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By Morris M. Fine, Norwood B. Melcher

It is out of the question, at this time, to select any one prereduction process as superior to the others. It is apparent that several share a basic similarity and that within the groups listed in Part 1, the reduction vessel is sometimes the only significant variable. Claims as to the virtues of one machine over another are difficult to substantiate: one may be rapid, another thermally frugal. Based on published data, however, all seem to be performing adequately. It would appear that processes based on carbonized pellets are most applicable to foundry iron at low production rates. Adaptation to large scale manufacture of blast furnace hot metal or to agglomeration of fine concentrates at the mine site is much less likely.

Jan 8, 1966

By Frank Harris

THE strength of hard drawn copper wire is a question of considerable importance to both manufacturer and consumer. Unlike steel and alloy wires, in which strength is governed by both chemical and physical considerations, the high conductivity required for copper wire in the electrical industry generally precludes the possibility of obtaining tensile strength through the use of alloys. Consequently, this strength is largely a matter of the physical structure, and all factors known to affect this structure, such as rolling temperature, die contours, lubricants, drawing speeds, etc., are matters of prime importance. The experiments described here have been carried out during the past year at the Baltimore plant of the American Smelting & Refining Co., in connection with a general investigation of some of the questions mentioned above, with the object of studying the physical structure of hard drawn copper, wire and the influence of certain factors on that structure. The work has been of an exploratory nature, rather than comprehensive, but it was thought that the results might prove of sufficient general interest to warrant their publication. The bulk of the hard drawn copper wire used in places where strength is an important factor is manufactured to strict specification, based usually in the United States on that of the American Society for Testing Materials (B-1-23). This specification calls for almost as high a value of tensile strength; consistent with elongation, as it is possible practically to obtain, and only physically perfect material can be relied on to meet such a specification. Obvious defects, such as laminations produced through fins in the original rods or brittleness due to overdrawing, are usually recognized and need only passing reference. Laminations can be detected by twisting and untwisting the wire several times; they will show up on the surface in the form of fins. Fig. 1 shows a very bad example of this defect. The wire may be perfectly smooth before twisting but when such laminations are present they will readily show up under this treatment. This trouble is caused by similar defects in the original rod produced by overfills in rolling. Fig. 2 shows the cross-section of the rod from which the wire in Fig.1 was drawn.

Jan 1, 1928

By Gordon H. Geiger, J. Bruce Wagner

Electrical conductavity and therrnoelectvic nzeasuretnents on synthetic hematite slabs with 0.01 to 0.90 at. pet Ti and with 0.30 at. pet Ca were made. Additions of titanium and of calcium both increased the electronic conductivity with titanium yielding greater n-type behavior and calciurn p-type behavior. Reduction studies of hematite to magnetite in CO-CO2 atmospheres between 600° and 900°C initially exhibited linear kinetics. These linear rates were increased by additions of titanium and decreased by calcium. IN recent years many studies have been reported in the literature on the kinetics of the reduction of hematite and magnetite to iron. In addition, Hansen and Josephl and Schenck and Schultz2 have reported studies on the reduction of hematite to magnetite, the first step in total reduction to iron. In order to evaluate the results of the studies of over-all reduction in terms of the actual mechanism of the reaction and to define further the important factors in the rate- controlling mechanism of the magnetic roasting reaction, the following experiments were undertaken. Specimens of undoped hematite and hematite containing titanium or calcium in solution as doping agents were reduced to magnetite in CO-CO2 mixtures. In addition, electrical-conductivity measurements were correlated with the reduction kinetics using concepts of defect solid-state chemistry. EXPERIMENTAL Fisher certified Fe2O3 powder was used to make specimens for both the electrical and kinetic studies (see Table I for analysis). Doping with titanium and calcium was accomplished by adding TiO2 and CaO powders to the Fe2O3 powder. The powders were mixed in a Waring blender for minimum times of 1/2 hr. Satisfactory blending was achieved based on comparison of analyses of individual specimens af- ter reduction. The specimens were formed in a steel die using opposed punches with a rectangular opening 10.0 by 40.0 mm. The Fe2O3-TiO, platelets were pressed cold at 16,000 psi. They were sintered for approximately 16 hr at 1075°C in air, in accordance with information in the literature3, 4 on the time and temperature needed to obtain solution of the titanium in the hematite. The Fe2O3-CaO mixtures were first cold-pressed at 20,000 psi and sintered for 3 hr at 1225°C to insure solution of CaO. This material was then ground to -325 mesh in a 6-in. ball mill and the resulting powder was used to make platelets in the same manner as above. The sintered platelets were usually between 1/16 and 1/8 in. thick. They were ground on a carborundum wheel and polished on 2/0 paper. Typical dimensions of the kinetic-study specimens were 1.6 by 0.8 by 0.05 cm, and a typical weight was 0.3 g. Conductivity and thermoelectric specimens were approximately the same size, but were subjected to further sintering in order to ensure maximum densification. Finally, all specimens were measured to the nearest 0.0005 in. and weighed on a Mettler H-15 balance to the nearest 0.0001 g and the density calculated. The average density of the specimens used for the reduction studies was 4.87 g per cc, or 7.1 pet total porosity. The standard deviation ranged from 0.14 to 0.063 g per cc within a composition group. In the present study, the apparent surface area as measured with a micrometer was taken as the true surface area. The chemical analyses for calcium and for titanium within a group showed maximum variations of 50.04 pet from the average values used in Figs. 9 and 11. In order to suspend the specimen from the balance for the kinetic studies, a hole, 0.03 in. in

Jan 1, 1965

By W. P. Sykes

ThiS investigation was undertaken primarily to establish the relations existing between temperature and mechanical properties in molybdenum, nickel, and an aluminum-copper alloy. Mlolybdenutn (m.p. 2500" C.) was chosen because it is partly similar to tungsten and partly similar to the common ductile metals. Also it is known to furnish, by proper treatment, a desirable material to use in studying relation of grain size and physical properties. The molybdenum used was of the quality that is drawn into wire 0.003 in. in diameter for use as filament supports in incandescent lamps; Chemical analysis shows less than 0.1 per cent. of impurities. Nickel belongs to the same class as iron. Its melting point is 1450" C. and an allotropic change at about 370" C. results in a loss of magnetism above that temperature. This feature made nickel doubly valuable for the purposes of these tests. The nickel used was obtained from the Driver-Harris Co. as 0.090 in. (2.3-mm.) wire, annealed; analysis showed 99.8 per cent. nickel and 0.150 per ccnt. iron. Aluminum is one of the low melting-point metals. Some tensile tests at clevated temperatures have been reported by Bengough but the possibility of learning more with the low temperature and sensitive apparatus available rccommendcd this metal. The samples marked A1 arc an aluminum-copper alloy that contains 3 per cent. copper, 0.42 per cent. iron, and 0.21 per cent. silicon. The presence of the copper somewhat coniplicates the analysis of the results; but the action of copper in aluminum has been studied so that its influence might have been foretold, in part at least. The material and analyses were furnished by the Aluminum Castings Co. The nickel wire, which was deformed at 400" C., was drawn under a bath of molten lead and through a die, which also was immersed in the bath. A thermocouple was suspended in the molten metal to indicate the temperature. Hot oil was uscd as the heating bath for drawing the

Jan 1, 1921

By J. J. Kanter

The choice of a nonferrous metal or alloy for a given Application is frequently predicated upon a consideration of properties other than merely the capacity to withstand stress. When ability to withstand stress is the dominant engineering requisite of the material to be used, economic considerations seldom lead to the choice of nonferrous metals and alloys. In most instances where a nonferrous metal is used it is because of some special quality of either corrosion resistance, electrical properties, thermal properties, antifriction, or fabrication advantage that commends its application. The mechanical properties, as a rule, present an incidental engineering consideration entirely secondary to the special quality deciding its use. Indeed, great ingenuity has often been exhibited by engineers and metallurgists in overcoming the mechanical shortcomings of a nonferrous base material. in order to take advantage of some outstanding property. . With this thought in mind, we might better appreciate some of the problems in stress design. encountered with nonferrous metals and alloys pertinent to a symposium on their creep characteristics. Our considerations must necessarily be far from complete because of the broad range of materials in the nonferrous category for which creep properties assume a technical interest. Creep deformation of these metals can be subject for study at temperatures ranging from ambient to incandescent, depending upon which one is under consideration. Whereas the steel metallurgist thinks of creep as an essentially high-temperature engineering consideration, the same is not necessarily true in the field at hand. The diversity of the creep problems in the nonferrous field is perhaps accountable to some extent for its virginity as a symposium subject. Each research has necessarily been sponsored by some organization or group interested either in promoting the use of a certain nonferrous base or in obtaining data toward the solution of a mechanical difficulty encountered in applying a material indispensable for its special attributes. Perhaps as many techniques of creep testing have been used as there are base metals implied under "nonferrous." Some of the creep problems that have occasioned researches are associated with steam-pressure vessels such as tubes, drums, castings, and forgings of copper-base and nickel-base alloys, cable sheathings of lead and lead-base alloys, electrical transmission lines of copper and aluminum, engine parts die-cast from alloys based on zinc, aluminum, copper— soldered and brazed joints-—as well as numerous duties at extremely high temperatures met with alloys based on cobalt, nickel, tungsten, molybdenum, platinum, and other precious or semiprecious metals. Postwar technology will have the benefit of much creep research on nonferrous metals, which for reasons of security cannot be discussed on this occasion. Suitability OF Metals As already intimated, the bulk of the constructional metal that ordinarily is

Jan 1, 1945

By Evan Evans

WITH the expiration on April 30, 1941, of the agreement between the anthracite operators and the United Mine Workers of America, a new agreement was entered into, providing for a general wage increase of 7 1/2 per cent effective May 1, to be brought to a total of 10 per cent on Oct. 1. Contract rates were increased from the rates established under the agreement of September 1923, and hourly rates were raised above the agreement of May 1936 as modified from the eight-to seven-hour day in May 1937. The new rates are to be in force for the duration of the agreement, ending April 30, 1943.

Jan 1, 1942

By Ogden B. Malin

In conducting the manufacture of extruded brass rods and brass forgings it has been noticed that there is considerable variation in the physical properties, particularly the machinability of different rods and forgings, even though the composition, working temperatures and method of manufacture remain the same. It is the purpose of this paper to attempt to establish the cause and extent of this variation, and also to determine whether variations in composition within certain defined limits influence hardness and machinability to any marked degree. The writer believes that this variation probably is due to the variation in grain size of the metal, therefore the microstructures of several compositions under various conditions of working were examined in an effort to establish this as a fact. Survey of Previous Work in Studying Extrusion Defects Very little has been published concerning defects in extruded and forged brass. In 1921, R. Genders1 $ delivered a paper before the British Institute of Metals, relative to a defect inherent in the extrusion process. This defect, commonly found in extruded brass rod, shows up in the form of a circle in a transverse section consisting of oxides and impurities, and is generally present in the last 25 to 30 per cent of the rod. Genders concluded that the defect is caused by the turning inward of the skin of the billet at the edge of the plunger because the inside of the billet is more plastic than the outside, which is in contact with the cooler container; the outside skin will lag behind to form the rear end of the rod. Genders suggested a movable die as a remedy, and while this met with fair success, it is not used in present practice. About the same time as Genders' experiments, Tucker2 and Rosen-hain3 conducted experiments using colored plasticene in the form of a billet, and found much the same defect as Genders. Dr. Rosenhain State College, Pa.

Jan 1, 1932

By PERCY E. BARBOUR

SECONDARY copper1 has &come more or less of a bugbear generally. What is its influence is often the subject of heated argument. The inedapable fact usually quoted is that since in 1929 primary production of copper in the United States was 1,026,348 tons and secondary production was 626,550 tons, there- fore, 0.6 lb. of secondary is produced for every pound of primary, and "How can you get around that?" The matter seems very plain, now that I have reached my conclusions, but they are the result of much laborious study and research. I shall show that' the production of secondary copper is not 0.6 per lb. of primary, in spite of statistical appearances; that the production of secondary is a function of primary production rather than of price; that secondary production has 'only a sub-. ordinate influence on the price of copper and then only in abnormal times; that there is not an accumulating reservoir of secondary from which the country is some- time to be drowned in copper, as is believed by some, or a reservoir from which we are going to draw much needed and more or less inexhaustible stores in the future, as is believed by others; and finally, that the United States always produces more copper than it uses and exports the surplus. These are all controversial points, and for that reason and to anticipate argument I have set forth my reasoning in considerable detail.

Jan 1, 1931

By Bjorge, Guy N.

MINING method improve through the gradual process of evolution and in 1340 there were no marked outstanding innovations. On the other hand refinements of detail and betterment: in equipment design continued to progress. Among the most important changes have been the increased application of trucks and highway equipment, including tractors and bull- dozers, to open-pit mining as exemplified by Phelps Dodge's Morenci operations; the Mesabi iron range; and the Tri-State district. Mass or bulk handling contributed its part underground with slurhers and conveyors at Consolidated Coppermines and slushers at Climax; and in open-pit mining. conveyors found increased use on the Mesabi range.

Jan 1, 1941

By Henry G. Granger

A RESIDENCE of 14 years in the Republic of Colombia, spent in almost continuous traveling and prospecting-trips, has given me an intimate knowledge of the resources of that wonderful country. The man who best knows Colombia is unquestionably General Rafael Reyes, President of the Republic for the past three years, and with seven years more to serve in his present term. Such is the strength of his personality and the wisdom of his policies that his term of office will no doubt endure as long as he is willing to serve. The vastly improved economic situation and the brilliant outlook for Colombia are so directly due to the influence of President Reyes that a few lines concerning him. will not be amiss, if they serve towards a better understanding of his personality. Born of a distinguished ancestry in the mountains of Boyaca, he is now 57 years old, just the age of his friend Porfirio Diaz when be began the work which has placed Mexico in the rank of great modern nations. It was Reyes who came to Washington to protest against the action of the government of the United States of America in reference to the establishment of the Republic of Panama, and, without entering into a discussion of this affair, it can be fairly said that there was not an American in Colombia whose feelings of justice were. not outraged at the government action and subsequent refusal to submit the matter to the impartial judgment of the' Hague. President Reyes is an accomplished linguist, speaking English, French, German, Portuguese, Spanish, and Italian. He has a remarkably. powerful voice, which can readily be heard by a large assemblage. His height is about 6 ft., and his weight exceeds 200 lb. He has clear gray eyes. Reyes was the leader of those who favored the approval of

Sep 1, 1908

By C. H. Lieb

ONE astounding fact in the production of petroleum is the comparatively recent realization by producers that flowing production is the cheapest crude produced. About 1910 or even later, operators actually endeavored to get a producing well to pumping as quickly as possible after completion. A well was not really considered to be completed until it was operating on the pump. Remarkable progress has been made since then. It was not until about 1920 that producers began to take a serious interest in pressures and to think a little about proper methods of handling oil wells. Pressure gauges were installed, and records of pressures maintained, which was quite an innovation. Desultory experiments were made with tubing of different sizes, as well as experiments with placing the bottom of the tubing string at different levels in the well. Probably the first important departure from customary procedure was about 1926, during the Seminole development, when gas lift

Jan 1, 1936

By Arthur V. Corry

GOLD was discovered in Alder Gulch, Virginia. City, Mont., on May 26, 1863. In a short time some 6000 people flocked to the new discovery, and on the banks of Alder Gulch six settlements sprang into existence, the principal one, Virginia City, alone surviving. This town today has a population of 800, and is the county seat of Madison County. It is estimated that between forty and fifty million dollars in gold was produced up to 1904. Virginia City is situated at the mouth of Alder Creek where that stream leaves the narrow canyon that cuts the steep foothills flanking Old Baldy Mountain, elevation 9572 ft., 12 mi. south. Virginia City itself is 5700 ft. above sea level.

Jan 1, 1936

By A. P. Watts

FOREWORD THE problem of concentrating the disseminated lead ore of southeast Missouri is extremely simple. The economic mineral is galena and the gangue is dolomite. The ore assays from 4 to .6 per cent. lead, 80 per cent. of which is recovered in a 70 per cent. concentrate.. The ore is crushed through 10 mm. and sized on 2 mm.; the oversize is jigged, while the undersize is tabled, and the slime treated by flotation. The district is the largest lead producer in the world, the output of metallic lead for the year 1915 being 183,906 tons. Over 20,000 tons of ore a day is being treated. The management of the different properties is progressive and always open to suggestion. The fact; however, must not be lost sight of, that the problem in the district is peculiar, as the average ore contains but 80 to 120 lb. of a metal normally selling at about 4c. per lb. The low price of the metal limits the treatment system to one of low cost. An elaborate treatment is neither logical nor advisable. An engineer first visiting the district may consider that the method of treatment could be improved

Jan 10, 1917

By H. S. Bell

IT SEEMS unnecessary to dwell upon the advantages of the modern pipe still as compared with the older type of distillation equipment used by oil refiners. The relatively low installation cost, coupled with remarkable operating efficiencies of pipe stills, precludes the consideration of other types except in rare instances where some peculiarity of product or plant may have an influence. The question of the actual heat required to distil petroleum is quite involved. We have extensive data on the latent heats of the various hydrocarbons under different conditions of pressure. We also have information regarding the specific heats of various oils and the effect of temperature thereon. Because of the complexity of petroleum and of each fraction, it seems impossible to theoretically analyze the partial-pressure effect of the great number of hydrocarbons upon one another during distillation. If a distillation curve and percentage analysis of any crude or product are available, it is possible to construct a curve with ordinates representing per cent. distilled and B. t. u. per pound or per gallon, or other desired unit. To do so the crude is split into fractions, of 5 or 10 per cent. The boiling point and gravity of each fraction being determined, it is possible to evaluate the heat required. As each fraction is removed, the residue must be raised to a higher temperature and latent heat supplied for the successive fraction. As the calculations progress, the latent heats decrease while the specific heats increase. Such a curve is illustrated by Fig. 1 for a typical 39.9 B° North Texas crude.

Jan 1, 1928

By E. C. Truesdale, Gerald Edmunds

A few years ago H. M. Cyr, working in the Research Laboratories of The New Jersey Zinc Co., produced a few pounds of zinc1 of such purity that no other elements were detected in it by spectrographic analysis, using the facilities then available. This zinc contained less than one ten-thousandth of one per cent of metallic impurities.&apos; During the decade that followed upon the laboratory production of this "spectro-graphically pure" zinc, commercial developments brought about the production of large tonnages of zinc of purity exceeding 99.99 per cent, and today zinc of 99.999 per cent purity is produced and marketed as "chemically pure" zinc. Typical analyses of present supplies of high-purity zinc are given in Table 1. Table 1.—Typical Analyses Percentnge by Weight Sum of Zinc Fe, Ib1 Fe Cd 1A1 cd Special High Grade*.......... 0.007b 0.005b 0.005b none O.OIOb C.P. (chemically pure)......... < 0.0002 0.0005c 0.000052 S.P. (spectrographically pure).. <0.0002d <0.00005d a A.S.T.M. Standard Specification for Special High Grade Slab Zinc (A.S.T.M. Designation: B 637). b Maximum. &apos; Fe chemically determined. Pb and Cd are spectrographically determined. d Differences between composition of C.P. and S.P. zinc are discussed later in this paper. The availability of commercial tonnages of special high-grade zinc has been the basis for the development of the zinc-base die-casting alloy industry which, in the year 1936, consumed one-eighth of the zinc used in the United States for all purposes. This and the C.P. and S.P. grades have given impetus to scientific investigations into the properties of pure

Jan 1, 1939

By E. C. Truesdale, Gerald Edmunds

A few years ago H. M. Cyr, working in the Research Laboratories of The New Jersey Zinc Co., produced a few pounds of zinc1 of such purity that no other elements were detected in it by spectrographic analysis, using the facilities then available. This zinc contained less than one ten-thousandth of one per cent of metallic impurities.&apos; During the decade that followed upon the laboratory production of this "spectro-graphically pure" zinc, commercial developments brought about the production of large tonnages of zinc of purity exceeding 99.99 per cent, and today zinc of 99.999 per cent purity is produced and marketed as "chemically pure" zinc. Typical analyses of present supplies of high-purity zinc are given in Table 1. Table 1.—Typical Analyses Percentnge by Weight Sum of Zinc Fe, Ib1 Fe Cd 1A1 cd Special High Grade*.......... 0.007b 0.005b 0.005b none O.OIOb C.P. (chemically pure)......... < 0.0002 0.0005c 0.000052 S.P. (spectrographically pure).. <0.0002d <0.00005d a A.S.T.M. Standard Specification for Special High Grade Slab Zinc (A.S.T.M. Designation: B 637). b Maximum. &apos; Fe chemically determined. Pb and Cd are spectrographically determined. d Differences between composition of C.P. and S.P. zinc are discussed later in this paper. The availability of commercial tonnages of special high-grade zinc has been the basis for the development of the zinc-base die-casting alloy industry which, in the year 1936, consumed one-eighth of the zinc used in the United States for all purposes. This and the C.P. and S.P. grades have given impetus to scientific investigations into the properties of pure

Jan 1, 1939

By D. R. Walker, M. C. Shaw

Dimitri Kececioglu (Allis-Chalmers Manufacturing Co., Milwaukee)—The idea of applying metal cutting theory to comminution and vice versa is very impressive. Among others, the demarcation of wheel-grinding data into two regions, namely Kick&apos;s and Rittinger&apos;s, draws attention here. A study of Figs. 6 to 9 shows the following: In Fig. 6, 1 point out of 8; in Fig. 7, 4 points out of 26; in Fig. 8 only 1 point out of 13; and in Fig. 9 practically none out of 13 points fall out of curve No. 2. Also when grinding particles smaller than 5x10." in. it is difficult to measure very accurately the grinding forces, chip geometry, and particle size. In view of the above it would be difficult to make a positive and distinct demarcation of the Wheel-grinding data into two regions, namely, Kick&apos;s and Rittinger&apos;s. The idea of using machine grinding to determine the comminution properties of materials is indeed unique. The following cautions come to mind, however, regarding applicability of machine grinding data to comminution: 1—Grinding gives uniform particle size, whereas comminution gives a variety of particle sizes in the same process. The fact that grinding gives uniform particle size is not necessarily an advantage because in comminution the overall energy under actual comminution is desired and comminution invariably results in the production of a variety of particle sizes. 2—In grinding, a small particle is ground off a comparatively large surface. In comminution small bodies are broken down to smaller bodies. This makes it difficult to establish a concept of reduction ratio in machine grinding. 3—The mechanics of machine grinding involve direct shearing action under very high strain and comparatively high compression at the shear zone, whereas: comminution involves direct dynamic compression and surface friction with comparatively little strain and shear. Consequently the mechanics of machine grinding appear to be different from those involved in comminution. Hence one might arrive at erroneous con- clusions when comminution characteristics are eval-uated from machine grinding results. It is noticed also that functions other &apos;than Eq. 16 which do not involve the concept of direct proportionality of useful energy input to new surface area created (Eq. 2 and particularly Eq. 12) may be derived to fit the, data of curve No. 2. One such relationship may be u = ct-", where c is a positive constant and n is a positive constant less than unity. This, of course, is made possible because data of a very small range. of particle size are being fitted by the curves of No. 2 and the hereby suggested relationship. A sound comminution theory should be applicable to a relatively large range of particle size. George B. Clark (Department of Mining Engineering, University of Illinois)—While the experimental work of Walker and Shawin this article is of intrinsic value in revealing certain fundamental aspects of machine grinding, milling, and related processes and in adding to the store of information concerning the comminution of solid materials by this particular process, it appears doubtful that the results of their research can be employed to verify either Kick&apos;s or Rittinger&apos;s theories. Both these laws were originally developed and proposed on the basis of very simple, idealized hypotheses. The creation of parallel idealized physical laboratory conditions which would be required for either their proof or disproof appear to be well beyond the scope of human ingenuity, at least at present. One great weakness of the imputed verification is that the spread of the points plotted on the graphs is not sufficient to permit accurate &apos;curve fitting. The range of particle sizes included in the belt and wheel grinding is not extensive enough to show any general trends, particularly for the horizontal portion of the curves, said to represent Kick&apos;s laws. That the milling; grinding, and turning data obtained by Walker and Shaw for both metals and minerals happen to comply with. certain interpretations of these two theories under certain specialized conditions

Jan 1, 1955

By M. J. Sinnott

WITH the advent of nodular iron as an engineering material, considerable interest has been shown in developing this material for various applications. Generally the strength, hardness, or ductility are the more common properties used for design purposes but occasionally applications involving a knowledge of the thermal conductivity of the material is required. A search of the literature showed, rather surprisingly, that relatively little work has been done on this property for all types of cast iron. Insufficient data are available on thermal and electrical conductivities to develop the Weidemann-Franz ratio, or the Lorentz relationship, for estimation purposes. There are no data on nodular irons and the published data on malleable irons are quite sketchy. For these reasons the conductivity of the group of nodular irons listed in Table I were measured. Irons I to IV were made in such a fashion as to maintain the carbon and alloy content essentially the same while varying the silicon content. Test specimens were cut from the mid-section of 4-in. keel castings. Iron V is a commercial casting of nodular iron. The test specimen of this iron was cut from the center of a large cast billet 3x10x26 in. All alloys were tested in the as-cast condition. A microstructural examination showed that each iron had spheroidal graphite but the size and distribution varied with the silicon content of the iron. The spheroid size decreased while the number of graphite nodules increased as the silicon content of the iron was increased. The matrix structures of each iron consisted of pearlite and ferrite with the proportions varying from predominantly pearlite in the low-silicon iron to mostly ferrite in the high-silicon iron. The commercial heat, iron V, was predominantly pearlite probably because of its higher manganese and phosphorus content. Two methods for measuring the thermal conductivity were used. The first was a modification of the techniques described by Powell and Hickman and Van Dusen and Shelton,² the second method was a simpler technique described by Jakob and Hawkins." Since the agreement of both methods as tested on two sets of duplicate samples was excellent, the simpler experimental technique was used. The results of the measurements are given in Table II along with a summary of the microstructural constituents. These conductivity data indicate that as the percentage of silicon increases there is a corresponding decrease in the thermal conductivity even though the structure is changing from pearlitic to ferritic. Such a change in microstructure is usually accompanied by an increase in conductivity. A third factor involved in the behavior of these irons is the size and distribution of the graphite nodules. The relative amounts of graphite do not change greatly but the size and distribution do. Generally graphite improves the conductivity but in the present case such an effect is probably masked by the alloying effect from the silicon and its dispersion through the matrix. The thermal conductivity of the nodular irons studied is less than that of regular foundry irons by some 10 to 30 pct and is less than that of regular malleable irons.&apos; The cause of the decreased conductivity is probably the more highly alloyed fer-rites obtained in these irons and the changed mode of distribution of the graphite as compared to the regular foundry irons. References R. W. Powell and M. J. Hickman: Journal Iron and Steel Inst. (1946) 154, No. 2, p. 99. &apos;M. S. Van Dusen and S. M. Shelton: U. S. Bur. Standards Journal of Research, RP668 (1934) 12, p. 429. ³M. Jakob and G. A. Hawkins: Elements of Heat Transfer and Insulation. 2nd Ed. (1950) New York. John Wiley and Sons. &apos; J. W. Donaldson: Journal Iron and Steel Inst. (1933) 128, No. 2, p. 255.

Jan 1, 1954

By J. Armanet

THREE MINING colleges are maintained in France; the École Nationale Supérieure des Mines, of Paris; École Nationale Supérieure des Mines, of Saint Etienne; and the École Supérieure de la Metallurgie et des Mines at Nancy. Besides graduates of these schools, a few graduates of the École Centrale des Arts et MIanufactures and of the École Polytechnique are employed as ]nine managers or engineers; however, most of the latter have taken a graduate course at one of the mining schools.

Jan 1, 1939

By Laurence Delisle, Aaron Finger

THE alloys formed by the addition of nickel to iron by convelltional metallurgical procedures show physical properties that differ widely from those of the individual metals. The effect of alloying on the mechanical properties is most pronounced in alloys containing between 15 and 25 per cent nickel. The tensile strength of an alloy containing, for example, 20 per cent nickel and 80 per cent iron (with 0.06 per cent carbon), in an annealed condition, is above 150,000 lb. per sq. in.? owing to a martensitic type of transformation, as compared with about 50,000 lb. per sq. in. for pure iron in the same condition. The object of this work was to determine whether the same beneficial alloying effect could be obtained in alloys of iron and nickel prepared by powder metallurgy technique. PROCEDURE Bars and pellets for tension and compression tests, respectively, were made. Two groups of specimens were prepared: (I) by cold-pressing the powders and sintering; (2) by cold-pressing the powders, sintering, repressing and resintering. Raw Materials Nickel powder supplied by Metals Disintegrating co., marked MD-151, was used. A typical analysis of this powder was as follows: sulphur, 0.040 per cent; copper, 0.18; iron, 0.23; manganese, 0.002; magnesium, 0.001 5 ; lead, 0.035; tin, 0.025 ; silicon, 0.08; chromium, 0.008. Electrolytic iron powder supplied by Plastic Metals Inc. was used. A representative chemical analysis for impurities other than gases, supplied by the vendor, gave the following results: carbon, 0.005 per cent; manganese, 0.002; silicon, 0.003; phosphorus, 0.001; sulphur, 0.004; nickel, 0.008. The fractions from these powders passing a 3 2 5-mesh sieve were reduced in hydrogen at 600°C. for one hour, to clean the surfaces of the particles. The reduced powders, slightly caked, were ground in a mortar and screened again through a 325- mesh sieve. Mixing The proper proportions of the powders were mixed overnight on rolls, in glass jars fitted with iron-wire baffles to break aggregates of particles that might form. Pressing All specimens were compacted on hydraulic presses. The pellets were compacted in a cylindrical die, ½ in. diameter. The ratio of thickness to the diameter of the pellets was maintained as nearly as possible at 0.9, as specifed for standard short compression pieces. The tensile bars were made by compacting 30 grams of powder. Their shape is shown in Fig. I. The compacting pressures for the pellets and the tensile bars were:

Jan 1, 1946