan 1, 1938

By W. E. D. Jr. Stokes

THE application of aviation to mining and petroleum operations, on the basis of economy and attainment, has become a demonstrated fact. According to Dominion Government records, 30. Canadian companies engaged in air transportation with northland mining camps, carried 13,000 tons of freight in 1935, and in 1936 carried 16,000 tons. In addition, many mining companies used planes to transport prospectors with canoes, outboard motors, gasoline drums and supplies to remote locations, and one company maintained a plane to take radium-bearing ore from its mine on Great Bear Lake nearly 1000 miles south to the rail-way at Waterways, Alberta. Heavy pieces of mining machinery weighing 2 tons are being carried by Ford trimotor planes over the Andes, at an altitude of not less than 15,000 feet. At Bulolo, New Guinea, 17,500 tons of disassembled gold-dredging equipment has been flown over inaccessible terrain, while supplies and building materials for a, community of 1000 whites have been transported by airplane. A 3 1/2-ton shaft was carried on one notable trip, while at another time an automobile, 2 tons of rice and a large safe went over the mountains in one plane. Fig. 1 shows an electric generator that was carried by plane to Bulolo.

Jan 1, 1937

By G. Sachs

THE iron-rich iron-nickel alloys have at-tracted considerable academic interest in recent years. The carbon-free alloys are of minor practical importance, but they are Atomic per cent nickel FIG. I. FIG. 2. FIG, I.-HONDA'S AND MERICA's IRON-NICKEL DIAGRAM, FIG. 2.-MARSH'S IRON-NICKEL CONSTITU-TIONAL DIAGRAM. the base of many alloys with various out-standing properties. The iron-nickel alloys, therefore, have been investigated exten-sively regarding both their structures and their properties. The researches on these alloys up to 1938 have been collected and critically reviewed by J. S. Marsh,1 and will be discussed in some detail in the sec-tions of this paper dealing with specific subjects. These numerous investigations have not succeeded in establishing the equilibrium conditions in this system. Alloys containing more than a certain amount of nickel (8 to10 per cent Ni) undergo the allotropic transformation extremely sluggishly, both on heating and cooling, showing a large hysteresis,2 which is not dependent upon

Jan 1, 1940

By William G. Kegel

Apart from a usable product and good mining conditions, the greatest asset for a profitable coal mining organization is an effective mine maintenance program. The first step in achieving this is to have good mechanics-or men who want to be mechanics and are interested in knowing ,more about the design and control of the machines in their charge. A good mechanic's knowledge and ability result from ambition, curiosity, and determination. Starting with these qualities, the aspiring mechanic can launch his career by learning all he can about mechanics, electricity, and hydraulics. Though the path is rough, the end result is rewarding. Mining machinery probably receives as much, if not more, abuse as any other heavy equipment in use today. Considering the conditions under which much of the repair work must be done, it is essential that the mine operator has the best men and tools to perform the work. Mining machines, from their inception, have utilized the electric motor ; and down through the years of mechanization, this power source has undergone many changes to better adapt it to the job. The first motors used were direct-current (d-c) motors since d-c power was the most economical power source for mining at the time of early mechanization. These motors were large open-type machines which are seldom used in modern mining. Because of the mine environment, the d-c motor has been reduced in size to better suit the application in mining machines and is now manufactured with dust-tight or explosion-proof enclosures. The d-c motor is constructed with either (or both) series and shunt fields located on the stationary part of the motor (stator) and an armature coil wound on the rotating part of the motor (rotor). Power is supplied to the armature by brushes which are held stationary and make sliding contact with the armature. The brushes requires regular and careful maintenance because worn or defective brushes will cause heat or arcing which can destroy the motor. D-c motors can be used as d-c generators when mechanical power is supplied to them by the rotating

Jan 1, 1981

By Charles T. Baroch, Charles J. Baroch

Nuclear energy probably has greater potentialities for changing the world's way of life than any other recent discovery. The atomic-bomb bursts over Hiroshima and Nagasaki suddenly changed the concepts of war. Peaceful uses of nuclear energy are advancing so rapidly that no study of economic trends is complete without giving them consideration. The minerals specialist, especially, must be aware of this new force in our lives, as minerals and metals are essential in harnessing the new force, and atomic energy itself is rapidly improving its competitive position in the energy field. Future historians may chronicle December 2, 1942, as the beginning of the Atomic Age. On that day Enrico Fermi and his co-workers at the University of Chicago produced and controlled the first self-sustaining nuclear chain reaction. Lie many inventions, the first application of nuclear energy was as a weapon of war. However, its potential usefulness in man's work and welfare far outweighs in economic importance its destructive use in war, unless its military effect would be considered so great and all-embracing that no major power will hereafter chance a world conflict. Recognition of this potential has generated a vast international effort to exploit the atom for peaceful beneficent purposes. Like its physical manifestation, the advent of nuclear energy has unleashed chain reactions that have pervaded the political, social, and economic environments of the world. The impact of nuclear developments in one of many fields is exemplified by the uranium mining industry. Uranium was discovered in 1789 and in the next century and a half it found only an insignificant use as a ceramic coloring agent; in fact, in the latter part of that period, it was a largely unsalable by-product of the radium and vanadium industries. Up to 1940 the total quantity of uranium metal produced was not more than a few grams, of doubtful purity. Thus the production of 12,400 pounds of pure

Jan 1, 1964

By T. R. Armstrong

During the year 1939, Mexican production totaled 42,479,000 bbl.; a daily average of 116,381 bbl. or a little over 2 per cent of the estimated world production. The Mexican Government operates 100 per cent of the refining branch of the industry, 100 per cent of the domestic distribution, 96 per cent of the crude production and 92 per cent of the total exports. No discussion of the Mexican petroleum industry in 1939 is adequate without reference to the "expropriation" of the foreign-owned oil properties in Mexico by executive fiat on March 18, 1938. The forcible seizing of the properties culminated a long series of efforts on the part of the Mexican Government to obtain control of the oil properties developed through foreign initiative and with foreign capital in Mexico. The heart of the issue is whether the Mexican nation or any nation may with impunity confiscate the legally acquired properties of American citizens. The Department of State of our Government has in its communications to Mexico emphasized the fact that its "expropriation" of American properties was confiscatory because Mexico had failed to make "adequate, effective and prompt compensation"; that the taking was no less confiscatory "because there may be an expressed intent to pay at some time in the future," and that, consequently, "Mexico has assumed and continues to assume to exercise a right without compliance with the condition necessary to give such exercise a recognizable status of legality." Mexico has professed its willingness to pay for the oil properties but at the same time through its Supreme Court it has declared that the owners or lessees do not have the exclusive right to extract and dispose of the oil in the subsoil. This is a reversal of the Mexican position with respect to oil as set forth in the Mexican mining laws, affirmed by Mexican Supreme Court decisions, and as clarified in the Warren-Paync and the Morrow-Calles agreements, as well as in diplomatic correspondence. Efforts to Settle the Controversy Responding to suggestions from the State Department, representatives of the principal oil companies undertook in 1939 to effect a direct

Jan 1, 1940

By T. R. Armstrong

During the year 1939, Mexican production totaled 42,479,000 bbl.; a daily average of 116,381 bbl. or a little over 2 per cent of the estimated world production. The Mexican Government operates 100 per cent of the refining branch of the industry, 100 per cent of the domestic distribution, 96 per cent of the crude production and 92 per cent of the total exports. No discussion of the Mexican petroleum industry in 1939 is adequate without reference to the "expropriation" of the foreign-owned oil properties in Mexico by executive fiat on March 18, 1938. The forcible seizing of the properties culminated a long series of efforts on the part of the Mexican Government to obtain control of the oil properties developed through foreign initiative and with foreign capital in Mexico. The heart of the issue is whether the Mexican nation or any nation may with impunity confiscate the legally acquired properties of American citizens. The Department of State of our Government has in its communications to Mexico emphasized the fact that its "expropriation" of American properties was confiscatory because Mexico had failed to make "adequate, effective and prompt compensation"; that the taking was no less confiscatory "because there may be an expressed intent to pay at some time in the future," and that, consequently, "Mexico has assumed and continues to assume to exercise a right without compliance with the condition necessary to give such exercise a recognizable status of legality." Mexico has professed its willingness to pay for the oil properties but at the same time through its Supreme Court it has declared that the owners or lessees do not have the exclusive right to extract and dispose of the oil in the subsoil. This is a reversal of the Mexican position with respect to oil as set forth in the Mexican mining laws, affirmed by Mexican Supreme Court decisions, and as clarified in the Warren-Paync and the Morrow-Calles agreements, as well as in diplomatic correspondence. Efforts to Settle the Controversy Responding to suggestions from the State Department, representatives of the principal oil companies undertook in 1939 to effect a direct

Jan 1, 1940

By H. H. Uhlig

SINCE its first mention in the literature in the eighteenth century1,2 the phenomenon of passivity in metals has stimulated much speculation and attendant controversy as to its nature and cause. No one of the numerous theories so far proposed has been generally accepted. ? Faraday,7 in 1836, associated the passivity of iron with a protective film over the surface of the metal, which materially prevents or slows down reaction with corrosive environments. His theory was that oxidizing acids like nitric acid form an unstable oxygen or oxide layer over the iron surface, which protects the underlying metal from further attack. This concept was simple yet plausible, and without alteration has frequently been assigned in present-day discussions as explanation of the passivity of many metals. With the advent in recent times of stainless steels, it is not surprising that this oxide film theory of passivity proposed by Faraday has been used to explain the phenomenal corrosion resistance of stainless steels and other passive alloys. The passive alloys, such as the chrome-iron alloys, are supposedly covered with a protective oxide film, which forms on exposure of the alloy to air, is extremely stable and self-healing, and accounts for the remarkable resistance of these alloys to corrosion. Within the past few years, several investigators, following the theory of film protection, have attempted to gauge the resistance of the supposed film on steels. Brennert8 and Donker and Dengg9 determined the poten-tial at which a negative ion (e.g., Cl-) moving in an electric field reacted with the metal anode, as detected by increased current flow or change in potential of the steel electrode in an electrolytic cell. The potential corresponding to reaction Brennert called the film break-through potential.

Jan 1, 1939

By Stephen Krickovic

THERE is today no proven continuous mining machine that can be used under all the varying conditions found in most bituminous coal mines. During the last five years, however, both the machines and methods of using them have been improved. Coal operators can now exercise a fair degree of selectivity, except those who must struggle with thick and hard partings and operate in seams less than 40 in. thick. It must be realized, then, that more than one type of continuous miner may be used advantageously in the same coal mine. Although this appears to violate the standardization generally sought after, the gain can more than offset added maintenance and, to a lesser degree, operating problems. It is equally important to realize that most coal mines will require one or more conventional loader setups in the plan of total mechanization. Seam variations, adverse physical conditions, and special designs of main headings for haulage and ventilation, to name only three reasons, may render 100 pct use of continuous miners uneconomical. Of course, this situation may change. In one mine, prior to 1954, machines that ripped coal from the face achieved only average results, as compared to the impressive performance of boring-type units in another coal mine. A boring-type unit was therefore selected for the first mine in the belief that the chance of success would be greater if it were used in a combined cutting and wedging operation, cutting a full face in its forward movement. The miner was located in a part of the mine where a special projection could be readily developed, a solid area scheduled for mining according to the overall progress plan. All openings surrounding the particular area were carefully investigated for the presence of sulfur balls. Fig. 1 (opposite) shows the representative seam section, containing the several pyritic bands 1/4 to 1/2 in. thick; a characteristic Pittsburgh seam parting averaging 5 to 6 in. of slate, coal, and slate; and the occasional py-rite lenses 2 to 3 in. thick. Under normal conventional mining methods, the top 10 or 12 in. and the bottom 4 in. are left in place to offer roof protection

Jan 1, 1958

By Walter Nummela

INTRODUCTION By the end of 1979 pellet productive capacity from the processing of low grade iron ores in the Lake Superior-District will total 86 million tons per year. Of that tonnage, 72 million result from the processing of magnetic ores such as taconite, about 6 million tons from the flotation processing of relatively coarse grained specular hematite, and 8 million tons from the processing of fine grained non- magnetic ores at Tilden. The Tilden flowsheet represents a break- through in the processing of this type of crude ore and hence is unique in the Lake Superior District (1). Operations at Tilden started in late 1974 with Algoma Steel, J&L Steel Corp., The Cleve- land-Cliffs Iron Company, The Steel Company of Canada, Ltd., Wheeling- Pittsburgh Steel Corp., and Sharon Steel Corp. as participants. Cleveland-Cliffs operates and manages the operation. Other companies have conducted extensive pilot plant tests or are in commercial production in the processing of fine grained non-magnetic ore materials (2). Flowsheets and reagent schedules may be different for each particular application, but some of the problem areas in the processing of Tilden ores have also been experienced at operations such as the IOC Plant at Sept-Isles, at Lamco and at Bong in Liberia, and in pilot testing of Fabrica ores of Ferteco Mineracao in Brazil. With a grind of about 80-85% -500 mesh resulting in 50% of the particles in the concentrate being less than 15 microns, a discussion of the pro- cessing of Tilden type ores fits the topic of this workshop. There are very large tonnages of fine grained non-magnetic crude ores which exist throughout the Lake Superior District and other iron ore producing regions. These fine grained non-magnetic materials constitute an important source of iron minerals. Before going into specifics of the flowsheet, it is important to

Jan 1, 1979

By Zay Jeffries

IT has been known for a number of years that certain aluminum alloys could be hardened by quenching from a temperature of about 500° C. Immediately after quenching the total increase in hardness is not marked, but the hardness increases gradually so that after about 4 days, it has reached a maximum. The actual increase in hardness probably continues for weeks or even months, but in order to detect the differences after 4 days, it is necessary to make tests at rather long intervals. So far as is known to the authors, Alfred Wilm was the first to discover these properties in aluminum alloys.1 The aluminum-copper alloys are amenable to this treatment and the addition of magnesium makes the heat-treatment effect more pronounced. Until recently heat treatment of aluminum alloys has been confined to the worked alloys in the form of sheet or extruded products. The alloy that has been most used in this connection is known commercially as duralumin and has about the following composition: copper not exceeding, 6 per cent.; magnesium not exceeding, 2 per cent.; manganese not exceeding, 1 per cent.; commercial aluminum,2 balance. A typically good alloy in this range consists of: copper, 4 per cent.; magnesium, 0.5 per cent.; manganese, 1 per cent.; commercial aluminum, balance. This alloy can be rolled into sheets or extruded; and in this condition it can be heated in the ordinary furnace atmosphere to a temperature near 500° C. and quenched in water. After about 4 days it will have the following physical properties: tensile strength 55,000 to 60,000 lb. per sq. in. (3866 to 4218 kg. per sq. cm.); elongation in 2 in., 15 to 20 per cent. No harmful effects of the furnace gases or even the air, if the heating is affected in an electric furnace in an air atmosphere,

Jan 9, 1919

By Daryl R. Tweeton, Jerry R. Riding, Grant Buma, Frank J. Rosswog

In situ solution mining of uranium has environmental advantages over conventional mining. The leaching of uranium, however, alters the ground-water quality in the aquifer where the mining occurs. Currently, regulations require that the ground water be restored to approximately its original condition. This paper, a summary of a study funded by the Bureau of Mines, reviews the state of the art in restoring ground-water quality after in situ uranium leaching. Current restoration practices discussed include disposal of liquid wastes in deep disposal wells and evaporation ponds, producing from all wells during restoration, and recirculating water purified in surface plants. Methods for predicting the effectiveness and cost of current techniques are presented. Possible alternative techniques are also described. Two restoration operations are discussed.

Jan 1, 1979

By Arthur Green

A GROUP of 13 cities situated in Los Angeles and Orange counties in Southern California is engaged in constructing an aqueduct to carry water from the Colorado River at a point near Parker, Arizona, to a distribution point sear Riverside, California. The aqueduct will have a total length of approximately 241 miles, and is designed to deliver 1605 cu. ft. of water per second, or a little more than one billion gallons per day. The aqueduct crosses a barren, desert waste and the project includes approximately 91 miles of 16-ft. tunnel. The large amount of tunnel driving that has been done in this country in the past few years has resulted in some remarkable developments in equipment and methods. The building of the Colorado River Aqueduct, with its 91 miles of tunnels, has called on the best engineering knowledge in the country. New and better equipment has been designed for all phases of the work, and this equipment has been coordinated and adapted to the various conditions with a high degree of efficiency. The result has been that records for tunnel driving have been set under adverse natural conditions that exceed the estimates for progress under good conditions. All of the tunnels in the main aqueduct, except the Valverde and Bernasconi at the western end, have a finished diameter, inside the concrete lining, of 16 ft. Fig. 4 shows a section of the tunnel with the concrete lining in place. Fig. 5 illustrates the finished tunnel in three typical sections. The standard tunnel grade is 3.432 ft. per mile in the 16-ft. tunnels, but the Valverde and Bernasconi tunnels have a steeper grade and a finished diameter of 15 ft. 3 in. The rough bore of the large main aqueduct tunnels averages 12.95 solid cubic yards of material per foot of advance in timbered sections and 10.76 solid cubic yards per foot in unsupported sections.

Jan 1, 1936

By T. E. Eagan, W. R. McCrackin

IN dealing with segregation in babbitt, and its effect on the final cast structure, which is a bearing, it is obviously impossible to cover all of the compositions manufactured. Each composition, of course, will exhibit certain specific types of segregation. However, as examples,, two compositions of babbitt are presented: one a tin-base of well-known analysis and the other a lead-base, which in the past few years has found wide usage. Bearings usually are cast either statically or centrifugally; therefore the effect of these two methods on segregation is presented. EXPERIMENTAL PROCEDURE A slab of babbitt 1/2 in. thick by 5 in. wide and 17 in. long was cast, using a book mold with the long edge vertical. An A.S.T.M. grade 2 babbitt was used (3.5 per cent copper, 7.5 per cent antimony, remainder tin), to which 0.10 per cent tellurium had been added. Unfortunately, no metal without tellurium was available. The mold to hold the babbitt was heated to approximately 300°F., the temperature being judged by the babbitter. The pouring temperature of the babbitt was 875°F. (470°C.). One slab was made by allowing the babbitt to cool without stirring. The other slab was stirred during the entire cooling cycle. This stirring consisted of a vigorous churning or puddling into the mold until complete solidification had taken place. Three samples were removed from these slabs. One was taken at the extreme bottom, another half way to the top, and another at the extreme top, all at the center of the width. Chemical, macroscopic and microscopic examination was made of all samples. Table I shows the chemical analyses obtained at the described positions [ ] in the slab. The analyses show no serious amount of gravity segregation. Microscopic examination from edge to edge of the slab showed little change in structure. From top to bottom there was a progressive coarsening of the grain size in the stirred slab but little change in the slab that was not stirred (Fig. I). No definite exhibit of segregation could be detected. In line with our experimental study on the tin-base babbitts, we cast an almost duplicate slab using A.S.T.M. Alloy No. 15, containing 0.9 to 1.25 per cent tin, 14.75 to 15.5. per cent antimony, 0.80 to 1.25 per cent arsenic and 0.4 per cent copper. The slab was 16 in. long and 3/8 in. thick, cast with the long side vertical. One slab was allowed to cool normally and the other was stirred continually during cooling. The pouring temperature of the babbitt was

Jan 1, 1944

By William F. Butler, Mo-Hung Che

DEVELOPMENT OF MONEY AND MONEY STANDARDS This chapter is concerned with the rise, and then the decline and fall, of gold and silver as monetary metals. As a first step in tracing the history of this process, it is necessary to consider the nature of money, and the manner in which different forms of money have developed over the centuries. The origins of money go back into deepest antiquity. Once men ceased to be pure nomads and entered into even a rudimentary form of society such as clans or tribes, money had to be invented The first step was barter as farmers or hunters swapped their surplus products for things produced by artisans such as shoes, clothing, and simple tools. But such barter trading is inconvenient even in primative societies It is difficult to match up buyer and seller at any point in time There are problems in arriving at viable and acceptable terms of exchange. The accumulation of savings-wealth-is complicated. No one can be sure that a pile of furs, or wheat, or certainly fish or game can be used in the future to trade for other goods or services. So even prehistoric man saw the need for money. There was a need first for something to serve as a medium of exchange This was an essential first step in the process of specialization-or the division of labor. A farmer, a hunter, or a shoemaker could only devote his full efforts to his trade if he could be sure that he could exchange his surplus production for the other things he needed for existence. This required a medium of exchange-a form of money which would be broadly acceptable. Money was needed for two other reasons Some system of market prices was essential to facilitate the exchange of goods and services. This required some form of common denominator-some standard of value-to govern the exchange process. And there was also need for something to serve as a store of value, a place to put any excess production (savings) with the assurance that it can be used in the future to acquire a general range of goods and services. As a result, money, in one form or another, developed at a very early state in civilization. Yet the centuries have been marked by a search for a form of money which will possess in full measure all of the attributes in money-a reliable and universally acceptable medium of exchange, standard of value, and store of value. -A wide variety of things have been used as money at one time or another: shells, beads, stones, feather, metals, and even the teeth of sharks and dogs. Some of these things were obviously of little or no practical value. They were used because people had confidence in their continued acceptance as a medium of exchange. As the world evolved and as trading ex-

Jan 1, 1976

By Clark B. Risler, Walter E. Thomas

MILL planning must include electrical drives and a system to supply them. These should be considered at the time metallurgical and mechanical plans are being made. Because it is convenient, flexible, reliable, and economical, electricity is the accepted source for powering mill concentrating equipment. Ore-treating mills have grown to the point where a single mill has been built using 360 motors ranging from 1 to 1000 hp and totaling 50,000 hp. Such a system of electrical drives can be scattered over a square mile and employ 4000 to 220 v. Drive Motor Characteristics: Since ore processing is predominantly a continuous operation, very few of its drives require wide speed variation after initial adjustment. Consequently squirrel cage, wound rotor, and synchronous alternating current motors are most often used.

Jan 5, 1957

By S. Senderoff, D. E. Couch

A PROCESS for the electrolytic preparation of molybdenum from molten salts has been described previously. This previous work centered on electrowinning and electroplating characteristics of the process. In this paper the properties of the process as a refining medium are discussed. In producing metals from ores, it frequently has proven most economical to obtain a comparatively impure metal by smelting, and to purify the product by electro refining. Direct electrowinning from molten salts is rather difficult when a porous diaphragm is required in the process, as in the case of molybdenum, since satisfactory refractory materials for such a diaphragm in molten salts have not yet been developed. In electrorefining, however, a soluble anode is used. By suitable control of anode and cathode current densities, the lower-valent molybdenum compound used in the electrolyte is not oxidized, and a diaphragm is not needed, thus avoiding difficulties which are encountered with other electrowinning processes. Electrorefining may result from two different processes in the cell: Dissolution of the molybdenum and the less noble impurities with a separation of the more noble impurities as an anode sludge; the electrodeposition of molybdenum and the more noble metals at the cathode, leaving the less noble metals in the electrolyte. The amount of separation which occurs in each process is determined by the potential of the operating electrode and the relative concentration of the various species at (or in) that electrode. Since molybdenum has a comparatively noble position in the EMF series in molten alkali halides,2 most refining would be expected to occur at the cathode. In this work only the cathodic process was studied. The objective was to determine to what extent various metallic ions, if they dissolve from the anode or are otherwise introduced, were concentrated in the electrolyte. The necessary conditions for the separation of each and the limiting concentration which may be tolerated in the electrolyte for effective refining were studied. The deposits were chipped from the cathode and analyzed spectrochemically for metallic impurities. Besides determining the major contaminant, a general qualitative analysis was obtained to be sure that other metallic ions were kept at a very low level during each series of runs and to be sure that the baths were not being contaminated accidentally. Samples of the bath, for analysis, were taken at the temperature of operation so there was no chance of selective crystallization during cooling. In this way the ratio of molybdenum in the bath to the other metal could be determined readily. These data permitted a check on the anode efficiency and any volatilization that took place during the electrolysis. Experimental Apparatus—The apparatus as shown in Fig. 1 was used to determine the effect of the various foreign ions upon electrodeposited molybdenum. The entry chamber A allowed the cathodes to be removed without cooling the bath and without allowing oxygen or moisture to enter." The cathodes were made Prom 0.25-in. tungsten rods and were rotated during the electrolysis. The balloon in the lower arm B was inflated with helium after the cathode was drawn up into the upper section for removal. A new cathode was then placed into the entrance chamber A after which the chamber was flushed

Jan 1, 1959

By E. S. Bumps, W. F. Craig, M. Baeyertz

Metallurgists have looked at fractures macroscopically for many years and have evolved a vocabulary in which such words as "cleavage," "brittle," "shear," "ductile," "granular," "fibrous," and "silky" are used to describe the appearance of the fractured surface; but the meaning of these words in terms of metal structure is not well established. Observations of the structural meaning of "brittle" and "ductile" fractures in plate steels have been made, notably, by Kramer and coworkers1 and by Tipper.2 Grossman3 has studied the fracture of tempered martensite and combinations of ferrite and martensite. Notwithstanding these and other less concerted attacks on the problem, present understanding of fracture rests more on assumptions and logic than on experiment. It is the purpose of this paper to add a little to the growing fund of experimental observations of the nature of fractures in steel. The particular fractures to be described were obtained in conventional impact testing of an ordinary structural steel shape. In impact tests of the Charpy type, the specimens fail in a characteristic manner that depends on the steel and the temperature of testing. With ordinary structural and many other steel products, an appropriate range of testing temperature will cause a considerable change in the energy absorbed before fracture. This change is known as the energy transition and is accompanied, more or less closely, by alteration in the appearance of the fracture. At testing temperatures below the transition, the terms "brittle," "cleavage," or "granular" are used to describe the fracture; above it, "ductile" or "shear" are often used. Within the transition, the fracture changes from "brittle" to "ductile" by a progression in appearance, wherein the "brittle" portion of the fracture becomes restricted to a smaller and smaller central area of the fracture, as the testing temperature is raised and the "ductile" type of fracture is approached. All this is well known to metallurgists. The specimens under consideration are of the conventional V-notch Charpy type. They were taken from a structural steel shape of the following analysis: C Mn P S Si 0.17 0.46 0.009 0.029 0.03 Both longitudinal and transverse specimens were tested and examined. Fig 1 shows the energy values plotted against testing temperatures in the usual way. The curves for both longitudinal and transverse specimens show an energy transition, although the maximum energy absorbed at testing temperatures above the transition is greater in the case of the longitudinal specimens. Fig 2 illustrates the changes in the macroscopic appearance of the fractures that are associated with the energy transitions shown in Fig 1. Macrographs of the fractured surfaces of the specimens have been identified with the fracture ratings at intervals on each fracture curve. The numerical fracture rating on the ordinate of Fig 2 indicates the percentage of the area of each fracture that was considered to be "brittle" on macroscopic observation. Such rating of the fracture type in impact tests is now customary in many laboratories. Hereafter the specimens will be identified by reference to Fig 2 as 90 pct "brittle," 80 pct "brittle," and so on, in accordance with this macroscopic evaluation of the appearance of the fractured surface. The discussion of the fractures is divided into three parts. The first two are concerned with the mode of fracture and its relation to general structural features. As the same metal-lographic features occur in both longi-

Jan 1, 1950

By J. T. Mackenzie

HENRY MARION HOWE, in whose memory we are gathered together, was one of the great thinkers who develop from time to time to whom is given the rare gift of synthesis. Analysis is given to few, but synthesis, the ability to show the relation of all parts to each other and thus to give a clear picture of the whole, is reserved for the very few. Analysis can be achieved by honesty, intelligence, and industry, but synthesis is only given to genius Professor Howe's crowning achievement is the picture of the whole iron-carbon series shown in Fig. I, which places steel, malleable, gray iron, mottled and chilled irons in their proper relation to each other and shows the essential unity of the series. Perhaps his best statement of the case is found on page go of the Metallography of Steel and Cast Iron in these words: "Each member of the gray cast-iron series consists of the metallic matrix approximately equivalent to that member of the steel-white-cast-iron series to which it corresponds in percentage of combined carbon with its continuity broken up-by masses of graphite . . . " Apparently he had taken considerable interest in this idea around the turn of the century, for he refers to a discussion at the Franklin Institute in 1900 in which he said: "Though many others had probably conceived this relation between the steels and cast irons, it was here enunciated for the first time, so far as I know. It was received with great incredulity." The concept was explained in some detail in a paper on 'The Constitution of Cast Iron" presented before the A.S.T.M. in 1902 when Professor Howe was retiring president of that young society. In the discussion Dr. Sauveur stated that he was "very well acquainted with Professor Howe's theory of the constitution of cast iron," and went on to say that while he "shared it to the fullest extent, some foundrymen . . . claim cast iron is a metal entirely different from steel . . . that steel and cast iron have very little in common, and that therefore the knowledge gained in the study of steel is of little or no value in the study of cast iron." Dr. Moldenke, in discussing the same paper, said he had been working on the same theory for 12 years but he laid no claim to publication. Discussing the difference in the micro- structure of the metallic matrix, Professor Howe pointed out that "such minor struc- tural differences are indeed to be expected, because of the difference in the conditions under which these constituents are generated. "One difference in these conditions is that the steel of most micrographs has been either forged or at least treated thermally in such a way as to give a new structure radically different from that which formed during the initial solidification, whereas the cast irons have not. Hence what we see in the steels is a transformation structure, but in the cast irons a solidification structure. By giving the cast

Jan 1, 1944

By R. J. Marcotte, C. T. Eddy, R. J. Smith

THE objectives of the investigation herein reported were to determine: (I) the S-curves for certain selected cast steels, (2) whether or not the published S-curves for wrought steels are satisfactory for use on cast steels of similar composition, and (3) to prepare hardenability curves of the selected cast steels. In order to make the final comparisons between cast and wrought steel more completely tangible, it was deemed advisable not only to determine S-curves for the steels submitted in the cast condition but also to roll some of the cast-steel test bars and determine comparison S-curves on such wrought material. This procedure eliminates the composition variable and makes it possible to reveal the differences resulting from plastic deformation of the cast structure in addition to providing the comparison with published data on wrought steels. CAST STEELS The cast steels selected for the preparation of S-curves, or time-temperature transformation curves, were similar to S.A.E. series 1030, 2330, 4130 and 4330. Of these the 1030 was supplied by The Crucible Steel Casting Co., Cleveland, Ohio, and the other three by The Sawbrook Steel Castings Co., Lockland, Ohio. The steels were furnished in the as-cast condition. The manufacturers supplied the chemical analyses and the properties that could be obtained in the heat-treated condition-all of which is summarized in Table I. [ ] PROCEDURE The metallographic and dilatometric procedures and equipment were in general standard. The specific technique employed was described in a report of the Steel

Jan 1, 1945