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By W. T. Roberts, N. G. Turner

A study of the fatigue properties of several grades of commercially pure titanium has established that the strain-aging process is of minor importance in the development of a fatigue limit and a relatively high fatigue strength ratio. Metallographic observations and damping measurements at room temperature indicate that striations are able to spread from grain to grain only at stress levels above the fatigue limit. This suggests that the fatigue limit represents the stress above which large-scale dislocation unlocking takes place. Fatigue tests on annealed material at - 60" and - 196" c showed that under conditions when a thermally activated diffusion process would be suppressed the fatigue limit is not eliminated. Prestraining at room temperature did not have a detrimental effect on fatigue strength at room temperature but a decrease was recorded at — 60°C. This is further evidence that initial dislocation locking is a important strengthening mechanism. TITANIUM and titanium alloys have S-N curves with a definite fatigue limit, and a high ratio of fatigue limit to UTS can be attained. Other materials which show similar fatigue characteristics are mild steel and some Al-Mg alloys. The fatigue limit of these materials has been associated with their strain-aging capacity. It is well-known that commercial-purity titanium contains interstitial impurities which can give rise to a sharp yield point, and a small strain-aging effect following static strain has been demonstrated.7 This type of aging reaction is differentiated from the dynamic aging process when aging occurs during plastic deformation, and which is generally observed at elevated temperatures. In a titanium at room temperature, dislocation locking is associated with the interaction of interstitial oxygen, nitrogen, and carbon atoms with dislocations. Ehr-lich has shown that the distortion produced by introduction of these atoms into the hcp lattice has no shear stress component and hence there is no interaction between the stress field and the screw component of a dislocation. Thus the dislocations as a whole are only weakly locked. It is clear that strain-aging effects in hcp a titanium will be much less pronounced than those observed in bcc iron and steel. In recent years, the attribution of the fatigue limit solely to strain aging has been questioned. It has been pointed out that a definite fatigue limit is observed at temperatures as low as -196°C in some titanium alloys,' and strain aging is not expected to be effective at this temperature. The role of initial locking of dislocations in determining fatigue behavior has been examined in low-carbon steel by Oates and Wilson. They showed that under conditions in which the aging potential is low the factors which control the buildup of local stresses and hence affect dislocation unlocking, e.g., grain size, are important. There are indications that other metals can have a definite fatigue limit with no established strain-aging capacity, an example being magnesium12 which has the same crystal structure as a titanium. The spread of plasticity from grain to grain in hexagonal metals may be more difficult than in cubic metals because of the limited number of slip systems in the former, and this may account in part for their fatigue behavior. The present work was undertaken to elucidate the relative importance of crystal structure, strain aging, and initial dislocation locking in determining the properties of commercially pure titanium when subjected to cyclic stressing. 1) EXPERIMENTAL METHODS Three grades of commercial-purity titanium were used and a material of lower interstitial content was prepared by melting high-purity Japanese sponge titanium (referred to as H.P. Ti). The compositions and typical mechanical properties of the materials are shown in Table I. Fatigue tests were made in push-pull (zero mean stress) using an Amsler Vibraphore machine at a frequency of about 160 cps. Two types of fatigue specimen were used—one with a waisted gage length for determination of S-N curves and the other with a parallel gage length for metallographic studies and damping measurements. After careful machining and mechanical polishing, all specimens were electropolished prior to fatigue testing. The electrolyte consisted of 10 parts methyl alcohol, 6 parts 2-butoxyethanol, and 1 part perchloric acid (SG 1.54) and it was maintained at a temperature of -10" to -20°C during polishing. Tests at room temperature were normally carried out with the specimen immersed in a silicone oil bath which could be heated for elevated-temperature tests.

Jan 1, 1969

By J. B. Newkirk, W. G. Martin

Oxidized cobalt powder is known to have a magnetic hysteresis loop which is asymmetric with respect to the magnetization axis. The experiment described herein shows that the orientation relationship between the basal plane of hexagonal cobalt and the oxide which forms upon it at 400°C is {111}ux//{100.1 }co <110>ux//<11.O> This orientation relationship allows a magnetic interaction between the antiferromagnetic oxide and the ferromagnetic substrate which could account for the offset hysteresis loop. Oxidized nickel powder has a symmetrical hysteresis loop and so is apparently not influenced by any magnetic interaction between metal and oxide. The orientation of the oxide (cubic) was found to be identical with that of the nickel substrate when the oxide forms on a polished surface parallel with {111} Ni. IN 1956 W. H. Meiklejohn and C. P. Bean discovered that fine particles of cobalt which had been prepared in a certain way have a magnetic hysteresis loop which in a strong field is asymmetric relative to the magnetization axis.&apos; The cobalt powder exhibited this unusual magnetic property only after it had been oxidized in air or oxygen; it lost the shifted hysteresis loop when the oxide was reduced in hydrogen. X-ray and neutron diffraction&apos; experiments showed the presence of cobaltous oxide (COO) and hexagonal cobalt in samples exhibiting the biased hysteresis loop and specifically showed no indication of any other compound with the exception of mercuric oxide.* The magnetic hysteresis loop becomes symmetrical above the Nee1 temperature (paramagnetic state) of COO. Therefore, it was concluded that the anomalous magnetic behavior is associated with the influence of cobaltous oxide upon the metallic cobalt. It has been proposed that crystallographic coherency may exist between the cobalt and a plane of some antiferromagnetic material which has unbalanced spin distribution and sufficient magnetic anisotropy to hold its spin in the direction which existed when the specimen was cooled. COO has these properties. Therefore, Roth&apos; has suggested that cobaltous oxide may form with a {111} plane parallel and coherent with the basal plane of the hexagonal cobalt metal and proposed that, as consequence of the antiferromagnetic interaction between COO and the underlying cobalt, the magnetization direction in oxidized fine Co particles may be ro-lated from the easy c-direction.2 Such a relationship, he proposed, would explain the observed magnetic effect in oxidized cobalt powder. The main purpose of this study was to determine the orientation relationship, if any, between the basal plane of cobalt and the oxide which forms upon it. Attempts to produce a film of COO which was strong enough to be handled were not successful. However we did succeed in making a film of CoCo2O, which was strong enough to be removed from the cobalt substrate and mounted on an electron-microscope grid. Because of the close structural similarity of COO and CoCo2O, we believe the orientation relation found for CoCo2O, on cobalt probably also holds for COO on cobalt. The epitaxial relationship of NiO and Ni also was investigated. To date no shifted hysteresis loop has been observed with nickel powder. However, the similarity of atomic array in cobalt and nickel leads to the prediction that a {111} of NiO may be parallel with a (111} of nickel. Experimental Method Cobalt-Cobalt Oxide—A coarse-grained specimen of a (hexagonal) cobalt was prepared by allowing a large crystal of fee cobalt to transform slowly at 400°C. The crystal was then cut to expose a surface parallel with the basal plane. A back reflection Laue X-ray photograph showed that the 00.1 plane was within 2" of the cut surface. The surface was mechanically polished and then electro polished in 85 pet orthophosphoric acid after which the crystal was held for 30 min at 400°C in air. During this heat-treatment the surface darkened slightly due to the oxide film which formed. The film was not thick enough to give an X-ray diffraction pattern, even by a glancing-angle technique. Glancing-angle electron diffraction was not possible either, owing to the interference of the electron beam with the high magnetic fields which exist at the 00.1 surface of the cobalt. However, it was possible to make an electron-diffraction photograph of the oxide film by stripping it from the cobalt substrate using the method described later. By maintaining reference marks carefully, it was possible to preserve the orientation relationship between the stripped film and the substrate on which it was formed. The oxidized surface of the crystal was first covered with a 1 pet solution of collodion (cellulose nitrate) in amyl acetate. When the film was dry, small rectangles were scored on the surface with a needle point. The specimen was then repolished

Jan 1, 1959

By Martin E. Chenevert

The early work of Terzaghi1 showed that the true stress state of a rock can be expressed by the principle of effective stress. This principle states that effective stress is equal to total applied stress minus the pore pressure. Since the introduction of this principle, a great effort has been made to measure the pore pressure of rocks so that the true stress state can be determined. For clean, permeable sandstones, it is usually found that the effective stress principle can easily be applied. Direct measurement of the pore pressure is achieved with a hydraulic pressure device and the effective stress state thereby computed. However, for fine-grained rocks which contain large amounts of clay (referred to herein as shales), pore pressure measurements are usually quite difficult because of the adsorptive forces of the clay platelets, which produce negative internal pressures. No suitable device is known for measuring internal pressures of dry shales; the effective stress approach is therefore not feasible and data are usually presented in another form. As an example, data from compressive strength tests are presented as a function of rock wetness, rather than effective confining stress. The work of Belopoloskii2 and Colback and Wiid3 are examples of such data. It was pointed out by Lambe and Whitman4 that a better way must be found to express the effective stress of argillaceous rocks. The information presented herein is an attempt to fill that need. Various authors have been able to measure moderate negative pore pressures (0-240 psi) within rather wet, argillaceous rocks by means of various pore pressure devices. In 1961 Lambe5 resented information which shows that pore pressures in argillaceous rocks are indeed negative ; he presented values of suction pressure as low as - 14 psi. Likewise,

Jan 1, 1970

By R. R. Unterberger

Three different physical techniques have been used to see through or probe into rocks, so miners might know what is ahead or overhead. These are radar, sonar, and a unique type of sonar called nonlinear sonar. Five radar systems have been developed. The highest frequency used is 4300 MHz for detecting small fractures at close range. This gives the best resolution. For longest range (over 2000 m, or 6560 ft) we use the 30 MHz radar for finding faults ahead of mining or ranging to salt dome flanks. Two types of salt, dome and bedded, are recognized. Radar works well in dry (dome) salt, but not in bedded salt which contains small amounts of water. The dipole moment of water absorbs energy from the radar. Thus was born the 30 MHz radar system and sonar probing systems. These can probe to 100 m (328 ft) even into wet salt. All probing systems measure data in time, which are converted to distance by measuring the time of travel of radar or sonar through salt pillars of known thickness. Ranges of probing in salt are from less than 1 m (3.3 ft) to more than 2000 m (6560 ft). Uses of radar and sonar probing in mines include mapping the top of salt above a mine; mapping salt dome flanks; finding impurities in salt such as anhydrite, sandstone, or potash stringers; locating old boreholes in salt pillars; locating fractures in salt; and finding faults or water zones ahead of mining.

Jan 1, 1985

By R. S. Shoemaker

Mines are closed for two reasons; exhaustion of ore or insufficient price for the mineral. On the other hand, the reopening of an old mine can be the result of any one of three events; the discovery of more ore, a sudden rise in the price of the product or the use of a new low-cost method of mining or milling the ore. Examples of the latter would be the open-pitting of an orebody previously mined underground as recently happened at Tyrone, N.M., or the adoption of acid leaching of an old pit as has been done at Miami, Ariz. The unique native copper mines of the Keweenaw Peninsula of upper Michigan have not been so fortunate. These deposits, which were first worked by prehistoric Indians, have been mined continuously from the early 1840&apos;s to 1968 when the last mines of Calumet and Hecla were closed and the Ahmeek mill. still using eight Nordberg steam stamps, was shut down. There are two types of deposits from which native copper is obtained; amygdaloid, which is a lava flow, and conglomerate, a sedimentary deposit of sand, rock fragments and pebbles cemented together. "In the amygdaloid, the copper is disseminated, or distributed much like the raisins in a cake; but in the rich Calumet conglomerate, the copper is more like a malleable rope or thread cementing the pebbles together." (C. Harry Benedict. Red Metal: The Calumet and Hecla Story, (Ann Arbor, Michigan, 1952), p. 42.) These deposits produced almost all of the copper used by the North in the Civil War and were substantial contributors to the copper needs of the United States in both World Wars. Some were mined to depths of as much as 9500 ft along the dip of the vein structure and 7500 ft vertically. Few of the mines ever really became worked out, but became uneconomical because of depth, pinching of veins or grades which dropped to about 1%.

Jan 5, 1972

By Alvin Kaufman

The industrial revolution of the early 1800&apos;s and the subsequent remarkable progress in raising American living standards are based not only on a constantly improving technology but on an ever increasing use of energy from mineral fuels and waterpower. Industrial nations require inexpensive energy sources in order to grow. The more complex the economy, that is, the more intensive the processing of raw materials, the greater the energy needs of that economy. As a result of the current international economic expansion, the worldwide search for sources of low-cost energy has accelerated. As a part of this search there is considerable interest in the potential for commercial development of geothermal power, particularly abroad and in the western United States. This interest is indicated by the fact that 40 exploratory wells have been drilled in the California thermal areas alone during the 1955-62 period. Of these, 24 were drilled in The Geysers, Casa Diablo, and Salton Sea areas.

Jan 9, 1964

By E. B. Swanson

There is only one way to transport natural gas and that is by pipe lines. In the past few years, these lines have been extended rapidly into areas which previously had been served mainly by solid and liquid fuels. In the subject given me, this extension is referred to as an invasion, which implies a rather forceful entry. Whether or not such an implication may be applied to recent natural-gas developments is unimportant. It is the fact of the extension, not its definition, which is important. For centuries, natural gas has been utilized for various purposes in many parts of the world. It was the foundation of fire worship at Baku. The Chinese used it for the evaporation of brine in salt manufacture. In our country, its history seemingly dates back 110 years to the vicinity of Fredonia, N. Y., where seepage gas was assembled and used for lighting purposes. A few years later, a %inch pipe was laid to a lighthouse on Lake Erie, and the early records of the Lighthouse Service tell of the difficulties surrounding this use. With the discovery of oil in Pennsylvania, there followed further development; the town of Titusville was piped with natural gas and, some few years later, gas was made available for manufacturing plants adjacent to the oil fields. For more than a half century, the industry was concentrated in the

Jan 1, 1932

By W. H. Meyer

During the seventeen years Fairchild has been making aerial surveys and aerial photographic equipment many changes and improvements have been made in the equipment and in the technique of using it. Aerial photographic operations have been developed from the crude methods and apparatus of wartime to a science upon which exact engineering calculations can be based. In the early days there was no airplane specially designed to meet aerial photographic requirements. One type of camera was used in all types of operations. Projects were made to conform to the products we could make and deliver. Obviously this entailed definite limitations. We now have airplanes designed specially for aerial photographic operations in accordance with the conditions encountered in actual service experience. We have cameras for every photographic purpose and our laboratory technique and equipment have been developed to the point where it is possible to make contour maps from vertical aerial photographs with contour intervals as close as five feet. Therefore, the selection of equipment now can be made in accordance with the time at our disposal, the justifiable cost, the scale desired, and the general requirements of the client. This does not mean, however, that arbitrary deliveries can be set for aerial photographic products. The factors in each project vary and each job must be considered in accordance with the factors involved. This accounts for the fact that products of aerial surveys may readily vary from $1.25 to $200 a square mile. Sherman M. Fairchild became interested in the design of a radically different aerial camera during the war. At its close he was about ready to demonstrate his design to the War Department. By 1920, he was able to bring out his first completed model. It had a number of radical features, one of which was the first dependable high-speed between-the-lens shutter, which makes for accuracy in aerial photographic work. Another feature was the use of metal throughout, eliminating the wooden parts that had been employed in wartime cameras. Another feature was the interchangeability of parts.

Jan 1, 1937

By Paul Averitt

The U. S. Geological Survey has been actively engaged in work on coal for more than 50 years. During this long period we have released more than 300 publications containing information about coal and coal reserves, including details on the thickness, distribution, and quality of coal, and the structure and stratigraphy of the coal-bearing rocks. We have also cooperated with state surveys on many similar publications. For many areas these reports are the only reliable published data on our resources of coal. During the last several years we have substantially increased our activities above the wartime low. We now have field work in progress, or reports in preparation, on 13 detailed mapping projects distributed as follows: 1. Pennsylvania anthracite field 2. Casselrnan Basin, Md. 3. Leslie County, Ky. 4. Deep River field, N. C. 5. Coosa field, Ala. 6. Powder River field, Mont. 7. Spotted Horse field, Wyo. 8. Yampa field, Colo. 9. Paonia field, Colo. 10. Trinidad field, Colo. 11. Durango field, Colo.

Jan 1, 1949

By J. T. Crawford

Although nearly 10 pct of the total tonnage of coal produced annually within the United States is handled by bulk freighters on the Great Lakes, very little of the detail connected with it has been published other than occasional newspaper stories and publication of tonnage statistics. Of the total tonnage floated on the Lakes each year some 10,000,000 is stored and distributed from the port of Duluth-Superior, at the western end of Lake Superior commonly known as the Head of the Lakes. This port has the largest single area concentration of coal docks in the world. Since this area contains the largest ore docks, the largest movable material handling bridge, the largest and highest grain elevator and the largest coal bri-quetting plant in the world, it is entirely fitting and proper that here also should be located the largest coal dock and what we believe to be the world&apos;s largest clam shell. Of the sixteen coal docks operated by ten companies, five are owned and operated by the North Western-Hanna Fuel Co. which has two docks on the Superior, Wis., waterfront and three docks in Duluth, Minn. It is with these five docks that we are primarily concerned, General History In the summer of 1871 a small sailing vessel entered the harbor of Duluth-Superior with the first commercial coal cargo. All the coal brought up that first year did not amount to more than 3000 tons. During the year 1877 the first dock equipped for handling coal was built in Duluth. Coal receipts increased to 52,785 tons in 1879 the first year for which an official record was kept. Since then the volume of water-borne coal to the Head of the Lakes steadily increased to a maximum of 12,688,321 tons in the year 1923. This tonnage was nearly equalled in the year 1927 and the next highest tonnage recent year was in 1946 when 10,105,703 tons were unloaded. The average annual bring-up over a ten year period 1938 to 1947 was 8,605,231 tons. Approximately 30 pct of the coal unloaded at the Head of the Lakes is handled over the docks of the North Western-Hanna Fuel Co. Competition of other fuels coupled with expansion of coal fields in the mid-west have held coal receipts for Duluth-Superior at a relatively constant figure during the last eight years although the total tonnage of coal floated on the Great Lakes has more than doubled in the past 25 years. From the shovel and wheelbarrow method of unloading early cargoes to the horsepowered windlass derrick with a wooden tub was but a short step. The first movable coal handling, steam operated,

Jan 1, 1949

By C. P. Lawhon, J. P. Simpson, W. M. Evans

Recent efforts to design drilling fluids for increased drifting rates have confirmed some laboratory results of other investigators, but have also produced additional data that should be considered. These data were obtained under controlled test conditions using a microbit drilling machine. Clays and some polymers have previously been reported to cause reduction in drilling rate. Recent data have shown that under laboratory conditions, suspensions of a single day or polymer have sometimes given faster drilling rates than when water was used. Measurements have been made of clay suspensions and polymer suspensions comparing filtration (I) under API conditions, (2) while drilling with temperature of 150F and differential pressure of 1,000 psi and (3) under dynamic conditions after drilling. Some correlation between instanraneous filtration (white drilling) and drilling rate has been observed. INTRODUCTION Several papers have been presented that related drilling fluids to penetration rate. Generally, it was found that a decrease in the solids concentration resulted in significant increases in the drilling rate. Of course, this change also resulted in a decrease in the viscosity of the drilling fluid.&apos; Conclusions from investigations by this laboratory are in agreement. Data have shown that of the simple mud measurements commonly made at the drilling rig (density, plastic viscosity. yield point, API filtrate and total solids), only the density and total solids have a significant relationship to the drilling rate in Berea sandstone when attempting to correlate a single mud property individually.&apos; More recent drilling rate experiments have been designed to study (1) effects of individual clays and polymers on drilling rates in Berea sandstone and Lueders limestone, (2) the relationship between drilling rate and dynamic filtration as measured after drilling and (3) the relationship between drilling rate and dynamic filtration as measured during drilling. Data show that drilling rates are dependent upon type and concentration of particles, type of formation and filtration of the individual fluids while drilling. Mud pressure: pressure of drilling fluid as measured after leaving the drilling chamber (Fig. 1). This is taken to be approximately the mud pressure just past the bit and at the face of the formation. Terrastatic pressure: pressure representing weight of overburden. Formation pressure: pressure of formation fluid as measured at outlet of drilling chamber (Fig. 1). This is taken to be approximately the pressure of fluid in the interstices of the formation. Differential pressure: difference between the mud pressure and formation pressure. LABORATORY EQUIPMENT AND TESTING PROCEDURE The drilling equipment was described in two previous publications."&apos; Main components are a drilling chamber, filter-heater, rotary drive and variable-speed circulating pump. Auxiliary pumps supply pressure boosts for the mud, terrastatic and formation pressures. All equipment is designed for 15,000 psi and 500F. Capacity of the circulating system is approximately 7 gal. The mechanical design was facilitated by moving the rock down onto the bit. Data collected with this design should not differ from that obtained by a normal design where the bit moves into the rock. Drilling fluid is pumped through 50 ft of ID pipe coiled in an oil bath, enters the rotary shaft at a right angle and is pumped through the jets on the bit (Fig. 1). Most of the drilled solids are extracted by a screen mounted in the circulating system on the suction side of the pump. Data reported in this paper were obtained by controlling these parameters: mud pressure, 5,000 psi; formation pressure, 4,000 psi; terrastatic pressure, 5,000 psi; force on bit, 1,000 Ib; formation, Berea sandstone and Lueders limestone; flow rate, 7 gal/rnin; bit, 11/4-in. diameter with two 0.078-in jets; mud temperature. 150F; and rotary speed, 60 rpm. Mud pressure was controlled at 5,000 psi, thus giving a differential pressure of 1,000 psi even though the fluid densities varied. Cores of 3%;-in. diameter and 8 in. long were selected from quarry blocks to provide some control of grain size distribution, permeability and porosity. A 2-in. section was cut off each core and a I -in. diameter plug was taken from this section. Permeability to 5 percent by weight sodium chloride solution was determined and the large cores were

By Francis Lucas

ANY metal which contains even a small percentage of aluminum possesses certain peculiarities of appearance and properties which are exhibited both when the metal is melted and after it solidifies. Pure aluminum, or an alloy containing a small proportion of aluminum, can be melted without flux-except for a layer of charcoal-because a film of aluminum oxide and metal forms at the surface of melted aluminum. Although very thin, this film is air-proof, and it prevents the metal underneath from oxidizing. This oxidized film does not move easily on account of its toughness and high surface tension. One very important point in connection with this process of still casting has not been strongly enough stressed, namely, that the same kind of surface film with the same peculiarities forms over the surface of all melted alloys that contain even a small proportion of aluminum. Experienced foundrymen know how desirable it is to cast aluminum under its "skin" or-under the surface of the film which tends to remain still. In the case of red copper, when in fusion, the surface shows pure copper only. This is due to the fact that liquid copper constantly absorbs the copper oxide which forms on the surface. By closely examining melting copper the oxide can be seen dissolving in the bath, and going into solution just as pulverized sugar dissolves in water. When copper is cast in the open, either in wire bars or cakes, the surface of metal exposed to the air is covered by a film of black, oxide that cannot be absorbed by the metal.

Jan 1, 1927

By Y. C. Liu

IN the study of the rolling recrystallization of face-centered-cubic metals, a most unusual observation is the frequent occurrence of a sharp re-crystallization texture of cube orientation. Although the general conditions under which this texture occurs are known,2,3 its origin is still not well understood. Based on the observed relationship between the {110}<112> deformation texture and the (113}<211> recrystallization texture, regardless of the effect of alloying elements2,4,5 or the symmetry of the deformation texture,&apos; there is a strong indication that a specific component of the deformation texture is related to a specific component of the recrystallization texture. Using the rotational reorien-tation relationship as a means of correlating the deformation and recrystallization textures, it was proposed that the deformation component which related the cube texture has {358)<523> indices."&apos; The investigation reported here was undertaken to seek experimental evidence for the validity of this proposition. Experimental Procedure Two copper single crystals having an initial orientation within 2" of (358) [523] indices were prepared in the manner described in Ref. 5. The purity of the copper was between 99.94 and 99.97 pct. The original dimensions of the crystals were as follows: specimen A, 0.465 in. thickness, 0.844 in. width, and 0.955 in. length; specimen B, 0.535 in. thickness, 1.120 in. width, and 1.36 in. length: Rolling was done on a laboratory rolling mill according to the following schedule: 0.010 in. per pass to 50 pct reduction in thickness, 0.005 in. per pass to 70 pct reduction inthickness, 0.002 in. per pass to 85 pct reduction in

Jan 1, 1958

By E. S. Machlin, S. Weing

GRAIN boundary stress relaxation has been the subject of several investigations in recent years, but as yet the phenomenon is not well understood. One of the major difficulties has been the lack of a sufficient amount of data with which to evaluate any proposed mechanism. Little information is available on the effect of small amounts of substitutional solutes on grain boundary stress relaxation. It is with this important phase of the problem that this investigation is concerned. The influence of substitutional solutes on grain boundary stress relaxation has been recently investigated in copper by Pearson: and in aluminum by Dorn et al.&apos; Pearson studied the effect of zinc, gallium, germanium, and arsenic on the relaxation peak of OFHC copper.* The pure OFHC copper decreased the peak intensity and a second peak appeared at a higher temperature. This latter peak was termed the alloy grain boundary peak. At the lowest binary concentration studied, approximately 1 atomic pct, the primary peak was almost completely obliterated. Pearson found that the activation energy calculated from the alloy grain boundary peak for all solutes, irrespective of the concentration, was 44,000 cal per mol. Pearson concluded that the increase in activation energy from 33 to 44 kcal per mol is not continuous but abruptly changes from the lower to the higher value. As no attempt was made to investigate the intermediate range of concentration and hence calculate the possible variation of the activation energy for the initial grain boundary peak, this conclusion is hardly valid. In contrast to these results, Dorn et al. studied the effect of zinc, silver, copper, germanium, and magnesium on the grain boundary stress relaxation of aluminum. No change in the energy of activation was observed for binary alloys of the flrst four solutes, but a linear increase was found for increasing concentration of magnesium. Saturation was not found up to the maximum of 1.6 atomic pct. The energies of activation were obtained by plotting the horizontal displacement of the dynamic modulus curve vs temperature for two vibrational frequencies. As the modulus is proportional to the square of the frequency, this requires the measurement of the torsional frequency over a range of temperature. However, the technique does not lead to an unambiguous interpretation of the grain boundary

Jan 1, 1958

By Y. Nakada, U. F. Kocks, B. Chalrners

THE orientation dependence of work hardening has previously been studied over the entire range, i.e., including special orientations of high symmetry, in aluminum1-3 and silver.* The differences between various orientations are substantial, and the trend is the same in all fcc crystals. However, there are quantitative differences in behavior between aluminum and silver at room temperature, particularly in the (100) orientation. While many experiments on gold have been reported,5&apos;9 none included the special orientations. We therefore undertook tension tests on gold crystals of the axial orientations (100),(110), (Ill), (211), and, as a representative of single slip, one whose Schmid factor was 0.5 (hereafter referred to as m = 0.5). Single crystals of dimensions 1/4 by .1/4 by 6 in. were grown from the melt1&apos; at a rate of 4 in. per hr, using gold of 99.99 pct purity obtained from Handy and Harman. A growth rate of 1/8 in. per hr, or a purity of 99.999 pct,ll produced no difference in results. The crystals were annealed at 1000°C in air for 24 hr and furnace-cooled down to room temperature, after which they were electro-polished in a solution of potassium cyanide (40 g), potassium ferrocyanide (10 g), soda (20 g), and enough distilled water to make 1 liter of solution, at a current density of 0.02 amp per sq mm. After 2 or 3 hr, a very smooth surface was obtained by this method. Nine m = 0.5, two (loo), one (110), three (Ill), and one (211; crystals were tested at room temperature in a floor-model Instron machine at a tensile strain rate of 0.5 pct per min. The accuracy of the stress measurement was k10 g per sq mm up to 500 g per sq mm, k2 pct for higher stresses. The strain measurement was accurate to t2 pct. The scatter of stress at a given strain among the crystals of the same orientation was small, *5 pct being the largest. The representative stress-strain curves for various orientations are shown in Fig. 1. Table I summarizes the work-hardening parameters as used by seeger.12 Results of other investigators are also included in this table for comparison. There are no previous data for the corner orientations. Values for m = 0.5 crystals agree fairly well with those of Berner. Tm is defined as the stress at which the stress-strain curve begins to deviate from linearity of Stage 11. However, in practice this is a very difficult value to estimate because each investigator has a different idea of linearity. Therefore, the comparison with the values of other investigators may not be valid. In the present experiment, (100) crystals had the highest 111, followed by (111) crystals. The work-hardening rate in Stage I1 was highest for the (111) crystal followed by the (100) crystals. Our value for 0x1 of m = 0.5 orientation agrees very well with those of other investigators. 1) Single-Slip orientation (m = 0.5). These crystals were oriented so that the primary-slip vector was contained in one side face. The dimension perpendicular to this side should then not change if single slip indeed takes place. Within the accuracy of measurement, this dimension did not change during the deformation. Since the accuracy is k0.2 pct, the amount of secondary slip is less than 0.7 pct of the slip on the primary-slip system at 30 pct tensile strain. This is in conformity with the results obtained by Kocks" for aluminum crystals. The tensile axis moved toward (211) during the deformation. Slip bands, Fig. 2(a), were very fine and closely spaced. Some deformation bands were observed. There were no clear-cut cross-slip traces such as the ones observed on aluminum m = 0.5 crystals. 2) (111) Crystals. The orientation of the tensile axis was stable during the deformation. From this observation, one can deduce that at least three slip systems must have operated, and probably all six because the remaining three all have cross-slip relation to one of the first three.&apos; It was very difficult to observe the slip markings. Consequently, we could not confirm by this method that six systems were operative during the deformation. At high strains (above 50 pct shear strain), this orientation had the highest stress-strain curve. At 80

Jan 1, 1964

By G. R. Lehman

The Inspiration Consolidated Copper Co. had an orebody at Miami, Ariz., of close to 100,000,000 tons of low-grade copper ore, and the method of mining this ore most profitably was of great importance. The selection of a method was practically limited to a "top-slicing," a "shrinkage-stope" or a "caving" method. The "top-slicing" method would give a high extraction of the developed ore, at a high mining cost, and the "shrinkage-stope" or "caving" methods a lower extraction of the developed ore, at a lower mining cost. Ore-Drawing Tests To decide on the method to be used it was necessary to know about what extraction of the ore could be obtained by the "shrinkage-stope" or " caving " methods. As no definite information regarding the,question was available at the time, C. E. Mills, the general manager, thought that some information could be obtained by experimenting in drawing ore, covered with capping, from an experimental box. Some work had already been done along these lines by W. C. Browning for the Inspiration Copper Co. and by myself for the Live Oak Development Co. The idea was to represent as nearly as possible, in the experimental box, the conditions within an area of caved stopes of caved ore all ready for drawing. That is, the area was supposed to represent a semibroken mass with the capping above it in the same condition and ready to follow the ore downward as it was drawn out of the chutes under the ore. To represent the above condition, in the experimental box, crushed ore from the mine was placed in it to a given height, and red barren capping from the mine was placed on top of the ore. The Experimental Box The experimental box shown in Fig. 1 was made of wood and glass. The glass was used for the sides so that the drawing action of the outside row of chutes could be seen and noted, the latter being cut in the center by the glass sides. The length of the box was 30 in., width 20 in. and the

Jan 1, 1917

By J. S. Dodge, I. M. Krieger

The laminarturbulent transition was studied for monodisperse rigid polymer latices as functions of particle diameter and concentration at several tube diameters. Breaks in the graph of friction factor US Reynolds number were used to characterize the transition; rates of shear were sufficiently high so that Newtonian behavior at the high shear limiting viscosity could be assumed. No abnormal behavior was noted at concentrations below 30 volume percent. At higher concentrations, suppression of turbulence was observed with critical Reynolds numbers rising to as high as 5,500 at 50 volume percent. No definite effect on the transition was noted due to variation of particle size or tube diameter. The type of surfactant used to stabilize the latex was found to have an important influence on the critical Reynolds number. INTRODUCTION For some polymer solutions and solid-in-liquid suspensions, the transition from laminar behavior to turbulence in pipeline flow has been reported to take place at unusually low1-5 and in some cases at higher than normal6,7 critical Reynolds numbers. Extreme values of critical Reynolds numbers (NRe*) have been found to range from 1 to 6,000, as opposed to the values of 2,000 to 3,500 which are obtained for ordinary liquids. Observations have also been reported of drag reduction in fully developed turbulent flow, i.e., a decreased value of the friction factor in the Reynolds number-friction factor plot6*10-14 in colloidal and polymeric fluids. In some cases, turbulence suppression (unusually large values of Nre*) was noted to occur preceding the drag reduction,6 while a normal transition was noted in other cases of drag reduction.14 To relate the occurrence of turbulence suppression and drag reduction to the molecular or particulate structure of the fluid, it is desirable to characterize the structural variables with some precision. For most colloidal dispersions and polymeric fluids, this is very difficult; particle sizes, shapes and stiffnesses may vary over wide ranges in the same sample. Recently, however, a colloidal fluid has become available which consists of rigid spherical particles of highly uniform diameter dispersed in a simple Newtonian liquid. These are monodisperse polymer latices, prepared by carefully controlled emulsion polymerization reactions. The purpose of this research was to study the transition to turbulence in these well-characterized colloidal fluids as a function of concentration, particle diameter and tube diameter. Typical flow curves of latices of high solids content are shown in Fig. 1. While these curves were obtained with monodisperse latices, the general shape of the curve is also typical of a polydisperse latex. It is observed that a shear-thinning region occurs for low to moderate rates of shear. At sufficiently high shearing rates a limiting Newtonian viscosity is reached. The viscosity µ diminishes with decreasing volume fraction 4 at all shear rates. For 4 less than 0.25, latices are Newtonian at all rates of shear.15 An increase in average particle size (at a given extends the Newtonian viscosity region to lower rates of shear. A third factor which influences the

By Earl W. Palmer, Cyril Stanley Smith

A study of the precipitation-hardening of copper steels1 led the authors to investigate malleable iron containing copper, for the low-carbon ferritic matrix in malleable iron should lend itself admirably to precipitation-hardening. It was soon found that in addition to rendering malleable iron susceptible to improvement by precipitation-hardening treatments, copper has another potentially useful effect as an accelerator of graphitization. Brief mention of these effects was given in a general paper by Lorig and one of the present authors2; the present paper gives further details on the graphitization and precipitation-hardening effects only. After the completion of this work a paper by L. Lykkin3 appeared, confirming the authors&apos; conclusions regarding graphitization. Material Used After some preliminary heats had been made in the laboratory to determine the effect of copper, several castings from commercial air-furnace heats were obtained, and data from these alone are given here. Part of the metal was poured directly and part was treated in the ladle with the desired amount of copper before pouring. Green-sand molds were used, each holding two tensile test pieces of the form adopted by the Malleable Iron Research Institute, or two bars for graphitization studies, 5/8 in, in diameter and 9 in. long, fed through two enlarged sections equidistant from the middle and ends of the bars. Risers of suitable size insured sound castings. Tensile tests were made on the castings after commercial mallealleizing and after special heat treatments to be described. The analyses of the white irons are given in Table 1.

Jan 1, 1935

By Cyril Stanley Smith, Earl W. Palmer

A study of the precipitation-hardening of copper steels1 led the authors to investigate malleable iron containing copper, for the low-carbon ferritic matrix in malleable iron should lend itself admirably to precipitation-hardening. It was soon found that in addition to rendering malleable iron susceptible to improvement by precipitation-hardening treatments, copper has another potentially useful effect as an accelerator of graphitization. Brief mention of these effects was given in a general paper by Lorig and one of the present authors2; the present paper gives further details on the graphitization and precipitation-hardening effects only. After the completion of this work a paper by L. Lykkin3 appeared, confirming the authors&apos; conclusions regarding graphitization. Material Used After some preliminary heats had been made in the laboratory to determine the effect of copper, several castings from commercial air-furnace heats were obtained, and data from these alone are given here. Part of the metal was poured directly and part was treated in the ladle with the desired amount of copper before pouring. Green-sand molds were used, each holding two tensile test pieces of the form adopted by the Malleable Iron Research Institute, or two bars for graphitization studies, 5/8 in, in diameter and 9 in. long, fed through two enlarged sections equidistant from the middle and ends of the bars. Risers of suitable size insured sound castings. Tensile tests were made on the castings after commercial mallealleizing and after special heat treatments to be described. The analyses of the white irons are given in Table 1.

Jan 1, 1935

By W. O. Philbrook, C. W. McCoy

The reduction of chromous oxide from lime silica alumina slags by carbon-saturated iron behaves as a first-order process having a rate of 0.001 grams Cr min 1 cm 2 (pct Cr ) , substantially independent of slag composition and temperature over an important range for iron smelting. The equilibrium ratio (pct Cr)/[pct Crl is below 0.04 for slags having lime-silica ratios above 0.6. MANY studies have been conducted on chromium in slag-metal systems under oxidized conditions. The Purpose of these investigations has been twofold; namely, (1) to determine those conditions which lead to greater chromium recovery in electric-furnace and open-hearth practice, and (2) to determine the nature of oxide inclusions and de-

Jan 1, 1959