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By W. C. Hagel

Previous inuestigators have repovted unusually low H* and Do values for self-dzf@szon in certazn bcc metals, e.g., chromium nnd y -uvanium. It has been postulated that this is nn experimental crl -tetion for the existpnce of a four -atom ring meclzanzsm, mid there could be. zmpovtant theoretrcal Implicatlons. By utilizing a precise sectioning technique with Cr51 as the tracer, self-dzffi-lsion measurements in large grains of 99.99-pct Cr were extended from 1200° fo 1600"C. A least- squares analysis of the data yields that D 0.280 exp (-73,20U/RT) cm2 sec-'. These AH* and Do unlues are not anomalous; there is little reason to believe that n vacancy mechanism is not opevatiue. Apparent differences at lower temperatures may result from preferential diffusion along short-circuititing paths and/or sample contamination. WITH continued technological effort, chromium and chromium-base alloys should ultimately become useful high-temperature structural materials. Accurate measurements of self-diffusion coefficients in the pure metal are necessary for a quantitative understanding of sintering, grain growth, creep, and other related rate processes. However, two conflicting determinations have been reported.* Using an Since careful diffusion studies normally yield Do values ranging from 0.1 to 10 cm2 sec-l, the Paxton-Gondolf results require independent experimental corroboration before an undue amount of speculation arises to explain the apparent anomaly. As discussed by Nowick6 and clearly shown by Hoffman and Turn-bull7 for self-diffusion in silver, a low AH* and Do can arise from preferential diffusion along grain boundaries or other short-circuiting paths. The most reliable data come from high-temperature measurements where volume effects predominate. Following a precise sectioning technique developed for determining silver diffusion in the intermetallic compound AgMg8 and cation diffusion in the corundum oxide Cr2O3,9 the purpose of this study was to measure true volume diffusion in high-purity, large-grain samples at higher temperatures than considered previously. Another point of interest is the frequent proposal10-12 that chromium undergoes an allotropic transformation between 1375" and 1800°C where the diffusion data might then show a discontinuity. I EXPERIMENTAL 1) Sample Preparation. The highest purity (99.997 pet) Cr currently available is produced by reduction of chromium tri-iodide. Three pounds of the resulting crystal bar were shipped in a sealed container with a complete chemical analysis from the vendor.* In conformity with the procedure used for

Jan 1, 1962

By L. C. Armstrong

A. E. ROSS*—Mr. Armstrong in his paper stated that they had experienced considerable difficulty in drilling the quartz-feldspar intergrowths. The dia-mor~d loss was excessive and the diamond bits polished quite rapidly. Mr. Davidson, who presented the paper, stated that bortx stones in the range of 20 to 30 per carat had been used in the bits on this job. I would like to suggest the use of bits employing stones in the range of 60 to 100 per carat, an average of possibly 80 per carat. If these stones had been used the bits might have lasted longer and not polished so quickly. As a basis for this suggestion I would like to point out that in northern New York State we had at least two examples where bits employing stones in the range of 80 per carat had solved a difficult problem. Bits set with stones in the range of 20 to 30 per carat had been used previously and had failed. With the finer stones, the cost per foot of drilling decreased material1y. It should also be noted from a technical standpoint that the smaller stones require higher drilling speeds than the larger stones. Greater pressures are not normally necessary, and it is the higher speed which seems to be the major factor of importance. It should also be noted that the finer stones afford a greater number or cutting surfaces for the same carat weight in a bit. Then too, the smaller stones, by virtue of their size, serve as sharper cutting edges than larger stones. There is no doubt that the diamond bit employing smaller stones costs more to set than the bit using larger stones. However, with the technique developed at the shops of Sprague and Henwood, Inc., we feel that the relatively slight additional cost required to set these bits is more than paid for by the resultant lower drilling cost. We feel that the highest quality stone available is the most economical to use when hard fine grained rock is encountered. In summary, I would suggest that it might be possible to solve the problem presented in this paper by using a diamond bit employing stones at least as small as 80 per carat of the highest grade possible and by using the diamond bit at the highest speed available with modern drilling equipment. L. C. ARMSTRONG (author's reply) —It is generally agreed that the use of smaller, high-grade diamonds and of higher drilling speeds, as suggested by Mr. Ross, may be the best approach to the solution of the problem.

Jan 1, 1950

By Charles A. Morgan

The proms of mire drawing depends upon the property which certain metals possess, termed ductility, which is defined in Brande's Dictionary of Science as a property inconhequcnce of which metals may be drawn out at length wilhotit interrupting the continuity of their constituent parts. As ticfincd thy M. Tresca, it is the property of flowing when subjected to pressure, and ie termed by him the "flow of solids," in his paper, read before the AcaiXemy of Sciences in Paris, November, 1866 * In the simple language of the wire shop, it is that quality in certain metals that thcm to be drawn (or etretched) out througl~ a tapering hole in a metal block or die, the die being more dense and harder than the metal to be redud. It is a fact well known to tllose slrillet1 in the ai*, that to eu~xeed in drawing iron or steel wire, it is of' the utmost, importance to have tborough lubritatiun, as a lack of it woullii udu-se abrasion of the wire, or of the walls of the tapering hole in the dia or plate, and quickly put an end to the operation. In drawing coarse or large sizes of pire, say & inoh diameter, the pressure upon the sides of the tay~dng hole, where the wire comes i.u contact with the die, so great that an ordina,y labricaot is equeezed out when the nsoal rc~luctions iu size are matie, and abrasion takea place. In order to meet this diffic:ulty, and emure proper lubrication, it has been a ccmmon prtictice for yazrs to apply a paste made of rye or wheaten flour, or lime, to the surface of the wire to be drawn, and when the pnstc is dry, to smwr tl~e wire with tallow or grease; the wire is then ready to be draw, the dried pa serving fo prevent the lubricant from being presetf out in the prows. Some years since, when Bessemer metal came iargely into use material for wire, 'the writer fourid that its dmwing requid so much more power than iron wire, that he was led to institute a. series of trials to ascertain the difference in power required. It was fotind that Bessemer wire requircd from 100 to 200 per cent. more power to makc the same reduction in sizes than soft iron wire, the difference depending npou the amount of carbon and other chemical constitu-

Jan 1, 1881

By John M. Gallow

Discussion of the paper of JOHN M. CALLOW, presented at the New York meeting, February, 1916, and printed in Bulletin No. 108, December, 1915, pp. 2321 to 2339. R. H. RICHARDS, Boston, Mass.-I think there is one note which would be interesting to have recorded in connection with this paper, and that is another form of flotation machine. The Minerals. Separation machine has a vortex action, with a vertical shaft and a propeller. This new frother has been developed for the Copper Queen Co. at Bisbee, Ariz. It has a horizontal shaft and a paddle wheel for a frother. It has eight cells, I think, all connected underneath in one continuous tank, and the only separation of the cells is in the upper chambers where the froth is. When this paddle wheel goes around it throws out the froth and the sand goes to the bottom and drifts over from the first to the second cell, where it is paddled again, and comes out with its froth; the sand goes to the third cell where it is again beaten. In that way the sand is continually drifting toward the last cell, while each new froth remains in its own cell. You can see in the working of this machine just the same effect that you see in Callow's machine, i.e., the earlier cell has the darker or richer froth, and the latter has the lighter or poorer froth until you get to the farthest one-which has very little froth, and is very light. JOSEPH W. RICHARDS, So. Bethlehem, Pa.-Speaking from the metallurgical standpoint, it is quite desirable, in many cases, that the oil be removed from the concentrate in order to facilitate the metallurgical work, and I think attention should be directed to the desirability of removing from zinc sulphide concentrates the oil which interferes with their subsequent roasting. The value of the oil is not large; in Mr. Callow's plant, for instance, it would be $20 a day, and it may be possible that a process might be developed which, within the limits of the value of the oil, would remove it, and thus facilitate the metallurgical treatment. LEONARD WALDO, New York, ,N. Y.-The question came up about a year ago as to why-Mexican crude was not an admirable oil for flotation. I have never heard any satisfactory answer to the question. The Mexican crude has the peculiar property of comparative freedom from dangers of fire, a very great reluctance to part with its water, and a specific gravity almost identically the same as water.

Jan 5, 1916

By H. Cecil Spicer

THE results described in this article are based on field work conducted during the periods April-May, 1939, and May-July, 1940. The United States Potash Co. is mining potash on Government land under a permit from the Department of the Interior and the geophysical investigation was completed under a cooperative arrangement made between that company and the Conservation Branch of the Geological Survey. The writer, a member of the Section of Chemistry and Physics of the Geologic Branch, was assigned to this investigation. Four definite objectives were in mind for the geophysical work in the studies over the salt deposits. The first was to determine the measure of success that could be attained in this type of work with the resistivity methods that were to be employed. These methods had been introduced into the work of the Conservation Branch by Benjamin E. Jones for the investigation of dam sites, and have been used under his direction by the author for such work. If the method proved to be applicable, an effort was to be made to contour the top of the salt beds and also the other formation boundaries known to be present in this area. Salt-water aquifers were to be studied in an effort to determine their boundaries, and an attempt was to be made to delineate the potash-bearing beds. EARLIER STUDIES Others have made, and reported, resistivity studies over saliferous deposits in different areas. Friede1 and Messrs. Schlumberger2 reported geophysical work performed in the discovery of the salt domes of Alsace; Carrette and Kelly3 described the geology of the same area. Leonardon and Kelly4 published a resistivity curve obtained over the Hettenschlag dome, and a further discussion of this same area was given by the Messrs. Schlumberger5 in a communication. Messrs. Alty6 described studies on salt deposits in which the single-probe method was used. Sinerez7 mentions that electrical methods were tried over salt deposits in Spain. Geoffrey and Charrin8 show a resistivity curve obtained over marl, gypsiferous marl and salt which is similar to that obtained over the New Mexico salt deposits. Kelly9 reported resistivity work performed with the ground comparator of Zuschlag over the salt deposits near Syracuse, N. Y., where the Salina formation is at a depth of 700 to B00 ft. Some structural studies on the potash basin of Alsace are described by Poldini.10 Another single-probe resistivity study, made over salt deposits in New Mexico, is briefly described by Heiland,11 through the courtesy of Harry Aurand, of the Midwest Refining Co.

Jan 1, 1941

By H. Cecil Spicer

THE results described in this article are based on field work conducted during the periods April-May, 1939, and May-July, 1940. The United States Potash Co. is mining potash on Government land under a permit from the Department of the Interior and the geophysical investigation was completed under a cooperative arrangement made between that company and the Conservation Branch of the Geological Survey. The writer, a member of the Section of Chemistry and Physics of the Geologic Branch, was assigned to this investigation. Four definite objectives were in mind for the geophysical work in the studies over the salt deposits. The first was to determine the measure of success that could be attained in this type of work with the resistivity methods that were to be employed. These methods had been introduced into the work of the Conservation Branch by Benjamin E. Jones for the investigation of dam sites, and have been used under his direction by the author for such work. If the method proved to be applicable, an effort was to be made to contour the top of the salt beds and also the other formation boundaries known to be present in this area. Salt-water aquifers were to be studied in an effort to determine their boundaries, and an attempt was to be made to delineate the potash-bearing beds. EARLIER STUDIES Others have made, and reported, resistivity studies over saliferous deposits in different areas. Friedel1 and Messrs. Schlumberger2 reported geophysical work performed in the discovery of the salt domes of Alsace; Carrette and Kelly3described the geology of the same area. Leonardon and Kelly4 published a resistivity curve obtained over the Hettenschlag dome, and a further discussion of this same area was given by the Messrs. Schlumberger5 in a communication. Messrs. Alty6 described studies on salt deposits in which the single-probe method was used. Sinerez7 mentions that electrical methods were tried over salt deposits in Spain. Geoffrey and Charrin8 show a resistivity curve obtained over marl, gypsiferous marl and salt which is similar to that obtained over the New Mexico salt deposits. Kelly9 reported resistivity work performed with the ground comparator of Zuschlag over the salt deposits near Syracuse, N. Y., where the Salina formation is at a depth of 700 to 8oo ft. Some structural studies on the potash basin of Alsace are described by Poldini.10 Another single-probe resistivity study, made over salt deposits in New Mexico, is briefly described by Heiland,11 through the courtesy of Harry Aurand, of the Midwest Refining Co.

Jan 1, 1941

By Jean Howard, E. V. Walker

ManY papers have been published during the last few years on the formation of cube texture in 3 1/4 pct Si-Fe, e.g., those of Assmus, Detert, Dunn, and Walter.1,5 All are concerned with the formation of the texture by a process involving secondary re-crystallization and the relative surface energies of (100) and other planes under certain conditions of annealing. The authors have found that cube texture can also be produced by heavily cold rolling strip in which the cube-on-edge texture has first been formed. Cube texture develops on annealing, but in this case it is not accompanied by secondary recrystallization. The starting material is a sintered compact, the preparation of which has been described elsewhere. Using a conventional processing schedule employed for producing commercial silicon-iron with the cube-on-edge texture, the sintered compact is cold rolled to such a thickness that, after annealing in pure hydrogen for 24 hr at 1350'~ to produce the cube-on-edge texture, the final thickness required can be obtained by giving a further cold reduction of 85 pct. Cube texture is developed by annealing at -900~~ in pure hydrogen: it has been produced in strip up to 0.024 in. thick. The microstructure of the strip consists of a mass of small primary grains within the boundaries of the much larger secondary grains which ex- hibited cube-on-edge texture before the final cold roll. If the strip is annealed at -1000 after the 85pct reduction, secondary recrystallization begins to take place, provided a strong cube texture is present. On raising the temperature more secondaries grow, complete secondary recrystallization being obtained on annealing at -1150'. From this it is concluded that the secondary crystals are produced by the texture inhibition mechanism: they show (110) and (111) planes in the surface of the strip, the former being the more numerous. It has been observed that the more perfect is the (110) [001] texture prior to cold rolling by 85 pct, the further from the ideal is the (100) [oo].] texture. A similar treatment applied to high quality commercial grain-oriented silicon-iron strip failed to produce cube texture. The tilt and rotation of the [loo] from the rolling direction was less than 10deg, but (to within a few degrees) the planes (130), (450) and (210) lay in the surface of the strip. Acknowledgment is made to the Engineer-in-Chief of the British Post Office for permission to use the information contained in this note.

Jan 1, 1962

EARLY this year the Board of Directors announced that, through the generous gift of past-president W. L. Saunders, a gold medal to be awarded for distinguished achievement in mining had been estab-lished. At the December meeting of the Board the medal committee reported that it recommended that the first medal be awarded to David William Brunton for "development and exposition of the principles and prac-tice of ore sampling; for systematic daily mapping of mine geology; for the Brunton mining compass; and for engineering achievements in connection with great tunnels." The formal presentation of the medal will be at the din-ner, on Feb. 16, in connec-tion with the annual meet-ing. Mr. Brunton, like several other prominent Institute members, was born in Can-ada, and came to the United States when he was twenty-four years old. He had then been in civil en-gineering work for three years and after a year more of it, deciding that mining was more attrac-tive he spent two years at the University of Michigan doing advanced work in geology a n d chemistry. His first mining engage-ment was with the Dakota and San Juan Mining Co., at Mineral Point, Ouray County, Colo. That was in June, 1875, and the young engineer had to travel 230 miles by trail from the then nearest railroad station at Pueblo. Having to come out because the company did not get in enough supplies to last through the winter he became metallurgist for the Hunt, Douglas & Stewart Co., at Georgetown, Colo. When the Hunt and Douglas plant proved a success, H. A. Taylor, the father of Mr. Brunton's later partner, Frank M. Taylor, engaged him to build the Clear Creek Reduction Works. Eighteen months later he built the Native Silver Mining Co. mill at Caribou and a year later a mill at Silver Peak, Nev., that was so successful that the principal owner shut it down to freeze out the minority stockholders. The winter of 1879 found him at Leadville where he did engineering work for the Robert E. Lee, Duncan, Wolftone, A. Y. & Minnie, and Dinero mines, eventually becoming manager of the Colonel Sellers. In 1886 he was called in on apex-side-line litigation at Aspen with the result that he went there to develop the mines for economic and legal pur-poses, and later became the manager of three of them. His most notable piece of work there was the driving of

Jan 2, 1927

By Franklin H. Sharp, Kenneth L. Clifford

During the last few years the New Lead Belt of Southeastern Missouri has become the main source of lead in the United States. It also produces significant amounts of zinc, copper and silver. The mines are located on a narrow, mineralized trend extending southward from Viburnum, MG. for about 35 miles. The ore occurs as replacement deposits in the Bonneterre lime- stone formation which is about 1000 ft below the surface. In most of the mines, enough water is produced to supply the milling requirements without any reuse. There are dry areas, however, and at least two mills must rely on water reclaimed from their tailings lake to augment the mine water. These mills have no choice but to utilize recycled mill water.

Jan 7, 1973

By Thomas T., Read

E DUCATION for the mineral industry was at first a single comprehensive curriculum, but it was early recognized that the main basis of mining is physics, while that of metallurgy is chemistry. The first school to offer curricula leading to degrees in mineral industry education in the United States (1853) had separate ones in mining and metallurgy. The Columbia School of Mines (the first really successful one) had only a single curriculum when it opened in 1864, but within a few years had so reorganized its work that it offered curricula in mining, metallurgy, geology, chemistry, and civil engineering. Interest in the metallurgy or geology curricula was slight at first, and for the next 30 years the great majority of Columbia students took the mining curriculum, probably partly because it contained nearly as much geology as the geology curriculum, practically all the metallurgy, and most of the chemistry, and partly because of the degree awarded for it. Other schools kept their mining curricula equally broad, and as late as 1900-1910 men were graduating as mining engineers who were practically as well prepared to make geology or metallurgy their life work, as they were for mining. Gradually, however, the subject matter of mining geology and metallurgy became so enriched through research and development that separate curricula in them became worth while; their progressive development is the subject of another chapter. Mining curricula also began to be somewhat diversified, and schools in areas where coal mining was of outstanding importance began to offer options in coal mining, the earlier curricula having been chiefly aimed at metal mining. The petroleum industry began its meteoric rise about the same time as mineral instruction in this country, but little more of applied science attended its birth than had attended such ancient practical arts as copper and iron

Jan 1, 1941

By Harry P. Hohenadel

DURING the past few years the amazing developments of the chemical industry have inspired so much publicity that the feature writers assure us that we are entering a "Chemical Age," industrially as important as the "Steel Age" and the "Electric Age," so-called. Whether or not these assurances are overstatements, it is a fact that the expansion of the chemical industry during the past 25 years has been enormous. The Chemical Bureau of the War Production Board calculates the value of chemicals produced during 1944 at $8,300,000,000, no small sum even in inflated dollars. As concerns us of the Southwest oil and gas country, four significant trends of the chemical industry are most important. (1) Many of the recently developed chemical products are new creations, not substitutes,. as new and original as the invention of the light bulb, and with a field for exploitation almost as wide. (2) Many of these chemical products will enter the mass consuming markets, which require enormous tonnages of products, and such markets are setting up an industrial demand for chemicals on a mass volume basis, compared to the relatively high-priced low-volume basis ordinarily considered as the chemical outlet of the past. (3) Most of the processes involved in producing these chemicals are adapt. able to the use, all or in part, of natural gas, oil, or refinery gases as raw mate-

Jan 1, 1945

By N. O. Gray, John Henderson

Hydrogen-reduction data for naturally occurring single crystals and Prepared polycrystals of dense hematite have been presented. Results cover the temperature range 400o to 1000oC, for particles from ten sources, ranging in size from 0.07 to 10 mm and in shape from spheres to cylinders, cubes, and thin slabs. A consistent pattern of behavior has been demonstrated for single crystals and the reduction mechanism shown to be temperature-dependent. Below 579oC reduction is a simple topochemical process but at higher temperatuves it is complex and occurs in two distinct stages. Prepared particles from these laboratories behave in a similar manner to the single crystals. Data from two investigators showing topochernical reduction of Prepared particles above 575°C are inconsistent with that for other dense hematites. It is concluded that topochenzical reaction should not be used as a model for generalized rate expressions for dense hematites. SINCE 1958, McKewan1-6 has brought to prominence a simple concept of dense hematite reduction. This model is that oxygen is lost from a hematite particle undergoing reduction only from an oxide-iron interface that recedes in such a way that the oxide remaining retains the original shape of the particle, i.e., reduction occurs topochemically. An adjunct to this concept is that any intermediate oxides in the transition from hematite to iron only form thin layers so that oxygen cannot be lost from the particle without movement of the oxide-iron interface. Further, the rate of oxygen loss from the particle is said to be proportional to the area of the receding interface so that the iron layer grows linearly with time and the over-all reduction process can be described by the equation where ro and do are the initial particle radius and density, respectively, R is the fraction of the original oxygen lost, i.e., the fractional reduction, at time t, and K is the rate constant. The idea of an underlying simplicity in hematite reduction is attractive because it gives a tractable basis from which general theories of hematite reduction can be developed and it has received wide support,7-14 based mainly on the large amount of data13 that can be fitted to Eq. [I]. However, despite the fact that this equation has been derived for dense materials, the bulk of the data that have been used to test it13 have been for materials of only about 90 pct of theoretical density (5.26 g cm-3) or less, so that its generality for dense hematites has not been demonstrated. In any case, as will be seen, adherence of reduction data to Eq. [1] does not necessarily imply that reaction occurs topochemically. In this work only data for hematites approaching theoretical density are considered and it will be shown that in only one study besides McKewan's is topochemical behavior observed over the whole range of temperature investigated. For the majority of materials a linear rate of interface advance is observed to complete reduction only when wustite is not a stable intermediate phase in the transition of hematite to iron, i.e., at temperatures below about 575°C. Above this temperature, reduction is an exceedingly complex series of reactions that takes place in two distinct stages and it is only in the first stage that reaction in any way resembles a topochemical process. This means then that, far from representing general behavior as has commonly been supposed, topochemical reaction for dense hematites is only a particular behavior that may be observed under some circumstances. EXPERIMENTAL Hydrogen-reduction data have been collected and cross-checked in these laboratories by three techniques, weight loss, collection of water evolved in the reduction reactions, and direct metallographic examination. Details of these techniques are discussed elsewhere," where it is shown that results obtained by the three methods are in close agreement. The weight-loss method, by which most of the results were obtained, consisted of hanging the sample in a platinum mesh basket from an Ainsworth Model AV-AU-1 vacuum recording balance inside a vertical l 1/4-in.-ID alumina tube furnace. Dry deoxidized hydrogen was flowed downwards through the tube at 2 to 4 liters min-1 (stp). Single crystals from two sources and artificial oxides from three sources have been examined. The single crystals were from hematite deposits at Yampi Sound, Western Australia, and Brazil, the latter being obtained from Gregory, Bottley and Co., London, U.K. The "Yampi Blue" crystals were hand-picked from washed, magnetically concentrated, sized fractions, -200 mesh BSS (mean diameter ca 0.07 mm) and —36 + 44 mesh BSS (mean diameter ca 0.4 mm) while 10-mm cubes were cut from the Brazilian crystals with a diamond saw. The starting materials for the prepared particles were hematites designated, respectively, "Specpure Iron Oxide", Laboratory No. S639 from Johnson Matthey & Co. Ltd., London, U.K., "Calcined Ferric Oxide" from B.D.H. Laboratory Chemicals Division, Poole, U.K., and "Pigment Grade Oxide", EPR-50, from C. K. Williams & Co., Easton, Pa., U.S.A. Approximately spherical particles were prepared from the artificial oxides by rolling the material, moistened if necessary, in a glass jar, and cylindrical compacts approximately 10 mm in diam and of approximately equal height were pressed in a steel die at 200 psi. These spheres and cylinders were subsequently fired in oxygen for 20 to 100 hr at 1370°C. The

Jan 1, 1967

By AIME AIME

THIS year the Chairman of the Institute's Iron and Steel Division is THIS William Anderson Haven, better known to the membership generally as Bill Haven. The Division Chairman is an individual endowed with a broad perspective of the ferrous metal industry he result of his earlier experiences as a successful operating man in the working and management of blast furnaces and his later experiences as an engineering-consulting executive concerned with the design and erection of and steel works throughout the world. William A. Haven was born to iron steel in the Pittsburgh district on ;. 1, 1888, and in due time--or in 1909 graduated from Penn State with a Bachelor degree in industrial chemistry.

Jan 1, 1944

MINING ENGINEERING presents the annual membership report of the Society of Mining Engineers; see page 147.

Jan 7, 1964

By G. Sachs, S. I. Liu

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

Jan 1, 1948

By Goerge F. Weaton

Since 1909, when an agreement between Minnesota&apos;s Tax Commission and the University of Minnesota&apos;s School of Mines was worked out, it has been the annual responsibility of the School to evaluate and classify the iron ore deposits within the State. These unique duties of an academic institution have provided School officials with an excellent view of the past, present and probable future of the mining industry in Minnesota as the average grade of iron ore (excluding taconite) * diminishes while at the same time it competes with beneficiated taconites and foreign high-grade ores for use in America&apos;s eastern blast furnaces. SYSTEM OF EVALUATION In the latter part of November of each year, the Mining Division of the Department of Taxation makes a preliminary study of the active mines which the Department wants the School of Mines to review. These are discussed with the engineers of the Ore Estimate Division of the School of Mines and with the mining companies. After these discussions, a list of the mines of each of the major operating companies is submitted to the Ore Estimate Division of the School of Mines with the request that these properties be reviewed by them as of the next assessment date (May 1st). At the same time, a letter is sent to the mining companies requesting that they submit to the Division their own estimates on the selected mines operated by them, together with all computations, drill records, maps and cross-sections. The mining companies are re- quested to send in this information during the first half of the year, and, as far as is possible, they have always complied with this request promptly. Much of this information received by the School of Mines is of a confidential nature and is treated as such.

Jan 1, 1965

By M. F. Hawkes

Austenite grain size has long been recognized by metallurgists as an important property of steels because of its influence on toughness, hardenability, ma-chinability and creep strength. Much research has been carried out on wrought steels to develop methods for disclosing austenite grain size, and to, provide knowledge of the grain-size characteristics of steels produced and heat-treated in various ways. Much less work in these fields has been done on steel castings; partly because, owing to the variable and complex microstruc-tures of cast steels, it is frequently very difficult to obtain results that are not questionable. The object of this investigation, therefore, was to establish, for a wide variety of carbon and alloy cast steels, suitable methods for disclosing austenite grain size and some knowledge of the grain-size variations to be expected. The steel foundryman is interested in austenite grain size at two different stages in the manufacture of his products; one is just after the steel is cast, and the other is after any reheating operation carried out above the critical temperature range. In both, it must always be kept in mind that the grain size being sought is actually a previous austenite grain size, and that the austenite no longer exists once the steel has cooled to room temperature. The prob-lem of the investigator is always to use evidence obtained from the structure at room temperature to deduce this previous austenite grain size, which was established the last time the steel existed at a temperature above the critical range. Since most steel castings today are at least annealed or normalized, the measurement of austenite grain size established by heat-treatment will he considered first. More than 50 commercially produced cast steels rcpresenting a wide variety of compositions and melting practices were used in the study. For each steel, grain-size determinations were made after each of three widely varying heat-treating schedules namely, one hour at I550&apos;F, one hour at I700°F, and six hours at 1700 F. The list of steels and results obtained on them will be found in the appendix. (See page 530.) A discussion of the knowledge gained on the applicability of various test methods and on grain-size characteristics of cast steels in general follows. MEASUREMENT OF AUSTENITE GRAIN SIZE ESTABLISHED BY HEAT TREATMENT Methods Suitable foR Determining Austenite Grain Size after Heat-treatment at Ordinary Temperatures and Times It was desired, as one of the results of this investigation, to be able to recommend to steel foundries a method, or methods, of disclosing grain size best suited to accurate

Jan 1, 1948

By M. F. Hawkes

Austenite grain size has long been recognized by metallurgists as an important property of steels because of its influence on toughness, hardenability, ma-chinability and creep strength. Much research has been carried out on wrought steels to develop methods for disclosing austenite grain size, and to, provide knowledge of the grain-size characteristics of steels produced and heat-treated in various ways. Much less work in these fields has been done on steel castings; partly because, owing to the variable and complex microstruc-tures of cast steels, it is frequently very difficult to obtain results that are not questionable. The object of this investigation, therefore, was to establish, for a wide variety of carbon and alloy cast steels, suitable methods for disclosing austenite grain size and some knowledge of the grain-size variations to be expected. The steel foundryman is interested in austenite grain size at two different stages in the manufacture of his products; one is just after the steel is cast, and the other is after any reheating operation carried out above the critical temperature range. In both, it must always be kept in mind that the grain size being sought is actually a previous austenite grain size, and that the austenite no longer exists once the steel has cooled to room temperature. The prob-lem of the investigator is always to use evidence obtained from the structure at room temperature to deduce this previous austenite grain size, which was established the last time the steel existed at a temperature above the critical range. Since most steel castings today are at least annealed or normalized, the measurement of austenite grain size established by heat-treatment will he considered first. More than 50 commercially produced cast steels rcpresenting a wide variety of compositions and melting practices were used in the study. For each steel, grain-size determinations were made after each of three widely varying heat-treating schedules namely, one hour at I550&apos;F, one hour at I700°F, and six hours at 1700 F. The list of steels and results obtained on them will be found in the appendix. (See page 530.) A discussion of the knowledge gained on the applicability of various test methods and on grain-size characteristics of cast steels in general follows. MEASUREMENT OF AUSTENITE GRAIN SIZE ESTABLISHED BY HEAT TREATMENT Methods Suitable foR Determining Austenite Grain Size after Heat-treatment at Ordinary Temperatures and Times It was desired, as one of the results of this investigation, to be able to recommend to steel foundries a method, or methods, of disclosing grain size best suited to accurate

Jan 1, 1948

By John S. Alexander

By E. C. Bain

THE more familiar compositions of iron-carbon-chromium1 and the iron-carbon-tungsten2 systems have been investigated with a degree of thoroughness which has permitted the construction of their three-dimensional equilibrium diagrams; and it is probable that these equilibrium diagrams are sufficiently accurate for the present metallographic needs. Strangely enough, in spite of their importance, the alloys of iron, carbon and manganese apparently have not been investigated in the same systematic manner, and so far as is known, no three-component equilibrium diagram for this system is available. Even iron-carbon-nickel alloys3 have been studied rather more thoroughly; for these the solidus and liquidus surfaces have already been determined, but the solid transformations in this, as in the manganese system, have not been reported systematically. The present paper deals with the constitution at equilibrium of a series of 36 iron-carbon-manganese alloys of commercial purity limited by 1.5 per cent carbon and 15 per cent manganese, a range of compositions including most of the manganese steels. The temperature range of melting has not been determined, nor has the high-temperature (delta iron) ferrite equilibrium been included in the study, it being considered that the more important characteristics of the manganese steels are their ordinary transformations in the solid state. The delta iron region is almost certain to be a small tetrahedron not very different in magnitude or contour from that in the iron-carbon-nickel diagram. It is probably true

Jan 1, 1932