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By Paul Weir

PRODUCTION METHODS in the bituminous coal mines in the United States are undergoing many changes. Although the primary object of these changes is the production of a better product at a cheaper cost there are other considerations such as the improvement of conditions under which miners live and work. The almost complete unionization of the manual workers in the industry during the past four years has 'brought with it a stabilization of wages on a relatively high basis and of hours of work per day and per week on a relatively low basis. With differentials in wages between producing districts firmly established, and with a nation- wide and uniform application of in-

Jan 1, 1937

By R. F. Hehemann, Darrell W. Smith

The kinetics of alloying- in W-5 rot pct Re powder compacts were investigated at temperature about the upper limit for the formation of the x phase, such that a single intermediate phase was involved in the process. The rates and directions of motion of the a-o and o-b interface were assessed as functions of tinze at the sintering teri7peraticve by quantitative izetallog-ralhic techtziques. The iiotion 01 these interjuces could be specified approxitnate1.y by u Parabolic )-ate law and deviations from this ,rate law were attribuled to a complex interaction between surface dif'fusion and volume diffusion during the initial stages of sintering. WHEN binary or more complex alloys are produced by sintering compacted blends of elemental powders, a complication is encountered which does not arise in the sintering of pure metals. In addition to concern for grain size and densification, the rate of inter diffusion of the component elements must be considered. The general problem of alloying during sintering has been treated by numerous investigators.'-7 These investigations have been concerned only with systems that form continuous series of solid solutions and a concentric-sphere diffusion model4 provides a useful description of homogenization in these stems.' Some controversy remains, however, over the contribution of surface and grain boundary diffusion to the homogenization process. Heckel% ePorts that homogenization can be described by volume diffusion at all temperatures, whereas other invetiators'' recognize the importance of surface and grain boundary diffusion, particularly at lower temperatures. Analysis of the homogenization process in partially miscible systems is complicated by the motion of the interfaces separating the individual phases. A simple analytical solution does not exist for such finite systems with spherical symmetry. It was the purpose of this work to examine the kinetics of the formation and dissolution of an intermediate phase in a binary system through an assessment of the motion of the interfaces separating this phase from the terminal solid solutions. PROCEDURE The W-Re system is an example of a partially miscible binary system and was selected for study because of its current importance in refractory-metal technology. The equilibrium phase diagram, Fig. 1, shows that the o phase will be formed by interdiffu-sion between tungsten and rhenium. At temperatures between approximately 2125" and 282O°C, the o phase will appear as the only intermediate phase in the diffusion system. In this work, a mixture of elemental powders containing 5 pct Re was employed. In such a mixture, the rhenium particles will be distributed randomly in a tungsten matrix. During sintering, a o-phase layer will form at the W-Re interface. The development and subsequent disappearance of the o phase are controlled by the relative rates and directions of motion of the 0-0 and a-p interfaces. The motion of these interfaces can be inferred from quantitative metallographic measurements of the average radii of the o shells surrounding rhenium particles. Elemental tungsten and rhenium powders of commercial purity were employed in these investigations. The rhenium powder was spheroidized from +200 mesh agglomerates by plasma-arc spraying and was then classified to yield a powder composed of essentially

Jan 1, 1967

By F. H. Gilpin

SINCE Noah pitched his ark within and without with pitch, the use of asphalt in human endeavor has been increasing-for Noah's pitch was asphalt. Asphalt is a bituminous material found in nature, either pure or admixed with smaller or greater quanti-ties of mineral and non-mineral materials, or obtained by the refining of crude asphaltic-base petroleum under proper methods of control. Native or "natural" asphalts are scattered through-out the world, though the commercial value of the various deposits varies greatly, depending upon both their accessibility and magnitude and the quality of the material found. It is an acknowledged fact that such asphalts have been produced through natural causes by practically the same application of tempera-ture and pressure as are used in the modern refining of crude asphaltic-base petroleum. The best known of all the native asphalt deposits are those of Trinidad Lake in the Island of Trinidad, British West Indies, and of Bermudez Lake in Vene-zuela. Asphalt from Trinidad Lake, after refining to remove organic and some inorganic diluents, contains approximately 35 per cent, of inorganic residue, and the asphalt thus produced must be fluxed with lighter asphaltic or semi-asphaltic base oil to make it com-mercially utilizable. The refined asphalt obtained from the Bermudez Lake deposit contains from 4 to 6 per cent. of inorganic material which cannot be removed. This asphalt, also, must be fluxed to produce com-mercial products. Small quantities of similar materials are available in other locations. The best pure native asphalt' is known as. gilsonite and is mined in com-mercial quantities in the State of Utah. In numerous places in the United States, particularly Oklahoma and Kentucky, there are deposits of sand¬stone and limestone impregnated with bitumen, which are known as rock asphalts. These rock asphalts may be used, particularly in the paving industry, either as found or by slight fluxing; from some deposits the asphalt is extracted and marketed commercially.

Jan 2, 1923

By Donald J. Knight

HEAT Treatment at 1500' F of a mild steel containing 0.1 pct C, in an atmosphere which is oxidizing to both carbon and iron, results in the progressive oxidation of the metal surface with little or no change in the carbon content of the underlying metal. Further heat treatment of the scaled metal in either a neutral atmosphere or in a vacuum may or may not result in the decarburization of the metal depending upon the physical nature of the scale. It is apparent that if a continuous layer of oxide is present on the steel surface, the reaction OScale + Cmetal Cogas cannot progress since the SO formed gas would be unable to leave the oxide/metal interface. Thus, in order for the reaction to progress, the oxide must be cracked or porous. Vacuum heat treatment at 1500" F of samples with a thick continuous oxide scale showed no decarburization of the steel. However, when cracks were introduced mechanically into the scale prior to the vacuum heat treatment notable decarburization of the metal resulted and a structure as shown by Fig. 1 obtained, i.e., reduction of the crack walls to ferrite. With reference to the diagram of Fig. 2, it would appear that a mechanism of the following type takes place. Carbon atoms arriving at an oxide/metal/void interface, such as 'A', Fig. 2(a), can combine with oxygen atoms from the scale and leave the reaction site as Cogas thereby reducing the oxide to metal. On a greatly magnified scale, Fig. 2(b),this will appear as a ferrite projection along the crack wall. Carbon atoms entering this projection can react with oxygen atoms at point 'C', which is a new interface, and so on leading to a progressive growth of the ferrite along the crack wall and to the surface, Figs. 2 (c) and 1. It would appear that the only means by which thickening of the ferrite film can take place is by a diffusion of oxygen through the ferrite film to react with carbon at the newly formed ferrite/ void interface. Since the diffusion rate of carbon is reportedly much greater than that of oxygen, and since there is a low probability factor of oxygen and carbon atoms arriving simultaneously at the same site on the ferritehoid interface, there will be a tendency for more rapid lengthening than thickening of the ferrite layer, as is observed.

Jan 1, 1962

By W. G. Pfann

A simple method of obtaining multistage batch separations by crystallization was described recently. Known as zone-refining, it comprises passing short molten zones through a long solid charge. This technique can now be used on a continuous basis by means of the zone-void method described in this paper. Feed enters, at an intermediate point, a column down which molten zones travel, and waste and product leave at the ends. Materials move in the column through the agency of voids, which are introduced at the ends and travel toward the feed inlet. The voids and molten zones are moved by external heaters in a simple manner, and the principle of reflux is utilized. ANEW method of obtaining multistage separations by crystallization was described recently.' Named zone-refinina.,-, the method comwrises slowly passing a series of molten zones through a long solid charge. Solute becomes concentrated at one or the other end of the charge, depending on whether it raises or lowers the freezing point of the solvent. The separation increases with the number, P, of zone-passes, approaching a limit as P approaches infinity. Zone-refining has been highly effective in purifying germanium and other substances.2,3 and new applications are steadily increasing. Zone-refining is a batch method and as such it has certain limitations inherent in batch operation. If it could be made continuous, its scope and utility would be greatly broadened. This end has been achieved by the zone-void method described in this paper. In the zone-void method feed is introduced continuously at an intermediate point in a column down which molten zones travel, while impure waste and purified product leave at the ends. Both the flows of feed, waste and product, and also the travels of the zones, are actuated by external moving heaters in a simple manner; and the system utilizes the principle of reflux. The method provides, in the field of crystallization, the counterpart of the continuous fractiona-tion column in the field of distillation. The following will be discussed: apparatus and mode of operation, fundamental nature of the separation, design theory, and practical considerations. The method will be described in terms of a binary solute-solvent system in which the solute is an impurity to be removed and the solvent is the desired product. The distribution coefficient, k, defined as the ratio of solute concentration in the solid freezing out of a molten zone to that in the liquid in the zone, is assumed to be constant and less than one. The process is equally effective for k's greater than one and for ternary or higher order systems. Method and Apparatus The essential features of a continuous zone-refining process are represented in highly generalized form in Fig. 1. A series of molten zones, produced by moving heaters, travels slowly down the column or charge (to the left in Fig. 1). If there were no flows of feed, waste, or product, the process would simply be batch zone-refining, the action of the molten zones being to sweep solute down the column, solvent up the column. For the process to be con- tinuous, with stripping and enriching sections in the column, feed must enter, and waste and product must leave, as indicated. The zone-void process accomplishes both objectives, namely, the indicated movements of zones and the indicated flows of material. Zones are moved by moving heaters, just as in batch zone-refining. Materials are made to flow by creating voids at the waste and product exits and causing these voids to move to the feed inlet. Since there must be a net flow of material from the feed inlet to each of the outlets, the indicated movements of voids are in the desired directions, because movement of a void in a given direction corresponds to flow of material in an opposite direction. In order to produce the desired movements of voids, the column is folded into two vertical sections having the feed inlet in common at their upper ends. Voids are displaced upward by the liquids in the molten zones and their travel is actuated by the motions of the zones. Voids travel with the zones in the enriching section and move continuously. Voids travel opposite to the zones in the stripping section and move intermittently. Creation and travel of voids will now be examined in detail. The enriching section of a column in operation, with its void generator, is shown in Fig. 2. The column section is a vertical tube around which a series of closely fitting, regularly spaced heaters travel slowly upward. Each heater produces a molten region, the temperatures of the heaters and the cooling between heaters being controlled so as to maintain the molten zones approximately constant in size. A void is normally present atop the molten zone in each heater. As the heater rises, it continuously melts solid above it, which drips through the void into the molten zone and continuously freezes out solid below it, of concentration k times that of the liquid in the zone. When a molten zone and void reach the feed inlet, which is kept molten, the void is displaced by an equal volume of feed liquid. Generation of voids of controlled size in the enriching section is shown in Fig. 3. The void generator is a tube of small cross-section, provided with lateral heat-conducting fins which sense the position of the heater. Liquid can escape only when the entire outlet tube is within the heater. If any part of the outlet tube is outside the heater, liquid cannot escape,

Jan 1, 1956

By G. Sachs, S. I. Liu

INTRODUCTION IN a previous investigation on the effects of repeated strains of large magnitude on the aluminum alloy 24ST, it was found that the reduction in ductility by straining in tension was partially restored by a subsequent compression.&apos; As illustrated by the dashed line in, Fig I,§ the ductility (EF) retained after prestraining in tension by a certain amount (EI) and measured in a subsequent tension test is represented by a straight line sloping down under 45°. If a compression of the same magnitude as the first tension is inserted (E2 - EI) between prestraining and final testing in tension, such a "balanced" tension-compression cycle yields a ductility considerably higher than that present after prestraining in tension only. . The results of these tests can be correlated with those of an investigation on the effects of prestraining in compression.2 As also shown in Fig I, the ductility in subsequent tensile tests decreased with compression, at a rate considerably slower than that after prestraining in tension. The above discussed testing conditions can be considered as special cases of a general straining cycle, consisting of first, straining in tension by an amount E1, subsequently straining in compression by an amount E2, and finally determining the retained ductility, Ef, in a tensile test. Prestraining in tension is then represented by E1 > o and E2 = o. Prestraining in compression is given by E1 = o and e2 < o. Balanced cyclic straining is defined. by the condition E1 > o and E2 = -El. In order to obtain further information on the effects of straining cycles consisting of tension and subsequent compression, further tests were made, varying both the tension strain, E1, and the compression strain, E2, within extreme limits; El varied between 0.06 and 0.28 and E2 between -0.008 and -0.60 approximately. Apparently, such tests have not been previously performed. They revealed phenomena which have not been recognized to date. The results of the investigation are herewith reported, without attempting to correlate them with internal processes within the metal structure. However, in order to assist in an analysis of this type, the results have been represented in various manners. In addition, further test data on the effects of prestraining by compression were provided by using specimens of various contours (notched specimens) in the subsequent tensile tests.

Jan 1, 1948

In 1973, US Borax & Chemical Corp. began investing three days wages and about $20 in training materials in every new employee before having him report to his first job. The result? Accidents involving new employees in the past two years have dropped by more than half from the 1972 level. What made this success possible was safety training done with programmed instruction materials-which, incidentally, US Borax also uses for vocational training.

Jan 4, 1976

By R. HAYDEN, H. B. HALLOWELL, H. O. Hofman

THE object of refining copper in the reverberatory furnace is to obtain a metal which will have the highest attainable degree of malleability, ductility and electric conductivity, and present at the same time a level surface when it solidifies in the mold after casting. These desirable physical properties are governed by the character of the impurities and the forms in which they are present, by the amount of cuprous oxide retained by the copper, by the quantity of gas held in solid solution, by the casting-temperature, and by the thickness of the casting. The effects of impurities, of cuprous oxide and of gases upon the mechanical properties of copper have been studied by Hampe in his classical paper "Contributions to the Metallurgy of Copper." The most recent research into the effect of metals upon the electrical conductivity of copper is that of Addicks.2 The influence of cuprous oxide upon the electrical conductivity has been investigated by Walker&apos; and Addicks.4 The absorption of gases has received&apos; attention by Hampe,5 Stahl 6 and Heyn.7 The effects of casting-temperature have been noted by Stahl.8

Mar 1, 1907

By Walter R. Hibbard, Harold Margolin

DURING preliminary tests on the aging of a Cu-plus 5 pct Ag alloy,&apos; a specimen which had been overaged 24 hr at 550°C was annealed in a nitrogen-hydrogen atmosphere first for 2 hr and then for an additional 28 hr at 600°C. After each anneal the specimen was cooled to room temperature in about ½ hr and X-ray photograms were made. The first film, Fig. la, revealed two sets of copper-base lines, one intense and corresponding to the parameter at 550°C, the other fainter and shifted away from the beam, corresponding to the larger parameter at 600°C (see arrows). The 30-hr film, Fig. lb, revealed the same two sets of copper-base lines with a reversal of intensity. In neither case do the copper lines form a broad band which would be indicative of a range of compositions. This phenomenon is thus a "discontinuous" type of solution. A similar phenomenon was observed in a Ag-rich Cu-Ag alloy.&apos; Finlay and Hibbard9 have suggested that directional rather than random solution of precipitate occurs in some alloys. Conceivably, for Cu-Ag alloys, the matrix-transition-precipitate precipitation sequence is reversible for the re-solution of the precipitate caused by rapidly raising the annealing temperature of an overaged specimen. A copper-base transition structure supersaturated with solute might be formed around the precipitate as it dissolves, thus obviating the necessity for a gradually changing solute composition of the matrix. The solute atoms then might be transferred rapidly and locally from the transition to the matrix phase in the proper amount and at the proper location to obtain directly the new ex- panded solid solution. The theory implies a minimum of diEusion of solute in the matrix (i.e., no significant range of matrix composition) and possibly suggests that the composition of the transition structure will vary with the conditions of re-solution. A transition copper phase found in aged Cu-Ag alloys1 might fulfill this function. Evidence regarding this suggestion could be obtained in Cu-Ag alloys by overaging a specimen until no trace of the expanded copper lattice is present and then subjecting the specimen to a retrogression treatment. Re-appearance of the transition copper phase would confirm the theory. Additional details could be secured by varying both aging and retrogression temperatures. References &apos;H. Margolin and W. R. Hibbard, Jr.: Effect of Ternary Additions on the Age Hardening of a Copper-Silver Alloy. Trans. AIME (1951) 191, p. 174; Journal of Metals (Feb. 1951) TP 3002E. 2 W. Ageew, M. Hansen, and G. Sachs: Decomposition and Changes in Properties of Super-saturated Silver-Copper Alloys. Ztsch. Physik (1930) 66, p. 350. 3W. L. Finlay and W. R. Hibbard, Jr.: Some Effects of Applied Stresses on Precipitation Phenomena. Trans. AIME (1949) 180, p. 255; Metals Technology (Sept.

Jan 1, 1952

By Harry H. Power

INDUSTRY has the right to expect the petroleum engineering schools to supply more than the minimum technical qualifications necessary to obtain or discharge the responsibilities of a particular job. The basic training, social and economic orientation, should go far beyond these minimum requirements. Petroleum engineering students should also be well grounded in the history of the oil business so that they may understand the industry&apos;s progress since the advent of the Drake well. Furthermore, according to P. H. Bohart, the schools "have a definite duty to help the students form a workable philosophy of life, which includes an appreciation of the service of science to mankind, and a belief in the obligation of the individual who enters a profession to exalt himself by continuing his studies and growth so that he may never cease making contributions to the advancement of science and industry."

Jan 1, 1948

Prof. J. W. Richards, South Bethlehem, Pa. (in reply to several questions):—The cut representing some of the round briquettes which were under test shows that, at the brcaking-stresses, they break into lumps, and do not disintegrate into powder. The process is simplicity itself. I have followed the different processes for sintering iron-ores and flue-dust, am interested in all of them and wish them all success; but this process appealed to me strongly by its simplicity. It is in line with a method which I once tried to work out myself, but which never came to anything, namely, the agglomeration of fine iron-ores by means of Portland cement. As small an amount as 5 or 6 per cent. of Portland cement will enable fine ore to agglomerate and set into a briquette, but when I came to estimate the cost, I found it was a little too high. The Schumacher process, curiously enough, does not work well on iron-ore, but flue-dust thus treated does harden and give a strong briquette. In my attempts to find a reason for this difference, it has occurred to me that possibly the particles of flue-dust had been coated over with some sublimed silica, which might be an agent in the setting. But I found by experiment that neither sublimed silica, nor ordinary silica, nor ordinary alumina, would briquette. Chemically pure iron oxide briquetted quite hard; but the application of pressure is a necessary part of the operation. If simply moistened with the solution and allowed to stand it does not set hard, but the more pressure applied to it the hardcr it sets. Evidently the flue-dust particles must be pressed very close together in order to get the small proportion of active material wet, so that the particles shall act at their points of contact; for it is evident that only at the points of contact does the cementing action take place. The reactions are facilitated by considerable pressure, bringing the acting particles close together, and may go on with

Jan 1, 1913

Discussion of the paper of Frederick Laist, presented at the Butte meeting, August, 1913, and printed in Bulletin No. 79, July, 1913, pp. 1147 to 1162. J. C. DICK, Salt Lake City, Utah :-I would like to ask Mr. Laist why a 10 per cent. salt solution was used. MR. LAIST :-The reason for using salt in the solution is to get .the sulphur. The solution of dilute sulphuric acid has no solvent action on the sulphur even after roasting, and the addition of the salt is made primarily to dissolve the sulphur chlorides. MR. DICK:-I would like to ask also if you made any experiments as to grinding fine your calcines, rather than leaving the coarse material. MR. LAIST :-We have not made any experiments along those lines except in the laboratory, but the objections which we have to grinding are that the difficulties of roasting are very much greater when roasting finely ground material than when roasting coarse material, and the difficulties of leaching are somewhat increased; the percolating system is simpler and easier to manipulate, particularly when acid solutions are used, so that we prefer from our experience not to grind. STUART CROASDALE,* Denver, Colo. (communication to -the Secretary +) :-In order to meet the conditions involved in his ore-treatment problem, Mr. Laist has developed a very interesting and apparently successful metallurgical hybrid which he calls the oxychloridizing roast. The lower floors of the MacDougall furnaces are made to accomplish what used to be done on the " cooling floor" in the old days of salt roasting and " hypo " or brine leaching of silver ores.

Jan 11, 1913

PITTSBURG MEETING The One Hundred and Ninth Meeting of the Institute, for the presentation and discussion of technical papers, will be held at Pittsburg, Pa., Oct. 8, 9 and 10, 1914. This meeting is to be under the auspices of the Iron and Steel Committee, the Committee on Petroleum and Gas, the Committee on Coal and Coke, and the Committee on Non-metallic Minerals. Thirty papers have been secured by these Committees and will be presented at the meeting. These papers will be published in the September and October Bulletins. The Local Committee of Arrangements for this meeting is as follows: SAMUEL A. TAYLOR, Chairman. FRANCIS C. PHILLIPS. GEORGE S. RICE. C. F. V. Rys. KENNETH SEAVER. JOHN S. UNGER.

Jan 9, 1914

By Kenzo Murao, Sei Nakao

HISTORY OF ASHIO SMELTER The Ashio copper mine, which formed the main part of Furukawa mining industry, is located inland of Kanto area, and is known as the oldest copper mine of Japan. The mining started even since 1610, and Mr. Furukawa began management in 1877. Afterwards, within a short period, the mine became to have the highest productivity in the Far East. The total quantity of mined copper reached approximately more than 800 thousand tons. The mother rock of the ore deposit in Ashio was rhyolite, and was formed of sissurefulling and irregular clod that was called Kajika deposit. The lode was nzrrow of 6 to 7cm. The mineral was formed mainly of chalcopyrite, including also pyrite, pyrrhotite, and arsenopyrite that were not favorable. After the founding of the copper mine, the Ashio smelter started the operation of Mabuki process as the beginning in 1611, and subsequently adopted the processes of the blast furnace, reverberatory furnace, and flash smelting furnace of the present use. As indicated above, the copper ore of Ashio mine included arsenic. For the purpose to remove it, the operation of the arsenic trioxide production using MacDougall&apos;s multiple hearth roaster was started in 1918, and it maintained the status of having the most qualified technique within the country. However, as the completeness in the disposition of anti-pollution and safety had been requested in those years, we studied and developed a unique equipment in 1970. It excludes the heavy metals especially arsenic and copper from the waste water of sulfuric acid process of Flash Smelter&apos;s exhaust gas.

Jan 1, 1976

By Henry Louis

IN the discussion on the paper on subsidence by R. V. Norris and H. W. Montz (Teohnical Publication No. 153), H. N. Eavenson has been good enough to quote some of my views regarding the phenomena of subsidence; he has, of course, only mentioned these briefly, and as he has not represented them quite correctly, it is evident that I have failed to make them clear. Seeing that he, and apparently some of the others who took part in the discussion, appear to hold views different from my own, I think it advisable to put my opinions down as definitely and as clearly as possible, because it appears to me at least possible that some of the differences above referred to may be differences of language and definition rather than of fact. The statements I propose to submit refer to the simplest cases, namely where an area in a practically horizontal bed has been entirely worked out. My experience has been confined to beds of bituminous coal and of ironstone, but D I do not at the moment see why there should be any difference in principle between the working of a bed of anthracite and one of bituminous coal, provided that the other conditions are the same. I wish to emphasize that I am considering the conditions of complete working out of the mineral bed with the roof allowed to come down and form goaf in accordance with the general British practice; 1 am excluding, therefore, methods of hydraulic, pneumatic, and hand stowage where extraneous material is brought in to hold up the roof. I am also excluding the case of bord and pillar working where pillars of small size are deliberately left in, apparently with the idea that these will subsequently crush and let the roof down gradually. Such a method of mining has long been discontinued in this country, indeed in Europe generally, and I venture to predict that the time will come when such a recklessly wasteful method will no longer be tolerated even in the United States. Further, I am referring entirely td static conditions after the mineral bed has been worked out and the ground has come to rest; the phenomena that occur during the course of extraction are much more complicated, and these I am not discussing here. Under these conditions, I have

Jan 1, 1929

By R. L. Orr, O. D. Sherby, J. E. Dorn

Creep data for pure metals at temperatures above those at which rapid recovery occurs (above about 0.45 the melting temperature) are correlatable by means of the equations and These correlations were applied successfully to data for aluminum, iron, nickel, copper, zinc, platinum, gold, and lead as well as for simple alloys. For a given metal, AH is a constant about equal to the activation energy for self-diffusion. THE early recognition that creep is stimulated by thermal activation prompted numerous investigators&apos;, &apos; to apply the same laws that are valid for the viscous behavior of liquids to analyses of creep data. To a good first approximation these laws are summarized by the equation were i is the creep rate; T, the absolute temperature; R, the gas constant in cal per degree per mol; T, the applied stress; AH, the activation energy in cal per mol; S&apos;, a constant dependent on the entropy of activation, the frequency of activation, and the contribution of each activation to the strain; and B&apos;, a constant dependent upon the size of the flow unit that is activated. Although Eq. 1 describes the flow of viscous fluids very accurately, its application to the creep of solids has been disappointing. Two reasons for the failure of Eq. 1 for creep are now known: First, the decelerating creep rates during primary creep demand that the internal structures of the metals are changing and that these changes might be reflected by changes in one or more of the three creep parameters S&apos;, AH, and B&apos;. Consequently when the conventional methods of evaluating these parameters are employed by comparing the secondary creep rates at a series of temperatures and at a series of stresses, the true effects of temperature and stress are masked because of simultaneous changes in one or more of the creep parameters. Second, as will be illustrated more fully later, three distinctly different types of investigations have shown that the stress term for high temperature creep enters the analysis as and not as t/T. This rather unexpected result points sharply to a significant fundamental difference between the mechanisms for the viscous behavior of fluids and the high temperature creep of metals. More recent extensive investigations",&apos;4 on the creep of high purity aluminum and several of its dilute a solid solutions have shown that where E is the total creep strain; temperature compensated time = for a constant temperature test; t, is the initial stress in a constant load test or the constant true stress in a constant stress test;" and t is the duration of test. • Eq. 2 is valid for either constant stress or constant load tests; but the total creep curve is difierent (i.e. the function, f, is differentl for each test. The fundamental origin of the validity of Eq. 2 is thought to arise from some equivalence of substructures in constant load creep tests at equal values of 0 or E. Both X-ray and metallographic examination revealed that practically identical lattice distortions and subgrain sizes are obtained for the same creep strain under the same load over wide ranges of test temperature.&apos; Furthermore the room temperature tensile properties following equal creep strains at different temperatures under constant loads were also identical, illustrating that identical substructures were indeed obtained.&apos; " A second type of correlation was obtained by differentiating Eq. 2 with respect to time, giving For the secondary creep rate, denoted by i,, But Eq. 2 reveals that 0, is a function of a, alone because the secondary creep rate in a given constant load test is always reached at a fixed value E,". Therefore where is the function that was introduced a number of years ago by Zener and Hollomon." Eq. 4 is not only valid for creep but will permit correlations between constant load creep and tensile data where e, is the rate of tensile straining and (TC is the engineering ultimate tensile strength.

Jan 1, 1955

By R. E. Powers, E. H. Kinelski, H. A. Morrissey

A group of 17 American blast-furnace sinters, an American open-hearth sinter, an American iron ore, and a Swedish sinter were used to evaluate testing methods adapted to appraise sinter properties. Statistical calculations were performed on the data to determine correlation coefficients for several sets of sinter properties. Properties of strength and dusting were related to total porosity, slag ratio, and total slag. Reducibility was related to the degree of oxidation of the sinters. THIS report to the American iron and steel industry marks the completion of a 1949 survey of blast-furnace sinter practice sponsored by the Subcommittee on Agglomeration of Fines of the American Iron & Steel Institute. The use of sinter in blast furnaces, sinter properties, raw materials, and sinter plant operation have been reported recently.1,2 After preliminary research and study," test procedures were adapted to appraise the physical and chemical properties of sinter to determine what constitutes a good sinter. During the 1949 to 1950 plant survey each plant submitted a 400-lb grab sample to research personnel at Mellon Institute, Pittsburgh, Pa. A 400-lb sample was also submitted from Sweden. In addition, 2 tons of group 3 fines iron ore were obtained from a Pittsburgh steel plant. The following tests were performed on the iron ore sample and on the 19 sinter samples: chemical analysis; impact test for strength and dusting; reducibility test; surface area measurements, B.E.T. nitrogen adsorption method; S.K. porosity test; Davis tube magnetic analysis; X-ray diffraction analysis for magnetite and hematite; and microstructure. Results of these evaluations are discussed in this paper and supply a critical look at testing procedures used to determine sinter quality. Sinter Tests and Results Each 400-lb grab sample of sinter was secured at a time when it was believed to represent normal production practice at each plant. It was not possible to use the same sampling procedures throughout the survey; consequently samples were taken from blast-furnace bins, cooling tables, and railroad cars. These were very useful for evaluation of test methods, since they were obtained from plants with widely divergent operations. With the exception of Swedish sinter and sinter sample N, which were produced on the Greenawalt type of pans, all survey sinters were produced on the Dwight-Lloyd type of sintering machines. Sinters submitted for test were prepared in identical manner by crushing in a roll crusher (set at 1 in.), mixing, and quartering. To secure specific size fractions for tests, one quarter of the sample was crushed in a jaw crusher and hammer mill to obtain a —10 mesh size. The remainder was screened to obtain specific size fractions. The group 3 fines iron ore was dried and screened and samples were taken from selected screen sizes to be used for various tests. Prior to testing, each ore sample except the —100 mesh fraction was washed with water to remove all fine material and was then dried. This iron ore, a hematitic ore from the Lake Superior region, was used as a base line for comparing results of tests on sinters. The iron ore did not lend itself to impact testing, since it was compacted rather than crushed in the test, and no impact tests are reported. However, the iron ore was subjected to all remaining physical tests to be described. Chemical Analysis: Table I presents chemical analyses performed on the survey sinter samples. Included in this table are data obtained from determination of FeO and the slag relationships: CaO + MgO and total slag (CaO + MgO + SiO, SiO2 + Al2o3 + TiO2). The percentage of FeO was used as an indication of the percentage of magnetite in the sinter. It was believed that slag relationships could be correlated with sinter properties. During initial determination of FeO great disagreement arose among various laboratories, both as to the results and the methods of determining values. Table I lists the values of FeO resulting from the U. S. Steel Corp. method of chemical analysis,&apos; which reports the total FeO soluble in hydrochloric and hydrofluoric acids (metallic iron not removed) with dry ice used to produce the protective atmosphere during digestion. Use of dry ice was a modification required to obtain reproducible results. In this method, the iron silicates and metallic iron are believed to go into solution and are therefore reported as FeO. This is important, for in the study of the microstructure of sinters, glassy constituents suspected of containing FeO as well as crystallized phases of undetermined identity which may also contain FeO have been observed. Strength Test by Impact: In evaluating sinter quality, one of the properties stressed most by blastfurnace operators is strength. This strength may be described as the resistance to breakage during handling of sinter between the sinter plant and the blast-furnace bins. It is also the strength necessary to withstand the burden in the blast-furnace. After

Jan 1, 1955

By E. R. Williams

Continuous casting of nonferrous metals has become a commercial reality. After years of slow and arduous experimentation by a number of independently working inventors, starting with Lord Henry Bessemer in 1865, success has finally been achieved. Nonferrous metals—aluminum, copper and brass—extremely vital to our production of war equipment, are being continuously cast every day in large quantities. In fact, some nonferrous metals —for instance, high-strength aluminum alloys—could not have been produced in the huge quantities required for planes and other war equipment if it were not for continuous casting. These casting processes for nonferrous metals have not been entirely perfected but continuous casting is here to stay. Continuous casting of carbon and alloy steel has not yet gone into commercial production but it is well on its way. A great deal of hard work has been expended and -small fortunes in money have been and are being spent in marching down the long road to success. Considerable tonnage of plain carbon, stainless and other alloy steels of high quality have been produced by pilot-plant continuous-casting units and at speeds that give indisputable evidence of commercial success. What has made the difference between failure and success? What is there left to do to revolutionize completely the method of casting metals, which has existed for centuries? These questions are being rapidly answered. Fundamental Methods Present continuous casting processes have many common problems but differ considerably in their methods of solution. The two fundamental methods are: I. Forming the solidifying metal against mold walls that move with the metal, so that there is no relative movement between the walls and the metal. This is a development of Lord Bessemer&apos;s idea of pouring metal between two rotating rolls. 2. Moving the solidifying metal along a stationary mold wall so that there is relative movement between the wall and the metal. This was proposed by Trotz in Germany as far back as 1889. Neither Bessemer nor Trotz achieved commercial success. The chief reason seems quite apparent today, inasmuch as they did not solve the fundamental problem of rapid heat removal from the molten metal. The Williams Continuous Casting Process is based upon this fundamental idea of fast heat removal and dissipation. The bessemer method of forming the ingot against a moving mold wall—either rotating rolls or endless moving plates—was carefully considered by the author and promptly abandoned as being commercially impractical. Primarily, only a very small tonnage output was possible except at terrific lineal speeds, because the very nature of this method required casting thin sheets rather than ingots. Secondly, the casting of a sheet between lolls that are pressed together meant the rolling of two layers of solidified skin separated by a molten core. Internal bursts and segregation of the metal usually resulted. Moving Solidifying Ingot Along Mold Wall It was decided therefore to devote our research activities chiefly to- the idea of moving the solidifying ingot along. a stationary mold wall. It was soon dis-

Jan 1, 1945

By R. B. BRINSJIADE

THE following is an attempt to form a formula by which a mine call be quickly evaluated, after all pertinent physical data have been collected from observations on the ground by a competent mining engineer. ASSUMPTIONS. Let G = price to be paid for the mining property. M = cost of developing the mining property to yield y tons of ore daily. P = cost of suitable plant to treat y tons of ore daily. p = value of said plant when the mine has.been exhausted. C = total fixed capital investment. W = working capital investment

Jan 1, 1908