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By D. A. Woodford

A number of observations have now been reported where the steady-state creep rate is apparently linearly dependent on the applied stress at high temperature and low stresses. This results in a creep rate greater than that predicted by extrapolation of high-stress data and has obvious practical implications. However, some of these observations are open to question. For example, the analysis by Harris and Partridge17 of the data of Greenfield et a1.18 was dependent on strain rates which, according to the original authors, were too low to be measured. Dr. Bernstein appears to have demonstrated a linear stress dependence at low stresses in two zirconium alloys. There are, however, a number of discrepancies in his treatment of the data and the subsequent theoretical analysis which require clarification. 1) It is incorrectly stated that steady-state conditions are revealed by a slope of unity on a plot of log i vs log (time). This objection is trivial if the author meant to say a slope of zero, although it is unclear how subsequent extrapolation was made to determine the steady-state creep rates at low stresses for the zircaloy-2. If the plot used was actually log c vs log (time), it is unlikely that a slope of unity would represent a constant creep rate. A plot of log (c - co) vs log (time), where c0 is the extrapolated intercept sf the steady-state creep rate on the strain axis, would have a slope of unity during steady-state creep. However, eo cannot be determined unless is is already known. 2) The author chooses to interpret his results based on the equation: where A, and B, are structure-sensitive parameters, Ql and Q, are the activation energies for the particular creep process, and n describes the sensitivity of the creep rate on stress. The first term represents a slip creep process and the second a diffusion creep process. However, it is stated later that "two distinct processes acting in parallel are involved". Eq. [I] surely represents two processes in series since each reacts to the total applied stress and t, is the sum of the individual creep rates. If the processes are acting in parallel, then the effective stress in each would be less than the applied stress. The component stresses would be given by sl + s2 = a but it is not clear how the magnitude of either, or the corresponding stress exponent, could be determined.

Jan 1, 1969

By William A. West

One manifestation of anelastic properties in solids is the mechanical elastic aftereffect, which may be described briefly as follows: If a stress is applied to a solid body, a deformation or strain is produced. On removal of the stress, this deformation disappears, at least in part. As a first approximation, this appearance or disappearance of deformation usually has been considered instantaneous. Actually, however, for a very wide variety of substances, on application of stress the instantaneous deformation is followed by a further slow yielding, which continues, although at a rapidly diminishing rate, for as long as the stress is applied. Similarly, on removal of the stress, the instantaneous recovery from deformation is followed by a further slow recovery, which continues, although at a rapidly diminishing rate, often for a long time. This latter phenomenon has been called the "elastic after-effect." Experiments upon the elastic after-effect in metals, when properly designed and when properly interpreted, are capable of giving quite precise information regarding the relation between stress and strain in the various constituent parts of the metal. For example, if certain parts of the metal, such as grain boundaries or slip bands, behave in a viscous manner—that is, if therein—the relaxation spectrum will contain lines or bands associated with the relaxation of shear stress within these parts. No attempts have heretofore been made to utilize elastic after-effects for obtaining such detailed information. The purpose of the present paper is to explore the possibilities of properly designed and interpreted experiments on the elastic aftereffect in metals. Since new procedures and principles are employed in this study, an attempt has been made to record each step taken. Elastic after-effect observations are susceptible of simple interpretation only when the stress level employed is so low that all effects are linear with the stress. Just how low the stress level must be can he determined only by experiment. An advnntage, other than simple interpretation, is associated with low stress levels. When all effects are linear, derived quantities, such as the relaxation spectrum, are independent of the stress distribution. It is, furthermore, possible to employ the type of deformation that is most convenient from the experimental standpoint; for example torsion. It appears that in experiments involving both loading and unloading the following would be observed: I. Instantaneous deformation, recoverable instantaneously in whole, or in part. 2. Delayed deformation, recoverable slowly in whole, in part, or not at all. 3. Permanent deformation, the difference between total deformation and total recovery. In the work here described, unloading experiments only were made. Wires were

Jan 1, 1947

By William A. West

One manifestation of anelastic properties in solids is the mechanical elastic aftereffect, which may be described briefly as follows: If a stress is applied to a solid body, a deformation or strain is produced. On removal of the stress, this deformation disappears, at least in part. As a first approximation, this appearance or disappearance of deformation usually has been considered instantaneous. Actually, however, for a very wide variety of substances, on application of stress the instantaneous deformation is followed by a further slow yielding, which continues, although at a rapidly diminishing rate, for as long as the stress is applied. Similarly, on removal of the stress, the instantaneous recovery from deformation is followed by a further slow recovery, which continues, although at a rapidly diminishing rate, often for a long time. This latter phenomenon has been called the "elastic after-effect." Experiments upon the elastic after-effect in metals, when properly designed and when properly interpreted, are capable of giving quite precise information regarding the relation between stress and strain in the various constituent parts of the metal. For example, if certain parts of the metal, such as grain boundaries or slip bands, behave in a viscous manner—that is, if therein—the relaxation spectrum will contain lines or bands associated with the relaxation of shear stress within these parts. No attempts have heretofore been made to utilize elastic after-effects for obtaining such detailed information. The purpose of the present paper is to explore the possibilities of properly designed and interpreted experiments on the elastic aftereffect in metals. Since new procedures and principles are employed in this study, an attempt has been made to record each step taken. Elastic after-effect observations are susceptible of simple interpretation only when the stress level employed is so low that all effects are linear with the stress. Just how low the stress level must be can he determined only by experiment. An advnntage, other than simple interpretation, is associated with low stress levels. When all effects are linear, derived quantities, such as the relaxation spectrum, are independent of the stress distribution. It is, furthermore, possible to employ the type of deformation that is most convenient from the experimental standpoint; for example torsion. It appears that in experiments involving both loading and unloading the following would be observed: I. Instantaneous deformation, recoverable instantaneously in whole, or in part. 2. Delayed deformation, recoverable slowly in whole, in part, or not at all. 3. Permanent deformation, the difference between total deformation and total recovery. In the work here described, unloading experiments only were made. Wires were

Jan 1, 1947

By AIME AIME

IN times of stress nations pick strong men to lead them. Similarly the Coal Division selected forceful Larry A. Shipman, fuel engineer for the Southern Coal and Coke Co., Knoxville, Tenn.. to lead it through the year 1945. He was born in Indianapolis May 13, 1891. Following graduation from a technical high school in that city Larry began his fuel career approximately 35 years ago attached to one end of a scoop shovel, firing locomotives for the Pennsylvania Railroad. At the end of two years he transferred to the New York Central Lines and held these jobs successively: locomotive fireman, engineer, fireman instructor, supervisor of instructors, and fuel engineer.

Jan 1, 1945

By W. W. Anderson

A formula for quantitative efficiency is proposed, in which the efficiency value is a function of the improperly distributed material at the, gravity of separation effected by the cleaning equipment. The misplaced material is expressed as a percentage of the total material discharged from the equipment. Numerous examples are given, demonstrating application of the formula to various types of separation, including multiple-product separations.

Jan 1, 1950

By George Newton

When Mr. Bailey asked us to present a paper describing our new BOF shop, he requested that we avoid a presentation heavily laden with detail and statistics. Not only have we attempted to do this, but also we have prepared a number of colour slides which, hopefully, will provide you with a graphic conception of the facility. The installation of the BOF facility at the Steel Co. of Canada's Hilton Works was delayed many years because of the remarkable production growth of the oxygen open hearth furnaces in No. 3 shop. However, in mid-1960 it became strongly evident that not only would increased ingot capacity be required, but also that N0.2 shop - with vintage non-oxygen open hearth furnaces - would have to clean its stacks in the near future, or be closed down. A decision to embark on the BOF facility was made in 1967 after an extended period of in-depth planning and assessment of industry trends.

Jan 1, 1972

By D. W. Fuerstenau, D. A. Sullevan

In the experimental work for this comparison of wet and dry grinding, it was found that the size distributions for wet grinding operations are characterized by a constant value of the distribution modulus, (a; whereas, for dry grinding the distribution modulus decreases slightly with increased size reduction. Wet grindability seems independent of the weight of material in the mill while dry grindability depends on weight. Experimental data and eqmtions for each process are presented for noncleavable isotropic material, for cleavable or material in which there is some form of internal stress, and for energy consumption. The equation ED/EW=BK-? (where ED and Ew are, respectively, energy for wet and dry grinding, k is the size modulus, and B and ? are constants) was found to give the ratio of energy. Dry grinding is generally considered to require more energy than wet grinding. Taggart' states that power consumption in wet grinding ranges from 60 to 90 pct of that required for dry grinding. Bond' states that dry grinding requires one third more power than wet grinding. It is interesting that Rose and Sullivan' note this same difference in power required for wet and dry grinding, but they state that on purely mechanical grounds it is difficult to see any great difference in fundamental principles between wet and dry milling, since dry milling may be regarded as wet milling with a fluid of low viscosity (i.e., air vs water). Yet it must be the viscosity of the fluid that is responsible for the differences between wet and dry grinding. Probably the most comprehensive investigation comparing wet and dry grinding has been that made by Coghill and Devaney. They compared the grind-ability of both chert and dolomite in a 19x36-in. batch ball mill under both wet and dry conditions. In these tests the weight of ore in the mill was varied from 35 to 200 lb and each grinding test was carried out for such period of time that the amount of -200-mesh material in the product was essentially the same for each test with a given material. Cog-hill and DeVaney's data for the grindability of dolomite, which are reproduced in Fig. 1, show that a comparison between wet and dry grinding is com- plex. The comminution of a material by a wet grinding method is characterized by a constant grindability over a wide range of mill loadings. Since grindability is the weight of material comminuted per unit of energy expended, it is equivalent to (w)/ (p)(t), where W is the weight of material being ground, P is the power, and t is the grinding time. In the case of wet grinding, the grindability of dolomite in the Coghill and DeVaney experiments was 0.546 * 0.009 ton per hp-hr when the load of dolomite in the mill ranged from 50 to 200 lb. On the other hand, for dry grinding no such simple relationship was found to exist between power, time, and weight of material in the mill. Dry grinding efficiency appears to depend greatly upon the amount of material within the mill. When the mill contained

Jan 1, 1961

By Edward Halse

THE occasional occurrence in metalliferous veins of rounded fragments of rock, matrix or ore, lying loose, embedded in clay, or enclosed in some kind of cement, may be attributed to four causes:¬ I. They have been washed in from the surface, or from an upper portion of the vein. II. They are of concretionary origin. III. They have been produced by movements in the country-rock or in the walls of the vein. IV. They have been found in situ, by the upward, downward or lateral flow of water in the vein itself. In this paper the word " conglomerate " is confined to a rock composed of rounded fragments or pebbles cemented together, as distinguished from a " breccia," in which the rock-fragments are angular. I. BOULDERS AND PEBBLES WHICH HAVE BEEN WASHED IN FROM THE SURFACE, OR FROM AN UPPER PORTION OF THE VEIN. In this type it is presupposed that the vein at onetime com¬municated by a fissure or open space with the surface, or with the upper portion from whence the fragments have been washed. One well-authenticated occurrence was described long ago by Fournet. Owing, no doubt, to later dislocations in the lode, pebbles from an old alluvium and sands containing titaniferous iron, as well as fragments of wood, were found in a vein at Huelgoët, in France. "Toutes les parties tendres du filon de Pranal ou ces pédnomènes sont les plus prononcés ont été excavés jusqu'a d'assez grandee profondeurs par l'impétuosité des torrents, qui ont deposé la matière alluviale."1

Jul 1, 1905

By M. A. Hunter

CHAIRMAN M. A. HUNTER. UP to this time our stress-corrosion sessions have been concerned with stress-corrosion cracking in brass. In the succeeding sessions a variety of other products which are susceptible to stress-corrosion cracking are to be considered and this afternoon's session is to be devoted to stress-corrosion cracking in light metals. The problems you have had to deal with up to now in brass have been very simple ones. From this time on the complexities become greater. You have already learned in the preceding sessions, that copper is not susceptible to stress-corrosion cracking and when you begin to alloy it with 3 per cent or larger proportions of zinc, then stress- corrosion cracking ensues. You apparently have few complications in the copper alloys you make. There is apparently no precipitation on the grain boundaries in the brass, and no precipitation within the metal itself. So, on the whole, the problem is a simple one. Yet it has been with the brass people for a very long time and it is apparently not yet settled from the fact

Jan 1, 1945

By Louis Raymond, John E. Dorn

The object of this investigation was to analyze the recovery that arises when the stress on a specimen undertaking creep is reduced. For this purpose annealed specimens of high-purity aluminum were precrept under a stress of 1000 bsi to a strain of 0.08 following which the stress was reduced for various periods of time to 10, 250, 500, or 700 psi. When the original stress was reapplied the subsequent creep curve lay above that for the unre-covered state and below that for the original annealed state. Analyses on the kinetics of this recovery as a function of the temperature gave a stress-sensitive activation energy that decreased as the reduced stress was increased from a value of 64,000 cal per mole at 10 psi to 37,000 cal per mole at 750 psi. Recovery was also detected and measured during creep under the reduced stress. Following a short initial period, the creep rate under the reduced stress increased monotonically until it reached the secondary-creep rate for the reduced stress. The temperature dependence of this phenomenon was also shown to be correlatable in terms of the previously deduced activation energy for recovery. The activation energies for creep of most pure metals at high temperatures have been shown to agree well with those for self-diffusion.'j2 Since the true secondary stage of creep is usually due to the steady-state balance between the rate of strain hardening and the rate of recovery, it is generally thought that the activation energy for recovery of the creep-induced substructure equals that for creep itself. A shoft time ago, however, Ludemann, Shepard, and Dorn~ found that the activation energy for recovery of the creep-induced substructure in high-purity aluminum under zero stress was almost twice that for self-diffusion, namely about 65,000 cal per mole; obviously recovery under reduced stresses differs in some significant way from the recovery that accompanies the secondary stage of creep. The major purpose of this investigation is to study the effect of stress on the re- covery of the creep-induced substructure in order to provide a better understanding of the recovery mechanism itself. EXPERIMENTAL TECHNIQUE High purity aluminum, containing 0.004 pct Cu, 0.002 pct Fe, and 0.001 pct Si, used in this investigation, was in the form of 0.100-in.-thick sheet which has been cold-rolled to the H-18 temper. Creep specimens were milled from the sheet with their tensile axes in the rolling direction. All specimens were then heated at 686°K for 1 hr followed by air cooling in order to produce an annealed structure which exhibited a uniform equiaxed grain size of about 4 grains per mm. Tests were run in creep machines fitted with Andrade-Chalmers type of lever arms so contoured as to maintain the stress constant to within 0.05 pct of the reported values. Constant temperatures to *O.l°K were obtained by complete immersion of each specimen in a temperature-controlled and agitated bath of molten KN02-KNOs mixture. Where changes in temperature were involved, the change was effected in less than 2 min by manually replacing one bath by another controlled at the second temperature. Displacements over the gage section were sensed by linear differential transformers, the output of which was autographically recorded. The calculated strain measurements were sensitive to 5x EXPERIMENTAL PROCEDURE The following analyses are based on extensions of the previously announced effect of the temperature on the creep strain,2 namely for a = constant, where e = the total true tensile creep strain for a given applied true tensile stress, t = the duration of the test, R = the gas constant, T = the absolute temperature, Q, = the activation energy per mole for creep which is independent of the stress, / = a function of 8, = and of the stress, and a = the stress. The validity of this correlation for high-purity aluminum is demonstrated in Fig. 1 for temperatures in the near vicinity of 600°K; the activation energy for creep, Q,, which is approximately that for self-diffusion, is insensitive to the applied stress

Jan 1, 1964

By Jacques B. Wertz

Detailed structural studies in southeast Arizona have successively revealed (1) the local attitudes of individual fractures (with lateral and/or vertical displacements), (2) the patterns exhibited by groups of fractures, and (3) the trends and directions shown by fracture groups or zones on a regional scale. The results of the studies have been twofold: First, domes were locally determined from these fracture arrangements, even where other criteria failed; and, second, fundamental breaks brought out the breadth of the Texas lineament in southeast Arizona as well as major northwest- and northeast-trending fracture zones. Coincidence of one or several domes with the major intersections of fundamental breaks can be centers of important mineralization, as in the instances of Bisbee, Ajo and Morenci. THE OVER-ALL STRUCTURE OF ARIZONA A northwest-southeast trending anticlinorium has been suggested as the structural setting of Arizona. Starting in Triassic and culminating in late Cretaceous times, this deformation resulted from stresses of considerable magnitude with varying ratios of com pres sional and uplifting forces. However, the series of parallel flexures could just as well have been caused by isostatic movements involving dilation under tension with only incidental compression, as later emphasized by dike filling and block faulting (Fig. 1). The anticlinorial deformation, which is also suggested by the fact that the Pre-cambrian rocks to the southwest are all concealed by sediments, could be somewhat reminiscent of the conditions that affected the classical swarm of parallel dikes of wager.' ANALYSlS OF DATA As a first step in this analysis, all structural information obtained on such features as fractures and their relative displacements, faults, dikes, anticlines, synclines, and Precambrian and Laramide-Tertiary intrusives were plotted on maps along with structural trends inferred from aerial photographic mosaics. Next, the faults in southwest Arizona were classified according to time of occurrence and relative importance. The fault assemblages were then examined as to geometric or spatial arrangement and correlated with the occurrences of domes and existing Finally, the conjunction of fracture intersections and domes was analyzed and compared with locations of known ore deposits. Differentiation of Faults According to Time and Relative Importance: The faults encountered were grouped as follows: (1) Basin and Range faults, latest in time; (2) secondary faults; (3) primary faults; and (4) lineaments, earliest in time by inference. BASIN AND RANGE FAULTS- Generally concealed by alluvium, the Basin and Range faults are normal

Jan 1, 1969

By Dudley L. Davis, E. C. Peterson

INTRODUCTION THE Darwin District is 30 miles east of Olancha which is 220 miles north from Los Angeles via U. S. Highway No. 6. The ore deposits occur in the Darwin hills that have been elevated above the Darwin Plateau by typical basin and range-type faults. Some of these faults have been active quite recently as shown by the displacement of Quaternary (?) basalt flows and the rejuvenation of erosion in Darwin wash. The ore bodies occur as fissure fillings and replacement of favorable beddings in a thick series of Paleozoic limestones, dolomites, shales and quartzites. Rich oxidized lead-silver ores were discovered in the early seventies. By 1875, Darwin had a population of about 5000, and by 1880 several small mills and smelters had been built. Early exhaustion of surface ores, the isolated location of the district, and fluctuation of metal prices caused intermittent operations until World War II. The district production is estimated at about $3,000,000 prior to 1900 and perhaps $4,000,000 between 1900 and 1945 when Anaconda purchased the major producing mines. For the past two years, daily production has averaged 75 tons of direct shipping and 150 tons of milling-grade ore. At present, 300 tons of mixed oxide and sulphide ore are treated by flotation, the oxidized lead minerals being activated by addition of sodium sulphide after galena and sphalerite have been recovered from the circuit. Extraction averages 85 pct of the lead, 80 pct of the silver, and about 33 pct of the zinc in a bulk concentrate. The mill is designed so that minor changes permit selective flotation of pyritic lead-zinc ores encountered at depth. GENERAL GEOLOGY The oldest rocks in the Darwin hills are a series of Paleozoic limestones, dolomites, shales and quartzites probably Pennsylvanian in age. These rocks have been intruded on the west by the Coso granite batholith and on the east by a granodiorite stock. Numerous sills and dikes grading from orthoclase granite to gabbro are exposed in the underground workings. The sedimentary rocks have been considerably folded and faulted, the most prominent structure being a northwest pitching anticlinal fold, the crest of which lies just west of the ridge line of the Darwin hills. The east limb of this fold has been intruded by the granodiorite stock and east of the stock the sediments show several closely spaced anticlines and synclines. The minor flexures on the west flank of the major fold are structurally important in localizing the ore in the Defiance and Essex mines of the Darwin group. There are three principal systems of faulting and fissuring, most of which are post-intrusive and premineral in age, with minor amounts of postmineral movement. The Darwin tear fault is the largest, most persistent fault in the district. It strikes N 60 to 95°W, dips steeply south and is traceable for about 1o miles. It is a normal

Jan 1, 1947

By Dudley L. Davis, E. C. Peterson

Introduction The Darwin District is 30 miles east of Olancha which is 220 miles north from Los z4ngeles via U. S. Highway No. 6. The ore deposits occur in the Darwin hills that have been elevated above the Darwin plateau by typical basin and range-type faults. Some of these faults have been active quite recently as shown by the displacemerit of Quaternary (?) basalt flows and the rejuvenation of erosion in Darwin wash. The ore bodies occur as fissure fillings and replacement of favorable beddings in a thick series of Paleozoic limestones, dolomites, shales and quartzites. Rich oxidized lead-silver ores were dis'Overed in the early seventies. BY 1875, Darwin had a population Of about 5000, and by 1880 several small mills and smelters had been built. Early exhaustion of surface ores, the isolated location of the district, and fluctuation Of metal prices caused intermittent operations until World War 11. The district production is estimated at about $3,000,000 prior to 1900 and perhaps $4,000,000 between 1900 and 1945 when Anaconda purchased the major producing mines. 'or the Past two Years, daily production has averaged 75 tons of direct shipping and 150 tons of milling-grade ore. At present, 300 tons of mixed oxide and sulphide ore are treated by flotation, the oxidized lead minerals being activated by addition of sodium sulphide after galena and sphalerite have been recovered from the circuit. Extraction averages 85 pct of the lead, 80 pct of the silver, and about 33 Pct Of the zinc in a bulk concentrate. The mill is designed so that minor changes permit selective flotation of pyritic lead-zinc ores encountered at depth. General Geology The oldest rocks in the Darwin hills are a series of Paleozoic limestones, dolomites, shales and quartzites probably pennsyl-vanian in age. These rocks have been intruded on the Rest by the Coso granite batholith and on the east by a granodiorite stock. Numerous sills and dikes grading from orthoclase granite to gabbro are exposed in the underground workings. The sedimentary rocks have been considerably folded and faulted, the most prominent structure being a northwest pitching anticlinal fold, the crest of which lies just west of the ridge line of the Darwin hills, The east limb of this fold has been intruded by the granodiorite stock and east of the stock the sediments show several closely spaced anticlines and synclines. The minor flexures on the west flank of the major fold are structurally important in localizing the ore in the Defiance and Essex mines of the Darwin group. There are three principal systems of faulting and fissuring, most of which are post-intrusive and premineral in age, with minor amounts of postmineral movement. The Darwin tear fault is the largest, most persistent fault in the district. It strikes N 60 to 75°W, dips steeply south and is traceable for about 10 miles. It is a normal

Jan 1, 1949

By Arthur Lubinski, K. A. Blenkarn

It is explained why the bottom portion of freely suspended tubing in a pumping well buckles and straightens in succession during the pumping cycle. Field evidence of resulting rod-on-tubing wear, excessive polished rod load, and excessive horsepower are given. The possibility that buckling hastens pump wear is strongly suggested. Means for either prevention of buckling or for mini-mizing its effects are explained, their relative merits compared, and field results of their use given. These means are: tension anchors, tail pipe, sucker rod guides, and corrosion inhibitors. Charts and formulas for best use of tension anchors, tail pipe, and guides are given. Use of tension anchors, or compression anchors with a heavy tail pipe, prevents both buckling and breathing, thus improving volumetric efficiency. Without tail pipe, buckling above compression anchors precludes such improvement. INTRODUCTION It is well known that a column must be subjected to some compression in order to buckle; and also that a structural member does not buckle if subjected to a tension. When consideration is given to a tubular column, the question may be asked, "How is the buckling phenomenon affected by inside or outside pressure?' At first, it seemingly should not be affected. However, this is not so. In order to arrive at a correct deduction one should first understand the basic reasons for buckling of a column under loading*. Then he should add to the effect of that loading the effect of pressure. Following this procedure, one may discover quite unexpected phenomena. In some cases, when subjected to more pressure inside than outside, a pipe may buckle under tension. In other cases, a pipe may remain straight, although subjected to a very large compression. In 1950 and 1951 it was explained why the bottom portion of a string of pipe freely suspended in a well does not buckle even when subjected to a large compression due to buoy- ancy.2,3 It was shown that the com-monly used concept of a neutral point, as being a point in the string with neither compression nor tension, is inadequate, and a more relevant definition of the neutral point was introduced. The findings were also generalized to cases of different pressures inside and outside a pipe.3a Later, in a further generalization, allowance was made for variations of stress and pressure with depth.' The findings were applied to the new technique of hydrostatic high pressure testing of lengths of pipe in the mill.5 In 1952 it was observed that previous theoretical findings apply to tubing in pumping wells. The lower part of freely suspended tubing buckles during the upstroke portion of the pumping cycle. Later, it was ascertained that this phenomenon is responsible for wear and malfunctioning of the equipment. Various remedial measures were devised and successful field trials conducted. Only brief mentions on the subject have been published.6,7 In this paper, the phenomenon of tubing buckling is explained, field

Jan 1, 1958

By G. G. Oberfell

THOUGH the largest volume use of natural gas has been, is. and in all probability will continue to be as a fuel for domestic and industrial heating, it has various market outlets, both as a fuel and as a raw material for the chemical industry. Natural gas is a preferred type of fuel where ease of control, fuel uniformity, and freedom from ash are of primary importance. Other industrially important uses are as a source of carbon black and as a fuel in various low-cost heating operations. Many other uses are of varying importance and new potential uses are continually being uncovered, some being of economic importance to the gas indus¬try as a whole, but most of them involve such small volumes of gas that they are only of passing interest. Since various products extracted from natural gas and recovered as by-products from petroleum refining, such as liquefied petroleum gas and fuel oil, are being utilized in many industrial and domestic heating applications, some consideration will have to be given such materials in order to present a reasonably complete story of the importance of natural gas. Some of these materials may prove to be transient competitors and will not be available when more profitable uses are found for them. Meanwhile, however, the potential volumes of such materials available, the current volumes being marketed, and the nature of the utilization are considered as constituting an essential part of the over-all fuel picture.

Jan 1, 1946

By S. H. Penn

One of the more challenging aspects of the unfolding age of space travel centers about the opportunity for man to use the natural resources of other worlds. The first of the extraterrestrial worlds to be exploited will be the moon. After only a scant few thousand years of scratching the earth's crust, man will embark upon a venture that for centuries has excited the imagination of many (while staggering that of most) and may become a reality within the next decade. There has never been a time when so much money and effort will have been expended to exploit an area about which so little is known. Paradoxically, this effort combines much of the detached objectivity so typical of our analytical time with the proverbial optimism of the indefatigable prospector. As the earliest manned lunar missions will be brief and exploratory in nature, astronauts will not be expected to attempt to exploit any of the possible lunar natural resources. In later missions, with a more extended period of time available for the astronauts to stay on the moon, it may be desirable or even necessary to "live off the land". The resulting exploitation of lunar resources will be intended primarily to reduce the dependence of manned missions upon terrestrial logistic support and to reduce the cost of maintaining lunar bases.

Jan 3, 1966

By John C. Cosgrove

IT was just five minutes past midnight, on Wednesday, Jan. 5, 1938, that Mrs. Cosgrove and I sailed from New York City. Our trip was to completely circle the globe, to cover over 40,000 miles and stop at thirty ports-from New York to Trinidad, to South America, via South Africa to the Orient, to India, to the Malay States, to Indo-China, the Philippines, Australia, New Zealand, Fiji, and across the Pacific home via Honolulu. It is not my intention to make this a complete, technical study of coal or coal mining in the various countries that .we visited but more to outline the general in- formation that the mining engineer and coal operator would absorb in his travels. Coal is the universal fuel and is in use wherever there is commerce and industry. Even on our ship, which, like practically all ocean liners was an oil-burner, a considerable quantity of coal was used for cooking.

Jan 1, 1939

By Samuel H. Dolbear

NOT WITHSTANDING the extremely low ebb of business activity, the nonmetallic industries have fared somewhat better than some other branches of mining. The average price level in nonmetallics, although far from satisfactory, has resisted any cataclysmic fall such as has been suffered by copper and other metals. Stocks, also, though too abundant, represent no corresponding overhang of the market, which should result, in some branches, in a more rapid recovery. Research work has continued in some industries with interesting developments.

Jan 1, 1933

By AIME AIME

THE following Officers, Directors, and guests were present: Herbert Hoover, A. R. Ledoux, Henry S. Drinker, Edwin Ludlow, Samuel A. Taylor, Charles F: Rand, William M. Corse, Arthur S.. Dwight, Glen H. Clevenger, L. W. Francis, F. G. Cottrell, Bradley Stoughton, Percy E. Barbour, E. P. Mathewson, Dorsey A. Lyon, Archibald Douglas, A. D. Flinn, RobertLinton, James F. Kemp, William Y. Westervelt, J. W. Richards, W. L. Saunders, George Otis Smith, Thomas T. Read, J..C. Murray, Ralph Arnold. A Committee on Mine Equipment was appointed composed as follows: Graham Bright, chairman, William Kelly, Howard N. Eavenson, R. E. Hobart, and S. P. Rumsey. B. D. Saklatwalla was added to the Committee on Miscellaneous Metals and W. Spencer Hutchinson was added to the Committee on Mining Geology. A revised budget for 1921 was approved. A petition duly signed to amend Section 1., of Article III of the Constitution, increasing the initiation fees from ten dollars to twenty dollars, was approved by the Board.

Jan 1, 1920

By J. F. Tavernelli, L. F. Coffin

The deformation and fracture characteristics of eight metals subjected to fully reversed cyclic strain ranging from 0.2 to 50 pct were investigated at room temperature. Strain-hardening characteristics unique to the interna1 structure of a particular metal were found. Complete removal of the strain-hardening effects resulting from prior deformation was brought about by subsequent cyclic strain. Further support for the validity of the inverse relationship between the plastic strain range and the square root of the number of cycles for failure is given. THE resistance of materials to cyclic plastic strain is of interest both from a fundamental and practical point of view. It is now a well-accepted fact that fatigue failure in metals is a consequence of the localized slip deformation which occurs within the individual crystals of metal.'-' Hence the failure process should be strongly dependent upon the magnitude of the gross cyclic plastic deformation of the metal under conditions where this is a measurable quantity. Therefore, an experimental investigation of metals in which the cyclic plastic strain is the independent variable should shed new light on some of the basic aspects of the problem. From the practical point of view, there are many uses for information relating to the cyclic strain resistance of metals. One is the case of thermal stress fatigue where fatigue failure can occur as a consequence of a com- paratively few cycles of thermally induced mechanical deformation. Another is the mechanical working of metals where large cyclic strains are employed. In recent years several publications have appeared relating to the cyclic-strain resistance of metals,8-11 dealing mostly with the fracture aspects where the temperature is cycled simultaneously with the mechanical strain. Some work has been reported on the cyclic-strain resistance of metals at constant temperature, again oriented more toward the fracture aspects of the problem than the deformation aspects. 12-16 The present research investigation was undertaken to obtain information regarding the deformation characteristics of several metals whose structure-property relationships were simple and straightforward under conditions of both cyclic and monotonic strain. It has been shown for example that under cyclic-strain conditions some materials will strain harden, while other materials, particularly cold-worked structures, strain soften and these effects required further clarification.8,17-19 It was also de-

Jan 1, 1960