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By Robert Baker

IT has been demonstrated in the laboratory by A. J. Phillips1 that a transformation or conversion from beta directly to alpha may take place in a brass of 61 to 62.5 per cent copper content. The completion of the transformation is dependent on a rapid rate of cooling from the all-beta field through the alpha + beta range to the alpha field. Phillips states that in a slowly cooled alloy containing 62 per cent copper and 38 per cent zinc the copper content of the beta is progressively decreased from 62 to 56 per cent by precipitation of alpha. Rapid cooling tends to prevent the separation of alpha with a copper content of more than 62 per cent by reducing to a minimum the time required for passing through the alpha + beta range. Upon crossing beyond the (alpha + beta.)/(alpha) boundary to the all-alpha region below, the material is transformed from beta to alpha. It is essential that there be no change in composition. Phillips obtained his results by quenching a 62:38 copper-zinc alloy from 850° C. in iced brine at -8° C. No reference to the occurrence of this transformation in a manufacturing process has been found in the literature. An investigation of the microstructures of a number of hot forgings made from leaded brass rods yielded one forging in which this striking conversion from beta to alpha had occurred. The purpose of this paper is to describe the transformation and certain conditions under which it may occur during the hot pressing of brass. The conversion was noted in a shape forged from a leaded brass rod, the composition of which was: Cu, 60.26 per cent; Zn, 37.86; Pb, 1.88. In this study the lead content was disregarded and the alloy was considered to be equivalent to an alloy of 61.40 per cent copper and 38.60 per cent zinc (98.12 parts = 100 parts). The possibility that the lead might obstruct or accelerate the precipitation of alpha was not studied. The lead appears as black globules in the photomicrographs and has a negligible solubility in the alloy.

Jan 1, 1931

By Stanley D. Michaelson, Norman Weiss

This was a year of realization. Some years are for planning and development, some for designing and building, others for fulfillment. With greater hopes and plans for the future than ever before, the year 1954, nevertheless, will be remembered principally because of project completion. Among copper mines, for example, there were Silver Bell, Copper Cities, Bisbee, Yerington, and White Pine. In iron, there were the Humboldt, Coleraine, Cerro Bolivar, and Eagle Mountain. In asbestos, Johns-Manville's new mill at Asbestos, Que. In uranium, completion of the ninth mill on the Colorado Plateau-Kerr-McGee's at Shiprock, N. M. In research, 1954 marked the completion of Kennecott's Research Center in Salt Lake City, one of the historic forward strides in the science of minerals beneficiation. The year was fruitful in other directions as well. Investigations of a fundamental nature were on the upswing, and pilot plant projects have also increased in size and number. Progress in new reagents and equipment was greater than normal. It can already be conservatively predicted-from the technological point of view-that 1955 and 1956 will be tremendous years.

Jan 3, 1955

By J. F. Kemp

IN submitting an additional contribution to the discussion on ore-deposits in the recent volumes of the Transactions, it is my desire to adhere closely to matters of material importance as affecting the actual processes. Judging from the discussion by Professor Van Hise, and from one or two reviews or other articles by associates of his in geological work, the impression seems to prevail that, in so far as my paper* referred to ,his masterly essay,†I was guilty of misconceptions regarding both the part attributed by him in it to the igneous rocks and the ubiquitous presence of the ground-water. I should regret extremely to be wanting in these particulars or to have misunderstood one for whose great services in this and other branches of geology no one has a higher esteem than myself. I have, however, in the most careful way, and with these points in mind, read his essay again, anti, taking it as a whole, I cannot gain any different impression of relative magnitudes than the one first received. The importance of the igneous phenomena and the restrictive influence of the processes described by " cementation " in their effect upon the ground-water, as set forth in Professor Van Hise's " Discussion " (Trans., xxxi., 292), impress me as being in very marked contrast with the same things in his first essay. If the point seems to anyone of sufficient importance, it can easily be decided by reading the originals. My paper was the result of some years of observation, reading and reflection, and was meant to be an independent contribution, controversial only in some subordinate particulars. In depicting the drama of the deposition of ores, I cannot but feel that Professor Van Rise assigned to the chorus and the scene-shifters some characters which, it seems to me, should

Jan 1, 1913

By James F. Kemp

In submitting an additional contribution to the discussion on ore-deposits in the recent volumes of the Transactions, it is my desire to adhere closely to matters of material importance as affecting the actual processes. Judging from the discussion by Professor Van Hise, and from one or two reviews or other articles by associates of his in geological work, the impression seems to prevail that, in so far as my paper* referred to his masterly essay, I was guilty of misconceptions regarding both the part attributed by him in it to the igneous rocks and the ubiquitous presence of the ground-water. I should regret extremely to be wanting in these particulars or to have misunderstood one for whose great services in this and other branches of geology no one has a higher esteem than myself. I have, however, in the most careful way, and with these points in mind, read his essay again, and, taking it as a whole, I cannot gain any different impression of relative magnitudes than the one first received. The importance of the igneous phenomena and the restrictive influence of the processes described by " cementation " in their effect upon the ground-water, as set forth in Professor Van Hise's "Discussion" (Trans., xxxi., 292), impress me as being in very marked contrast with the same things in his first essay. If the point seems to anyone of sufficient importance, it can easily be decided by reading the originals. My paper was the result of some years of observation, reading and reflection, and was meant to be an independent contribution, controversial only in some subordinate particulars. In depicting the drama of the deposition of ores, I cannot but feel that Professor Van Hise assigned to the chorus and the scene-shifters some characters which, it seems to me, should

Jan 1, 1903

By William L. Fink

Nickel is used as an alloying element in several complex commercial aluminum alloys, among which are found some very interesting properties, such as relatively high strength at elevated temperatures, relatively low coefficient of expansion, the absence of permanent growth, ability to take a good polish, and a bright, pleasing as-cast surface. For that reason the aluminum-nickel system was included in the list of binary aluminum systems that are being studied as a preparation for the investigation of more complex commercial alloys. This paper is the fifteenth of a series from the Research Laboratories of the Aluminum Company of America reporting the results of investigations of equilibrium relations in aluminum-base alloys of high purity. The aluminum-nickel equilibrium diagram from 0 to 18 per cent nickel was determined, using the purest material available. Previous Investigations The entire aluminum-nickel system was studied thermally and microscopically by Gwyer.1 At the aluminum end of the system he found the intermetallic compound NiA13. He found a eutectic at 6 per cent nickel with a melting point of 630" C. A slight thermal arrest, which he could not explain, was also noted in alloys from 2.5 per cent to 41.9 per cent nickel at 550" C. Bingham and Haughton,2 in a later investigation of alloys of aluminum with copper and nickel found the eutectic concentration of the binary aluminum-nickel system at about 5.3 per cent nickel. The melting point of the eutectic was about 633" C., or slightly higher than that found by Gwyer. Although the solid solubility of nickel in aluminum could not

Jan 1, 1934

By J. V. W. REYNDERS

FIRST of all let me express my affectionate gratitude for the cordiality and good will of your reception. On the part of the men I venture to interpret the character of your greeting, not only as a recognition of the position to which you have been good enough to elect me, but also as an expression of your friendly attitude. However, I cannot pass over the tribute of the ladies so casually: Nor does it seem possible to do justice to my sentiments in addressing them collectively. I would feel more equal to the task if I could have the opportunity to talk to them singly, in doing which I know I may count upon their good sportsmanship not to compare notes. There has been some discussion between Mr. Kelly and myself as to our respective duties on this occasion: The precedents are not clear as to whether the retiring or the incoming president is expected to speak at length. Mr. Kelly's argument was that as the incoming president confines himself to promises for the future his field is a broad one and his opportunities for extending his remarks correspondingly unlimited.

Jan 1, 1925

Through the courtesy of Mr. J. H. Batcheller, we are able to give the following extracts from a letter written by Mr. Caetani: It has been a nice idea of yours to collect for me all those scraps of news I received a few days ago and to send me such a long interesting letter. In four years war I have had practically no news. Burch wrote several times but several of his letters were lost and so mine. I believe I even wrote to you. Much has changed since our last days in Telluride; here and there many have disappeared. Of myself I will tell you in a few words: for a year I was in Cadore(?), where I had the good luck to do to the others what they wished to do to me, and had good luck on my side. Then I went to Macedonia for 5 months, did little fighting but lost my faithful fellow officer and companion.

Jan 6, 1919

By William B. Plank

FOR the third consecutive year, I have collected the data on enrolment and employment of graduates from the schools in. the United States and Canada that grant degrees in mineral technology. The data were collected in the same way as formerly; namely, by questionnaire, dated Jan. 5, 1935, and are therefore comparable with the figures reported for former years. This year, along with the names of the 48 schools in the United States and the six in Canada, are listed the courses offered and the degrees granted by each, school, together with the names of the professors in charge. The names and addresses of the four schools in Mexico are also given. The list is on pages 450-1, which should he valued as a directory by those interested in mineral technology education. So far as is known, this is the most complete and up-to-date list that has ever been published.

Jan 1, 1935

Edwin A. SpeRry, Denver, Colo. (communication to the Secretary*) :—Since writing my former paper on this subject I have had several discussions concerning some of the statements contained therein, with men who have had a large experience with the old form of buddle, both in this country and in Cornwall. The present paper gives a brief statement of some of the points debated, together with the arguments and proofs in their substantiation. The first point is the question of the capacity. In my origi-

Jan 1, 1904

By Samuel Hoyt

THE writer has long been interested in seeking an explanation of the upper heat effect in the copper-tin alloys over the a + ß range, first described in 1913. These notes are offered, not at all as the final explanation of this heat effect, but rather to indicate certain progress which has been made toward establishing what happens over this temperature interval. While working on the thermal analysis of the copper-rich kalchoids (copper-tin-zinc alloys), it was noted that those alloys containing major portions of tin and minor portions of zinc exhibited two marked heat effects, one at about 520° C. and the other at about 600° C., instead of the single effect which is generally observed in either of the two binary series. This matter was discussed with Dr. Guertler, who suggested that a heat effect at about 600° C. in the pure copper-tin alloys might be expected. This led to a more searching examination of the thermal critical points in the pure copper-tin alloys, with the result that a marked, although somewhat weak, heat effect was located at about 600°. Somewhat later, this upper heat effect was discussed with Dr. Burgess, and it was requested that the Bureau of Standards make heating and cooling curves of one of these alloys for the purpose of removing any possible doubt as to the actual presence of the heat effect. Results obtained by the Bureau are given in Plate I. In an earlier paper1 differential curves were published showing that the heat effect occurred at constant temperature over the a + ß range and increased in magnitude with the amount of a up to a point somewhat above 20 per cent. tin. No heat effect was noticed at this temperature in the eutectoid alloy. The existence of this heat effect seems to require a modification of the present copper-tin diagram in the a + ß field, and it has been the object of the work here presented to secure the evidence upon which such a change should be based.

Jan 12, 1918

By S. T. Wlodek

The scale md subscale reaction products were identified and their rates of formation were studied in air over the range 1600" to 2000°F (871 " to 1149°C) for periods of up to 400 hr and for hoth the solution-annealed and aged conditions. The effect of prior sltrface preparation on suhscale oxidation was also studied The general oxidation behavior of both Ni-Cr-Mo-Al-Ti type alloys was similar. A surface film of a, Al2O3, forms immediately on exposure Subsequent oxidation continued at a linear rate (QL = 55 * 5 kcal per mole) as colonies of Cr2O3 nucleated at the A12O3/gas interface Further oxidation proceeded at a paraholic rate zvhiclz could he fitted to two successive rate constants. During paraholic oxidation, and depending on temperature, the scale consisted of Cr2O3, NiCr2O4 , and TiO2 with traces of NiO. In the case of Rene 41, the activation energy of both paraholic processes was 66 * 3 kcal per mole suggesting that diffusion of cations tlzrozrgh Cr2O3 was the rate -determining process. An unusual decrease in the oxidation of Udimet 700 at 1900°F where a spinel of Ni(A1,Crh0, zuas the predominant reaction product prevented the accurate assignment of activation energies for this composition. In both alloys internal oxidation of Al2O3 commenced shortly after parabolic scaling was observed. Prolonged exposure prod7tced intemal oxidation of TiN, and in Udimet 700 a complex Mo-Ni nitride was also found. At 1900oF, the subscale reactions in Udimet 700 undergo an inversion which parallels the decrease in surface oxidation; internal oxidation ceases hut is replaced by the formation of "spherodized" 3.' colonies. Surface-preparation techniqtles which introduce appreciable working, such as coarse surface grinding or grit blasting. increase the amount of alloy depletion and internal oxidation in Reni 41. The reverse is true of Udimet 700 for which electropolished or mechanically polished specimens show much more subscale oxidation than strongly worked stirfaces. The strongest commercial nickel-base alloys presently available are generic to the Ni-Cr-Mo-A1-Ti base which exploits the precipitation of Ni3(A1,Ti) as the main strengthening mechanism, while relying on solid-solution strengthening by molybdenum and chromium reinforced by the pre- cipitation of carbides to attain maximum properties. This study characterizes the oxidation behavior of Rene 41, the strongest alloy of the Ni-Cr-A1-Ti type commercially available in sheet form, and Udimet 700, whose higher aluminum and titanium content allows it to exhibit one of the more attractive combinations of high-temperature properties available in a wrought product. The scaling processes of complex, type nickel-base alloys have received relatively little attention. Malamand and vidal as well as Poulignier et al.2'3 have determined the composition gradients across the metal/oxide interface produced by high-temperature oxidation and considered the effect of surface perature, Limited weight-gain data has also been published by Fere 5 for alloys of this type and Radavich6 has identified the reaction products on Udimet 500 and Inco 702 after oxidation at 1832°F. Reference can, of course, be made to the excellent reviews of Kubaschewski and Hopkins7 or Ignatov and Shamgunova8 for a summary of the data available on the oxidation of binary and ternary alloy systems which are related to the more complex alloys considered here. EXPERIMENTAL The analyses of the different commercial heats studied are given in Table I. Using the experimental procedures previously established,9 continuous weight-gain data were obtained on both heats of Rene 41 sheet (A and B) and 150-mil-thick slices of cast Udimet 700. Subscale oxidation reactions were followed by static exposure of cylindrical specimens obtained from swaged Rene 41 (Heat C) and Udimet 700 (Heats E and F). In brief, continuous weight-gain tests were performed on specimens with a surface area of 10 to 12 sq cm. These were abraded through 600 grit Sic paper, electropolished to 2p rms in an electrolyte of 10 pct H2So4 in ethanol, and lightly etched in 10 pct HCl in ethanol before final washing and rinsing in ethanol. All continuous weight-gain data were obtained in dried (-70°F dew point) flowing (1 liter per min) air to an accuracy of +0.1 mg. Subscale oxidation processes were followed by the metallographic examination of 0.5-in-diam by 1.0-in.-long specimens. After an initial center-less grinding, various additional surface treatments were employed to determine the effect of surface preparation on subscale oxidation processes. Before exposure in zirconia crucibles, all samples were lightly etched in 10 pct HCl-ethanol, washed in ethanol, and dried. The depth of internal oxidation was measured to ±0.00025 in. on unetched specimens mounted so as to provide a taper mag-

Jan 1, 1964

By J. HUNER

Twenty-four new fields were found in Louisiana during 1945. Of this number 15 were oil fields, eight were gas condensate, and one a dry gas field. None of these fields, with the exception of West Delhi, is as yet of any great consequence. The Weeks Island field in Iberia Parish may eventually develop into a considerable reserve.

Jan 1, 1946

E. S. MOORE (author's reply to discussion*).-I have read with much interest Dr. W. F. Smeeth's criticism' of my article on the air blasts in the Kolar Gold Field, India. However, before answering the questions he asked, I should like to suggest that possibly the phrase "difference of opinion" might be substituted for the word "misapprehension" when applied to my statement that the matrix of the conglomerate resembles a hornblende schist. This conglomerate is certainly regarded as a metamorphosed sediment. Dr. Evans, who has had wide experience with metamorphic rocks, has regarded this as a clastic rather than an autoclastic rock and mentions it as a probable glacial deposit2 and similar to the Lower Huronian conglomerate of North America. I was greatly impressed by the similarity between this rock and the bands of Huronian conglomerate in the United States and Canada where metamorphism has rendered the matrix of the rock schistose. It was scarcely intended that the word basal, as used in my text, should be extended to the Kolar field, although possibly it may be equally applicable there. The word is so frequently used on this continent for the Lower Huronian conglomerate, which in many places is the basal formation of the predominantly sedimentary Proterozoic group, overlying the more largely igneous Archeozoic rocks, that it was inadvertently used without special stratigraphic significance for the Kolar area. In reply to Dr. Smeeth's question as to how the conglomerate indicates a syncline, it would seem that if there is present in a closely folded area a band of sediment that is younger than the surrounding rocks, it must be in a syncline in those rocks. As to an apparent contradiction in the statement on page 693 regarding the compressive stress, it does not seem that such contradiction exists; I think every one will take the same meaning as Dr. Smeeth has taken, which is exactly what was intended.

Jan 12, 1918

By Leo J. Vogel, E. D. Hummer, David J. Akers

INTRODUCTION An efficient refuse-disposal system is a necessary part of the modem cleaning plant. The large-scale refuse system and disposal area, engineered for the lifetime of the plant, has become more important due to the greater tonnages of refuse produced from increased quantities of mechanically mined and prepared coal. Laws and increased government regulations have affected the design and operation of disposal systems. THE EFFECT OF MINE AND PLANT OPERATION Refuse disposal starts at the mining face. The mining system, the type of roof support, the machinery used, and the degree of discipline at the face contribute to the amount and type of refuse that must be removed through the disposal system. Economies gained through modification of the mining system or mining machinery may be partially offset by increased dilution of the mined coal with impurities from associated rock formations. In some cases the change in the mining system and equipment has reduced the dilution. In all cases the ratio of impurities that must be removed from the raw-coal feed to the plant not only affects the maintenance and

Jan 1, 1979

By W. M. Myers

MINERAL Economics is the most recent profession to be recognized as a separate division of the mineral industries. It has originated from the increasing awareness of the importance of the economic aspects of industries concerned with discovery, extraction, and utilization of minerals. It is concerned with the interrelated fields of economics and technology. The individual trained in economics alone cannot qualify. The curriculum in the School of Mineral Industries at The Pennsylvania State College was approved in May 1946, and enrollment begun in September of that year. Due to the transfer of advanced students from other courses, particularly metallurgy and electrical engineering, it was possible to graduate the first seniors in June 1947. The next class was graduated in February 1948. From experience derived from placing these graduates in industry, and from information supplied by prospective employers, valuable data have been obtained in the organization and operation of the course of study.

Jan 1, 1948

By E. T. Hayes, A. H. Roberson, M. H. Davies

R. F. Dornagala and D. J. McPherson (Armour Research Foundation, Chicago)—I should like to compliment the authors for a workmanlike job in determining the partial phase diagram of a system comprised of two rnetals which are certainly not easy to work with. We are completing work at Armour Research Foundation on an Atomic Energy Commission-sponsored project for the determination of eight zirconium binary diagrams. Work on the Zr-Cr system has been completed and should be published within the next year. For our work, Westinghouse Grade 3 iodide crystal bar served as the zirconium melting stock. Johnson-Matthey, electrolytic chromium, specially treated for oxygen removal, was employed. The overall constitution of the system determined at Armour Research Foundation is in very good agreement with the present work. We found a eutectic at 18 pct Cr and 1280 °C, somewhat lower than the value reported. This temperature was confirmed by thermal analysis, incipient melting studies, and regular isothermal anneals. The eutectoid was located close to 1 pct Cr and 835°C by metallographic analysis of annealed specimens. Maximum solubility of chromium in /S zirconium was 4.5 pct at the eutectic temperature. Chromium solubility in a zirconium was less than 0.28 pct at all temperatures. We found the compound at 53 pct to melt around 1700°C, with an open maximum, but determined its crystal structure to be hexagonal close-packed (MgZn, type). The lattice parameters were in excellent agreement with those determined by Wallbaum in 1942. The diagrams are in substantial agreement, and .part of the differences are undoubtedly due to the use of different zirconium melting stock. M. K. McQuillan (Birmingham, England)—I read this paper with a great deal of interest, as it covered the same field as some work of my own.' There are a number of points in the present paper on which I would like to comment. First, I should say that I, too, used zirconium prepared by magnesium reduction of the tetrachloride and electrolytically prepared chromium, and melted the alloys in a Kroll-type arc furnace. The purity of my alloys should, therefore, be comparable with the purity of those of the present authors, and any differences in our observations would not be expected to be attributable to this cause. The differences between my observations and theirs concern the presence of the eutectic, the temperature of the eutectoid, and the melting point of the compound. I would be very much interested in any further evidence the authors may have for the occurrence of the eutectic at 1380°C. During the course of my work I noted that a number of my alloys containing 60 to 90 pct Zr melted at about 1400 °C, and for a time assumed that a eutectic occurred at this temperature as described in the paper. On further investigation, however, I found that the structures of the as-melted alloys could not be made to fit in with this interpretation of the system. If a eutectic exists in this region of the system it would be expected that the as-melted alloys would show the usual type of cast structure, i.e., dendrites of the compound plus eutectic. This, however, does not occur, as may be seen from Fig. 9. The compound seen there is not dendritic in form, and the remaining material is by no means certainly eutectic. It may be argued that a compound such as ZrCrl would not form dendrites but would tend to crystallize in geometric shapes. In this case, however, I have evidence to the contrary, as on the chromium side of the compound, where a eutectic occurs at about 1545"C, the compound formed from the liquid takes on a conventional dendritic form, and the eutectic is observed in the interdendritic spaces in the usual way. There is no reason to suppose that the compound would behave differently in an alloy lying on the zirconium side of the compound composition if a eutectic existed there too.

Jan 1, 1953

By Albert Ladd Colby

PAGE I. Introduction,...........577 11. PRocess of Manufacture. 1. American Specifications. 2. Foreign Specifications, . ......... 580 III. Chemical Properties. I. Chemical Composition: (a) American Specifications ; (b) Foreign Specifications. 2. Chemical Analysis: (a) American Specifications ; (b) Foreign Specifications ; (c) Number of Analyses Required ; (d) Sample for Analysis ; (e) Check-Analyses Impracticable ; (f) Rejection Solely on Variation in Com-' position,............581 IV. Physical Properties. 1. Drop-Test and Drop-Testing Hachine: (a) American Specifications ; (b) Foreign Specifications ; (c) Limits in Deflection. 2. Tensile Test: (a) American Specifications; (b) Foreign Specifications ; (c) Test-Pieces are not Representative ; (d) Specified Tensile Strength is Affected by the Section ; (e) BpeciBed Tensile Strength is Often Inconsistent with Specified Chemistry ; (f) Specified Tensile Strength is Often Inconsistent with Specified Elongation ; (g) Amount of Tensile Testing Required is Excessive ; (11) Conclusions. 3. Dead-Weight Test: (a) American Specifications; (b) Foreign Specifications; (c) Number of Tests Specified. 4. Bending-Test: ((1) American Specifications ; (b) Foreign Specifications,..........589 V. Section. 1. American Specifications. 2. Foreign Specifications: (a) Templets ; (b) Sample Piece of Rail; (c) Allowable Variation from Templet,...........601 VI. Weight. 1. American Specifications. 2. Foreign Specifications,. . 603 VII. Length. 1. American Specifications. 2. Foreign Specifications, . . 604 VIII. Drilling. 1. American Specifications. 2. Foreign Specifications, . 604 IX. Finish. 1. American Specifications. 2. Foreign Specifications, . . 50.5 X. Branding. 1. American Specifications. 2. Foreign Specifications : (a) Data to be Rolled in Raised Letters on Web of Rail ; (b) Marking of the Blow-Number on Each Rail; (c) Additional Marking and Painting of Rails,........605 XI. Inspection. 1. American Specifications. 2. Foreign Specifications: (a) Prior Notice of Rolling; (b) Free Access to the Works ; (c) Cost of Inspection, Analyses and Tests to be Borne by the Manufacturer ; (d) Rails after Inspection by Manufacturer to be Sorted into Lots Prior to Inspection by the Engineer ; (e) Disposition of Rejected

Jan 1, 1907

By John Freeman

THE tensile properties of steels at elevated temperatures have been studied by numerous investigators,1 primarily for the purpose of determining their suitability for structural uses. Tests with this objective have been confined largely to the temperature range of approximately 20° to 500° C., because of the rapidly decreasing tensile strength at the latter temperature. Tests have also been extended to higher temperatures for the purpose of determining the most suitable forging range. This temperature range is also of theoretical interest. The phenomenon of increased tensile strength and decreased ductility in the so-called "blue-heat" range, approximately 200° to 300° C., is well known. It was suggested to the Bureau early in 1926 that a study of the properties of rail steels in this temperature range might prove of interest in relation to the studies of transverse-fissure failures in rails. There were available from another investigation3 several new rails from several different heats made to approximately the same specification requirements, the complete manufacturing histories of which were known. It was decided to determine, at least in the preliminary series of tests, only the ultimate tensile strength, elongation and reduction of area, because of the difficulty, time and cost involved in determining the proportional limit and yield point at elevated temperatures.

Jan 1, 1930

By D. J. Jr. McAdam

PART I.-OUTLINE OF INVESTIGATION, DESCRIPTION OF METHODS AND MATERIAL Previous Investigation of the Influence of Stress on Corrosion IN 1917 Haigh1 presented evidence that under simultaneous corrosion and cyclic stress metals may fail at lower stresses than if the corrosion is prior to the cyclic stress. In 1926 the author, while investigating the cooling effect of water on the fatigue resistance of metals, found that under these conditions steel specimens fail at stresses far below the endurance limit.2 (By "endurance limit" is here meant the fatigue limit obtained with specimens as free as possible from stress concentration and corrosive influences.) This led to an investigation (at the Naval Engineering Experiment Station, Annapolis, Md.) of the influence of cyclic stress on corrosion. This investigation maybe divided into three parts. The first part was a general survey of the conditions necessary to cause complete failure under corrosion and cyclic stress of relatively high frequency. The entire process by which metals fail under these conditions was-called "corrosion-fatigue." "Corrosion-fatigue limits" for a large number of metals were determined and the relationships of these limits to chemical composition, heat treatment and physical properties were established. The conclusion was reached that corrosion-fatigue is due to the accelerating influence of cyclic stress on corrosion. Results of this part of the investigation were presented in five papers.2-6 The second part of the investigation was a preliminary study of the influence of cyclic stress on corrosion. Each experiment was conducted in two stages. The first was a corrosion stage in which the specimen was corroded under cyclic stress; the second was a fatigue stage, in which the previously corroded specimen was tested (without further corrosion) to determine its fatigue limit. The difference between this fatigue limit and the endurance limit was used as a criterion of the "damage" due to

Jan 1, 1931

By J. S. Owens, R. W. Marsden, J. W. Emanuelson, R. F. Werner, N. E. Walker

The iron ores of the Mesabi Range occur in a 340 to 750-foot thick, Precambrian cherty iron formation termed "taconite." For about 65 years, extensive natural iron ore bodies were mined, and the ores either shipped as a direct ore or processed by gravity methods to a shipping grade iron ore. Since 1956, magnetite taconite ores, occurring in magnetite-rich horizons in the Biwabik iron formation, have been commercially concentrated and agglomerated. The transition from natural ores to concentrating-grade ores is progressing rapidly so that, in the near future, a major percentage of the iron ore shipped from the Mesabi Range will be as iron ore pellets produced from taconite. Natural iron ores of the Mesabi Range occur in the Biwabik formation as trough ore bodies in elongated channels and as irregular and tabular deposits in fractured areas associated with faults and folds. Ore bodies range in size from a few thousand tons to hundreds of millions of tons and may occur in any part of the iron formation. In some areas of strong ore development, ore was formed from the hanging-wall argillite to the footwall quartzite. The natural ores and beneficiating-grade natural crude ores were formed by the oxidation of the iron minerals, magnetite, greenalite, stilpnomelane, minnesotaite, and siderite, to hematite and goethite and by the removal of much of the silica in the cherty quartz and in the associated silicates by leaching. The ores are believed to have formed by the oxidizing and leaching action of surface waters. Magnetite taconite ores occur as stratigraphic zones in the Biwabik formation where it contains sufficient magnetite to be concentrated profitably, by magnetic methods, to give a magnetite concentrate that is agglomerated into a high quality product. Unoxidized taconite has an extensive distribution away from and between channels of oxidation and leaching but only a part of the unoxidized taconite is of ore grade. Two general types of magnetite taconite ore occur: ( 1) magnetite taconite of the Main Mesabi Range, generally west of Mesaba, which is composed of magnetite associated with cherty quartz, greenalite, stilpnomelane, minnesotaite, and carbonates and (2) magnetite taconite of the Eastern Mesabi, generally east of Mesaba, composed of magnetite associated with quartz, cummingtonite, actinolite, ferrohypersthene, hedenbergite, fayalite, hornblende, pyroxene, garnet, and biotite. The Mesabi taconite is a metasediment derived from an iron- and silica-rich chemical sediment that has been regionally metamorphosed and, on the eastern end, additionally metamorphosed by the Duluth Gabbro Complex.

Jan 1, 1968