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By J. G. Baragwanath

CUBA'S lateritic iron ores, occurring on the northern coast of that island, though known to the Spaniards. did not receive any general attention until the close of the Spanish-American War. Preliminary studies of these deposits at that time indicated that the limonite contained small percentages of nickel and chrome, and it ryas subsequently discovered that although the average nickel content was only approximately 0.6 per certain limited areas of ore were suffiniently high in nickel to be considered commercial provided a suitable process fur its recovery could be developed. Early in 1937, Pardners Mines Corp. began a series of investigations which led to the development of such a process. Coincidentally, this company acquired option' on certain properties in the Levisa Bay and Moa Bay regions and conducted a systematic campaign of exploration by test pits and hand-auger holes in the course of which an aggregate of 90.000.000 tons of ore was developed in eight deposits.

Jan 1, 1945

By CHAS. A. R. LAMELY

In the extreme northeast corner of the State of Washington, on the Canadian border, lies the Metaline mining district. This district is old in history, but young in production. The Metaline district is a zinc-lead area of the replacement type in dolomite and limestone. The ore bodies of the Josephine horizon are in many ways similar to the ore bodies of the famous Tri-State zinc fields. The beds are faulted and folded and have varyng low dips in varying directions, and underlie large areas of the district. Production started in 1927 on a very limited basis. The property is now mining and milling 700 tons per day. The mine is opened by adit tunnels and a vertical shaft. As the ore horizons gained depth, it was necessary to sink inclines to follow the ore horizon (see Fig 1). From 1927 to date, approximately 600,000 ft of diamond drill was put down This work indicated that sufficient tonnage existed to justify a redesigning of the whole operation, surface and under- ground. After four years of general study, the following program was planned :

Jan 1, 1949

By Clarence P. Linville

(Pittsburg Meeting, March, 1910.) IT is recognized that, in all metallurgical operations, the greatest possible uniformity in all conditions is essential to the best results. It is the constant aim of metallurgists to secure this uniformity, and their success in this respect has been in many cases the cause of great advances in the metallurgical processes themselves. Of all such processes, the production of pig-iron in the modern blast-furnace is perhaps the most complex and the most difficult of control. Notwithstanding the great progress of recent years, there is still great difficulty in obtaining anything like uniform conditions and results in the manufacture of pig-iron. The reason is not far to seek. The ores vary in composition and physical properties, often carrying a varying amount of gangue material, unevenly distributed The coke may vary in composition, cell-structure, moisture, hardness, and other properties. The blast, the weight of which far exceeds that of any other constituent, varies in its moisture-content and consequently in its chemical composition ; and its temperature, by reason of the method of heating, is not uniform, but, besides varying from time to time with atmospheric and other outside conditions, has a maximum and minimum for every changing of stoves. Now, with regard to these variations, the modern demand for uniformity has been greatly aided. Chemical analysis has made it possible to select ores so that the composition of the charge can be kept fairly constant; coal may be obtained from a given field, and coked in the same kind of ovens under conditions which . make the fuel practically uniform ; the Gayley

Mar 1, 1910

By John G. Hall

The pumping operations at the Chief mine have been unique in the respect that for many years the entire flow of water into the mine has been disposed of by pumping into natural underground " caverns" or "sinks." Volumes up to 4000 gpm have been pumped into these caverns with no apparent tendency for the caverns to fill with water, and it has never been proven that any of the water returns to the mine workings. Major pumping operations have been carried on during two periods, the first from 1918 to 1927, and the second from 1942 to the present time.

Jan 1, 1949

By Cuppam Dasarathy

THE object of this note is to report briefly certain results of investigations on the Fe-In phase diagram. BISRA-high purity H-iron and 99.9 pct pure indium were used to prepare the alloys. The experimental techniques consisted of thermal analysis, optical metallography, and X-ray diffraction. A phase diagram based on the present results as well as those reported earlier by the author' is shown in Fig. 1. It is seen that the liquidus points fall on a smooth line which meets the monotectic isotherm at 1470°C. The liquidus extends up to 3.4 at. pct In. The phase boundary separating the two liquidus L1 and L2 is shown dotted. The experimental solidus meets the monotectic isotherm at -0.9 at. pct In. The 6/6 + L2 boundary drops steeply to the 6 + La/y + L2 boundary at -1350°C. In this region, it is impossible to detect satisfactory thermal arrests because of the steep phase boundary. The present diagram shows that indium lowers the temperature of the d/y transforma-tion and raises the temperature of the y/a transfor-mation. The y +d region is found to be very narrow. Indium gives rise to a restricted y field when alloyed with iron. The width of this field is between 0.4 and 0.5 at. pct In. Details of the alloys containing 40 and 50 at. pct In have already been reported by the author' and the transformation temperatures of these alloys are included in Fig. 1. It appeared from optical metallography and X-ray diffraction that the room temperature solubility of indium in a iron is less than 0.28 at. pct since alloys of 0.28 at. pct In and above, slow cooled to room temperature, contained dark etching second phase particles situated both in the matrix and grain boundaries of the a-grains, see Figs. 2 and 3. These particles were identified to be unalloyed indium by X-ray diffraction. The lattice parameter of the a phase reached a maximum of 2.8672A at the indium level of -0.28 at. pct. The present diagram, Fig. 1, is in substantial agreement with that of Stadelmaier and Fiedler' except for certain differences in detail. For example, they found the monotectic composition and temperature to be 7.0 at. pct In and 1443oC, respectively, while the present work indicates them to be 3.4 at. pct In and 1470°C. The 6 + L2/y + L2 transformation is indicated in the present work to occur at -1350°C, whereas Stadelmaier and Fiedler find this to occur at -1320°C. They also claim that the width of the y field is 0.2 at. pct In while the present work shows the width to be between 0.4 and 0.5 at. pct In. 1) Indium, when alloyed with iron, gives rise to a restricted y field, the width being >0.5 at. pct In.

Jan 1, 1970

By Alfred Boyles

"Heredity"1 in cast iron has been a subject of much discussion. Numerous experimenters have found that the properties of gray iron may vary greatly without corresponding variations in composition or thermal treatment. The main structural difference in such cases is in the size and distribution of the graphite flakes and the explanations given usually attribute this difference to some chemical element not shown by ordinary analysis or to some physical factor, such as inclusions in the melt. It cannot be said that any of these theories is completely satisfactory. Much remains to be learned about cast iron and for this reason a study of the material was undertaken as a part of the program of fundamental research at Battelle Memorial Institute. A review of the literature indicated that very little systematic work had been done on the mechanism of freezing in cast iron. The experiments described below are largely concerned with that problem. Normal and "Dendritic" Cast Iron As examples of variation in type of structure, photomicrographs of two test bars of cast iron are shown (Figs. 1 and 2) and the composition and properties are given in Table 1. Both are common, unalloyed gray iron. Test bar No. 13 has normal graphite flakes while No. 49 has very fine, lacy graphite arranged in a dendritic pattern, the matrix in both being pearlite. These two types of cast iron are well known to foundry-men and need no detailed description.

Jan 1, 1937

By R. D. Nelson, F. E. Bowman

Assumptions are made of ideal mixing and that the density of silver can be obtained by extrapolating reported liquid density-temperature data through the freezing point back to the temperature range of interest. The results of this procedure using liquid silver density data of Kirshenbaum et al.5 are presented in Table I1 where it is observed that agreement is everywhere within <0.1 pct and generally is within 0.05 pct. Because the Sn-Ag alloys are dilute, the assumption of ideal behavior is, therefore, probably justified. In conclusion, the densities of dilute liquid solutions of silver in tin have been determined. Even for concentrations as low as 0.1 pct, the effect of silver on the density of liquid tin is clearly measurable. This work also suggests that for dilute alloys at temperatures far below the freezing point of the solute metal, densities may be accurately calculated by extrapolation of the pure metal data without having recourse to physical measurement on the alloy itself. plutonium having a grain size of about 100 µ. This paper presents data showing that large elongations of fine-grained a Pu can be obtained by using slow deformation rates. Large plasticity, however, of a Pu in compression has been observed.4 Reductions in thickness of 90 pct have been observed with no edge cracking. These large reductions are accompanied by concurrent re-crystallization. The deformation modes, which are quite complex, have been studied extensively by observing the deformation microstructures of polished surfaces that had been deformed in compression.5-7 Although slip apparently is a predominant mode of deformation at room temperature, grain boundary sliding and concurrent recrystallization become more predominant at high a temperatures.4&apos;7 Although recovery occurs,8,9 no grain growth has been reported in a Pu even at temperatures near the a =ß equilibrium temperature (-115oC), which is 0.7 of the calculated melting temperature of a Pu.10 From studies on other materials, it appears that high elongations can be obtained in alloys when the THE purpose of this technical note is to present briefly some data revealing high ductility of a Pu, which is normally considered brittle. The very low ductility of a Pu in tension has been reported by many investigators.&apos;-3 Gardner,1 for example, reported that the total elongation of a Pu at a testing speed of 0.015 ipm is less than 0.1 pct at room temperature and only about 1 pct at 100°C. The only tensile creep studies that have been reported&apos; indicate no large ductility, but they were performed on relatively low purity

Jan 1, 1970

The Role of the Drilling Contractor BY FERRIS E. SAINSBURY Ron Haxby, Occidental Minerals What is the best method for drilling a 12-in. diam hole to a depth of 1200 ft and maintaining the deflection within 25ft from vertical? Ferris Sainsbury: In order to drill a 12-111. hole down to 1200 ft, In most places you would have to employ a rotary tricone bit With a down-the-hole hammer, I expect by that depth significant Inflows of water would be experienced Even with foams, we would not be able to get the water out of a hole of that diameter So the down-the-hole tricone method of drilling would be best. To keep it straight, we would probably employ the largest square drill stem compatible with the diameter of the hole. Ron Haxby: Is it common in drilling contracts to put in a vertical hole clause? Ferris Sainsbury: You can put in the vertical hole clause Ron Haxby: Does it cost more? Ferris Sainsbury: Normally, if the hole deviates, the driller can correct it with deflection wedges and will charge it back to you at cost, plus 10% or somewhere along that range Any drill hole has a tendency to go perpendicular to the dip, and there are times when stabilization systems are not successful in preventing the hole from turning into the dip of the formation. The only solution, in this situation, is to go in with an oriented wedge and kick the hole back out.

Jan 1, 1979

By Jerome F. Kuzmick

Many investigations have been made on the effect of the variables of pressure, sintering temperature and sintering time on the physical and microstructural charactcristics of metal-powder compacts. Severa1 such investigations have indicatcd that pressure is the least important of these three factors in an attempt to secure a dense. strong compact by a simple coltl-pressing and sintering procedure. However, it was felt that a further study of the effect of pressure on pressed and sintered metal powder compacts might prove interesting, for the following reasons: In work done in the past on the effect of pressure, temperature. arid time, the, metal-powder compacts were subjected to long sintering periods, and temperatures right up to the melting point of the metal were applied. It was thought that pressure might exert a more profound effect under short-time simtering and within narrower ranges of temperature. such as normally would be applied in large-scale production of metal-powder parts. 2. It was hoped that something further might be learned of the nature of the bond in pressed and sintered metal-powder compacts. 3. It was thought that interesting infor mation concerning the work-hardening effect of pressure on the crystal structure. of sintered metal-powder compacts would be obtained. Procedure Rectangular bars, 2 by 1/2 by 1/4 in. were molded from the following metal powders: Atomizcd till powder, 325-mesh Atomized aluminum powder, 325-mesh Reduced copper powder, 100-mesh Electrolytic iron powder, 100-mesh Atomized 70-30 brass powder, l00-mesh The, till powder was molded at various pressures up to 40 tolls per sq. in. This was the maximum, because at higher molding pressures there was considerable extrusion of tin into the die wall, jamming the die plungers. The tin specimens were not -in tered, as this phase of the work was- done merely to see how much a very sold metal could be compressed. The aluminum powder was compressed at various pressures up to 50 lons per sq in. Higher pressures could not be used because of extrusion into the die wall The compacts were sintered one hour at 000 in pure dry hydrogen. The copper powder was molded at vari-ous pressures up to 96 tons per sq. in. One set was sintered at 750°C., another at 050 C. for one hour in pure dry hydrogen. The electrolytic iron powder was molded at various pressures up to 00 tons per sq. in. and sintered, one set at Soo°C and one set at 1300°C for one hour in pure dry hydrogen. Extra 325-mesh specimens were also prepared to study the effect of reduced particle size on grain structure. The brass powder was molded at various pressures up to 96 tolls per sq. in. and silltered for one hour. one set at 65o°C. and one set at 800°C, in pure dry hydrogeu.

Jan 1, 1945

By Wilbur E. Sanders

AT some period during the operation of metalliferous and other commercially valuable mineral-deposits in connection with their underground mining, when the developments therein have become so extensive that their description is tedious and confusing, some scheme for naming or numbering the various workings and their parts is necessary for convenience of ; reference.. A simple and symmetrical yet expansive system of classification must be devised, one that is capable of being extended to cover all possible exigencies and conditions of future operations within the property. Such a scheme, properly arranged, greatly simplifies communication between the various departments of the mining business, as, for instance, between the administrative and the operating departments of the concern, and is of the greatest assistance to the officers of the mine in enabling them to locate and describe particular points and parts of workings and specific kinds of work. Again, in the proper segregation and differentiation of mine-accounts, when they are carried out with that detail which will furnish ready information concerning the cost of a particular piece of work, or the various items and totals of expense connected with the, development,, operation and repair of each or all of the mine-workings, some such method of designation becomes a necessity. . Moreover, such a plan is admirably adapted to the needs of the mining engineer, who, in connection with his reports upon mining-properties, is sometimes required, in his descriptions of certain blocks of ore, to locate lists of assays of samples taken from many and various places, and to designate workings and parts of workings that are located in different parts of the mine, sometimes at points wide apart.

May 1, 1906

By Carl F. Floe, Michael B. Bever

ACCELERATED by the demands of war, research and development work in nonferrous physical metallurgy has continued at a rapid pace during the past year. In particular, advances have been made in processing and fabrication, especially of the light alloys, and in the surface treatment of metals. Theoretical physical metallurgy, although less active, has not been neglected and the year has brought forth some -notable contributions to our understanding of the fundamental structure of metals and their behavior in service. Of course, much work that has been done cannot be publicly discussed because of wartime restrictions.

Jan 1, 1945

By J. R. Stone, G. D. Storm

Design features and operating methods of ASARCO&apos;s new unit for the continuous melting and casting of tough pitch copper at Perth Amboy are described. Preliminary studies made for determinitzg economic feasibility and design details are also presented. Cathodes are preheated with oil and melted in an electric furnace at 40-ton per hr rate, from whence the molten copper is fed simultaneously to the wire bar casting wheel and the continuous casting of cakes and billets. In the early 1950&apos;s the copper refining furnaces at ASARCO&apos;s Perth Amboy plant reached a point where major expenditures would have to be made for replacement of the furnaces and the auxiliary equipment. The problem was whether to continue with the standard reverberatory furnaces or to consider continuous melting in electric furnaces. Reverberatory furnaces have been used for years in the copper industry and for some 50 years at the Perth Amboy plant. Reverberatory melting practice, however, imposes certain restrictions. First, labor costs are high, usually requiring three shifts per day. Secondly, they operate on a batch basis, the conventional operation being a 24-hr cycle including

Jan 1, 1961

P. W. BRIDGMAN.-Owing to a misunderstanding, I did not see Dr. McAdam&apos;s and Dr. MacGregor&apos;s remarks on my paper on Flow and Fracture (Metals Technology, December 1944, Pp. 32-38), until after their publication. Both Dr. McAdam and Dr. MacGregor speak of my analysis for the stress distribution at the neck of a tension specimen as containing several assumptions; in particular, that the strain is uniform across the section of the neck, that there is no hoop tension at the periphery, and that the plasticity conditions of von Mises hold. As far as the mathematics goes, the situation is no different in this problem of plastic flow than in a conventional problem of elasticity. That solution is unique which satisfies the boundary conditions on the stresses, the stress equations of equilibrium, and in addition the constitutive equations connecting stress and strain in the elastic case, or a corresponding set of equations, of which the von Mises relations are a special form, in the plastic case. In the particular case of the necked tension specimen I have found that there is a solution satisfying the boundary conditions, the stress equations of equilibrium, and the von Mises plasticity conditions in which the strain is uniform across the section, and there is no hoop tension at the periphery. This is therefore the solution, and the uniformity of strain and vanishing of hoop tension at the periphery are to be described as discoveries, over which the operator has no control, rather than as assumptions. The only part of the solution that can properly be described as an assumption is the von Mises plasticity condition. With regard to this it is to be noted that the condition is needed only in a much weakened form, for the analysis uses the condition only at the neck, where the strain is approximately constant. Thus, in the extreme case referred to in a footnote of my paper (p. 37, Met. Tech. Dec. 1944) the actually measured strain across the section varies from 2.4 to 2.6. Obviously it is a much weaker assumption to postulate that the von Mises condition holds in the strain range 2.4 to 2.6 than to assume it to hold for the entire range of strain from o up to 2.6, which would be necessary if the solution applied to the entire tension specimen rather than to the immediate region of the neck only. Furthermore, it is to be commented that under the special conditions of this problem the von Mises condition becomes identical with the maximum shearing-stress criterion of plastic flow; this amounts also to a weakening of the restrictions imposed by the von Mises condition. Dr. MacGregor refers to actual experiments of his own in which the strain was found not to be uniform across the neck. It is to be emphasized, however, that these were experiments on bars of rectangular section, and that the nonuniformity established was a nonuniformity around the perimeter, not a nonuniformity from the surface toward the axis. My method of solution applies only to a circular cross section. It can be said that the solution that satisfies the boundary conditions, etc., would definitely not be expected to demand a uniform strain for noncircular sections. In discussing my results, Dr. McAdam uses a definition of "flow stress" different from mine, so that the immediate applica-

Jan 1, 1945

By Emma Smith, R. W. Guard

INVESTIGATION of the nickel-rich end of the Ni-Zr system has been prompted by an interest in the effect of small amounts of zirconium in high temperature alloys. Hansenl presents a hypothetical diagram based on the work of Allibone and Sykes,2 who investigated the system up to 44 atomic pct (55 wt pct) Zr by metallographic means. Since the alloys they used were melted in Alundum crucibles they were probably contaminated with appreciable amounts of aluminum. They found two compounds which they called Ni3Zr and Ni4Zr. Hayes, Roberson, and Paasche3 identified a compound NiZr (50 atomic pct Zr) with a melting point of 1470°C. Such a high melting compound is not compatible with the observation of Allibone and Sykes2 hat a eutectic is formed near 50 atomic pct. The alloys containing up to 60 atomic pct Zr were melted in an inert atmosphere in a noncon-sumable electrode arc furnace. Analysis of most of the alloys indicated negligible loss of zirconium. The alloys were examined in the as-cast condition and also after annealing for 6 hr at 1175°C (or 1000°C for the alloys between 25 atomic pct and 45 atomic pct). Metallographic specimens were etched using mixtures of HF-HNO3-H2O or acetic acid- HN0,-H,O. The specimens for the solidus determinations were wrapped in molybdenum foil and sealed in evacuated quartz tubes. Specimens to be heated above 1300°C were enclosed in zirconia tubes inside the quartz to prevent reaction with molybdenum. The solidus determinations were carried out by heating the specimens at various temperatures for a few minutes and then examining the interior structure metallographically to determine at what temperature melting began. The 150 mesh powders for X-ray analysis were annealed in an evacuated quartz tube for 2 hr at 540 °C to remove cold work. Alloys with 22.5 atomic pct Zr and 44.4 atomic pct Zr required annealing at 700 °C for complete recovery. The grains of both of these alloys were soft and rather ductile. Both Debye-Scherrer film patterns and spectrometer traces were made for each alloy using filtered copper radiation. Results and Discussion The presence of a substantial amount of second phase in an alloy with 1.1 atomic pct Zr indicated that the solid solubility of zirconium in nickel is somewhat less than 1 atomic pct. The a0 value for the face-centered-cubic matrix in the same alloy was equal to that of pure nickel, so that the solubility must be very small. This observation is as expected from the large atom size difference. Annealed specimens of alloys with 15.0, 16.7, 22.5, 28.6, 44.4, and 59.4 atomic pct Zr showed. micro-structures that were essentially single phase. When

Jan 1, 1958

By O. Chanute

all of&apos; level atid grade curve excepting Nos. 897, 898, 899, and 900, because of the impossibility of grouping them in the same nlonner, no two Iraving the chemical composition and physical prnprtiw as tho only v:iriubles. Phosphorus ~tnits have been taken to show the relatia h:wdnes. Of these 16 groups, 10 decidedly indicate slower wear firr tile harder rail. Of the remaining 6 groups, three (groups 2, 9, and 15) come well within the limits of error (.25 pound per yard) inherent in the palculation of the data as pointed out by Dr. Dndley; they catrnot, therefore, be considered tls exceptions. Group 2 and 15 arc but little outside of the limita of error. Rail 923 of group 9 is obviously abnornlal. This is probahly due to its being overheated, which the chemical analysis shows might easily be the case, and which the physical tc~ts and its low specific gravity tend to c-nfirm. We inry say, then, thnt 13 of these 16 groups fairly indicate, if they do not definitely point out, th:kt, under the same condition% tbe harder rail gives the slower wear. Of course, these comparisons are too few to enable us to arrive at positive ~?o-nclusions; but indications thus obtained are, I believe, fir more vsluitblc and tresttvc~rthy than those fhzt averages rvottld give us, mnde up from any ~lumhr of rails under intloy difi~rcal, conditions. Finally, it, seems to me, that the conclusions arrived at earlier in my remarks, together with, and confirmed by the last, show strong evidence that, under the same conditions, the harder rail will givc the slower wear. 0. C~~anute, New York CITY: We are very much shlipl, 1 ant sure, to Mr. Sandberg for his paper upn " Rail Ryaifications and Rail Inspertion in Europe." We have in thp United States bithhrto Been inspecting mils sonlewl~at haphazard, and we ore glad to gtbt tfie results of Mr. Sandberg&apos;s long experience. We recognize that he was an)ong the first, if not the very firwt, to iipply mare rittional and scientific rules to the designing of irou rails., niora recently, to adapt tlitve rules to the clesigtting of steel I&apos;:I~]R, to conform to the oapaljilities and rqniretnento of this new n1:ttcrial. Although we have generally adopted, in this country, sectinns for hteel rails which marly of our railway men think even bottar than those of Mr. Snlldlmrg, he is neverthelees the Ieat3er in foot.iito11~ we have followed ever since it has been est~blished

Jan 1, 1881

By O. W. Ellis

THE question of the influence of gases upon the properties of copper has received the attention of a number of investigators, among whom Sieverts,1 Iwasé,2 Lobley and Jepson3 stand preeminent. SOLUBILITY OF . GASES IN. COPPER Sieverts and Iwasé concerned themselves with the solubility of a variety of gases in the metal in the solid and liquid states. They determined the absorption coefficients of these gases and in all cases found a sharp change in solubility at the melting point of the metal. In this respect they disagree with Lobley and Jepson, who have based their opinions upon the appearance of small ingots of the metal which had been fused in an atmosphere of one or other of three gases and had then been rapidly cooled, while surrounded by gas, to the freezing point (rate-possibly 30° to 60° C. per sec.). The ingots that had been fused and cooled under nitrogen and carbon monoxide were free from blowholes and it was assumed that these gases were not absorbed in amounts much in excess of those which would dissolve in the solid metal; the ingots similarly treated under hydrogen were full of blowholes and it was assumed in this case that gas was ejected on solidification of the copper. The effect of varying the rate of freezing upon the character of the test ingots was not examined by these investigators; otherwise, it is felt, their views might have been subject to modification. Sieverts&apos; most important contribution is that the solubility of a gas in any metal is proportional to the square root of its pressure or concentration. Knowing then the absorption coefficients of the various gases in copper, it should be possible to determine the analysis of the

Jan 1, 1928

By Ursula E. Wolff

The precipitation of carbides from an alloy containing 33 pct Ni, 21 pct Cr, balance iron, was investigated electron microscopically by means of extraction replicas and thinned metal foils. Annealing temperatures ranged from 565°to 870°C and up to several thousand hours. M23C6 precipitated in pain boundaries, incoherent and coherent twin boundaries in that sequence. The orientation relationship between carbides and austenite matrix was determined and correlated with the morphology of the carbides and with the type of boundary in which precipitation occurred. In large-angle grain boundaries, as well as in coherent twin boundaries, the carbides had the same orientation as one of the adjacent pains. These carbides formed sheets of individual flakes with shapes related to the orientation of the boundary. In incoherent twin boundaries carbides precipitated in ribbons composed of pavallel rods. An unidentified subcarbide was found to precede precipitation of M23C6 in these boundaries. The M 23 C6 rods had a kind of fiber texture with (110) parallel to the long dimension of the rods and ribbon, and with orientations of both of the adjacent twin-related austenite crystals Predominant in the texture of the carbide. A hard sphere crystal model has been used to discuss orientation and morphology of the carbides in terms of free volume and vacancies available in the boundaries. A number of papers have dealt with the morphology of chromium carbide (M23 C6) precipitated in austenitic stainless steels.1"7 In all these investigations, the carbides were examined in the electron microscope by means of extraction replicas. With this technique, the carbides retain the spatial distribution they had in the bulk sample. However, since the matrix is dissolved in the process, the particles can turn in an unpredictable way; and the orientation relationship between matrix and carbides cannot be established. In this paper the results of studies on extraction replicas and on thinned metal foils are reported. These studies were undertaken to determine the matrix-to-car bide orientation relationship, and to correlate the orientation of the carbides with their morphology. PROCEDURE The material used was an austenitic alloy with 33 pct Ni, 21 pct Cr, balance iron, containing approximately 0.05 pct C. Coupons of 1.25-mm sheet were first solution-annealed at 1050°C for 15 min and air-cooled. Then, to precipitate the carbides, samples were isothermally annealed in the range from 565" to 870°C for times up to several thousand hours. All further specimen-preparation procedures were carried out after the final anneal. Carbon extraction replicas from polished and etched surfaces were made with 10 pct bromine in methyl alcohol.&apos; Thin foils were prepared from punched-out 3-mm-diam disksg which fit into the electron-microscope holder. The disks were prethinned by grinding to approximately 0.5 mm thickness, and then electro-polished in a polytetrafluoroethylene holder1&apos; with a solution containing 5 pct perchloric acid in acetic acid to which 10 g per 1 Cro3 and 5 g per 1 nickel chloride were added (etchant modified from that of Briers et al."). This solution dissolves neither the carbides nor the austenite around the carbides preferentially. By using extraction replicas, electron micrographs and selected-area electron-diffraction patterns were taken from the same carbide arrays. By using thin foils, electron micrographs were made from a grain boundary area containing carbides. Electron-diffraction patterns were then taken from the same area and from each of the adjacent grains separately. In this manner, the orientation of each grain could be determined without interference by the carbide pattern. A peculiarity of extraction replicas should be pointed out. After the matrix is etched away, the carbide arrays float freely in the etching and washing solutions, and are held in place only at the anchoring points in the carbon replica. When the replica is picked up with a screen the carbide arrays tend to flip to one side. Thus, while the surface features are preserved, the original arrangement of the carbides may severely and unpredictably be disturbed whenever the specimen contains large amounts of interconnected carbides. Nevertheless, it is possible to correlate the different morphologies of the carbides with the type of boundary in which they have precipitated. RESULTS 1) Extraction Replicas. Fig. 1 shows that the grain boundaries usually are curved, multicornered surfaces of random orientation. The coherent twin boundaries (which are (111) planes) cut a grain into parallel slices. Incoherent twin boundaries occur at the ends and on the steps of twins and are often narrow, parallel-sided strips which are much longer than they are wide. Different morphologies can clearly be distinguished for the M23Ce carbides precipitated in each of these types of boundaries, and agree well with those observed by kinzel.2 The kinetics of this precipitation has been investigated." The first carbides precipitate in junctions of three grain boundaries and fan out from there into the adjoining boundary surfaces, Fig. 2(a). These carbides are oriented randomly, Fig. 2(b), and become coarser and thicker as annealing time increases. The large-angle grain boundaries are next to fill

Jan 1, 1967

For handling rough rock, the shovel-train system is unexcelled. The ideal application is a physically large, but not excessively deep, open-pit mine from which the coarsely blasted ore and waste must be transported distances in excess of three miles. If, in addition, a high production rate is to be maintained, railroad haulage will probably afford a lower cost per ton transportation than will any other haulage method. Relatively gentle grades must be employed- usually 3% for uphill hauls and 4% for downhill hauls. The greater the differences in elevation the greater are the railroad track grade space requirements. By way of illustration, a 3% ramp out of a pit only 300 ft deep must be almost two miles long. Mainline track locations should be selected carefully so that the frequency of movements during the life of the mining operation is minimized. This applies both to ore and to waste haulageways. Such moves are not only expensive but difficult to execute without adversely affecting production rates. The large mine affords greater opportunities for judicious location of semi-permanent trackage.

Jan 10, 1967

By J. S. Marsh

AN incomplete statistical analysis performed wearily on the morning after Thursday, Feb. 12, indicates that the unavoidable items of conversation among steelmen were the current shortage of sleeping time and the "Normandie." No analysis is needed, however, to be certain that many thousands of valuable words were uttered, both in and out of technical sessions, concerning matters of deep interest to members of the Iron and Steel Division. The opening session consisted mostly of papers that have appeared, or will appear shortly, in Metals Technology. One, however, that was not finished in time to be printed in any form, but that aroused great interest, was by E. L. Ramsey and L. G. Graper (Wisconsin Steel Works). Its subject was the production of high-sulphur steel by treatment with sulphur dioxide derived from anhydrous sodium sulphite or bisulphite added to the ladle or to the mold. The sulphide distribution in the finished steel is such that increased machinability and longer tool life result. Both items are of obvious importance in these days of mighty production.

Jan 1, 1942

By Zay Jeffries

TUNGSTEN has the highest melting point of all the known metals, namely 3350° C.; it is one of the hardest of the metals; it has the highest equiaxing or recrystallization temperature after strain hardening, of any pure metal known. It is particularly distinguished because, when composed of small equiaxed grains, it is extremely. brittle and fragile at room temperature, and when possessing a fibrous structure it maybe ductile and pliable at room temperature. The common ductile metals act in exactly the opposite manner in this respect. The present paper will include a brief note regarding the manufacture of wrought and. ductile tungsten. The metallography of wrought and ductile tungsten in the various stages of manufacture will be considered more or less in detail. The general relationships between the properties of tungsten and other metals will also be considered. A discussion will be given explaining why fibrous tungsten is ductile at room temperature, even though past experience with other metals would indicate that it should be brittle. Finally, a brief note regarding some new fundamental metallographic propositions relating to all metals will be given.

Jan 6, 1918