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By Samuel S. Wyer

Discussion of the paper of SAMUEL S. WYER, presented at the New York meeting February, 1916, and printed in Bulletin No. 110, February, 1916, pp. 263 to 279. DAVID T. DAY, Washington, D. C.-I would like to ask whether the court decisions quoted in the paper are general, or do they represent one side of the case; if so, are there any decisions that represent more than one side of the case? Are they of general application, or do they affect only one side? Also, what is the difference between a pump and a compressor from the standpoint of the natural-gas industry? I notice stress is laid on the word "pump" in. connection with some of the legal decisions, and then it is stated. that they must not pump or compress above 300 lb. The question is, is a pump a compressor and a compressor a pump, under certain conditions? SAMUEL S. WYER, Columbus, Ohio.-Answering the first question, I will say that the decisions cover both sides of the case very thoroughly, and are uniformly on the side that a company is justified in the use of gas compressors; in other words, there are no decisions holding it to be illegal to use gas compressors, with the exception noted in Indiana, Kansas, and Oklahoma where you cannot go below atmospheric pressure. In regard to the second question, I think the engineers and the gas operators themselves are responsible for the confusion. It is because the use of the term "pump" is almost universal, and so many people have obtained the idea that the primary function of a gas compressor is to pump air into the gas, in order to increase the consumers' gas bills. I appreciate that it is very hard to draw a clear line of demarcation. between a pump and a compressor. The distinction I have always made myself, and which I think is a logical one, is that you do not get the pumping action until you get below atmospheric pressure. As far as the compression end is concerned, there is only one State, namely, Indiana, that has any statutory limitation with regard to how high the pressure may be increased in order to put the gas into the transmission lines. The State law in Indiana limits the maximum pressure to 300 lb. per square inch.

Jan 5, 1916

By John S. Brown

As a part of a symposium on the relations of structure to ore deposition, in February 1938, the writer presented some tentative opinions derived from his experience with a number of important lead-zinc replacement deposits. These ideas were set forth, as a basis for discussion and a stimulus to further inquiry, in a mimeographed leaflet that read as follows Intimate acquaintance with a number of lead and zinc deposits in metamorphosed limestones seems to indicate the existence of certain common features from which can be established some general principles governing the localization of ore in this type of formation. It is suspected that these principles can be applied, with modifications, to mineralization in unmetamorphosed limestone. In metamorphosed formations, some observed rules are as follows: 1. Bands or masses of pure limestone are very resistant to replacement by ore solutions, and are likely either to contain no ore or to resist replacement until near the end of mineralization. The reason for this apparently is physical, not chemical, since microscopic data indicate that when ore is deposited by far the greater part of it substitutes for carbonate. The chief factor is believed to be a lack of porosity in massive limestone that has undergone flowage and recrystallization. 2. Masses of intensely siliceous or silicated rock are likewise unfavorable ore receptacles. This seems to be accounted for by two factors: (a) chemical unsuitability or resistance to replacement, and (b) physical resistance to small-scale brecciation, which might facilitate the opening of effective channelways for solutions. Some low-grade ore may occur, however, and also sporadic fracture fillings. 3. The optimum condition for ore reception appears to be found in bands or areas containing carbonate and silicates (or quartz) intimately mingled in something like equal proportions. In this situation movement is likely to result in mixed flowage and fracture, producing a fine-textured porosity that admits solutions freely and provides access to an abundance of replaceable carbonate. Cleavage cracks in some minerals such as diopside are believed to facilitate the penetration of solutions. 4. Certain minerals or assemblages are regarded as favorable impurities in a limestone and others as unfavorable. Original quartz, and subsequently developed diopside, and perhaps garnet, are typical favorable pre-ore gangue; in general rather equidimensional, brittle minerals. Tremolite, biotite, and probably wollastonite, are typical unfavorable pre-ore gangue; in general highly elongated and somewhat flexible minerals likely to develop under strong shearing stresses. 5. Tentative opinion is that the ratio of lime and magnesia in a limestone is of little or no importance.

Jan 1, 1940

By Sherwin F. Kelly

The need for geophysicists to adopt a uniform mode of expressing the electrical resistivity of geological formations has been stressed by Dr. A. S. Eve.1 The present paper is to emphasize the point he raised, to bring the weight of disinterested authority to bear on the matter, and to urge the adoption henceforth, save in exceptional cases, of a standard expression for resistivity; all in the hope that the needed reform will thus actually be brought about. The general definition of the resistivity of a material is the resistance in ohms between two opposite faces of a unit cube of that material. No account need be taken here of the cases in which the unit volume is not a cube, and the units of length and cross-section are different, encountered principally when dealing with metallic conductors such as wires. The idea of the resistance of a unit volume of earth or rock has found expression in geophysical literature in a number of forms and with a variety of units. Fortunately, the metric system has been adhered to in most cases, so ordinarily the meter or the centimeter, usually the latter, has been the measure chosen. The resistivity is then the resistance of a cube of the given rock, or soil, one centimeter on an edge. This is far from always being the same thing, however, as the resistance of a cubic centimeter. A long thin wire could contain a cubic centimeter and have a high resistance, whereas the same volume formed into a flat plate would have an entirely different, and quite low, resistance between faces. Consequently, it is not proper to express resistivity in ohms per cubic centimeter, inch, etc., as has been done occasionally by some writers. In an effort to emphasize the idea of cubic volume, some geophysicists, the writer among them, have used the phrase, ohms per centimeter cubed. This is a graphic way of picturing the measure, but is not in favor among highly qualified authorities. In this connection, an appeal was made to the U. S. Bureau of Standards for advice, and the Director, George K. Burgess, kindly replied in detail as to the practice adopted by his Bureau: 'I.., such expressions as 'ohms per centimeter cubed' or any similar expressions are objectionable, because they certainly carry the implication that the resistivity is found by dividing ohms resistance by the volume in cubic centimeters." Actually, of course, resistivity is found

Jan 1, 1932

By Sherwin Kelly

THE need for geophysicists to adopt a uniform mode of expressing the electrical resistivity of geological formations has been stressed by Dr. A. S. Eve.1 The present paper is to emphasize the point he raised, to bring the weight of disinterested authority to bear on the matter, and to urge the adoption henceforth, save in exceptional cases, of a standard expression for resistivity; all in the hope that the needed reform will thus actually be brought about. The general definition of the resistivity of a material is the resistance in ohms between two opposite faces of a unit cube of that, material. No account need be taken here of the cases in which the unit volume is not a cube, and the units of length and cross-section are different, encountered principally when dealing with metallic conductors such as wires. The idea of the resistance of a unit volume of earth or rock has found expres-sion in geophysical literature in a number of forms and with a variety of units. Fortunately, the metric system has been adhered to in most cases, so ordinarily the meter or the centimeter, usually the latter, has been the measure chosen. The resistivity is then the resistance of a cube of the given rock, or soil, one centimeter on, an edge. This is far from always being the same thing, however, as the resistance of a cubic centimeter. A long thin wire could contain a cubic centimeter and have a high resistance, whereas the same volume formed into a flat plate would have an entirely different, and quite low, resistance between faces. Con-sequently, it is not proper to express resistivity in ohms per cubic centi-meter, inch, etc., as has been done occasionally by .some writers. In an effort to emphasize the idea of cubic volume, some geophysicists, the writer among them, have used the phrase, ohms per centimeter cubed. This is a graphic way of picturing the measure, but is not in favor among highly qualified authorities. In this connection, an appeal was made to the U. S. Bureau of Standards for advice, and the Director, George K. Burgess, kindly replied in detail as to the practice adopted by his Bureau: ." . .' such expressions as ohms per centimeter cubed' or any similar expressions are objectionable, because they certainly carry the implica-tion that the resistivity is found by dividing ohms resistance by the volume in cubic centimeters." Actually, of course, resistivity is found

Jan 1, 1932

By Nicholas J. Grant, Robert F. Wilde

TAYLOR and Floyd's"" work in establishing phase diagrams based on the elements Ni-Cr-Ti-A1 has led to an understanding of the precipitation hardening mechanism in alloys based on these elements. Nordheim and Grant4 concluded that in simple alloys, and where the aluminum to titanium atomic ratio was such that less than three out of five aluminum atoms were replaced by titanium, the precipitate on aging is the face-centered-cubic Ni 3A 1 phase, called They further found that increasing amounts of hexagonal ? phase, Ni3Ti, precipitated from these alloys when the titanium content exceeded the solid solubility of both matrix and Ni3A1. For alloys of Ni-Cr-Ti-Al, in which the titanium and aluminum contents each ranged from 0 to 4 wt pct, the titanium-rich was superior for strengthening to either pure ?' or 7. It was also noted that the combined titanium plus aluminum content (atomic pct) was a direct measure of the high temperature strength and overaging temperatures for these alloys.4 The present investigation was undertaken to extend existing data on precipitation hardening in the more complex commercial alloys containing higher titanium plus aluminum, and with significant quantities of cobalt, molybdenum, and carbon. Experimental Procedure Reforging of As-Received Bar Stock—The alloys were received as ground, forged bar stock. Chemical analyses and the as-received bar diameters are shown in Table I along with the ASTM grain size after the various treatments. All stock except the Waspaloy was reforged to % in. diam to gain material and to facilitate machining of stress-rupture specimens. Forging was carried out at 2100°F, and discontinued when the bar temperature fell to 1800°F. Heat Treatments—For experixental simplicity it was desirable to heat treat all of the alloys at, the

Jan 1, 1958

By F. R. Hensel

Up to the present time few attempts have been made to produce hard nonmagnetic materials by heat treatment of austenitic steels. The usual result has been to cause them to pass into the martensitic stage, thus destroying to a great extent the typical austenitic properties, since this involves a transition of a portion of the iron from a face-centered to a body-centered type of atomic arrangement. High-strength nonmagnetic materials such as might be provided by properly hardening austenite are required in the electrical industry for different machine parts. In Europe nonmagnetic retainer rings for restraining the end-turns of the rotor windings in turbo-alternators have been developed as a special application of high-strength austenite. In testing1 a 28,000-kva. three-phase Siemens turbogenerator running at 3000 r.p.m. at full load current, the losses in the short-circuit test were 450 kw. for the magnetic ring and 286 kw. for the nonmagnetic, and the difference should be attributable to the magnetic ring. The differences in temperatures during the same test are given in Table 1 and these show the advantage of a nonmagnetic over a magnetic retainer ring. Hardening in this case was obtained by cold working, such as hammering, rolling or some means for stretching the steel while at a temperature near 500" C. One means for stretching2 is to rotate the forged or rolled ring in a centrifugal machine so as to develop within it stress higher than

Jan 1, 1931

By George W. Bain

The good work of the surveys supported by the different branches of the government needs little mention to geologists but is underappreciated by people at large. Geologists and engineers realize their usefulness and yet even from this group one hears occasionally an undercurrent of discontent about their work or the distribution of it. The very fact that discontent arises within and without this group and has drawn attention of legislative bodies of the country in the present time of stress means that a large number of people do not receive or do not realize that they receive benefit from these public works. This seems to be a clear indication that more than the relations between government surveys and the mining industry is involved and that if the mining industry is interested in continuation of the work of these surveys on the past scale they must consider the other survey divisions and their activity. Also, relations between government surveys and certain specialized types of mining have not been as close as they should be. I have been employed in almost the entire range of fields offered to geologists and have studied closely the feeling of people towards geological service. Recently it has been a pleasure to be closely associated with men who were as deeply interested in civic welfare and affairs of state as in the financial success of a large industry developing natural resources. Previously I had seen service in a national survey, a state survey, summer employment by a large mining company exploring new property and detailed geological work for a large corporation. Major responsibility as a college instructor has left me free to view each of these assignments in unprejudiced fashion and at the same time study the relation of government surveys to large natural resource industries, average industrial and construction work and service to nongeologists and laymen. Considerations Governing Geologic Public Service Three groups of people must be satisfied by the surveys if dissatisfaction is to be dispelled. First there is a large group of people who pay taxes to support the government activities and must receive some service

Jan 1, 1935

By R. Maddin, S. K. Tung

SUCCESS of the dislocation theory in formulating the transitional lattice theory proposed by Har-greaves and Hill in 1929' is well established for low angle grain boundaries. The theoretical work of Burgersa and Read and Shockley,3 together with the experimental observations of Aust and Chalmers4 and Parker and colleagues,6 leaves little doubt as to the structure of grain boundaries with differences of orientations up to between 15" and 20". Beyond these angles, the structure of the boundary is not so clear, and is still a matter for conjecture. There have been notable experiments devised from which the data could be used to calculate energetics for possible arrangements of atoms in forming a large angle boundary.6 Most of these experiments deal with diffusion through and along the grain boundary. The recent work of Rhines and Cochart7 and Rhines, Bond, and Kissel18 was concerned with the relative movement of grains in aluminum bicrystals under constant tensile loads with their boundaries aligned at 45 " to the tension axis. The gliding along the grain boundary was cyclic and began after an incubation period. The velocity of gliding increased with the sum of the angular difference, 8, between the operative slip direction in the conjugate crystals and the angular difference between the active slip planes as measured between their traces upon the grain boundary. The initial gliding rate varied with temperature, and the logarithm of the average gliding taken over a considerable period was a linear function of the reciprocal of the absolute temperature: the slope gave an activation energy of 11,000 ±1,000 cal per mole. Since the rate of grain boundary shear is sensitive to the misorientation of the grains themselves, as shown by several workers,7,8 it is suggested that further work of this type might be fruitful in adding information regarding the behavior of boundaries under stress. The techniques devised by Chalmers" added impetus to the facility for observing grain boundary behavior, in that they provided a simple means for producing bicrystals of predetermined orientation so that the angle of the boundary could be controlled,

Jan 1, 1958

By George W. Bain

The good work of the surveys supported by the different branches of the government needs little mention to geologists but is underappreciated by people at large. Geologists and engineers realize their usefulness and yet even from this group one hears occasionally an undercurrent of discontent about their work or the distribution of it. The very fact that discontent arises within and without this group and has drawn attention of legislative bodies of the country in the present time of stress means that a large number of people do not receive or do not realize that they receive benefit from these public works. This seems to be a clear indication that more than the relations between government surveys and the mining industry is involved and that if the mining industry is interested in continuation of the work of these surveys on the past scale they must consider the other survey divisions and their activity. Also, relations between government surveys and certain specialized types of mining have not been as close as they should be. I have been employed in almost the entire range of fields offered to geologists and have studied closely the feeling of people towards geological service. Recently it has been a pleasure to be closely associated with men who were as deeply interested in civic welfare and affairs of state as in the financial success of a large industry developing natural resources. Previously I had seen service in a national survey, a state survey, summer employment by a large mining company exploring new property and detailed geological work for a large corporation. Major responsibility as a college instructor has left me free to view each of these assignments in unprejudiced fashion and at the same time study the relation of government surveys to large natural resource industries, average industrial and construction work and service to nongeologists and laymen. Considerations Governing Geologic Public Service Three groups of people must be satisfied by the surveys if dissatisfaction is to be dispelled. First there is a large group of people who pay taxes to support the government activities and must receive some service

Jan 1, 1935

By Wm. C. Coffin

THE refractory linings of open-hearth steel furnaces above the bath line are subject to severe wear not only from the heat caused by the combustion of the fuel and the reactions of the bath, but also from the melting action of the gases when not controlled and directed, and from the scouring of the oxides, etc. with which the products of combustion are charged. The framework that encases or binds the furnace is made up primarily of an iron or steel pan in which the furnace proper is built, side and end buckstays, and tie-rods. The expansion and contraction are so great and variable that the bindings may be subjected to severe stresses unless the tie-rods are carefully adjusted in heating up the furnace, but they are most affected by direct heat and usually become deformed from that cause when the lining is worn thin and, sometimes, when sections of the lining fall in and expose some of the framework. A deformed framework displaces the skewback of the roof arch and tends to distort or crush the roof. Bent buckstays deform the front wall, causing the door frames to stand away from the lining so that the gases burn between the lining and the frames, destroying both of them. Frequently the frames are attached to the buckstays; then when the latter bend the frames usually break. Preventing the distortion of the framework and maintaining the economy of the refractories are real factors in the cost of steel making. Not only does the cost of general repairs and reconstruction add directly to the cost of steel produced, but the time lost in making repairs cuts clown the steel production and increases the overhead expense of both the furnace shop and its allied foundry or mills. Many years ago water-cooled equipment applied to iron blast furnaces made it possible to increase greatly not only the size and production of the furnaces but also the life of the lining. It also cut down the loss from frequent repairs. The open-hearth furnace is a much later invention, especially as a commercial factor; for though it dates from the Fred Siemens patent of 1856, much more progress was made in the Bes-

Jan 2, 1919

By D. D. Button, L. D. Jaffee

INTEREST in the use of graphite as a high-temperature engineering structural material has recently increased markedly. However, actual use of this material has been limited, in part because information about its high-temperature mechanical properties has been lacking. The information needed includes not only reliable values for the properties, but also how to control these properties. Malmstrom, Keen, and Greenl have reported on the tensile and creep properties of some graphites above 2700° F (1500°C). They observed measurable creep under tensile loading at 4000 OF (2200 °C) and higher, with elongations of about 7 pct at 4500°F. Their typical elongation-vs-time curve showed the normal three stages of creep found for many metals at elevated temperatures. The specimens used were heated by passing an electric current through them. This method of heating caused a significant difference between the surface and axis temperatures, and may have affected the results. More recent work by kattus, in which the specfinens were also heated by their own resistance, showed very little plastic deformation for either slow or fast tensile testing or for creep testing. Work at this Laboratory, already reported,3 showed that for temperatures above 4500 "F and under conditions of slow tensile loading some commercial graphites exhibited elongations up to 20 pct. The work reported here is the continuation of a study of the tensile creep behavior of some commercially available synthetic graphites at temperatures up to 5300°F, and is preliminary to a more systematic investigation of the variables governing the high-temperature mechanical properties of graphite. MATERIALS TESTED The tests were conducted on six blocks from four lots of synthetic graphite bearing four different commercial-grade designations. These blocks were selected because their tensile stress—strain properties had been determined in previous work.3 Table I pre- sents the available information, supplied by the producers, on the processing of these materials. Also included in this Table are the densities and the tensile strengths at room temperature and 4500°F determined by the authors. EXPERIMENTAL TECHNIQUE The furnace used to heat the specimens for testing is shown in Fig. 1. The heating element was a graphite tube, 3-in. OD by 2 1/2 in. ID by 24 in. length. A spiral was cut into the 6-in. center portion of this tube to provide a high-resistance sec-

Jan 1, 1961

By R. A. Esmonde

This paper describes the building and testing of a prototype welded aluminum truck body to a new design concept. The results of these tests are given along with an outline of further developments in the design and field application of aluminum bodies. The results of field service history are recorded with special reference to types of mining operations, service performance, wear, maintenance and economics of operation. Mention is made of current U.S. usage and predictions given as to future development of aluminum bodies in the mining industry. The use of aluminum for off-highway truck bodies in hauling rock for the mining and construction industries is by no means the novelty that it may seem. In 1932 an aluminum unit proved very satisfactory in service on the Hoover Dam project but at that time the only high strength aluminum alloys available were not weldable and with the high cost of construction, a sound economic case for an aluminum body could not be made. After World War I1 great advances in aluminum welding techniques, using the inert gas shield, combined with the development of high strength alloys with good welded properties and welding characteristics changed the whole picture. Welded aluminum bodies were rapidly developed and by 1958 attention was again focused on the use of aluminum for off-highway truck bodies. EARLY DEVELOPMENT WORK In 1959 Alcan, the Aluminum Co. of Canada, embarked on an extensive development program to prove the durability and economics of aluminum truck bodies for the mining and construction industries. The first step was to design a prototype aluminum body which took particular advantage of the fact that the modulus of aluminum is only one third that of steel. This means that within the elastic range, aluminum moves three times as much as steel which makes it more flexible and capable of absorbing much greater impact shocks. A body was built and mounted on a 22-ton truck and taken to the Jeffery Mine of Canadian Johns Manville Company at Asbestos, P.Q., Canada. Very little information was available as to the order of stresses that were set up in off-highway truck bodies and so it was therefore decided to carry out a test program to find out this information.

Jan 1, 1969

By Jerome Alexander

It is an outstanding fact of Nature that many of the practical properties of substances are dependent, not on their ultimate chemical composition, but on the kind and degree of aggregation of their constituent particles. Thus, a granite boulder is unmoved by wind or water, but if reduced to a fine dust it will be blown about by the wind and washed away by the rain. Carbon in one crystalline state of aggregation (diamond) is the hardest known substance, whereas in another crystalline state (graphite) it is so soft that it is used as a lubricant. Laying too much stress on the mere chemical analysis of substances is apt to obscure the fact that the nature of the aggregation of their particles is always a factor of importance, and sometimes the most important factor. Colloid chemistry deals with matter in a very fine state of subdivision; its sphere begins with particles just a little smaller than a wave length of light and extends down until they blend into molecular dimensions. With particles of this size, such phenomena as surface tension and adsorption, which depend on the development of free surface, become enormously magnified. Thus a cube of 1 cm. edge has a surface of only 6 sq. cm.; but if it is reduced to colloidal dimensions by being cut up into cubes each having an edge of 0.01 µ (0.00003 mm.), it will yield one million, million, million (1,000,000,000,000,000,O~) such cubes, having a combined area of 600 sq. m., or 21,274 sq. ft. The tiny force with which a drop of rain clings to the window pane becomes a factor to be reckoned with, if the surface involved is increased millions of times. From the colloid-chemical viewpoint, metals and alloys may be regarded as jellies or sponge-like structures,. the viscosity or stiffness of which at ordinary temperatures is exceedingly great; and like all jellies their properties are dependent on the composition and degree of dispersion of their constituent phases. These, in turn, depend on chemical composition, mutual solubility, speed of chilling, subsequent mechanical and heat treatment, etc. In fact, in preparing metals and alloys for practical use, we remove undesirable constituents (as in the conversion of pig iron into steel), add desirable constituents (as in

Jan 1, 1919

By C. F. Austin

lined-cavity shaped charge is an explosive mass with a cavity at one end and the detonator at the opposite end. The cavity is lined with a dense material, such as metal, glass, or a ceramic. Such an explosive device can be a useful drilling tool. Lined-cavity shaped charges are constructed to do just one thing — create a high-velocity jet of liner particles that can bore a hole in a target. The liner must be smooth and symmetrical, and high-velocity, high-brisance explosive must be used rather than ordinary commercial dynamites. Since the depth of target penetration is related to jet length, a standoff distance should be provided to hold the charge a short distance from the target. This allows the jet to lengthen prior to target impact. The best results are obtained when the jet is perpendicular to the target surface. Charges can be positioned for firing by taping them to a stake or simply laying them on a flat surface at the proper distance and angle with respect to the target. EFFECTS ON THE TARGET When a jet strikes a rock target, the jet and target particles at the jet-target interface move outward radially with respect to the jet axis to create a tremendous compressive load on the target material immediately below the target surface. The result is a shallow crater formed by spalling at the point of target entry. After cratering ceases, the steadily deepening hole continues to form as a result of the jet's imparting radial motion to the target particles at the jet-target interface. These radially moving particles collide with one another and with the hole walls, the net motion of the spent jet particles and target particles being back out of the hole in an axial direction (the backblast). The backblast keeps the penetration free of debris during penetration, al- though loose surface rock often falls into the hole after penetration ceases. The sudden stress relief after penetration ceases sometimes results in minor hole-wall rebound, which can partially fill the hole. The hole bottom will taper as the jet velocity decreases, until the jet velocity is too low to maintain the backblast. At this point the remaining jet and the following slug material are simply packed into the hole bottom. HAZARDS INHERENT IN USE Air blast from the highly brisant explosives used in shaped charges can damage nearby structures

Jan 1, 1961

By Leonard D. Jaffe, Donald C. Buffum

THE importance of temper brittleness in alloy steels has long been realized in Europe, In the United States recognition of its importance has developed within the last several years. Many brittle failures encountered in parts made of alloy steel are undoubtedly attributable, wholly or in part, to temper brittleness. These failures have occurred particularly at low temperatures, under shock loading, and in the presence of notches, restraints and combined stresses. It has been almost universally accepted that plain carbon steels are not susceptible to temper brittleness. As a result, considerable effort has been expended in attempts to discover the manner in which alloying elements introduce temper brittleness. It is desired to raise the possibility that plain carbon steels are not only susceptible to temper brittleness, but are much more susceptible than alloy steels, in the sense that they embrittle much more rapidly. It is suggested that previous views, (that plain carbon steels are not susceptible), are based upon an erroneous interpretation of the experimental results. INTERPRETATION OF PREVIOUS DATA For many years the standard criterion for susceptibility of a steel to temper brittleness consisted of comparison of the energy absorption, in a notched-bar impact test at room temperature, of specimens that had received two heat treatments.1 One specimen (or group of specimens) was quenched, tempered, and quenched from the temper. The other specimen (or group) differed only in having received an embrittlement treatment, which might consist of a slow cool from the tempering temperature, or of an isothermal hold in the range 450-550°C subsequent to quenching from the temper. If the energy absorption of the specimen receiving the embrittlement treatment was lower than that of the specimen not given this treatment, it was said that the steel was susceptible to temper brittleness, If the energy absorptions were the same, it was said that the steel was not susceptible. Several investigators2,3 found that plain carbon steels showed negligible difference in energy absorption in such tests (at least when their manganese content was below 0.60 pct), and concluded that plain carbon steels are not susceptible to temper brittleness. Recently the deficiencies of the criterion mentioned above have been pointed out.4-6 The criterion now generally used for susceptibility to temper brittleness retains the heat treatments used in the earlier scheme, but instead of the notched-bar impact tests being made only at room temperature, they are made over a range of temperatures, covering the transition from ductile to brittle fracture, If the transition temperature of the specimens receiving the embrittlement treatment is higher than those

Jan 1, 1948

By R. Bakish, W. D. Robertson

IN the course of a study of stress corrosion cracking of AuCu,, it was necessary to develop new electropolishing and metallographic etching methods. The techniques are generally useful for Cu-Au alloys, including the AuCu composition in which transformation markings are well delineated. For electropolishing, the only satisfactory electrolyte and procedure that has been found1 has the composition given in Table I. The solution must be vigorously stirred while polishing and the temperature maintained in the range of 55" to 62°C. The electrolyte is very unstable and can be used only for 10 to 15 min after which its color changes and a dark-brown precipitate forms. The polishing time is between 1 and 4 min depending on the initial surface preparation. The use of a hood is recommended to avoid the danger of cyanide gas which may form at one of the electrodes even though the solution is alkaline. The optimum current and voltage conditions for vertical anode and platinum cathode are on the plateau shown in Fig. 1, in which voltage is measured across the cell terminals. At voltages below the plateau, etching of grain boundaries occurs and under some conditions, which have not been clearly defined, octahedral etch figures are observed. For general purpose grain-size determination in polycrystalline alloys, a 3 pct solution of iodine in methyl alcohol is used with excellent results. However, when it is necessary to reveal small orientation differences or concentration gradients in an alloy, the iodine etch is not satisfactory. For this purpose, a highly satisfactory etching procedure was developed during this investigation. It involves the use of the vapor given off by freshly prepared aqua regia. The solution employed is 3HC1 to lHNO, which decomposes in accordance with the reaction HNO, + 3HC1 = NOCl + 2H,O + Cl,. The polished specimen surface is held about 1 to 2 cm above an aqua regia solution for 2 to 10 sec depending on the intensity of the contrast required and the surface is not subsequently washed. The results obtained with a coarse grained cast structure are shown in Fig. 2. Subgrain boundaries in a single crystal and concentration gradients within the boundaries are developed by the same treatment with the results shown in Fig. 3. Obviously, any conclusions regarding structure-dependent properties will be modified by the pronounced heterogeneity, which is not clearly evident when more conventional methods are used. Interesting structural details are also revealed by treatment for 4 hr at 850°C in unpurified tank argon. Fig. 4 shows a pattern characteristic of orientation-dependent oxidation.

Jan 1, 1956

By Francis H. Crockard

DURING the past five years we have probably witnessed greater technological advances than in any similar period. Industry and science have steadily marched ahead. The makers of iron and steel products have watched with great interest the development of stream-lined trains, faster and safer airplanes, the entirely new science of air-conditioning and the widespread use of stainless steels. Since 1930, we have witnessed the erection of the world's largest suspension bridge, the largest and fastest ocean liner and the spectacular Boulder Dam, while even greater things are planned in these particular fields. Other industries, too, have been moving ahead rapidly. This advance in a few years has been caused primarily by the fierce competition of the depression. Now, more than ever, is the emphasis placed upon quality and service. Makers of southern merchant pig iron have been no exception and have been confronted with increasingly strict chemical specifications and with much greater stress on physical characteristics than ever before. For example, sulfur in the iron must be held very low, competition demanding that it be in the 0.020's and low 0.030's; silicon content must be held within a very narrow range, and definite requirements of phosphorus and manganese are an essential part of the specifications. Physical characteristics are becoming of increasingly greater importance. The introduction of triple-skimmed, slow-cooled iron several years ago was the first step in this direction. Now there are a few customers who buy iron by chemical analysis and physical appearance, having found that the analysis alone is an insufficient guide to their requirements.

Jan 1, 1935

By Francis Crockard

DURING the past five years we have probably witnessed greater technological advances than in any similar period. Industry and science have steadily marched ahead. The makers of iron and steel products have watched with great interest the development of stream-lined trains, faster and safer airplanes, the entirely new science of air-conditioning and the widespread use of stainless steels. Since 1930, we have witnessed the erection of the world's largest suspension bridge, the largest and fastest ocean liner and the spectacular Boulder Dam, while even greater things are planned in these particular fields. Other indus-tries, too, have been moving ahead rapidly. This advance in a few years has been caused primarily by the fierce competition of the depression. Now, more than ever, is the emphasis placed upon quality and service. Makers of southern merchant pig iron have been no exception and have been confronted with increasingly strict chemical specifications and with much greater stress on physical characteristics than ever before. For example, sulfur in the iron must be held very low, competition demanding that it be in the 0.020's and low 0.030's; silicon content must be held within a very narrow range, and definite requirements of phos-phorus and manganese are an essential part of the specifications. Physical characteristics are becoming of increasingly greater impor-tance. The introduction of triple-skimmed, slow-cooled iron several years ago was the first step in this direction. Now there are a few customers who buy iron by chemical analysis and physical appear-ance, having found that the analysis alone is an insufficient guide to their requirements.

Jan 1, 1936

By E. R. Borcherdt

RECENT years have seen great progress in drilling practices. The partial change from heavy drills and stopers to lightweight airleg machines has had great impact on stoping and drifting methods. The change was sparked, of course, when the Germans applied tungsten carbide to drill bits during World War II. This invention made it possible to drill nearly cylindrical blastholes, with a very mini- mum of drill steel changes, so that small fast-cutting bits* could be used without sacrifice of powder-loading density at the bottom of the hole. This is one of the few instances of increased efficiency through reduction in size. Usually the opposite is true. Application of these lightweight drills and small bits has lessened the vibratory stresses set up in the drill steel rod, and rod breakage has been greatly reduced. During the past several years phenomenal reduction in drill steel breakage has resulted from the use of carburized rods. These rods are now supplied by several manufacturers, with carburization of both the exterior and interior surfaces of the hollow drill steel. The rods are heat-treated over their entire length after the completion of bit connections, collars, or lugs (in the case of 7/8 Hex and round steel). This eliminates breakage from the usual metallurgical notch existing in conventional rods-there are instances of more than 2000 ft of drilling in hard ground before breakage. Steel rod failure results from fatigue checks, at right angles to the rod axis, progressing to a point where parting or breaking of the rod occurs. There are many of these checks in a used rod. Only the most advanced check causes the break, but with a small additional amount of drilling another check advances to the breakage point, and most of the value of reconditioning is lost. Since the development of carburized rods, the practice of discarding drill rods after the first break may be economically justified.

Jan 4, 1957

By W. H. Newhouse

DURING the past few years the writer has been impressed by the close relation of many epigenetic orebodies with anticlinal structures. In the literature on ore deposits there is occasional mention that an oreshoot or district is on an anticline, but in most of the descriptions no weight or significance is attached to the relation, and usually the fact is concealed in a mass of structural detail. A few writers have stressed the relationship in a few districts or on a certain type of deposit. Church, Spurr, Butler, Stahl and Schuette have called attention to certain features, but the general extent of such a correlation has not been made known in any publication that the author has seen. A recent article1 on the localization of ore deposits, by well-known geologists, does not consider this common association. The author has seen in the field a number of the structural features described, and in addition has made a fairly complete review of the literature. This paper presents enough of the examples found to show the frequency of the relation to anticlines, and since only a few deposits on synclines are known, all of these of any importance of which the writer knows are mentioned. With certain qualifications which are discussed later, epigenetic ore deposits of replacement or vein type are mostly found where local upwarps of the earth's crust have taken place. Where formations antedating the ore deposits are present in the proper attitude to demonstrate vertical warping (i. e., more or less horizontal beds) the structural feature on which a mineral district, or mineralized area is located is almost always anticlinal, or domelike in nature. Some or even most of the ore deposits in a given district may be on the flanks of the upwarp, but few major districts are located definitely on downwarped areas. Synclinal basins within certain limits of size appear to be unfavorable to the type of fracturing that admits ore-bearing solutions.

Jan 1, 1931