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By Eugene F. Poncelet

Glass squares compressed on edge by steel jaws in poor contact with them developed jagged "partial-contact" cracks caused by the formation of local tensile stresses. Compressed by steel jaws in perfect contact, they developed smooth "release cracks" during release of the pressure, caused by the formation of local tensile stresses during the release of the pressure. All these cracks were parallel to the pressure. A Microflash photograph of a disintegrating specimen under sufficient pressure reveals a network of fractures roughly normal to each other, also "release cracks" and a disintegration cloud. The Griffith theory is amended to account for the formation of a first crack. A new theory, based on the theory of thermal agitation and wave propagation, is proposed to account for the progress, velocity and forking of cracks. The network of fractures is shown to have been caused by reflection at a free boundary of pressure pulses emanating from a first crack. Postulating equal distribution of energy in the pulses emitted on either side by a crack in particles, the smaller fragments are shown to continue fracturing preferentially while some of the coarser fragments remain as residual pieces. As comminution of the smaller fragments proceeds, the solid is reduced to a collection of residual particles of smaller and smaller sizes, accounting for the disintegration cloud. Experimental Procedure Apparatus A crushing device was built, consisting of a steel frame and two polished, hardened steel jaws to crush plate-glass samples. This device was placed between the plates of a hydraulic press (Fig. I). For centering the pressure, the upper jaw was guided vertically and provided with a rounded top. Later it was replaced by a steel jaw ground out of a 2½-in. steel ball, the lower surface being ground to an optical flat (Fig. 2). Four rollers were used to eliminate side thrust. Screws and centering blocks served to center the specimen in the crushing device. Hard steel shims placed under the shoulder of the upper jaw limited the "follow through'' of the jaw after failure of the specimen. Stress distribution was first examined with a polariscope mounted on an optical bench, using monochromatic light. It was found convenient to mount polaroid, quarter wave and monochromatic plates directly on the device itself. A Microflash unit* was used as light source for the photographs. A gold-paint pattern was fused on the plate-glass specimens and connected into the spark-

Jan 1, 1947

By D. T. Peters, S. Floreen

The age hardening behavior of an Fe-8Ni-13Mo alloy was studied after the matrix had been varied to produce either ferrite, cold u~orked ferrite, or nzassive nzartensite. The aging behavior of the cold worked ferrite and murtensite structures were very similar. The martensite aging kinetics were much different from those observed in earlier studies of aging of maraging steels, even though the martensite wzatri.r had the same dislocation structure as those found in maraging steels. The results suggest that the previously observed precipitation kinetics of maraging steels ?nay have been controlled by the nucleation be-haviov, which in turn were dictated by the alloy compositions and the resultant identities of the precipitating phases. IT is well known that the rate of precipitation from solid solution depends not only on the degree of super-saturation, but also on the density and distribution of dislocations in the matrix structure. These imperfections often act as nucleation sites, and may also enhance atomic mobility. 'Thus, the presence of dislocations is important since the type and distribution of precipitates may be determined by them. The precipitate density and morphology in turn affects the mechanical properties of the alloy. A number of studies have been devoted to the precipitation characteristics in various types of maraging steels.'-" These are iron-base alloys containing 10 to 25 pct Ni along with other substitutional elements such as Mo, Ti, Al, and so forth, that are used to produce age hardening. The carbon contents of these steels are quite low, and carbide precipitation is not believed to play any significant role in the aging reactions. After solution annealing and cooling these alloys generally transfclrm to a bcc lath or massive martensite structure characterized by elongated martensite platelets that are separated from each other by low angle boundaries, and that contain a very high dislocation den~it~.~~~~~~~~-~~ Age hardening is then conducted at temperatures on the order of 800" to 1000°F to produce substitutional element precipitation within the massive martensite matrix. Most of the aging studies to date have revealed several common traits in these alloys, regardless of the particular identity of the precipitation elements. Generally hardening has been found to be extremely rapid, with incubation times that approach zero. The agng kinetics, at least up to the time when reversion of the martensite matrix to austenite begins to predominate, frequently follow a AX/~~ = ktn type law, where x is hardness or electrical resistivity, t is the time, and k and n are constants. The values of n are frequently on the order of 0.2 to 0.5, which are well below the idealized values of n based on diffusion controlled precipitate growth models. Finally, the observed activation energy values are typically on the order of 30 kcal per mole, and thus are well below the nominal value of about 60 kcal per mole found for substitutional element diffusion in ferrite. The common explanation of these observations is that the precipitation kinetics are controlled by the massive martensite matrix structure. Thus, the absence of any noticeable incubation time has been attributed, after ~ahn," to the fact that the precipitate nucleation on dislocations may occur without a finite activation energy barrier. The low values of the activation energy are generally assumed to be due to enhanced diffusivity in the highly faulted structure. If this explanation that the precipitation kinetics are dominated by the matrix structure is correct then one should observe a distinct difference in lunetics between aging in a martensitic matrix and aging the same alloy when it has a ferritic matrix. Such a comparison cannot be made with conventional maraging compositions, but could be made with the alloy used in the present study. In addition, the ferritic structure of the present alloy could be cold worked to produce a high dislocation density so that one could determine whether ferrite in this condition would age similarly to martensite. EXPERIMENTAL PROCEDURE The composition of the alloy used in this study was 8.1 pct Ni, 13.0 pct Mo, 0.10 pct Al, 0.13 pct Ti, 0.012 pct C, bal Fe. The alloy was prepared as a 40 lb vacuum induction melt. The heat was homogenized and hot forged at 2100°F to 2 by 2 in. bar, and then hot rolled at 1900°F to $ in. bar stock. The aging lunetics were followed by Rockwell C hardness and electrical resistivity measurements. Samples for hardness testing were prepared as small strips approximately 2 by $ by 4 in. thick. Electrical resistivity was studied on cylindrical samples approximately 2 in. long by 0.1 in. diam. The method for making the alloy either martensitic or ferritic was based on the fact that the alloy showed a closed y loop type of phase diagram. At high temperatures, above approximately 24003F, the alloy was entirely ferritic. Small samples on the order of the dimensions described above remained entirely ferritic after iced-brine quenching from this temperature. In practice, a heat treatment of 1 hr in an inert atmosphere at 2500°F followed by water quenching was used to produce the ferritic microstructure. These samples were quite coarse grained and usually en-

Jan 1, 1970

Discussion of the paper of W. R. SHIMER, presented at the New York meeting, February, 1915, and printed in Bulletin No. 99, March, 1915, pp. 557 to. 585. WILLIAM R. WEBSTER, Philadelphia, Pa.-I would like to ask Mr. Shimer how the finishing temperature of the H-beams and other beams rolled on the Gray mill at Bethlehem compare with the rolling temperatures of the rails referred to in this paper. Also, how the reductions in the rolling of the beams compare with the reductions in the rolling of the rails. I would also like to know if any drop tests were' made on the rails referred to as having been allowed to cool and then annealed; in other words, what results, if any, were obtained from tests on rails after the internal strains of rolling had been removed; and in the matter of the rail blooms, I would like to ask if they are not often heated to a higher temperature than is desirable on account of the thin flanges in order to carry the heat through to the finishing pass. The tensile strength of the steel in these rails is given as 125,000 lb. per square inch, which is almost as high as tire steel. If some of these blooms were rolled into rounds of about the same section as the head of the rail, would you not get better results from tension tests than those from the head of the rail? In other words, in rolling rounds, whether you would not be able to control the rolling and finishing temperatures better than is possible in the rail, owing to thin section of the rail flanges. Some years ago I had experience with the rolling temperatures of tire steel, running from about 127,000 to 133,000 tensile strength. These tires had the tensile strength and the deflection specified. One of the manufacturers had no trouble whatever, after a little experimenting, in meeting the conditions of the specification. Another manufacturer who made some of these tires came to the office and stated that he had tried tires from three heats of steel and could not meet the specifications and

Jan 5, 1915

By R. W. Lai, I. Iwasaki

Some physical as well as chemical aspects of the methods of dispersion of various corn starches and their derivatives are investigated and their effects as depressants in anionic silica flotation of iron ores ascertained. The adsorption behavior of starches on hematite and quartz is strongly affected by their molecular sizes as inferred from viscosity measurements. The implication of this behavior on flotation and flocculation is discussed. Mechanical treatment of causticized starch solutions is shown to reduce the starch requirements in flotation appreciably. Starches and starch products have been used as depressants for iron oxides both in amine flotation of siliceous gangue and in soap flotation of activated silica from iron ores. Cooke and his associates1,2,3,4 extensively studied the effects of certain starches and their derivatives in the amine flotation of iron ores at near-neutral pH and found that although most starches were good flocculants for hematite and de- pressed that mineral more or less selectively1,3 they did not flocculate quartz suspensions. Further, that replacement of active groups in corn starch modified its behavior as a flocculant for hematite or quartz suspensions1 and as an iron oxide depressant. Schulz and cooke2 showed that many starches and their derivatives, except aminoethyl starch, were abstracted more effectively by Brazilian hematite than by quartz and that the adsorption of a starch product was strongly dependent on pH and on the presence of calcium ion. In soap flotation of calcium-activated quartz, certain starches and their products have been used to depress iron oxides.5'6 The behavior of these substances in flotation appears at times to be at variance with those previously reported and especially with results obtained in the Mines Experiment Station laboratories. This is attributed, at least in part, to differences in flotation procedure and flowsheets and in the method of preparing the depressant. Most of the investigators referred to above, solubilized the starch products by autoclaving at 120°C. Others have used acid,7 alkali8 or oxidizing agents.9 In view of the limited knowledge of the depressing action of starches and their derivatives in iron ore flotation, particularly in soap flotation of calcium-activated silica at high alkalinity, an extensive study

Jan 1, 1965

By J. A. Elias, R. H. Heyer, J. H. Smith

Plastic anisotropy determined by the ratio of width strain to thickness strain in tensile specimens of low-carbon steels is strongly related to crystallographic preferred orientation. Using(222) Pole figures, a method was developed which permits rapid Predictions of plastic anisotropy for any crystallographic texture or orientation. The method is applied to low-carbon steel sheets in which four different crystallographic orientations were produced by variations in cold rolling and annealing treatments. AnISOTROPIC behavior of metal sheets during plastic deformation has long been evident. A familiar example is earing in cup type draws. During tension testing of sheet specimens, anisotropy results in a difference in width strain as compared with thickness strain. Carpenter and Elam1 observed this phenomenon in single crystals of aluminum for both sheet and rod samples. Lankford, Snyder, and Bauscher2 made tension tests on sheet samples of aluminum-killed low-carbon steel to determine the ratio of the width-to-thickness strains, and showed that this ratio was related to drawing performance. Burns and Heyer3 calculated theoretical ratios of width strain to thickness strain for two specific orientations of the bee system, using <111> as the operative slip direction. These calculated values were in fairly good agreement with the ratios determined by tension tests of low-carbon steel sheets in which these preferred orientations existed. The high degree of plastic anisotropy of silicon steel sheets could also be predicted from their crystallographic structure by these calculations. The present study has been made to show that the anisotropy observed in plastic tensile straining is strongly orientation dependent and can be adequately predicted for many orientations and textures. PLASTIC STRAIN RATIO R In the region of uniform elongation of a tension test specimen the plastic deformation may proceed at different rates in the width and thickness directions. Such anisotropy has been described in the past by the plastic strain ratioR:

Jan 1, 1962

By R. E. Reed-Hill, W. H. Hartt

High-purity magnesium single crystals, oriented with basal plane parallel to stress axis, were deformed in tension at room temperature so as to form second-order (1011)- (1012) twins. Investigation by optical and replica electron microscopy revealed that these twins can support very large internal strains approaching 1000 pct and that fracture follows as a direct consequence of these strains. At low strains the basal plane within (10i1)- (10i2) twins rotates with increasing deformation until it becomes approximately parallel to the twin boundaries. This rotation is not consistent with deformation by basal slip in the double twin, but may be rationalized in terms of nonbasal slip. Observations also indicate that basal slip in the primary (1011) twin, prior to second-order twinning, may contribute to this rotation. Deformation markings that are difficult to interpret in terms of slip on previously observed systems were noted in the twin bands. A possible means of rationalizing these markings is to relate them to grain boundary shear. The fracture associated with these twins is thought to initiate by formation of voids at the twin boundaries. These grow into microcracks, with ultimate fracture occurring by tearing of the interconnecting regions. THE significance of deformation and fracture along second-order (10i1)-(10i2) twins in polycrystalline magnesium1-&apos; and many magnesium alloys4 was discussed in a previous paper.5 It was noted that this double twinning mode effectively controls the room-temperature deformation and fracture of magnesium single crystals, oriented with the basal plane parallel to the tensile axis. Reed-Hill and Robertson6 observed that, although these crystals may fracture at a macroscopic strain of less than 1 pct, shear strains up to 1000 pct could occur within (1011)- (10i2) twin bands. They concluded that the fracture was "ductile" and resulted from concentrating the deformation into a very small volume. The present research was undertaken to obtain a better understanding of the deformation and fracture associated with these twins. EXPERIMENTAL TECHNIQUES The experimental procedure involved straining high-purity magnesium single crystals in tension at room temperature. Specimens were oriented so that the applied stress direction was within 2 deg of the [1010] crystal axis. The specimen cross section was rectangular with faces closely parallel to (1210) and (0002). The specimen preparation and testing procedures have been described in detail elsewhere.5 Second-order (1011)- (1072) twins nucleated during straining were studied using optical and replica electron microscopy techniques. For the latter, cellulose acetate-carbon double replicas were employed. Observations were made on the (1210) crystal surface, which is the plane of shear for twins of this type. In addition to the single crystals, some investigations were carried out on longitudinal polycrystalline specimens. These were obtained from high-purity magnesium plate with a texture in which the basal planes of the grains tended to be nearly parallel to the specimen axis. All. polycrystalline specimens were annealed prior to testing in order to produce a coarse grain structure, permitting Laue back-reflection X-ray photographs to be obtained from grains of interest. EXPERIMENTAL RESULTS a) Deformation Within ( 101 l )-( 1072) Twins. Fig. 1 is an optical micrograph demonstrating the extent of the plastic deformation that can occur in (1011)-(10i2) twin bands. Notice at the lower left corner of the photograph the large displacement of the dark band (a polishing step) where it crosses the twins. The shear strain in the twin band at this position was computed to be 700 pct, using the ratio of step width to twin thickness. It was previously shown5 that (1011)- (1012) twin bands are often composed of small, separate twins aligned close to the macroscopic habit plane. Fig. 2 is an electron micrograph from near the upper end of the twin band in Fig. 1. This illustrates that the twin habit often does not coincide exactly with the macroscopic band habit, but may be inclined at a slightly smaller angle to the matrix basal plane. Figs. 3 through 6 are electron micrographs of the twin band in Fig. 2 illustrating successive steps in the development of deformation inside the band. A twin band such

Jan 1, 1969

By J. M. Stuart, G. D. Bengough, A. R. Lee

Corrosion tests should be designed so as to facilitate as far as possible the interpretation of results, consequently factors which may affect the rate of corrosion should be controlled as far as practicable, and very full data should be given regarding the conditions of the test. Among the most important factors affecting the rate of corrosion is often the rate of supply of oxygen to the metal surface. It is essential therefore to understand the mechanism by which oxygen is transferred from the liquid surface to the surface of the metal. The work of Adeney and his coworkers has thrown much light on this mechanism. They have shown1 that the aeration of deaerated water and salt solutions proceeds much more rapidly than can be accounted for by mere diffusion, and have suggested that downward "streaming" takes place from the surface of the water, due mainly to an increase of density brought about by evaporation. The evaporation reduces the temperature of the surface layer, and also increases the concentration in the case of salt solutions. The effect of evaporation in facilitating the transfer of oxygen to a metal and increasing the corrosion of the metal was shown in some experiments due to Friend.2 He tested the corrosion of mild steel plates immersed in water in glass jars, a steady stream of air being drawn over the surface of the water in the jars. The air passing through half the number of jars was saturated with moisture, that passing through the others was dried with calcium chloride. He found that "in every case the water exposed to dry air was approximately twice as corrosive as that exposed to air saturated with water vapor." Conditions for Quantitative Corrosion Tests These results show that we must either control or prevent evaporation at the liquid surface, if we wish to avoid effects on the rate of cor-

Jan 1, 1929

By A. R. Lee, G. D. Bengough, J. M. Stuart

Corrosion tests should be designed so as to facilitate as far as possible the interpretation of results, consequently factors which may affect the rate of corrosion should be controlled as far as practicable, and very full data should be given regarding the conditions of the test. Among the most important factors affecting the rate of corrosion is often the rate of supply of oxygen to the metal surface. It is essential therefore to understand the mechanism by which oxygen is transferred from the liquid surface to the surface of the metal. The work of Adeney and his coworkers has thrown much light on this mechanism. They have shown1 that the aeration of deaerated water and salt solutions proceeds much more rapidly than can be accounted for by mere diffusion, and have suggested that downward "streaming" takes place from the surface of the water, due mainly to an increase of density brought about by evaporation. The evaporation reduces the temperature of the surface layer, and also increases the concentration in the case of salt solutions. The effect of evaporation in facilitating the transfer of oxygen to a metal and increasing the corrosion of the metal was shown in some experiments due to Friend.2 He tested the corrosion of mild steel plates immersed in water in glass jars, a steady stream of air being drawn over the surface of the water in the jars. The air passing through half the number of jars was saturated with moisture, that passing through the others was dried with calcium chloride. He found that "in every case the water exposed to dry air was approximately twice as corrosive as that exposed to air saturated with water vapor." Conditions for Quantitative Corrosion Tests These results show that we must either control or prevent evaporation at the liquid surface, if we wish to avoid effects on the rate of cor-

Jan 1, 1929

By F. F. Craig

Many full-scale waterflooding operations are preceded by pilot floods, one purpose of which is to provide an estimate of recoverable oil. A laboratory model study was made to determine the influence of the producing wells&apos; effective productivity on the oil recovery efficiency of single five-spot pilots, as well as single injection well pilot floods. The effective productivity is indicated by the value of Condition Ratio, defined as the actual well productivity to that of on undamaged and non-stimulated, normal-sized well in the same formation. The effects of initial gas satrcration and mubility ratio on recovery eficiency were also investigated in this model study. Model test results skowed that at favorable mobiliry ratios, a five-spot pilot flood can provide a direct quantitative estimate of the recoverable oil in the pilot area. If the pilot producer&apos;s Candition Ratio is 2.2 or more, upwards of 90 per cent of the recoverable oil in the pilot area is recovered from the inside producer, regqrdless of the mobility ratio or initial gas saturation. This Condition Ratio can be achieved with preyent fracturing techniques. Model studies also showed that over the range of imposed injection pressure differences and regional pressure gradients normally encountered in field operations, there was no effect on the recovery efficiency of a five-spot pilot waterflood. Model studies of single injection well pilot waterfloods showed that with no initial gas saturation, the total oil recovery at the offset producing wells can indicate the oil recovery possible by full-scale waterflooding. It is essential that the Condition Ratios of the offset wells be above 1.4. If an initial gas saturation exists prior to water injection, the recoverable oil cannot be directly evaluated by a single injection well pilot flood. However, the production per formance of such a flood can be used to provide information on volumetric sweep efficiency. INTRODUCTION Oil reservoirs are conlplex structures and cannot always be fully studied in the laboratory. Therefore, many operators consider it prudent to evaluate a waterflood prospect by means of a pilot flood. Pilot waterfloods generally involve one of two well arrangements: a single five-spot pilot waterflood, involving four injectors and an internal pilot producing well; and a single injection well pilot flood (sometimes called an inverted five-spot pilot) having one injector and four sur- rounding pilot producers. Some pilot floods are composed of multiple five-spot pilot patterns. To yield information applicable to field-wide performance, the pilot must be located in a representative portion of the reservoir. Pilot floods generally are conducted for one or more of the following reasons: (1) to determine whether water could be injected at desirably high rates, (2) to determine whether an oil bank or zone of increased oil saturation is formed by water injection, and (3) to estimate the oil recovery by waterflooding. Many of the early pilot water-floods were conducted for only the first two reasons. As soon as a buzz in oil production was obtained in the pilot, water injection was initiated throughout the entire lease or field. A number ot laboratory studies have been directed toward determining conditions under which a pilot flood could yield a quantitative estimate of the oil recovery possible by full-scale pattern flooding. One of the early studies of single five-spot pilot flooding&apos; showed that well damage to the inside pilot producer could reduce the total amount of oil recovered. In a study of the single injection well pilot flood pattern,&apos; the results indicated that if the model boundaries were no closer than a half-well spacing beyond the pilot pattern, the pilot performance in the laboratory is unaffected by these boundaries. In another study,? he effect of initial gas saturation and mobility ratio on the ratio of production to injection rate for various groupings of five-spot patterns was defined by mathematical and analog methods. In a study4 involving both potentiometric and flow model experiments at a mobiliry ratio of unity, four different pilot patterns were studied. These included a single five-spot, a single injection well pilot, a cluster of four single injection well pilots and six inverted five-spots. In this study the ratio of well diameter to the distance between injection and producing wells was held constant at 1:1000. The effect of the 7 ratio-—the ratio of the pressure drawdown at the producing wells to the pressure build-up at the injection wells on the pilot performance-was studied. The values of 7 ratio ranged from 0 to 0.34. Results showed that both the total oil recovery and the total fluid production from the pilot relative to the cumulative injection increased with increasing values of the 7 ratio. The effect of both the ratio of injection to producing rates and mobility ratio on the oil recovery performance of a liquid-saturated single five-spot pilot flood was studied in a series of flow model tests.5 Rate ratios ranged from one to four, and mobility rates ranged from 0.1 to 10. Resulls of these tests showed that at low rate ratios, the pilot producers may recover up to four times the recover-

Jan 1, 1966

By Fred C. Bond

The Standard method of determining the crushing resistance of rocks consists of crushing prepared shapes under slow compression, and expressing the ultimate crushing resistance at the load causing failure in pounds per square inch of cross-sectional area perpendicular to the crushing force, with the height approximately equal to the diameter. One-inch cubes or cylindrical drill cores are commonly used. Cubes and drill cores are cut by a highspeed steel disk with diamond dust embedded in the edges, and running under a water spray. such a saw will cut one square inch or more of hard stone per minute. An oiled, spherical, swivel compression block of small diameter should be used to equalize the pressure. Each sample is crushed between sheets of cardboard or blotting paper extending about one-half inch beyond the edges of the stone. A cloth is wrapped around it to prevent dangerous explosive shattering. It is probably preferable to place the swivel block below the specimen, with either a rigid head or another swivel block above. Whatever the arrangement, the conditions should be selected that will develop the maximum crushing strength of the specimen, even though its top and bottom planes may not be precisely parallel. The cardboard pads may be dispensed with if the ends of the specimens are polished smooth. The use of lead pads was discontinued because of the observed tendency to split the material. The samples are weighed and measured before breaking, and the density is calculated. Cubes that contain bedding lanes or veinlets are usually placed with these vertical and parallel to the crushing force, in order to develop the maximum resistance possible. A number of compression tests were made on Canadian ores, by Forrest Nagler, of the Allis-Chalmers Manufacturing CO., and are listed alphabetically in Table I. These tests were made on one-inch cubes or on diamond-drill cores approximately one inch in diameter and One inch long. The drill cores represent virgin rock, while the cubes may have been previously weakened by explosives. compression tests have been made in the Allis-Chalmers Milwaukee Laboratory on a number of ores and other materials. These are listed alphabetically in Table 2. In test NO. 1339, on limestone from the Hanna Coal Co., comparison was made between 2 by 2-in. diamond-drill core segments and one-inch cubes cut from the cores in the same strata. Results for the cylinders are tabulated directly below those for the cubes. The bedding planes were normal to the compressive force in breaking the cylinders and parallel in breaking the cubes, which accounts for the lower strength obtained from the cylinders. The percentage of net linear compression at the ultimate pressure was measured in test No. 1055 for Fontana TV A quartzite as 0.30 for cube A, and 0.37 for cube D.

Jan 1, 1947

By Fred C. Bond

The Standard method of determining the crushing resistance of rocks consists of crushing prepared shapes under slow compression, and expressing the ultimate crushing resistance at the load causing failure in pounds per square inch of cross-sectional area perpendicular to the crushing force, with the height approximately equal to the diameter. One-inch cubes or cylindrical drill cores are commonly used. Cubes and drill cores are cut by a highspeed steel disk with diamond dust embedded in the edges, and running under a water spray. such a saw will cut one square inch or more of hard stone per minute. An oiled, spherical, swivel compression block of small diameter should be used to equalize the pressure. Each sample is crushed between sheets of cardboard or blotting paper extending about one-half inch beyond the edges of the stone. A cloth is wrapped around it to prevent dangerous explosive shattering. It is probably preferable to place the swivel block below the specimen, with either a rigid head or another swivel block above. Whatever the arrangement, the conditions should be selected that will develop the maximum crushing strength of the specimen, even though its top and bottom planes may not be precisely parallel. The cardboard pads may be dispensed with if the ends of the specimens are polished smooth. The use of lead pads was discontinued because of the observed tendency to split the material. The samples are weighed and measured before breaking, and the density is calculated. Cubes that contain bedding lanes or veinlets are usually placed with these vertical and parallel to the crushing force, in order to develop the maximum resistance possible. A number of compression tests were made on Canadian ores, by Forrest Nagler, of the Allis-Chalmers Manufacturing CO., and are listed alphabetically in Table I. These tests were made on one-inch cubes or on diamond-drill cores approximately one inch in diameter and One inch long. The drill cores represent virgin rock, while the cubes may have been previously weakened by explosives. compression tests have been made in the Allis-Chalmers Milwaukee Laboratory on a number of ores and other materials. These are listed alphabetically in Table 2. In test NO. 1339, on limestone from the Hanna Coal Co., comparison was made between 2 by 2-in. diamond-drill core segments and one-inch cubes cut from the cores in the same strata. Results for the cylinders are tabulated directly below those for the cubes. The bedding planes were normal to the compressive force in breaking the cylinders and parallel in breaking the cubes, which accounts for the lower strength obtained from the cylinders. The percentage of net linear compression at the ultimate pressure was measured in test No. 1055 for Fontana TV A quartzite as 0.30 for cube A, and 0.37 for cube D.

Jan 1, 1947

By G. S. Jenkins

The statistics set forth by Professor Mitchell in a proceding paper very carefully brought out the points that indicate that a marked amount of consideration must be given to" the haulage problem to adapt it to local conditions as encountered. Professor Mitchell&apos;s paper showed a spread of from 10 tons per man to 50 tons per man on the production crews, which spread can be recognized as entirely too large when one considers that the product is being sold at a price within very close limits. While a portion of this spread may be explained by different methods in cost accounting as to what employees are applicable to the production crew, it cannot all be blamed on an accounting method. A good portion must be explained by the improper application of equipment to the needs incurred by the local conditions. It is in an endeavor to go into this phase that this paper is given. It will be necessary to qualify the points covered in order to keep the subject from becoming too wide in scope. Along this line, conditions will be only those involved in bituminous coal mine practices and only the haulage of coal that is loaded with mobile loading machines in seams 4 ft thick and better. Haulage Methods Employed The Consolidated Coal Co. (Illinois) has been operating on a modernized basis for about 20 yr. By modernized we mean the loading of coal with mobile loading equipment. In review of haulage methods, it must be remembered that the main line electric haulage locomotive has been in service for some 40 or jo years. To augment this main line haulage, the mule did a quite satisfactory job during hand-loading days, but was later replaced by the gathering locomotive, either battery or cable-reel operated. This type of haulage was the method in common use at the time the mechanical loading of coal became of major importance and the success or failure of loading machine installations may be largely accredited to haulage facilities in the early days; that is, in the period around 1930. The Consolidated Coal Co. had its struggle with this problem beginning in about 1927 or 1928. We were somewhat fortunate in that we were already using gathering locomotives powered by storage batteries at the time we introduced mechanical loading. This meant that we did not have to spend as much time training motormen and trip riders as many mines did that utilized only mules for their secondary haulage. This was all advantage, and our efforts could be focused on ways and means of providing adequate car service to the loading machine. Like most operations, we endeavored to gear the car service to the capacity of the machine, with a large crew endeavoring to load the maximum tonnage that the machine would handle. Toward that end our first move was to install switches

Jan 1, 1949

By J. P. Heller

The purpose of this discussion is to comment briefly on one of the points raised in the paper. The topic is that referred to in the Conclusion 2, in which the authors note a "disproportionate increase in mixing rate" as they proceed from a displacement performed at viscosity ratio 0.998 to one at 1.002. The recovery curve of this displacement, Fig.2A, shows a quite noticeable difference between the two runs in which displaced and displacing liquids were interchanged. This difference is ascribed by the authors to the change in viscosity ratio between the two experiments. This interpretation of the experimental results must certainly be based on rather precise measurements of the fluid viscosities or, at least, of the ratio of their viscosities. The ordinary Ostwald viscometer, employed in the usual way, is only just able to distinguish between liquids whose viscosities differ by two or three parts per thousand. The experimental refinements which then must have been necessary to measure with any precision a viscosity ratio of 1.002 would be worthy of mention. Indeed, one would have expected the authors to devote at least a paragraph to the display of this technique. For the same reason - to emphasize that the details of such unusually critical experimental work should be reported and discussed in the literature — I would have liked to see some comment by the authors on the requirements for temperature control during both the viscosity measurements and the displacement experiments. The temperature coefficient of viscosity of Soltrol C at room temperature has been measured in this laboratory at about - 1.9%/1°C. How much did the coefficients for the fluid mixtures used in the experiment differ from this and from each other Even if the two fluids were identical in this respect, it would appear that a temperature difference of .l°C between them in the flow system would produce a viscosity con- trast equal to that imposed by their composition. Reference to the experimental solutions of these problems would render Conclusion 2 more credible. Published theoretical work on the stability problem contains no indication of such extreme sensitivity to the viscosity ratio in the immediate neighborhood of unity. On the contrary, perturbation calculations such as those made by Chuoke1 and Perrine2 lead to initial finger growth rates proportional to the first power of the viscosity difference. The later instability growth calculated by Scheidegger,3 using the assumption of zero pressure gradient perpendicular to the average flow, is also simply proportional to the viscosity difference. The conflict regarding the sensitivity of the dependence of instability growth or mixing rate on the viscosity contrast needs explicit recognition in the literature. In particular, it would seem that the experimental work reported here should be supported by a more detailed description of the viscosity controls. Further discussion of possible alternative interpretations of the data would also be in order. For instance, is it possible that the unconsolidstted bead pack used changed its characteristics between the runs (due, perhaps, to the handling and inverting involved in the injection of the front) Or, are the data points of Fig. 2A averages from several runs performed in a series in which the two liquids alternated as displaced and displacing fluids? To summarize, it seems to me that the relationship asserted by Conclusion 2 in the paper needs the support of more detailed experimental evidence. REFERENCES 1. Chouke, R. L., van Mews, P. and van der Poel, C.: "The Instability of Slow Immiscible Viscous Liquid-Liquid Displacements in Porous Media", Trans., AIME (1959) Vol. 216, 188.

By W. T. Read, W. Shockley

THE subject of this chapter is the application of the dislocation theory to two problems of physical metallurgy where the theory has been able to give definite predictions that subsequently have been verified by experimental observations. Much of the history of dislocation theory has consisted of the explanation of already established results on the basis of ad hoc assumptions. Scattered bits of fundamental theory were formulated as needed-in particular explanations. The result had the appearance of a hodgepodge of ingenious ideas and exciting but possibly artificial speculations. The review article by Koehler and Seitz in this volume gives an excellent picture of the breadth, diversity, and flexibility that have made dislocation theory attractive to speculative theorists, although occasionally bewildering to others. Since 1950, there have been two developments, which have helped to establish dislocation theory, on the one hand, as a systematic coherent body of theory and, on the other, as a means of making predictions that can be tested experimentally and thereby guide experiment into more fruitful channels. The first and easier of these developments has been the systematic derivation of the classes and properties of dislocations from fundamental crystallographic concepts. An example of one phase of this development is the rigorous treatment of

Jan 1, 1954

By W. R. Johnson, M. Hansen, John M. Parks

AS part of a research project sponsored by the Signal Corps Engineering Laboratories, which had the objective of obtaining a magnet wire of good conductivity and low temperature coefficient of resistance, a comprehensive literature survey, supplemented by experimental work, revealed that a linear relationship exists for solid-solution alloys between the electrical conductivity, K, and the temperature coefficient, a, as expressed by the equation: k = a/ß where ß is constant for the solvent metal and a - per°C. tR0 It has long been known that the electrical conductivity at a given temperature and the temperature coefficient of resistance of binary alloys are related to their constitution by the LeChatelier-Guertler rules, as illustrated by Figs. 1 and 2: Rule 1—In alloy systems consisting of a heterogeneous mixture of two phases, the electrical conductivity and temperature coefficient vary as a straight line, if the composition of the alloys is given in volume percentage, Fig. 1. Rule 2—In solid solutions, the electrical conductivity and temperature coefficient are always lower than those of the solvent metal, and usually a considerable decrease occurs with the first small percentage additions of the solute metal, Fig. 2b. If the two components form a continuous series of solid solutions, the electrical conductivity and temperature coefficient curves take the form of a U-curve, Fig. 2a. That some kind of proportionality exists between electrical conductivity and temperature coefficient of resistance is implied by the LeChatelier-Guertler rules and by study of data such as those given by Smith and Palmer,&apos; Fig. 3. Dellinger2 in 1910 first recognized this relationship in a number of commercial copper wires, ranging in conductivity from 94 to 100.7 pct I.A.C.S. He gave the ratio of temperature coefficient to the percentage of conductivity as a constant, C = 0.003939. A year later, Lindeck observed that the linear relationship was valid for a wider range of conductivity in "various sorts of copper," and concluded that the product of resistivity and temperature coefficient was 6.78x10-5 1.5 pct. Since then, this relationship seems to have been entirely ignored. Conductivity-Temperature Coefficient Relationship If the electrical conductivity of copper solid-solution alloys with phosphorus, silicon, arsenic, antimony, aluminum, nickel, manganese, and iron is plotted against the temperature coefficient of these alloys, the diagrams in Figs. 4 and 5 are obtained. Similar data were found with copper-rich solid solutions containing magnesium, cobalt, and titanium,&apos;" as shown in Fig. 6. In all cases, a linear relationship exists. The point representing the highest

Jan 1, 1952

By Edmund Newton

The steel industry of the United States has depended in the past almost wholly upon imports for its supplies of manganese. Many of the important domestic sources yield ores leaner in their natural condition than the foreign ores the steel industry. has been accustomed to use. To make them available, therefore, either the ores must be concentrated or the practice of the steel industry modified. Roughly 25,000 T. annually of high-grade manganese ores are used for dry batteries for chemical purpose, and in other ways; while approximately 750,000 T. are required for making steel. , By present practice, every ton of steel takes an average of about 14 lb. (1.8 kg.) of metallic manganese. This is generally added to the steel in the form of an alloy, the standard alloys being the 80-per cent. ferro-manganese and the 20-per cent. spiegeleisen, During the year 1917, 286,000 T. of ferromanganese and 193,291 T. of spiegeleisen were made in this country, the former largely from imported ores; and 45,381 T. of ferromanganese. was imported. The metallic manganese represented by these alloys was 304,000 T., the product of roughly 800,000 T. of high-grade ore and 345,000 T. of low-grade ore. Manganese Deposits in the United States Before the war manganese ore was mined in relatively small quantities in the Appalachian region, including Virginia, Tennessee and Georgia, and in Arkansas, but owing to the increase in prices during the past three years manganese mining has been undertaken also in Montana, California, Arizona, New Mexico, Nevada, Utah, and Minnesota. From data now available it appears that in this country deposits of high-grade manganese ores are usually small, while materials lower in manganese and higher in iron occur in appreciable quantities. Our total quantity of manganese-bearing material is relatively large, but on

Jan 1, 1920

By Avnulf Muan, P. V. Riboud

The effect of Cr2O3 on melting relations of iron oxide at oxygen pressures slightly above those prevailing in contact with metallic iron has been determined. Liquidus and solidus temperatures of wüstite are raised by the addition of Cr2O3, from 1385°C for pure iron oxide to 1420°C at the peri-ledie point where wüstite, iron chromite, liquid, and gas coexist in equilibrium under the atmospheric conditions used in the present investigation (CO2/H2 = 1). It has been shown in a previous investigation1 that the liquidus and solidus temperatures of iron oxide are drastically increased by the addition of Cr2O3 under the relatively oxidizing conditions prevailing in air. This is to be expected in view of the easy substitution of cr3+ for Fe3+ in crystalline oxide structures which are stable at high oxygen pressures, as demonstrated for instance by the completeness of the solid solution series Fe2O3-Cr2O3 at high temperatures (>1000°C). The stable phase of iron oxide at oxygen pressures approximating those prevailing when metallic iron is present is wüstite. This phase, although commonly represented by the simplified formula FeO for sake of convenience, in reality has a defect structure in which a part of the iron ions are present as Fe3+. It is to be expected that at least a limited amount of cr3 ions will substitute for Fe in this structure when Cr2O3 is added to wüstite. Depending on the ease of this substitution in comparison with that of cr3 substitution for Fe in iron oxide-Cr2O3 liquids under the same atmos- pheric conditions, the liquidus and solidus temperatures of wüstite may increase or decrease upon addition of Cr2O3. The methods of establishing these melting relations and the results obtained are presented in the following. I) EXPERIMENTAL METHOD 1) General Procedure. The quenching technique was used in this study. Oxide mixtures were heated at chosen constant temperatures in an atmosphere consisting of equal parts of CO2 and H2 until equilibrium was established among gas and condensed phases. The samples were then quenched in mercury to room temperature, and the phases present were determined by microscopic and X-ray investigation. 2) Preparation of the Mixtures. Starting mixtures were prepared by weighing and thoroughly mixing Fe2O3 and Cr2O3, or wüstite and Cr2O3. The Fe2O3 and Cr2O3 used were "Baker Analyzed" reagent grades, whereas wüstite of composition was synthesized by reducing Fe203 at 1325°C in an atmosphere consisting of equal parts of CG andHz. In order to avoid contact with crucibles, the equilibration runs were made with small pellets suspended from thin (-0.004-in.) platinum wires. Mixtures made from FOs and Cr203 were readily pelletized at a pressure of 500 atm in a 9.5-mm die, whereas mixtures made from wüstite and Cr203 when treated identically were too weak for handling. In order to obtain a stronger product, these pellets were sintered by heating for 2 min at -1200°C in the same atmosphere as was subsequently used for the equilibration runs (CG/H2 = 1:1). During the sintering, these pellets were wrapped in thin (0.0004-in.) platinum foil, which was stripped off before the equilibration runs. In order to reduce the time needed for equilibrium to be attained, preliminary equilibration of relatively large pellets of each mixture was carried out at -1200°C for 4 to 12 hr. Smaller pellets

Jan 1, 1964

By Nicklaus Heil, L. D. Clark

As political tensions in African and Asian mineral producing regions increase, the orientation of Latin America&apos;s economic development assumes importance not only in the U.S. hemispheric policy but also in our mineral-based economy. Latin America as a mineral supply source has been confronted with regional, political and economic problems which may, at best, have limited further investment and, at worst, have suggested possible repudiation of existing investments. Historically, the mining industry has provided a basis for the national economies of Bolivia, Chile and Peru, and recently the governments of these countries have sought to force increased development of the industry through new and somewhat revolutionary mineral legislation. The extent to which the mineral industries are intended to finance economic development is uncertain and the influence of this legislation on economic freedom and incentive for foreign and domestic investment is a matter for some thought. Two facts are outstanding: first, mining, at present, provides approximately 80% of the foreign exchange in Chile and Bolivia and 42% of that in Peru and, second, existing tax revenues are insufficient to finance a developing economy.

Jan 5, 1967

By Rex W. Woods, Morris Muskat

A leastmsquare analysis procedure has been developed and applied for the study of the deviations in estimations of oil in place as given by the material-balance equations. The data used were those obtained from field observations on the Jones sand in the Schuler pool, Arkansas, and the Monroe dolomite in the Reed City pool, Michigan. Possible effects of water intrusion were taken into account by expressing the cumulative water influx in terms of various functions previously proposed in the literature. Formulas were developed and values calculated for the minimum deviations and minimal percentage deviations in the calculated volumes of oil in place from the average values, as could be obtained by suitable choice of the water encroachment and initial gas-cap volume parameters. The results show that the fluctuations in these calculated volumes are very insensitive to the values chosen for the rate of water intrusion and initial gas-cap volume, and hence cannot be safely used in discriminating between spurious values for these parameters and such as actually pertain to the producing reservoirs. Moreover, the exact form of the water-intrusion function seems to have but little effect on the fluctuations in the computed oil in place. Accordingly, it is concluded that the material-balance method does not of itself provide a satisfactory criterion for determining the basic physical unknowns of producing reservoirs or in making conclusive decisions regarding the production mechanism, unless independently established geological control data are available for eliminating unreasonable values for the reservoir parameters, even though they may still satisfy the material-balance formulas. If, however, from core or logging data the initial oil in place and the gas-cap volume can be established in advance, the material-balance formulas can be inverted to find the water intrusion. Moreover, by determining by such calculations the water-intrusion coefficient, the iuture production performance can then be predicted by the aid of the materiaI-balance formulas for specified operating conditions. This type of application may be of particular value in predicting the results of Pressure-maintenance operations. Introduction The evaluation of the forces acting upon an oil reservoir is a problem of considerable interest to the operator as an aid in determining the proper method of operation for the reservoir to obtain an optimum recovery of oil. In many pools, the nature and magnitude of the forces acting upon the reservoir remain unknown until an appreciable amount of ultimate recovery is obtained. To be of value to the operator, a reliable interpretation of reservoir performance should be available in the early life of the pool to permit an optimum plan of operation. Progress has been made in an understanding of reservoir behavior and the importance of the different factors involved. The material-balance method of estimating oil in place has been proposed as a tool in analyzing reservoir-performance problems.l The solution of such problems by this method ordinarily involves two or more unknown values relating to the nature of the reservoir, and the results

Jan 1, 1945

By C. M. Loeb, T. E. Norman

The use of ball, rod and tube mills for grinding ore, cement and other materials has grown so rapidly during the past forty years that the world&apos;s annual consumption of ferrous grinding media for these mills is now estimated to be between one half million and one million tons per year. Ferrous grinding balls constitute the major portion of this tonnage. Obviously they represent sufficient value to justify thorough studies of the factors governing their performance. The selection of grinding balls is governed principally by: I. Quality (wear resistance, impact resistance, soundness, and the like). 2. Sources of supply and delivered cost. 3. Grinding characteristics or efficiency in the ball mill. This paper deals principally with the quality of ferrous grinding balls. In the study of these factors certain data relative to the fundamental nature of ball wear in ball mills have been obtained. These data are also presented and discussed briefly. The Development of a Suitable Wear Test A study of the fundamental factors governing the quality of grinding balls has been hampered seriously by the fact that a competent test has, in the past, involved the purchase of several hundred tons of balls of a specific type which were then run in one or more ball mills for a period ranging from several months&apos; to several years&apos; duration. Often, during the period of test, it became necessary to change operating conditions or the character of the ore fed to the test mill with the result that the rate of ball consumption changed and the test figures became of little value. Under such circumstances, progress in the development of better grinding balls, has been necessarily slow. Economic factors and variations in the quality of balls produced by different sources of supply generally make it necessary for each mill operator to determine for himself the most suitable type of balls for his mills. In our own ball mill grinding operations at Climax, Colo., we were faced with this problem. After we had run a few large scale wear tests at considerable expense we decided to investigate the possibilities of a small scale wear test which would be capable of testing numerous types of balls within a relatively short time. The most important requirement of any test is, of course, that it give results which can be used to predict accurately the wear in full scale operations. It was known that Ellis and his associates1,2 had developed a method of testing grinding balls by small scale tests run at the Ontario Research Foundation. Ellis&apos; method of testing was used as a starting point in our investigations. In the course of our tests a number of modifications of the original method were found to be desirable so that, by an evolutionary procedure, a method of small scale

Jan 1, 1949