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By E. L. Mann

Asbestos is the generic name given to a group of fibrous mineral silicates found in nature. They are all incombustible and can be separated by mechanical means into fibers of various lengths and cross sections, but each differs in chemical composition from the others. The commercial grades of asbestos consist of a spectrum of lengths and sizes and are not definitive as are most organic fibers. It is generally recognized that there are two main groups of asbestos. The first only contains the fibrous serpentine called chrysotile and comprises about 94% of the world production of asbestos. The second group contains five minerals in the amphibole series-crocidolite, amosite, anthophyllite, tremolite, and actinolite. The latter two have no commercial importance. Properties Physical The structures of asbestos fibers have been studied intensively over a number of years. X-ray diffraction patterns have been used as a means of identification and classification. Low angle X-ray scattering techniques have shown that chrysotile fibers are "hexagonally close packed" and parallel to each other, having cross-sectional diameters varying from 18Å to 300 Å units, while the amphibole fibers are many times larger in cross section, have considerably smaller surface areas, and the fibers are less symmetrical than those of chrysotile. Electron micrographs of the more common types of asbestos are shown in Figs. 1-4. Fig. 1 illustrates the softness and flexibility of chrysotile which make it suitable for textile-type products. For a number of years there was considerable controversy over the exact nature of chrysotile fiber, but the photographic evidence in Figs. 5-7 clearly show that it is tubular in structure. The curvature is the result of the mismatch in the dimensions of the silica [Si2O5] and brucite [Mg(OH)2] layers which are on the inside and outside, respectively, of a double sheet. This curvature had been predicted by Pauling (1930) years ago based on the molecular dimensions of the two component structures. In contrast to this, the structure of the amphiboles consists of two ribbon chains based on Si4O11 units separated by a band of seven cations with two hydroxyl groups attached to

Jan 1, 1983

By L. L. Swift

AT the present time there are four base metals being used for automo-tive bearing alloys. Of course there are numerous variations in the amounts of alloying elements added to each base metal and nearly all of these alloys have the conventional, if not classical duplex structure; that is, they are composed of a hard constituent embedded in a soft matrix. The well-known theory is that the former will wear well, while the latter will be plastic enough to allow the bearing to be broken in and conform to the contours of the shaft. The requirements of the modern bearing have been most aptly described by W. M. Corse: In order to meet the engineering demands of today a good bearing metal must be able to carry the weight of the shaft and stand up under steady or suddenly applied loads, or even blows in some types of service. A certain amount of plasticity is desired to compensate for minute irregularities in the shaft or bearing surface, and to permit yielding, thereby avoiding dangerous stresses in bearing and shaft and pre-venting overheating and rapid wear of parts. Less plasticity is required in a bearing metal if the surfaces of bearings and journals are machined accurately, aligned, and kept in alignment. It is desirable, of course, that a bearing metal have a low coeffi-cient of friction. Under most operating conditions the friction depends on the unit pressure of the bearing, the speed, the temperature, and the properties of the lubricant. A good bearing metal must have a low rate of wear to reduce the necessity for frequent replacements, and adjustment of the bearings. It must wear more rapidly, however, than the journal or shaft running on it, because replacement of the journal or shaft is more difficult and costly than replacement of the bearing.1 The hardness of the bearing alloy is a property closely related to several of the foregoing. With a duplex microstructure, the measure-ment of hardness with any of the usual commercial devices means little. The Bierbaum method of measuring the hardness of the individual constituents was developed to fill this need.

Jan 1, 1938

By Ernest G. Enck

"The Rockets' Red Glare" of the Fourth of July is produced by strontium compounds. However, strontium has a number of less spectacular uses; i.e. in, or in connection with, the manufacture of ceramics, caustic soda, glass, railway and truck signal flares, beet sugar and steel. The principal ore of strontium for use both as the mineral and for production of compounds is celestite (SrSO4). This mineral varies in color from white to pink or blue depending on presence of impurities. It has a hardness of about 3.5 and specific gravity of 3.9. It is brittle and has perfect basal and prismatic cleavages. The high grade ore is obtained from England, hence it has become the standard for all other producing areas. (See analyses, Table 1.) The most objectionable impurity in English celestite is iron, coming mostly from adhering clay. On the other hand, Mexican celestite, while no higher in strontium sulfate content, is extremely low in iron (less than 0.2 pct), hence it is more desirable for certain uses. Most of the celestite in Spain and in the United States is high in calcium and barium, and commonly high in iron, and requires some form of beneficiation in order to be equal to English ore. The natural carbonate (SrCO3), or strontianite, is less important than celestite as a source of strontium, because it is less abundant and is not so widespread in its occurrence. Furthermore, it generally occurs with calcite (CaCO3) and lead sulfide (PbS), and for most uses these impurities are detrimental. This mineral is generally white or yellowish, forming needle-like crystals. It has a hardness of about 3.7 and a specific gravity of 3.68-3.8. The mineral is brittle and has an imperfect cleavage. A typical analysis of German strontianite is shown in Table 1. [ ] Distribution of Deposits UNITED STATES Occurrences of strontium minerals are known in Arkansas, Arizona, California, Illinois, Ohio, Pennsylvania, Tennessee, Texas, and Washington. Celestite occurs in the Vulture Mountains, Maricopa County, Arizona in beds three to ten feet thick associated with sandstone, gypsum, and barite. Because of the low strontium content, approximately 86 pct SrSO4, it has no commercial value. A large deposit of celestite occurs in San Bernardino County, California, in the Cady Mountains near Argus Station, about eight miles west of Ludlow. The celestite here is interbedded with shaly and clayey tuff in a zone about 300 ft thick. Massive, finely crystalline ore has been recovered with an analysis

Jan 1, 1960

By Oscar A. Glaeser

MINE VENTILATION is an important factor in mine maintenance as well as having direct bearing on labor efficiency. Effective ventilation systems are costly, especially those for the deeper mines, but with intelligent direction the worth of a system is usually greater than its cost. In most mines using mechanical ventilation, and practically all deep mines, it has been found beneficial to equipment, timber, and the ground, to run the fan or fans continuously even though production has been curtailed or entirely suspended. Therefore, economies in ventilation may be overlooked when general cost reductions are necessary. The operating costs of a well-designed ventilation system should be capable of reduction during periods of curtailed or suspended operations. A mine that is ventilated by splits, or that can be sectionized, can reduce its fan-power costs considerably, and provisional divisions can sometimes be made in other mines, in which the air is ordinarily coursed through all the workings, without harmful effects.

Jan 1, 1932

By AIME AIME

THOUGH the dust-control systems in the crushing plants and other buildings at Morenci do not differ materially from similar installations in other large copper reduction works, it is probable that in few other plants has as much attention been paid to the dust problem. Possibly the most striking feature of the Morenci installation is the manner in which the necessary equipment has been built into the various structures, and the absence of unsightly pipes, ducts, and fan houses. That this result has been attained is due, in no small part, to the basic conception that the control of the dust in a milling plant should be an essential part of the process itself and not something to be tacked on later after the plant is in operation. The control systems were designed and developed along with the general plant construction program and when the first car of ore was dumped into the crusher the dust-control equipment was ready.

Jan 1, 1942

By Chester A. Rowland, David M. Kjos

Mineral ore comminution is generally a feed preparation step for subsequent processing stages. Grinding, the fine product phase of comminution, requires a large capital investment and frequently is the area of maximum usage of power and wear resistant materials. Grinding is most frequently done in rotating drums utilizing loose grinding media, lifted by the rotation of the drum, to break the ores in various combinations of impact, attrition and abrasion to produce the specified product. Grinding media can be the ore itself (autogenous grinding - primary and secondary), natural or manufactured non- metallic media (pebble milling) or manufactured metallic media - steel rods, steel or iron balls. This chapter covers rod and ball mills which utilize manufactured metallic grinding media. Fig. 1 shows the cross section of an overflow rod mill, Fig. 2 an overflow ball mill, and Fig. 3 a diaphragm (grate) discharge ball mill.

Jan 1, 1978

By J. E. Pogue

That the domestic consumption of gasoline displays a marked seasonal variation, with a low in the winter and a high in the summer, is well known. It is logical to expect that the nature of the variation has itself been undergoing a change as a result of improvement in roads, general employment of closed cars, and growth of mass haulage; but so far as I am aware the change in seasonal variation has never been investigated and measured. It is the purpose of this paper to present the method and results of such an investigation, undertaken as a contribution to the technique of planning operating schedules now so prominent in connection with the functioning of the industry under a Federal quota system. For the method employed I am indebted to the suggestions and help of Frederick R. Macaulay,1 who kindly looked over the work sheets; and

Jan 1, 1934

By W. M. Brown

SEQUACHEE Valley includes portions of the counties of Marion, Sequachee, Bledsoe and Cumberland. It extends in a general direction parallel with the Great Valley of East Tennessee, some 75 miles northward from the Alabama state line. It is separated from the Valley of East Tennessee by a mountain arm about a dozen miles wide, known as Wallen's or Walden's Ridge. The genesis of the valley, geologically speaking, is simple. It is an erosion-valley along the axis of an anticlinal. The point of the wedge remains in a row of low "saw-tooth" hills, running up the center of the valley. These hills are of Lower Silurian age, and consist of Trenton limestone, covered and protected in some measure by chert. Walls of Carboniferous age form the inclosing mountains on either side; whilst a magnificent arch of Hudson River, Niagara, Hamilton and Subcarboniferous strata closes the valley at the

Jan 1, 1886

By William Barrett

IN order properly to evaluate the data related to geomagnetic surveys, it is highly desirable to have all the available information concerning the magnetic properties of the, involved media. This is true of surface as well as subsurface formations and becomes of increasing importance as advancement in instrumental and interpretative technique permits the analysis of relatively slight magnetic reflections of buried masses. Since the magnitude and areal distribution of the usually complex resultant magnetic field at the surface of the earth is a function of the susceptibility1 of the involved matter, it necessarily follows that susceptibility determinations will afford valuable data for geophysical correlation. The present method was developed to meet the need for routine analysis of specimens in the geomagnetic laboratory where it was felt that general utility, ruggedness, ease of manipulation and reproducibility of results was of greater importance than extreme sensitivity.

Jan 1, 1931

By Wolfgang Pietsch

Direct Reduced Iron is a product obtained during solid state reduction of iron oxides into metallic iron. General chemical and physical characteristics of all direct reduced iron materials result in a noticeable reoxidation tendency and a relatively low ignition temperature. As most of the chemical reactions are exothermic, normally heating occurs and if water is present hydrogen evolves. Dry direct reduced iron deactivates quickly in air but is still reactive if it comes into contact with moisture. Because of these characteristics, special requirements are necessary for safe storage, shipment, and handling. In an effort to improve this situation passivation techniques were and still are being developed. The paper discusses the properties of direct reduced iron, presents past experience with storage, shipment, and handling of MIDREX® Iron, a direct reduced iron material produced in the MIDREX® Direct Reduction Process, and evaluates benefits derived from different passivation techniques.

Jan 1, 1978

By James P. Kimball

In a paper which I had the honor to present to the Institute at the Montreal meeting, September 1879,I took occasion to refer incidentally to certain practical difficulties in the sampling of coal-seams {Trans. Vol. VIII., p. 181-3). This reference was particularly to the unequal distribution of sulphur in the form of pyrite, and to the necessity of discriminating between the several members or " benches " of a coal seam as to their relative proportion of visible sulphur. What is a practically truthful estimation of the sulphur of a coal seam, is not necessarily the estimation of an average of sulphur in any given line of cross-section of the seam. Cornparatively speaking, the range of sulphur in quantity is generally so low that errors in its determination, arising from neglectful sampling or from slips in the laboratory, fall chiefly upon this single ingredient. Not so,

Jan 1, 1884

By C. L. Meyers, A. V. Levy, G. Y. Onoda, R. J. Kotfila

This paper presents the hypothesis that solid-solution hardening of regions in the order of tens of angstroms thick along grain boundaries is the most important mechanism controlling the ductile -brittle transition behavior of poly crystalline bcc refractory metals. Further, a physical model is developed and a general equation is derived to describe the dependence of the solute concentration at grain boundaries on temperature, nominal impurity concentration, thermal treatments, vain size, and prior plastic deformation. Analytical curves of the solute concentration at grain boundaries us temperature, calculated by means of the derived equation, are found to have the same general form as curves of ductility us temperature plotted from experimental data. Senziquantitative relationships between the transition temperature and metallurgical variables can he determined by using the physical model. The room-temperature brittleness of the poly-crystalline refractory metals (tungsten, molybdenum, and chromium) is a result of their high ductile-brittle transition temperatures. Recently studies on single crystals have revealed that, when sufficiently pure, these crystals have much lower transition temperatures than polycrystalline specimens of similar purity.'-3 For example, the transition temperature (measured by reduction in area in tensile tests) for very high-purity tungsten crystals has been reported to be as low as -50°F whereas polycrystalline specimens of similar purity had a transition temperature near 400" ~.' These results suggest that the ductile-brittle transition behavior of these polycrystalline metals can be attributed principally to the influence of grain boundaries on plastic flow and fracture. This paper contains a discussion of the manner in which grain boundaries influence the ductility of the poly-.crystalline bcc refractory metals and proposes that the segregation of impurities to grain boundaries is the most important mechanism for controlling the ductile-brittle transition behavior of these metals. Further, this paper contains an analysis of the effect of the compositional and structural variables on the grain boundary-ductility relationship, and introduces a semiquantitative model that can provide a foundation for more theoretical treatment to describe the influence of these variables on ductile-brittle transition behavior. PHYSICAL MODEL FOR PREDICTING DUCTILE-BRITTLE TRANSITION BEHAVIOR Grain Boundary Segregation of Impurities. Based on their own observations and on theoretical grounds, numerous investigators have suggested that impurities segregate to the grain boundaries. Such segregation would be expected because regions exist where both large and small foreign atoms fit with less strain than within the undistorted crystal structure. Therefore, the concentration of impurities should be higher at boundaries than within the grain body. TO estimate the degree (i.e., the ratio of grain boundary to nominal bulk concentration) to which an interstitial solute tends to segregate at boundaries within a solvent metal, the solubility rather than the size misfit could be used as a guide because solubility expresses the joint effect of both elastic and electronic factors.5 The solubilities of interstitial elements such as carbon, hydrogen, nitrogen, and oxygen are low in the group V-A metals and very low in the group VI-A metals.6 These low solubilities suggest that segregation to grain boundaries should occur for each of these solutes in both refractory metal groups. The difference between the ductility of single-crystal and polycrystalline bcc refractory metals can be described in terms of two distinct effects.4 The first of these is the general observation that grain boundaries hinder slip within grains and slip transfer between grains, and the second is that deformation is more complex in each grain of a polycrystalline specimen than it is in a single crystal. Mc Lean has pointed out, furthermore, that strong slip-hindrance effects at grain boundaries should occur in metals having strong segregation of impurities to grain boundaries. Therefore, the effect of grain boundaries on the hindrance of slip is expected to be the dominating influence on the ductile-brittle transition behavior of these polycrystalline refractory metals. cahn5 has suggested that temperature and solute mobility should influence solute equilibrium segregation at grain boundaries, and Fig. 1 illustrates

Jan 1, 1965

By W. van der Knapp

A theoretical and experimental ana1ysis is given of the change in volume of a porous medium due to changes in external and internal pressures. The result enable one to deduce directly the effect of large increlents in stresses. It is shown that the three-dimensional representation of the volume of a nonlinear porous system is a cylindrical rules surface, the generating lines of Which have a slope according to the solid rock compressibility. Analytical expression for such a ,surface is very simple. It follows that the bulk and pore compressihilities depend only on the difference between pore fluid and external hydrostatic pressure, i.e., the effective rock frame pressure. From measurements on a number of sandstones as well as limestones it can be conduded that for practical values of this effective frame pressure the pore compressibility falls in the range between the compressibility of water and that of undersaturated crude oil. In general, pore compressibility is found to be higher the lower the porosity. For a particular limestone reservoir pore compressibility and porosity could he related by means of a simple empirical formula. Results from the described study find a direct applicxtion in material balance calculations and in prob1ems of liquid flow through porous media. Since the elastic constants of the rock bulk material enter into equatiorls for velocity of acoustic waves, the results are also of importance for calculating rates of wave propagation in these media. It is shown for sandstones with 1.5 to -10 prr cent porosity that laboratory measured porosities may differ from those lender reservoir conditions by about I per cent of their value. The difference for low porosity limestotnes can be of the order of 10 per cent. The subsidence caused by elastic deformation of reservoir rock is shown to he very small. General formulas relating pore and bulk volume to external and internal pressure can be derived, as has been shown by Biot1, Gassmann2 and Geertsma.2 Their theories describe the differential change in volume caused by a variation in pore fluid tension and external hydrostatic tension. It has been known for a long timei that the stress-strain relations of a packing of spheres are essentially noninear. Our experiments show that for almost all reservoir rocks which arc elastically deformable the relation between volume and loading is also a nonlinear one, resembling that of a packing of spheres very closely. The behavior of these media is often described by using the linear stress-strain relations for small incremental stresses and strains in the vicinity of a pre-stressed condition." The present study differs from these considerations in that it enables one to deduce the effect of large increments in the stresses directly. In analogy to the stress tensor for a homogeneous body the stress tensor for a porous body can be written in the conventional way: where the tensor components, o, and t, represent the total forces acting on the faces of a unit cube of porous material. This tensor can be split into two parts. a hydrostatic and a deviatoric part, as follows2,3,1 where the component of the hydrostatic stress system, a. equals The hydrostatic stress causes a change in volume whereas the deviatoric stress system gives rise to a change in shape only. One of the difficulties in describing changes of volume occurring in reservoir rocks is that the relations connecting these volume changes with external and internal stresses are essentially non-linear. A complete description requires the bulk volume, V,,, as well as the pore volume,V,,. to be known as a function of both the changes in pore fluid tension (v) and the hydrostatic tension on the outer boundary.

By Dorsey Hager

THE possibility of oil and gas production in Alabama has been little considered as yet. Gas and some oil have been found in northwestern Alabama, near Birmingham, in the Pennsylvanian beds, but the oil and gas possibilities in the Cretaceous beds are not generally appreciated. The recent activity of oil companies in that State has attracted much attention, and in this paper the main structural and the general stratigraphic features are described. Four favorable areas are outlined. These contain folds of major interest. There are other favorable areas which have not been mapped. Commercial pools discovered in this area would have the advantage of being near tidewater. Mobile, Ala., on the Gulf, of Mexico, would be the logical site for refineries and shipping facilities. A pipe line could readily be laid to that city from the Hatchitigbee and the Jackson areas. The logical outlet for the Geneva and the Gordon areas would be Panama City, Fla., on the Gulf of Mexico.

Jan 2, 1918

By H. H. Alexander

IN the early part of the last century textile fabric was used for the filtration of products of combustion and lampblack was obtained by passing smoke through a series of canvas bags. Natural draft was, used to draw and force the smoke through the bags. About 1850 bag filtration was used for collecting zinc oxide. Around 1876 it was introduced for collecting the fume from lead-ore hearth smelting in. Missouri. Shortly afterward it was used, first at Portland, Me., and later at Canon City, Colo., for the collection and production of zinc-lead pigment in treating mixed zinc-lead sulphides. In 1890 the Globe Smelting & Refining Co., at Denver, Colo., installed a bag house containing 1,458 bags for the recovery of fume from silver-lead blast furnaces. This installation was too small to handle all of the gases and was increased to approximately 2,300 bags. . In 1900 the number of bags was again increased, making a total of approximately 2,800: The usual difficulties incident to new installations were encountered, but they were gradually overcome and the bag house became accepted as standard practice for this class of smelting. As all of the bag houses built since have followed the general lines of the Globe installation, a short description may be of interest. The general construction of the Globe bag house is shown in Figs. 1, 2, and 3. The building is 149 ft. 8 in. long by 67 ft. 4 in. wide and 40 ft. 2 in. high from the basement floor to the eaves of the roof, having brick walls 26 in. thick from the foundation up to the thimble floor, from there an 18-in. wall for 16 ft. and a 13-in. wall from this point to the top, a distance of 14 ft. 2 in. Additional stiffening is given to the walls above the basement by pilasters located every 16 ft. The end-wall construction is similar to that of the side walls with the exception of the spacing of the pilasters, which is somewhat greater. The roof is made of corrugated iron laid on 1-in. boards and supported by a timber frame work spaced 16 ft. apart resting on the basement partition walls. On top is a louver running the

Jan 8, 1914

By H. H. Alexander

In the early part of the last century textile fabric was used for the filtration of products of combustion and lampblack was obtained by passing smoke through a series of canvas bags. Natural draft was used to draw and force the smoke through the bags. About 1850 bag filtration was used for collecting zinc oxide. Around 1876 it was introduced for collecting the fume from lead-ore hearth smelting in Missouri. Shortly afterward it was used, first at Portland, Me., and later at Canon City, Colo., for the collection and production of zinc-lead pigment in treating mixed zinc-lead sulphides. In 1890 the Globe Smelting & Refining Co., at Denver, Colo., installed a bag house containing 1,458 bags for the recovery of fume from silver-lead blast furnaces. This installation was too small to handle all of the gases and was increased to approximately 2,300 bags. In 1900 the number of bags was again increased, making a total of approximately 2,800. The usual difficulties incident to new installations were encountered, but they were gradually overcome and the bag house became accepted as standard practice for this class of smelting, As all of the bag houses built since have followed the general lines of the Globe installation, a short description may be of interest. The general construction of the Globe bag house is shown in Figs. 1, 2, and 3. The building is 149 ft. 8 in. long by 67 ft. 4 in. wide and 40 ft. 2 in. high from the basement floor to the eaves of the roof, having brick walls 26 in. thick from the foundation up to the thimble floor, from there an 18-in. wall for 16 ft. and a 13-in. wall from this point to the top, a distance of 14 ft. 2 in. Additional stiffening is given to the walls above the basement by pilasters located every 16 ft. The end-wall construction is similar to that of the side walls with the exception of the spacing of the pilasters, which is somewhat greater. The roof is made of corrugated iron laid on 1-in. boards and supported by a timber frame work spaced 16 ft. apart resting on the basement partition walls. On top is a louver running the

Jan 1, 1915

By Eugene Stebinger

PAGE Introduction.............. 890 Position oF Montana in the Western Coal Province*..... 890 Montana's Total Coal Tonnage.........891 THe Coal-BearINg Formations,........891 General Statement............. 891 Kootenai Formation............ 895 Eagle Sandstone............896 Judith River Formation............ 896 Homethief or Lennep Sandstone.........897 Lance Formation..........• 897 Fort Union Formation............ 898 Tertiary Lake Beds............. 899 Distribution of the Coal Fields.......... 899 Classification of Montana Coals.........900 General Statement............. 900 Comparison of Chemical Analyses and Heating Values..901 DESCriPTions of the CoaL Fields.......... 905 • Fields Containing Bituminous and Higher Grade Coals..905 Bridger Field............. 905 Stillwater Field............ 906 Electric Field............ 907 Trail Creek Field...........908 Gallatin Field............909 Lombard Field...........910 Great Falls Field............ 910 Lewistown Field............ 911 Valier Field............. 912 Blackfoot Field............ 913 Fields Containing Sub-bituminous Coal.. 913 Bull Mountain Field..........913 Red Lodge Field............ 914 Missoula and Drummond Fields......... 916 Milk River Field............ 916 The Eastern Plains Region of Lignite and Sub-bituminous Coal.... 917

Jan 1, 1914

By John C. Smock

THE question of the proper valuation of mines of iron ore was suggested to me by the difficulties experienced in getting answers for the United States Census Office, while I was engaged in the work of collecting the statistics of mines in New Jersey and New York The answers to the questions relating to values of real estate of mine properties varied so greatly that it was necessary to revise them according to some general principles of valuation. Generally the returns of mine proprietors Seemed to be too low. There were, however, examples of what would be termed excessive valuation. The Subject appeared to be of practical importance, and led to the paper here presented. The following table of selected mine statistics is given, prefacing the discussion of the principles of valuation. It is in part made up of census returns and partly of data obtained directly from mine owners and managers. The mines which were Selected for the Several groups and mining districts include nearly all of those from Which the more full and carefully filled returns were received, and are also representative of their respective districts. Hence the averages obtained from them become good types of these groups or districts. The mines of New Jersey appear in Six groups, each containing from three to eleven mines, or, in all, thirty-four mines. The magnetic iron ores of New York are in four well-marked groups, and there are twenty-six mines in them. Then follow the red hematite mines of St. Lawrence and Jefferson counties; and, lastly, the brown hematite groups of Dutchess and Columbia counties, and those of the adjacent parts of Connecticut and Massachusetts. The whole number of mines represented by the table is eighty-eight, of which twenty-eight are hematite mines. The first column gives the value of the real estate; the second that of the plant; the third is the sum of these two, or the capital invested. Then follow the number of men employed, the amount of wages paid during the census year, and the value of materials used in mining and preparing the ores for market.* The seventh column gives the total expendi- * The value of materials is somewhat uncertain in many cases, as royalties are included under this head. Likewise, under wages, the cost of explosives and light is often included. Hence it is impossible to draw the line sharply between these items of expenditure.

Jan 1, 1882

By E. R. Parker, T. H. Hazlett

An understanding of the mechanism of creep of metals requires an accurate knowledge of shape of the time-deformation curve. An expression is developed which accurately expresses the creep curve for a number of structurally stable metals and alloys. VAST strides have been made in the development of high temperature creep resistant alloys; however, no sound understanding of the physical mechanism of creep exists to date. Consequently, creep resistant alloys are still developed by "cut and try" methods formerly so successful but now yielding returns at a continuously diminishing rate. It is apparent to all workers in the field that if the mechanism of creep were understood, much fruitless labor could be avoided. The dirth of fundamental knowledge has not discouraged the theorists. Speculation has flourished and numerous theories of creep have been proposed. A critical review of these theories reveals that, even though there are some general areas of agreement between the majority of the workers, there are many basic questions yet to be resolved.' It is generally conceded that theoretical speculation is far in advance of experimental evidence. The shortage of reliable creep data greatly hinders more rapid progress in this field. It is essential that the effects of different stresses and temperatures on the creep characteristics of metals be quantitatively determined. Once this has been accomplished, it will then be possible to evaluate the effects of alloying additions and, it is hoped, to provide a firm basis of facts for theoretical treatment of the creep phenomenon. The work reported herein was undertaken to determine the effects of such variables as stress, temperature, alloying, and structure on the creep characteristics of some metals. Material and Equipment Nickel was selected as the base material for the current investigation and an experimental program was initiated to determine the effects of temperature and stress on the creep characteristics of this material. Since a large quantity of high purity nickel was required for the proposed program and such material was not commercially available, it was decided to refine, cast, and prepare the required metal in our own laboratory. The resulting nickel test bars had the following composition, given in percentage by weight: Fe, 0.030 (1); Si, 0.003 (2); Ca, 0.001 (1); Mg, 0.020 (2); and S, 0.002 (2); to make total impurities of 0.056. The nickel (balance by difference) is 99.944 pct. The details of the purification process are described elsewhere.' This

Jan 1, 1954

By F. M. Yans, A. D. Donaldson, A. R. Kaufmann

Beryllium was mixed by powder. metallurgical techniques with copper, nickel, iron, and chromium, respectively, to form beryllium -rich binary alloys which Mere then extyuded and rolled transtverse to the extrusion direction. The effect of each alloying element was determined by tensile testing. In solid solution, small amounts of iron and nickel had an embrittling effect, while copper in solution increased the strength but had no effect on ductility. The effect of chromium was complicated and not readily explainable. Observations concerning the planes and modes of fracture were made. BERYLLIUM possesses some very attractive properties for general design applications, especially its strength to weight ratio which is approximately twice that of aluminum and three times that of stainless steel. Equally significant, however, is its combination of high moduli , high strength (approximately 70,000 psi tension and 40,000 psi shear), and low density (0.0658 Ib per in.3), which has made it a potentially important structural material for use in high-speed aircraft and missiles. The main attractions of beryllium are most marked when compared to other constructional alloys now in use. For example, while its density is approximateiy that of magnesium, its modulus of elasticity is approximately seven times that of magnesium, three times that of titanium, four times that of aluminum, and 1 1/3 times that of steel. Furthermore, its relatively high strength and high melting temperature permit design for service temperatures to about 1100°F. It is felt by the aircraft industry in general,' that the high cost of beryllium can easily be amortized by the savings in fuel costs, and increases in aircraft payload and range. The only factor which has prevented the use of the metal in structural applications is its lack of sufficient ductility. It is this property that has retarded the development and utilization of beryllium. Beryllium's modes of deformation, Fig. 1 indicate that the main fracture planes at room temperature in a randomly oriented sample are the (0001) basal planes; the (1150) prism planes are the planes of secondary fracture.' Klein, Macres, Woodard, and Greenspan3 obtained elongations of up to 40 pct in beryllium sheet rolled above 700°C when the (0001) basal planes were oriented parallel to the plane of the sheet (see Fig. 2).

Jan 1, 1962