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By Royal Preston Jarvis

The jig, in one form or another, continues to hold a leading place among the machines designed to separate two or more

Jan 1, 1909

By Alan Morris

In a previous paper1 the results of cutting tests on free-cutting brass rod were reported. Investigation was made of the effects of variation in lead content, microstructure and cold drawing. The author's reply to the discussion of that paper includes a study of the directional cutting properties of drawn and annealed rod. The present paper records the results of tests made on series of samples in which the tin, iron and copper contents have been varied. The apparatus used and method of testing are described in detail in the previous paper. The machine is of the pendulum-operated milling type used and described by Airey and Oxford.2 Angular readings of the height to which the pendulum rises after falling from a fixed position, both when a cut is made and when the pendulum swings freely, give the basis for calculation of the energy consumed in making a cut. Careful weighing of the sample before and after cutting gives a measure of the amount of metal removed. The results are expressed in footpoiinds per cubic inch of metal removed, and have been called "unit cutting energy." In the course of the discussion of the author's earlier paper, W. B. Price reported large-scale tests involving some 50,000 lb. of material. These tests indicated that the addition of as much as 0.6 per cent of iron and 0.25 per cent of tin had apparently no adverse effect on the highspeed cutting characteristics of the rod. The rod also contained a small amount of nickel. The test results reported here tend to confirm his observations. Effect of Variation in Tin Content The castings for this series were made 2 by 1 by 9 in. and were processed as follows: 1. Castings were annealed at 500" C. for 7 hr. 2. Cold-rolled to 0.700 in.

Jan 1, 1933

By Newell G. Alford

Forecasts of future timber consumption in soft-coal mining are handicapped by the lack of adequate experience records for estimating properly the timber requirements of the industry. Data were obtained from plants where records are kept or from operators who collected the information and to these were added composite figures for the continental United States in 1905 and 19191 and for central and western Pennsylvania and for Illinois in 1922.2 The result, representing slightly over 928,000,000 net tons, is shown in Table 1. Some of the companies furnishing data were unable to segregate the timber into classes of use but for those who did, Table 2 shows the board feet of posts and cross ban used per ton of coal mined and the percentage of the total timber consumed that was used in roof support. The wide variation in amounts of timber per ton of coal mined is the result of

Jan 1, 1924

By B. W. Howlett, M. B. Bever, Somnath Misra

The heats of Formation of the compounds Sb2Se3, Bi2Se3, Sb2Te3, and Bi2Te3 and the heats of solution of tellurium and selenium in liquid bismuth have been measured in a liquid metal solution calorimeter. The heat capacities near the melting point, the heats of fusion, and the melting points of the two tellurides have been measured in a constant temperature gradient calorimeter. The thermo-dynamic quantities are interpreted in relation to the stability of the compounds and the nature of the solid-liquid transition. THE selenides and tellurides of several elements of Group VB of the periodic system are of interest because of their electronic properties. The compounds Sb2Se3, Bi2Se3, Sb2Te3, and Bi2Te3 are semi- conductors; they also have gained prominence in the fields of thermoelectricity and photoconductivity. However, little is known about their thermody-namic properties. As part of a research program on the thermo-dynamic properties of intermetallic compounds, the heats of formation of the compounds Sb2Se3, Bi2Se3, Sb2Te3, and Bi2Te3 were measured in a liquid metal solution calorimeter. The heat capacities near the melting point, the heats of fusion, and the melting points of the two tellurides were measured in a constant temperature gradient calorimeter. The results, in addition to their intrinsic interest as thermodynamic quantities, contribute to an understanding of the stability of the compounds and the nature of the solid-liquid transition. 1) EXPERIMENTAL 1.1) Materials. Samples of the compounds SbzSe3 and Bi2Se3 were prepared by melting the elements in stoichiometric proportions in evacuated Vycor capsules followed by quenchinn in water. They- were then annealed in vacuum for 12 hr at 550°C. A sample of Sb2Te3, consisting mainly of one large grain, supplied by the Lincoln Laboratory,

Jan 1, 1964

By J. T. Burwell

The crystal orientation in silicon iron that has been given a particular treatment described by Goss,l has been studied by Goss, by Bozorth2 and by Sixtus,3 but their results do not agree and are almost entirely qualitative. The following pages give a description of the orientation of the crystals in the material as determined by means of X-rays and expressed graphically in a pole figure. The treatment consists of hot-rolling the material into strip and then giving it two cycles of cold reduction followed by recrystallization. This produces remarkably good properties in the rolling direction, the product having a maximum permeability in this direction of more than 25,000 and a permeability at 16,000 Gauss of more than 2200. It is now generally agreed that Goss's original conclusion1 that the crystals in the final product are randomly oriented was incorrect, since Bozorth2 and Sixtus,3 using different methods, have shown that there is a decided preference in orientation. Those writers, however, expressed their results only in terms of one or more ideal orientations with deviations therefrom. X-ray Data A strip of the material containing 3.1 per cent Si, prepared by Goss,† 1.2 by 0.0125 in., was etched rapidly in warm dilute hydrochloric acid until it was 0.005 in. thick, in order to eliminate the effect of the two surface layers. The specimen was then mounted in an integrating camera similar to one described in the literature.4 The purpose of this camera is to translate the specimen during exposure, so that a statistically large number of grains contribute to the pattern photographed. The camera also allows the plane of the specimen to make various angles with the X-ray beam. An area 5 by 1.2 in. was scanned by a beam of unfiltered radiation from a molybdenum target tube operating at 37 kv., and the measurements were made principally on the peak of the white radiation. X-ray photographs were taken at intervals of 15" in a plane

Jan 1, 1940

By J. T. Burwell

The crystal orientation in silicon iron that has been given a particular treatment described by Goss,l has been studied by Goss, by Bozorth2 and by Sixtus,3 but their results do not agree and are almost entirely qualitative. The following pages give a description of the orientation of the crystals in the material as determined by means of X-rays and expressed graphically in a pole figure. The treatment consists of hot-rolling the material into strip and then giving it two cycles of cold reduction followed by recrystallization. This produces remarkably good properties in the rolling direction, the product having a maximum permeability in this direction of more than 25,000 and a permeability at 16,000 Gauss of more than 2200. It is now generally agreed that Goss's original conclusion1 that the crystals in the final product are randomly oriented was incorrect, since Bozorth2 and Sixtus,3 using different methods, have shown that there is a decided preference in orientation. Those writers, however, expressed their results only in terms of one or more ideal orientations with deviations therefrom. X-ray Data A strip of the material containing 3.1 per cent Si, prepared by Goss,† 1.2 by 0.0125 in., was etched rapidly in warm dilute hydrochloric acid until it was 0.005 in. thick, in order to eliminate the effect of the two surface layers. The specimen was then mounted in an integrating camera similar to one described in the literature.4 The purpose of this camera is to translate the specimen during exposure, so that a statistically large number of grains contribute to the pattern photographed. The camera also allows the plane of the specimen to make various angles with the X-ray beam. An area 5 by 1.2 in. was scanned by a beam of unfiltered radiation from a molybdenum target tube operating at 37 kv., and the measurements were made principally on the peak of the white radiation. X-ray photographs were taken at intervals of 15" in a plane

Jan 1, 1940

By E. T. Turkdogan, L. S. Darken, R. J. Fruehan

Further consideration is given to the application of the quadratic formalism to evaluate the thermodynamics of binary metallic solutions from experimental data. The use of the thermodynamic relation, in(r1/r2) dN2= 0, in the evaluation of activity data is discussed. The empirical correlations derived previously for enthalpies and entropies of solutions in Part II are shown to be predicted theoretically for a special case. The applicability of the quadratic formalism to the activity coefficients for binary organic solutions is demonstrated. DARKEN&apos; introduced a quadratic formalism describing the composition dependence of the activity coefficient in the terminal regions of binary metallic solutions. In a subsequent paper (Part II) Turkdogan and Darkeen2 extended this formalism to the enthalpy and excess entropy of binary metallic solutions, and showed that the available data for the activity coefficients and heats of mixing of many solid and liquid binary metallic solutions confirm reasonable applicability of the quadratic formalism. Much variation was noted, however, in the extent of the terminal regions from one system to another, commonly from about 10 to 70 at. pct. For the present purpose, equations derived previously need be given only for one of the terminal regions, e.g. region (I), 0 < N2 < N&apos;2: where subscripts 1 and 2 indicate quantities for components 1 and 2 and superscript ° the values at infinite dilution; other terms are: N = atom fraction, y = activity coefficient, = partial molar enthalpy of solution, ?HM = molar heat of solution, ?Sx = excess partial molar entropy, ?Sx = excess molar entropy. The heat and entropy like terms (constants) el, and S12 are defined in the following expression for the temperature dependence of a12, thus a12 £12 — s12 rnl 2.303RT 2.303 R l J Using this formalism, the thermodynamics of binary systems in the terminal regions may be described over a temperature range of experisental interest in terms of eight quantities: Lº1—Lº2, ?Sx1,?Sxº2 , £12 ,£21,fiai, S12, and S21. In the previous paper, these quantities were evaluated for many solid and liquid binary solutions, and two significant correlations were observed between these thermodynamic quantities pertaining to the terminal regions, thus [10] and [11] Combining Eqs. [9], [l0], and [ll] and rearranging gives a12 -a21 = 1.382R log rº2- 0.08(?S2xº- ?S1xº) [12] Since the second term involving entropies is small and Eqs. 1101 and [ll] are empirical relations, the above equation may be simplified to a12 = 2.74 log rº2 [13] Using the values of a&apos;s and y°&apos;s compiled in Parts I and 11, a12 - a21 is plotted against log(rº2/rº1) in Fig. 1; the line drawn has a slope of 2.74. For Hg-K at 300°C, log(yº2 /yº1)= —5.10, not shown in Fig. 1, and from correlation [13], a12 - a21 = -13.97; this is to be compared with -10.76 derived from the activity data (Part II).

Jan 1, 1970

By W. E. D. Stokes

WHEN history is written, the year of the blitzkrieg will go down as giving aviation its greatest impetus. No perceptible drop in military business, even with cessation of hostilities abroad, seems likely. The combined air force of the U. S. Army and Navy on July 1 was approximately 5000 planes, as against 50,000 planes currently discussed as necessary. Observers at the fronts are giving designers and metallurgists back home some realistic ideas to shoot at. As conventional runways reveal the location of airports to enemy raiders, operating bases are now masked. Difficult, often muddy and rough landing strips, requiring strong landing gears and exacting take-off and maintenance characteristics, are the specifications of war. This is "old stuff" to numerous mining operators in mountainous jungle areas where gradients up to 8 per cent are in more or less common use in such mountain landing fields. Although airplane building is not readily adaptable to assembly-line methods, a trend towards mass productions is now in evidence. Incidentally, a U.S. Army "Curtiss P-40" requires about 10,000 man hours of work to complete and is tied together with 75,000 rivets. During the past year a number of aircraft factories adopted the "shot-

Jan 1, 1941

By Arthur B. Foote

Ore production from the property of the Miami Copper Co. began early in 1911. Until 1925 this ore came from the so-called high-grade orebodies, which contained a little over 2 per cent. copper. This ore was mined by the following methods: 1. Top slicing after mining the peaks by square setting, which produced 4,524,347 tons, including ore from square setting. 2. Shrinkage stoping with sublevel caving of the pillars, which produced 2,230,577 tons. 3. Undercut caving with hand tramming, which produced 15,427,672 tons. Estimating December tonnage, the total ore mined to the end of 1929 will amount to slightly more than 43,000,000 tons. The first method was described by E. G. Deane&apos; and the second by D. B. Scott,&apos; and the third, together with a general description of the mine, by J. H. Hensley, Jr.&apos; The geology of the district has been worked out by Dr. F. L. Ransome.2 The author acknowledges also the assistance of R. W. Hughes, assistant mine superintendent, E. V. Graybeal, chief mine engineer, A. J. McDermid and S. R. Burdick, engineers of Miami Copper Co., Miami, Arizona. Factors Influencing Selection of Mining Methods The mining method described herein was selected primarily with a low mining cost in view and was developed to avoid as far as possible dilution of the already very low-grade ore. In 1924, with the exhaustion of the high-grade orebodies in sight, it was decided to develop the low-grade orebody, which at that time contained 36,000,000 tons of ore assaying 1.06 per cent. copper, and had an area of 50 acres with an average thickness of 206 ft. overlain by an average thickness of 320 ft. of barren capping.

Jan 1, 1930

By H. D. Strain

Potash is a generic term used to describe a number of compounds containing the element potassium (K), which is one of the three major plant nutrients. Potash content of these compounds is commonly expressed as percentage potassium oxide (K20), and the market value of the products is usually dependent on contained K20. Most of the potash produced (approximately 95%) is used in agriculture as fertilizer. Potash products today are shipped by producing countries all over the world to meet the need for increased food production. WORLD POTASH RESERVES Apparent world potash reserves are shown in Table 15.2B.1 and total some 96 billion mt of recoverable potassium oxide. The Canadian reserves account for approximately one-half the known world reserves. The reserves shown represent the potassium oxide content of a variety of potash-bearing ores. The major ore is sylvinite (a mechanical mixture of KC1 and NaCl) from which KC1 or sylvite is recovered (63.2% K20 equivalent). Other ores, such as langbeinite (potassium, magnesium sulfate-22.7% K20) and carnallite (potassuim magnesuim chloride-17.0% K20) are also mined in various parts of the world, mainly for the potassium content. Theoretically, potassium is available in almost unlimited qualities from brines and saline waters. To date, the cost of recovery from salt brines has been greater than the costs by mining operations, but new technology could make brines and seawater an increasingly important source. POTASH PRODUCTION Potash production dates back to the 1860s in Germany, which was the only recorded producing country until 1912. By 1912 Germany was producing approximately 1 million tpy of K2O equivalent. Production began in France in 1913 and in the United States in 1915. World potash production and consumption are shown in Table 15.2B.2 for the years 1950-51 through 1967-68. In 1967 and 1968 the major potash-pro¬ducing countries in order of importance were those listed in Table 15.2B.3. By 1972 Canadian production had outstripped U.S. production. WORLD CONSUMPTION World consumption of potash for the years 1950-51 through 1967-68 is shown in Table 15.2B.2. Table 15.2B.4 shows total world consumption of potassium materials in 1967-68 by country. More than 70% of the world&apos;s potash is

Jan 1, 1976

By Richard E. Gray, Robert W. Bruhn

INTRODUCTION Underground coal mining has been practiced in the United States for over 200 years. Much early mining was not as efficient as today and unrecovered coal pillars, often of variable size and spacing, remain to support the overlying strata after mining has ceased. These conditions constitute a potential subsidence problem since the pillars will eventually fail. The possibility of subsidence above an abandoned mine must be anticipated except when total extraction has been achieved, permitting subsidence concurrent with mining, or when large coal pillars which have an adequate factor of safety for long-term support remain in the mine. Coal is found in 37 states and is mined under- ground in 22 states (HRB Singer, Inc. 1980). Underground mining produced 40 percent of the 7.5 x 10" kg. (830,000,000 tons) of U. S. coal mined in 1980 (Keystone, 1981). There are approximately 70,000 abandoned or inactive underground coal mines in the United States and approximately 2000 active underground coal mines (NAS/NAE, 1975). Underground coal mining in the United States will eventually extend beneath 162 x 109m2 (40 million acres). Thirty-two billion m2 (8 million acres) are already undermined (HRB Singer, 1977). Subsidence due to mining has affected more than 8 x 109m2 (2 million acres) in 30 states, 7.7 x 10 9m2 (1.9 million acres) from bituminous coal mining and the remainder primarily from anthracite mining (Johnson and Hiller, 1979). Subsidence from all other underground mines has affected only 6.9 x 10 7m2 (17,000 acres) (Johnson and Miller, 1979). Subsidence appears to be particularly widespread in two states, Pennsylvania and Illinois, although serious subsidence is found in localized areas of numerous other states (HRB- Singer, Inc. 1977). Host underground coal mining has occurred in the eastern United States, where the U. S. Bureau of Mines estimates 1.6 x 109m2 (398,600 acres) in urban areas in 18 states (out of a total 1.7 x 109m2 1418,400 acres]) are threatened by subsidence (Table 1) (Johnson and Miller, 1979). Pennsylvania and West Virginia contain 57 percent of the total threatened areas. The U.S. Bureau of Mines estimates the total cost to stabilize the estimated 1.7 x lo9m2 (418,400 acres) of subsidence prone urban land located above abandoned mines is over $12.5 billion (1978 costs).

Jan 1, 1982

?ADAIR, ARTHUR C., Corp 4th Co., 1st. Training Bat., 154th Depot Brigade. ADAMS, HENRY, Major: Chemical Warfare Service. ARLUCK, A. A Headquarters, 1st Corps of Artillery. ASKIN, THOMAS B. H Ensign. BANKS, H. R., 2d Lieut Canadian Engineers. BAYLESS, G. E. S Supply Dept. U. S. Submarine Base. BELL, L. R Co. C, 302d Engineers. BELLIS, ARTHUR E., Capt Ordnance Reserve Corps. I BIRRETT, HOWARD, Lieut., Aviation Section, U. S. Signal Corps, Ellington Field. BOISE, PAUL T 2d Regiment, 24th Squadron. ?BRADLEY, CLARENCE I Convois Automobile Section 585. BROWN, GEORGE M Co. G lot Engineer Replacement Regiment. BUCKINGHAM, ALBERT U. S. S. " Coronet," S. P. 194, Section Base No. 7. BURNS J. J Co. 1-B, E. R. O. T. C. BURT, Co. B, let Engineers Replacement Regiment. ||BYERS, WHEATON B., 2d Lieut Ordnance Dept. CANTON, WILLIAM R., Sgt Headquarters Co., 80th F. A. CARSON, JOSEPH A., Capt A.S. S. R. C.&apos; CHAPMAN, LEWIS C. Corp 29th engineers. CHETNEY, P. C., 2d Lieut 15th Bat. Headquarters Co. CHEVRILLON Louis French Red Cross. CHIDESTER, W. B., 1st Lieut 24th Machine Gun Bat. CHURCH, JOHN L., Capt 308th Engineers. CLAGHORN, D. MONTGOMERY, 1st Lieut 45th Engineers. CLAQHORN, JAMES L., Lieut Aviation Section, Signal Corps. CLARKE, ALEXANDER F U. S. Naval Aviation Service. COMINS, WALDO H. Ca t 41st Co., 164th Depot Brigade. COOK, FREDERICK A., Capt., Engineer Reserve Corps, Asst. to Div. Engr. 79th Division. COOPER, CLAUDE H. Capt C. A. R. C., 50th Artillery. COPELAND, N. R., Lieut. ||CORBY H.. G., 1st Lieut Co. D, 109th Supply Train. CORSA, BEAN, Capt Co. D, 612th Engineers. CORTESE, EMILIO Italian Army. COULDREY PAUL S., Corp British Expeditionary Forces. || CRAGIN, RODNEY S Co. E, 115th Engineers. CURRIE, JOHN M., Ca t Royal Engineers. || CUTTING, G. W., 2d Lieut U. S. Reserves, Field Artillery. V DARRINGTON, PAUL N., 1st Lieut U. S. Infantry. DAVIS, ANGUS W., Lieut-Col British Expeditionary Forces. || DAVIS, THORNTON, 1st Lieut 13th Field Artillery. ELAND, FREDERICK A., Major Engineer Reserve Corps. DOUGLAS, JAMES $ American Red Cross. DOVE, D. R., Candidate 21st Training Battery, F. A. C. O. T. C. Dover JAMES J 6th Co. C. B. DOWS, DAVID,Capt Coast Artillery, Officers Reserve Corps. || DRAKE, M. 6., 2d Lieut Headquarters Co., 325th Infantry. I || EMMERSON, E. Roy British Navy. EVERIT, RICHARD STURTEVANT Heavy Artillery Officers&apos; Training Camp.

Jan 1, 1923

By Richard Hamburger

(1) Introduction: The purpose of this paper is to call attention to certain methods which will shorten and simplify the calculation of plane tri-angulation. These methods, though not new,&apos;,2 do not appear to have been properly publicized in the United States. The cotangent (or tangent) solution of a triangle permits calculation of coordinates in a smooth series of operations of the calculating machine with a minimum of notation. The semigraphical solution permits the simultaneous solution of a number of intersections, at one station, without the added burden of solving additional triangles. This in turn encourages more numerous field checks and more complete office computation than would normally be undertaken. RICHARD HAMBURGER, Junior Member AIME, is Junior Engineer, Inspiration Consolidated Copper Co., Inspiration, Arizona. TP 2798 A. Discussion (2 copies) may be sent to Transactions AIME before March 31, 1950. Tables I and I1 show the distinct advantage which the combined use of the cotangent and the semi-graphical solutions hold over, what might well be called, the standard solution. It will be shown that the positions for the entire net in fig. 1 may be calculated without computing any distances, thus saving much computation. (2) Comparison of Cotangent and Standard Solutions: To compare the cotangent method with the standard method, the notation involved in the solution of triangle 1-X-4, fig. 1, by both methods is shown. Fig. 2 shows the given information, that is, the coordinates and azimuths of Stations 1 and 4, and angles of the triangle or the azimuths from Stations 1 and 4 to Station X. (Azimuths are used here because the author feels that they are easier to handle, but bearings may be used by those who prefer them). It will be seen from the above comparison that the advantages of the cotangent solution of a triangle are: (a) rapidity, (b) full use of the calculating machine, (c) the small number of

Jan 1, 1951

By Fred Bond

This paper is a continuation of two earlier papers,1,2 and presents new data on the grindability of various ores and other materials-the results of several years of intermittent research work on the nature of grinding and interpretation of test results. It is divided into five parts: 1. The tabulated results of several hundred grindability tests on a wide variety of ores. 2. A method of correcting screen analyses and calculating from them the surface and other properties. 3. A description of a. new method of measuring the "surface energy" of in ore by pendulum impact tests. 4. Test results. 5. A general discussion of the test results and their application to grinding problems.

Jan 1, 1938

By B. W. Vallat

(San Francisco Meeting, October, 1911.) THE Newport mine, located at Ironwood, Gogebic county, Mich., on the Gogebic iron-range, is owned and operated by the Newport Mining Co., for the mining of iron-ore. I. GEOLOGY. The general geology of the Gogebic range has been determined and recorded at different times by well-known geologists,) and their work will be referred to briefly in connection with the local conditions in the mine. The strike of the formation across this property is about 15° north of east. The, general dip is 68° to the north. At the base of the formation on the south lies the granite. Looking north, at right angles to the strike of the formation, we have the foot-wall of quartz-slates and quartzite about 400 ft. wide; the iron-formation about 800 ft. wide, and the hanging-wall of black slates. The iron-formation is composed of banded jasper and quartzite together with iron oxide and concentrations of iron-ore. In character the ore is a soft red hematite, with occasional masses of hard blue "steel ore." The formation is crossed in many places by diorite dikes, which cut through at various angles, the larger or main dikes dipping into the foot-wall in a SE. direction at angles varying from 15° to 30°, while numerous small dikes occur which strike through the formation in a vertical plane and at approximately right angles to the main dikes. There are various theories concerning these dikes, especially as to the time of their origin with relation to the ore-deposition. The commonly-accepted theory is that the dikes were there first, but there are some who contend that they were formed

Nov 1, 1911

By J. Sajkiewicz

In a synthetic way discussed are certain results of papers realized at the Wroclaw Technical University in a field of the theory of exploitation of machine systems with conveyor-belt transport. The attention is paid to the two lines in these works which are concerned with the development of analytical as well as simulation methods, in both cases realized with the help of digilat computers.

Jan 1, 1977

By K. R. Van Horn, L. W. Kempf

Plastic deformation of most commercia1 metals within a sufficiently low temperature range results in profound changes in structure and properties, of which the causes and effects are not completely understood. One of these effects is the presence of internal residual stresses and strains, which ordinarily do not appear to require specific consideration in most structural applications but which may be quite undesirable in particular instances. For example, in heavy sections that require considerable machining before assembly, residual stresses may be undesirable because of the distortion they cause when their balance is disturbed by machining or otherwise. In addition, the distribution of stresses may be such that it acts in the same direction as the applied load, thus bringing about premature failure or reducing the load-carrying capacity of the member. One source of residual stress in metal structures is the plastic deformation that may occur during rapid cooling from relatively elevated temperatures, as in the cooling of a casting in the mold or the quenching of a heavy section from elevated temperatures during heat-treatment. These residual stresses are usually undesirable because their direction of operation and magnitude cannot be controlled well enough to permit utilization of the changes in properties of the metal that they may bring about. The most convenient manner of controlling such residual stress is by proper selection of the cooling rate or by reheating to a temperature at which plastic flow can take place, resulting in relief of the residual stresses and strains. Both of these methods of control, however, may cause a reduction in the optimum properties obtainable from the previous operation. A compromise must be struck, and if it is to result in the best possible combinations of properties, specific information must be available regarding the magnitude of the stresses and the rate at which they are affected by variations in cooling rate or in reheating temperature. The complete quantitative estimation of residual stress in complicated metal shapes is exceedingly difficult, if not impossible. In simple sections, however, relatively quantitative analysis may be applied and useful cstimations of stress distribution may be made. This paper is concerned largely with the rate of relief, upon reheating, of internal residual stress in simple aluminum-alloy structures. Since even with simple structures quantitative estimation of residual stresses is laborious and costly, an attempt was made to find other means of collecting data upon which commercial heat-treatments might be based. Incidentally, a few data were collected bearing on the problem of relaxation of aluminum alloys. Determination of Residual Stresses The magnitude and distribution of residual stresses in simple aluminum-alloy shapes rapidly cooled from elevated temperatures has been discussed in a previous paper.&apos; Fig. I reproduces some of the data

Jan 1, 1942

By L. W. Kempf, K. R. Van Horn

Plastic deformation of most commercia1 metals within a sufficiently low temperature range results in profound changes in structure and properties, of which the causes and effects are not completely understood. One of these effects is the presence of internal residual stresses and strains, which ordinarily do not appear to require specific consideration in most structural applications but which may be quite undesirable in particular instances. For example, in heavy sections that require considerable machining before assembly, residual stresses may be undesirable because of the distortion they cause when their balance is disturbed by machining or otherwise. In addition, the distribution of stresses may be such that it acts in the same direction as the applied load, thus bringing about premature failure or reducing the load-carrying capacity of the member. One source of residual stress in metal structures is the plastic deformation that may occur during rapid cooling from relatively elevated temperatures, as in the cooling of a casting in the mold or the quenching of a heavy section from elevated temperatures during heat-treatment. These residual stresses are usually undesirable because their direction of operation and magnitude cannot be controlled well enough to permit utilization of the changes in properties of the metal that they may bring about. The most convenient manner of controlling such residual stress is by proper selection of the cooling rate or by reheating to a temperature at which plastic flow can take place, resulting in relief of the residual stresses and strains. Both of these methods of control, however, may cause a reduction in the optimum properties obtainable from the previous operation. A compromise must be struck, and if it is to result in the best possible combinations of properties, specific information must be available regarding the magnitude of the stresses and the rate at which they are affected by variations in cooling rate or in reheating temperature. The complete quantitative estimation of residual stress in complicated metal shapes is exceedingly difficult, if not impossible. In simple sections, however, relatively quantitative analysis may be applied and useful cstimations of stress distribution may be made. This paper is concerned largely with the rate of relief, upon reheating, of internal residual stress in simple aluminum-alloy structures. Since even with simple structures quantitative estimation of residual stresses is laborious and costly, an attempt was made to find other means of collecting data upon which commercial heat-treatments might be based. Incidentally, a few data were collected bearing on the problem of relaxation of aluminum alloys. Determination of Residual Stresses The magnitude and distribution of residual stresses in simple aluminum-alloy shapes rapidly cooled from elevated temperatures has been discussed in a previous paper.&apos; Fig. I reproduces some of the data

Jan 1, 1942

By J. D. Forrester, Erich Sarapuu, T. C. Cheasley

RANKING high in the nation&apos;s wealth of natural resources, readily available liquid and gaseous hydrocarbons are nevertheless falling steadily in supply, while industrial requirements for hydro- carbon compounds are greater today than during the peak period of World War II. Theoretically, several processes will increase the future supply of liquid and gaseous fuels, but the practical application of these methods depends on two controlling factors: 1-that enough carbon- bearing material be available to warrant industrial exploitation, and 2-that the given process be physically, chemically, and economically applicable. With regard to the first factor, the Western Hemisphere is fortunately well supplied, see Table I.

Jan 9, 1954

By C. F. Kaiser, T. J. Roberts, I. A. Thomson

The Broken Hill Pty. Co. Ltd. grate-kiln pelletizing plant located at Whyalla, South Australia, produced a total of 250,000 tons of fluxed pellets during 1970. More than 180,000 tons were exported to Japan, while the remainder was used in B.H.P. Co. blast furnaces. The pellet plant treats high grade hematite ore fines and has a nominal capacity of 1.5 million tpy. The induration equipment includes a grate 12-ft 2-in. wide by 164-ft 1-in. long, a kiln 18-ft 6-in. diam by 118-ft 8-in. long, and a rotary cooler 50-ft mean diam by 7 ft wide. Operating problems encountered in the production of fluxed pellets are detailed. The most significant aspect of the trial was the increased production, from about 5100 tpd up to a maximum of 7100, brought about by the addition of artificial magnetite to the plant feed. Laboratory evaluation of fluxed pellets showed that pellets having a basicity ratio (CaO to SiO2) in excess of 1.2 have excellent physical qualities. Reducibility and compressive strength after reduction were both higher for these fluxed pellets than for normal acid pellets. Although it was not possible to publish blast furnace operating data, blast furnace trials on fluxed pellets indicated that production was higher and dust losses substantially lower, compared with similar operations on acid pellets.

Jan 1, 1973