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R. W. Raymond, New Pork City: It seems questionable to me whether Mr. Mezger's identification of the rock-structure he describes, as the Augengneiss of previous authors, is warranted by the definitions given by them. Naumann (1854)t describes Augengneiss as a porphyry-like variety, " which has assumed, by reason of single large kernels or granular concre-

Jan 1, 1896

J. K. EVELETH, Anaconda, Montana (Communication to the Secretary): Partly for the reasons which Mr. Jones enumerates, and partly because of the presence of copper in greater or less quantities in so large a proportion of the ores throughout this region, I have also found Marguerite's method the most convenient and satisfactory for the determination of iron. In order to avoid the previous precipitation of the copper with H2S on the separation of the iron by means of ammonia, with the consequent necessity for re-precipitation

Jan 1, 1889

By AIME AIME

THE first fall meeting of the new Coal Division started on time on Thursday morning, Sept. 11, at Pittsburgh, with Paul Sterling of the Anthracite Section presiding and over a hundred members and guests in the room. The attendance increased from session to session, the total registration being 248. Excellent arrangements had been made by the officers of the Division covering all features of the meeting, the only drawback being that more papers-were listed for presentation than could be discussed in the time available. Howard-N. Evensong, chairman of the Division, explained this situation as sore and sore papers case in by likening it to the case of the small boy who wanted a second niece of pie at the end of a large seal. When his mother remonstrated that if he ate any more he would certainly burst, the young man replied, "Well, you just hand over the pie and then get out of the way." With that Mr. Evensong turned the meeting over to Mr. Sterling, who handled it so well that with ample discussion it was still possible to adjourn at lunch time, all but the group of junior papers having been heard. This series of papers, the output of the .very lively Junior Section organized last spring by the younger men of the Division was regretfully put over until Friday morning, when that on "Heat Drying" by S.. M. Parsley was read.

Jan 1, 1930

The Bureau of Mines extends. a cordial invitation to all members of the Institute to visit Pittsburgh, Sept. 29 to Oct. 1, to participate in the dedication of the Mines Experiment Station. Accompanying this will be a nation-wide participation in a First-aid and Mine Rescue Contest. The Pittsburgh Chamber of Commerce will cooperate. The Institute will be represented by a special delegate appointed by the President. MONDAY 8:30. A. M. Bureau Building open for inspection. 10:30 A. M. Dedicatory Ceremonies in rear of Main Building, .4800 Forbes St. 2:00 P. M.. Special Train and Automobiles to Experimental Mine near Bruceton, Pa. 3 to 6 P. M. Mine Explosion and Inspection of Experimental Mine . and of Explosives Testing Plant near Bruceton, Pa. 6:00. P. M. Return by Special Train and Automobiles to B. & 0. Station, Pittsburgh. 8:00 P. M. Informal Reception and Organ Recital Carnegie Music Hall. Arranged by Carnegie Institute of Technology.

Jan 9, 1919

By Cloyd M. Smith

A FEW years ago, the Ventilation Committee established the practice of presenting one topic each year for discussion at the annual meeting. The practice has met good response on the part of committee members and I suggest that it be continued. The topic chosen for this year, "Underground Anemometry," is a topic which has bothered me for more than 20 years. It seems to me that the coal industry is content to rely on slipshod methods for measuring the rate of flow of air underground, so I prefaced my discussional charge to committee members with the statement that I regard air measurements made in the usual way, with hand held anemometer, as no good. Agreements and disagreements came in from more than a dozen engineers, some of whom are with operating companies, coal and metal; some with manufacturers; others with government agencies.

Jan 1, 1949

By Steven Mitchell

BACKGROUND Homestake Mining Company began milling operations at the Bulldog Mountain Mine near Creede, Colorado in 1969. The Bulldog Mill, rated at 350 tpd, produces a bulk flotation condentrate assaying about 180 oz/T Ag and 20% Pb, from heads of about 16 oz/T Ag and 2% Pb. The circuit is straightforward with two-stage grinding to 1-5% plus 65 mesh, followed by rougher and cleaner flotation. Reagents used are Z-6, Z-11, Aerofloat 242 and Aero Promoter 404, with an Aerofroth 65-MIBC mixture for a frother. Additional information on the geology, mine and mill are available in references (1) and (2). A flow sheet for the mill and CIP plant together is attached as Figure 1. Final flotation tailings normally vary from 1.5 - 2.0 oz/T Ag. These tailings are cycloned to produce sand for underground backfill. After cycloning, the sands are repulped and given a final scavenger float. This sand scavenger recovers a small additional amount of silver which recycles back to the main flotation circuit. The tailings are recycloned and pumped to the mine or, if the mine cannot accept sand, to tailings. The majority of the silver in the flotation tailings exists in the fine fractions; cycloning upgrades the slimes and lowers the assay of the sand. The sand, after scavenging, typically assays 0.5 oz/T Ag, and the slimes assay about 3.0-3.5 oz/T Ag. From 1969 to 1976 all of the slime tailings and the sand tailings not used underground were impounded in a tailings pond located about

Jan 1, 1983

By Beall, John V.

THIS is not simply the story of how a water filled shaft was developed into a million-ton- a-year producing mine in the space of four critical years, although it is reason enough for telling it, but it is also the saga of an engineering achievement in which knowledge nurtured by years of experience in coal and ore mines was blended together and the best from each type of mining selected. The entire system of mining was detailed on maps by the mining engineering department before the shaft was unwatered, and subsequent development followed these plans nearly to perfection. The selection of machinery was particularly critical as it was necessary to push production from only a few headings in the early stages of development and metal mine machinery was being used in a coal panel-system of mining. At the start of World War I1 the demand for iron ore to supply Woodward blast furnaces, and rapid exhaustion of the main source of Wood- ward ore, No. 3 Red Ore mine, necessitated speedy opening of the Pyne mine. The mine is three miles southwest of Bessemer and is responsible for 80 pct of Woodward ore, the rest coming from the Songo mine. The Woodward Iron Co. is one of the old producers of the Birmingham district. S. H. Woodward, an iron-master of Wheeling, overheard two Union soldiers conversing about ore and coal lands in Alabama, which lead to the acquisition of the first ore lands of the Woodward Co. in 1869. Development was not begun until after the death of S. H. Woodward; his two sons, W. H. Woodward and J. H. Woodward, formed the Woodward Iron Co. in 1881 and purchased a tract of land midway between the ore vein on the southeast and the coal field on the northeast about 12 miles southeast of Birmingham for the

Jan 1, 1950

By Frank G. Miller

The lower cost of producing oil from naturally flowing wells compared with pro-luction costs accruing from artificial lifting methods has stimulated much research, rith the joint purpose of extending the natural flowing life of wells and of increas-ng the productivity of small wells. The iboratory investigation described herein was made to determine the effect of a lotted liner on the pressure gradient in the icinity of the wall of a flowing well. Flow estrictions caused by the liner induce nergy losses between the oil-bearing for-lation and the inside of the liner, which lay be reduced by improved liner design, nd thereby the flow capacity of wells may e increased. These losses have been evalu-ted for rectangular slots of different sizes, nd means are suggested for reducing them. The dearth of information concerning the ature of the flow of fluids from uncon-slidated sands through small openings in he walls of. pipes—as represented by the ow of oil from an oil sand into a slotted ner—is acknowledged. Although the bene-ts to be realized by operators through the se of optimum liners is just beginning to e recognized generally, Coberlyl in 1937 ointed out that the functioning of screen is is an important factor in the pro-uction of oil. From his study on the :lection of size of oil strings for wells in California, Parks2 concluded, in part, that the perforated section of the oil string deserves continued study, especially with respect to the selection of perforations. The growing use of gravel packing resulting from certain research findings lends even more significance to the problem of selecting optimum liners, as the application of these methods usually requires slotted liners or other kinds of perforated liners. The present study was made to obtain further information for the guidance of engineers and operators in selecting slotted liners and to develop a laboratory method that may be used in analyzing possible pressure conditions surrounding most types of perforated casings used in producing oil wells, so that the present inadequate fund of knowledge on this important subject may be expanded. Discussion of ProbleM At the beginning of the investigation the following assumptions were made regarding bottom-hole conditions of a producing oil well and the oil-sand reservoir it penetrates: (I) Conditions of steady-state flow exist, (') a a homogeneous liquid is being produced) (3) no contaminating material (such as drilling fluid) is present between the liner and the face of the oil-bearing sand, (4) the well is vertical and completely penetrates a horizontal sand stratum of uniform thickness occurring between two impermeable strata, and (5) the flow is wholly viscous. If the foregoing assumptions are made, with the added requirements that the sand

Jan 1, 1941

By Frank G. Miller

The lower cost of producing oil from naturally flowing wells compared with pro-luction costs accruing from artificial lifting methods has stimulated much research, rith the joint purpose of extending the natural flowing life of wells and of increas-ng the productivity of small wells. The iboratory investigation described herein was made to determine the effect of a lotted liner on the pressure gradient in the icinity of the wall of a flowing well. Flow estrictions caused by the liner induce nergy losses between the oil-bearing for-lation and the inside of the liner, which lay be reduced by improved liner design, nd thereby the flow capacity of wells may e increased. These losses have been evalu-ted for rectangular slots of different sizes, nd means are suggested for reducing them. The dearth of information concerning the ature of the flow of fluids from uncon-slidated sands through small openings in he walls of. pipes—as represented by the ow of oil from an oil sand into a slotted ner—is acknowledged. Although the bene-ts to be realized by operators through the se of optimum liners is just beginning to e recognized generally, Coberlyl in 1937 ointed out that the functioning of screen is is an important factor in the pro-uction of oil. From his study on the :lection of size of oil strings for wells in California, Parks2 concluded, in part, that the perforated section of the oil string deserves continued study, especially with respect to the selection of perforations. The growing use of gravel packing resulting from certain research findings lends even more significance to the problem of selecting optimum liners, as the application of these methods usually requires slotted liners or other kinds of perforated liners. The present study was made to obtain further information for the guidance of engineers and operators in selecting slotted liners and to develop a laboratory method that may be used in analyzing possible pressure conditions surrounding most types of perforated casings used in producing oil wells, so that the present inadequate fund of knowledge on this important subject may be expanded. Discussion of ProbleM At the beginning of the investigation the following assumptions were made regarding bottom-hole conditions of a producing oil well and the oil-sand reservoir it penetrates: (I) Conditions of steady-state flow exist, (') a a homogeneous liquid is being produced) (3) no contaminating material (such as drilling fluid) is present between the liner and the face of the oil-bearing sand, (4) the well is vertical and completely penetrates a horizontal sand stratum of uniform thickness occurring between two impermeable strata, and (5) the flow is wholly viscous. If the foregoing assumptions are made, with the added requirements that the sand

Jan 1, 1941

By K. Reinhardt

The idea of burning blast-furnace gases directly in gas-engines, instead of under steam-boilers, as had previously been done, was first put into practice barely ten years ago, almost simultaneously in Great Britain, Germany and Belgium. The pioneers of this movement made their first experiments with small engines. After these experiments had given satisfactory results, and it had been shown that the thermal value of the poor blast-furnace gases, in spite of defective scrubbing, could with safety be directly transformed into mechanical work in the gas-engine, there very soon arose a considerable demand for gas-engines of large power, similar to the large steam-engines employed in metallurgical works. In face of these sudden requirements, the gas-engine builders were placed in a difficult position; for up to that time the gas-motor was considered as suitable for small engines only, and it was generally believed that the limit of size had been attained with 100 to 150 effective h.p. in a single cylinder. Manufacturers of gas-motors, however, did not underrate the advantages offered by this new field for their manufactures, and it so happened that in Germany the Berlin-Anhaltische Masch-inenbau-Gesellschaft, of Dessau, was the first to undertake the construction of a 600-h.p. two-cycle gas-engine, with two cylinders of the Oechelhauser-Junkers type, for the Hoerder Mining & Smelting Company. The engine was started in 1898, and, with a few improvements and alterations, is still working satisfactorily. This engine worked with astonishingly high effciency, considering the period. The builders were therefore

Jan 1, 1907

By Charles E. Hughes

HERBERT HOOVER had to sit through an hour and a half of eulogy of himself at Carnegie Hall last night, said the Sun and New York Herald of Feb. 19. When his turn to answer came he remarked that, although one of the speakers had referred to him as a modest man, he would never, in view of this experience, be able to prove it. The occasion was the presentation by the Civic Forum to Mr. Hoover of its medal of honor for distinguished service, the only recipients in past years having been General Goethals, Thomas A. Edison, and Alexander Graham Bell. Only by distortion of intent could there be said to be anything political in the affair, which was carefully described by the chairman, Charles E. Hughes, as non-partisan. Nevertheless, the praise bestowed on the former Food Administrator by the former Republican candidate for President, proved specially interesting to a much applauding audience which filled the hall to the uppermost gallery. A piece of real news was supplied by Horace V. Winchell, whom Mr. Hoover succeeded on Tuesday as President of the American Institute of Mining and Metallurgical Engineers. He said that Mr. Hoover, when in Europe after the . armistice, caused to be collected the literature of the war in all Europe.

Jan 1, 1920

By D. D. Dunkin

SANDSTONE has been prepared for glassmaking purposes, and marketed from the White River Valley in-Arkansas at Guion, Izard County, since about 1910-soon after the completion of the White River Branch of the Missouri Pacific R. R. Co. Until 1921, operations were somewhat spasmodic and ended in many failures. In that year a plant was built by the Silica Products Co., Inc., and since that time the operation has been continuous and steady. The land is held under leases, covering about 30 sq. mi. of the best sandstone adjacent to the railroad. Most of the product is shipped to glassmakers. GEOLOGY The St. Peter sandstone is rather widely distributed in north central Arkansas and- is exposed most prominently in outcrops along the slopes of the White River Valley and its tributaries that form the division between the Boston Mountains to the south and the Salem Plateau of the Ozarks to the north. It is of Ordovician age and is generally underlain by Cotter dolomite and capped by Plattin limestone, except in the vicinity of Bellefonte and Everton. At those places, it is a massive cross-bedded, laminated, saccharoidal sandstone; underlying it is the Everton limestone and overlying it, the Joachim magnesium limestone. The sandstone at Everton contains numerous phosphatic pebbles and inclusions of sandy limestone. The irregularity of cross-section, the evidence of sorting action and the phosphatic pebbles appear to be indications of secondary deposition.

Jan 1, 1928

By Thomas Leonard Watson

I. HISTORICAL. BARITE has been mined for many years in various parts of Virginia, probably the earliest mining-operations being in Prince William county, within 600 ft. of the Fauquier county line, about 4 miles south of east from Catlett, a station on the Southern Railway. It is claimed that the mineral was mined here as early as 1845. Mining-operations in Campbell and Pittsylvania counties in the Piedmont region, and near Marion in Smyth county, in the southwest Virginia Valley region, were begun about 30 years ago. The mining and milling of barite on a commercial scale in Tazewell and Russell counties are more recent, and commenced about 15 years ago. II. GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION. Barite occurs in many counties in the State, as shown in Fig. 1, but the industry has been confined to only a few of them. Its occurrence is noted in two of the three major divisions of the State-namely, the Piedmont region east of the Blue Ridge, and the Paleozoic area west of the Blue Ridge. In the Piedmont region the mineral has been mined in the following counties:, Bedford, Campbell, Louisa, Prince William, and Pittsylvania. In the region west of the Blue Ridge, composed of Paleozoic sediments, barite has been mined in Montgomery, Russell, Smyth, and Tazewell counties. Of the counties mentioned, Bedford, Campbell, and Pittsylvania of the Piedmont region, and Russell, Smyth, and Tazewell of the Valley region, have been the principal producers. In 1906, operations were confined to five counties-Bedford, Louisa, Pittsylvania, Russell, and Tazewell-but in the first two counties named there was no production, the work being solely development.

Jan 9, 1907

By Murray Kaufman

Using en; 41 for a base alloy, 15 modifications were made in sheet form. The elements Al, Ti, C, Mo, Co, and Cb were varied. The effects on the phases formed and their temperature dependence, the aging characteristics, tensile and stress-rup- ture properties, and weld cracking were determined. The A1-Ti content and balance is the most important factor influencing the major sCrengthening phases [Ni,Ti and Ni,(Al, Ti)] and, consequently, mechanical properties. THE mechanical properties, fabricating and joining characteristics, dimensional stability, and so forth, of alloys containing secondary phases are largely determined by the phases present, their distribution, and their temperature dependence. The phases in the basic ternary and quaternary Ni-Cr-Al-Ti combina- tions have been investigated thoroughly.'* The phase behavior of many commercial nickel-base alloys has been determined also. In some cases, for example U500, 5 the effect on mechanical properties has been found. However, little systematic work has been done to clarify the action of each of the important alloying elements in controlling the phases formed in complex commercial alloys and their behavior. The effect of molybdenum on the carbides formed in M252 was investigated by Beattie and verSnyder.6 Application of the results provided by that work

Jan 1, 1963

TWO very interesting sessions on mine ventilation were held on Monday. George S. Rice, chairman of the Mine Ventilation Committee, presided at the morn-ing session. Formal reports from two subcommittees were presented, as well as two technical papers. Daniel Harrington, for the subcommittee on metal mining, gave a most interesting report, devoting most of it to a review of the literature that had appeared during the past year, to the cooling of mine air, and to a discussion of mine fires. In the absence of Dr. R. R. Sayers, chairman of the Physiological subcommittee, Mr. Harrington gave a resume of that report. The main points covered were in connection with silicosis but some attention was also paid to the associated prob-lems of air cooling and humidity. The paper by Prof. W. S. Weeks on the "Air-Current Regulator" was briefed by Prof. A. C. Callen. Pro-fessor Weeks brought out the fact that the common application of Murgue's equivalent-orifice formula to regulator problems was incorrect, inasmuch as the dis-charge from the regulator was not released into the open air but into a slow-moving current beyond the regulator. He applied the shock-loss theory of Bordoni to the problem and worked out a formula for solving regulator problems, giving coefficients of contraction he had determined experimentally.

Jan 3, 1928

By A. Kaufmann, B. Cullity, G. Bitsianes

T0 determine the bulk of the phase diagram, techniques for melting, thermal analysis, heat treatment, metallography, and X-ray diffraction that have already been described were used.' It proved difficult to get definitive results for most of the alloy system because of the large number of compounds, their high melting points, and their extreme brittle-ness which made metallography difficult. The final phase diagram, essentially as shown in Fig. 1, was issued with considerable trepidation.' The phase relationships at the two ends of the system were defined with satisfactory accuracy. In the central region between U,Si, and USi, there was great uncertainty concerning the melting points and even the composition of the compounds. At the uranium end of the system, it is quite clear that a eutectic exists at about 985 °C and approximately 8 or 9 atomic pct Si. The a-to-8 transformation is not appreciably altered by silicon, but the 8-to-y transformation is raised to about 795°C. There is appreciable solid solubility in y-uranium, as demonstrated by the micrographs of Fig. 2. The occurrence of the E phase was not suspected at first, since the alloys as melted and furnace cooled gave no X-ray diffraction or thermal arrest indication of it. However, suitable metallography revealed a rim around each of the compound particles as shown in Fig. 3. Heat treatment above 600°C revealed that the rim was another phase which formed by peritectoid reaction between uranium and U,Si,. This reaction proceeds slowly and it is difficult to get it to go to completion. Consequently, there is some uncertainty concerning the exact composition of P and the exact peritectoid temperature. On the basis of various metallurgical studies, it was decided that the most probable composition for t was about 23 atomic pct Si. Metallographic examination shows the closest approach to a single phase at this composition. Likewise, density and hardness measurements of heat-treated alloys shown in Figs. 9 and 10 show a change in slope at 23 pct Si. This is revealed most clearly by plotting the difference in hardness or density between chill-cast and heat- treated alloys as shown in Fig. 4. Zachariasen2 was able to index the diffraction lines of P and to determine the arrangement of the atoms in the unit cell. He concluded that the composition must be US. However, it is felt that the metallurgical studies are reliable and that Zachariasen's X-ray work does not furnish positive proof that the P phase exists exactly at the stoichiometric composition U3Si. There are many instances in alloy systems where a phase does not occur at the composition dictated by the molecular structure. It is possible that the chemical analyses used in the present work were subject to some systematic error. This seems unlikely, however, since recent work in several laboratories seems to show excess compound at 25 atomic pct Si.

Jan 1, 1958

The Round Table on Qualities of Pig Iron, under the auspices of the Joint Committee on Qualities of Pig Iron, which is made up of members of the American Institute of Mining and Metallurgical Engineers, the American Foundrymen's Association, the American Society for Testing Materials, the Gray Iron Institute, and the Malleable Iron Institute, was held at the Palmer House, Chicago, III., on Oct. 1, 1935. Prcoeedings R. H. SwEEtseR,* New York, N. Y.—Seven years ago last June, in Chicago, we had a round table on qualities of pig iron1, and at that time the foundrymen were out with their battle-axes for the blast-furnace men, and the open-hearth men were doing the same thing. After that meeting there was really a determined effort to find out about the qualities of pig iron, and great progress has been made all along the line. This afternoon we want to have a frank discussion of the qualities of pig iron, whether it is the molten pig iron going into the steel plant, or cold pigs going to the different foundries. We ought to hear something from Dr. J. T. MacKenzie, who is chairman of the Joint Committee, and from Mr. R. E. Kennedy, the Technical Secretary of the American Foundrymen's Association. J. T. MacKEnzie,† Birmingham, A1a.—As a result of that meeting in Chicago, there was considerable agitation in the Foundrymen's Association to develop a set of tests for pig iron. One of the difficulties was that nobody talked the same language on shrinkage, draws, live iron, dead iron, and so forth, which were the main complaints against pig iron. By request of a committee of the Foundrymen's Association, the Bureau of Standards ran a comprehensive set of tests that did develop the principles governing the optical pyrometer as applied to cast iron and pig iron. Then the Bureau went on further with the fluidity test, and developed a method for the absolute changes of volume at the freezing point. There is one serious gap in the yardstick, which has never been developed, and that is the tendency to draws from heavy sections to light. Everyone who has worried about the differences of section, and sponginess in changes of section, realizes that the

Jan 1, 1936

The Round Table on Qualities of Pig Iron, under the auspices of the Joint Committee on Qualities of Pig Iron, which is made up of members of the American Institute of Mining and Metallurgical Engineers, the American Foundrymen's Association, the American Society for Testing Materials, the Gray Iron Institute, and the Malleable Iron Institute, was held at the Palmer House, Chicago, III., on Oct. 1, 1935. Prcoeedings R. H. SwEEtseR,* New York, N. Y.—Seven years ago last June, in Chicago, we had a round table on qualities of pig iron1, and at that time the foundrymen were out with their battle-axes for the blast-furnace men, and the open-hearth men were doing the same thing. After that meeting there was really a determined effort to find out about the qualities of pig iron, and great progress has been made all along the line. This afternoon we want to have a frank discussion of the qualities of pig iron, whether it is the molten pig iron going into the steel plant, or cold pigs going to the different foundries. We ought to hear something from Dr. J. T. MacKenzie, who is chairman of the Joint Committee, and from Mr. R. E. Kennedy, the Technical Secretary of the American Foundrymen's Association. J. T. MacKEnzie,† Birmingham, A1a.—As a result of that meeting in Chicago, there was considerable agitation in the Foundrymen's Association to develop a set of tests for pig iron. One of the difficulties was that nobody talked the same language on shrinkage, draws, live iron, dead iron, and so forth, which were the main complaints against pig iron. By request of a committee of the Foundrymen's Association, the Bureau of Standards ran a comprehensive set of tests that did develop the principles governing the optical pyrometer as applied to cast iron and pig iron. Then the Bureau went on further with the fluidity test, and developed a method for the absolute changes of volume at the freezing point. There is one serious gap in the yardstick, which has never been developed, and that is the tendency to draws from heavy sections to light. Everyone who has worried about the differences of section, and sponginess in changes of section, realizes that the

Jan 1, 1936

By G. A. Stamboltzis, N. Arbiter, C. C. Harris

Fracture under low-velocity free-fall and double impact and under slow compression have been investigated. The pattern of breakage and the size distribution of resulting fragments of sand-cement and glass spheres have been determined. Photoelasticity methods were used to simulate the stress distributions in free-fall impact in order to explain the observed patterns of breakage. Oblique fracture planes, occurring only in free-fall impact, develop along lines which coincide with the trajectories of maximum compression as determined by mathematical analysis. Breakage efficiencies for different modes of fracture were compared for both types of spheres. For the same specimen and loading system, static loading and low-velocity dynamic loading induce geometrically similar stress fields resulting in reasonably similar fracture patterns and shapes of fragments. This work had its origin in a desire to understand three fundamental processes involved in autogenous comminution: namely; free-fall impact, double impact, and slow compression. To simplify the investigation, it is preferable to reduce the entire multi-stage fracture process to its most elementary form; that is, to study products resulting from a single-stage operation, such as the breakage of a specimen under single fracture conditions. The goal of this research is to study the energy utilization in the single fracture of brittle specimens and to relate the pattern of breakage and the resultant fragment size distribution with the nature of the material, the specimen size, the manner of load application, and the rate of loading. Published works on single fracture have mainly been concerned with tests on large (> 1-in.) irregular mineral pieces, especially coal and coke. These were mainly friability tests employing a single blow on closely sized pieces. More recently, small mineral specimens in the sieve range and glass spheres have been investigated.5-7 Kick8 has reported free-fall and double impact tests with large large cast-iron, cement, and clay spheres. The establishment of a minimum breaking height independent of size in the free-fall impact tests, and the direct proportionality between the minimum work required for fracture and the volume of the specimen in double impact tests were used by Kick as an experimental proof of his classical law of "Proportional Resistances." In the present work, spherical shapes were chosen because of their simple body geometry and consequent impact and stress field symmetry. Because the study involves several physical principles in connection with brittle-fracture, it may be of interest in fields where the strength of materials is of importance. APPARATUS The equipment for the free-fall impact testing is illustrated in Figs. 1 and 2. This consisted of a massive (17 x 17 x 3-in.) hard steel plate onto which specimens were dropped and a specimen release mechanism which could be set at any desired height up to 10 ft above the plate so that the impact velocity could be varied up to about 25 ft per sec. Double impact breakage is characterized by two points of loading situated at opposite poles. For this mode of breakage the apparatus was modified (Figs. 3, 4 and 5) so that a falling mass provided an impact of predetermined magnitude on a specimen resting on the plate. A spring-loaded device operated immediately after fracture to arrest the falling mass and to record its residual kinetic energy. Precautions were taken to avoid secondary breakage. Slow compression tests were performed on a conventional hydraulic testing machine, the specimen being held between two hardened parallel bearing blocks. In the case of glass spheres, carbide bits were used. Photoelasticity studies were performed on two-dimensional models held in a loading frame equipped with a force gauge (Fig. 6). The models were viewed in a polariscope and isochromatic fringe patterns were recorded photographically. SPECIMENS Sand-Cement Spheres: A series of sand-cement spheres were prepared by molding in spherical glass flasks.

Jan 1, 1970

By G. K. Manning, A. R. Elsea, C. R. Simcoe

Boron increases the hardenability of hypoeutectoid steels by decreasing the nucleation rate of ferrite and bainite. It is postulated that concentrations of lattice imperfections, such as exist at the grain boundaries, furnish the necessary energy for nucleus formation. Boron, because of its atomic diameter, will concentrate at lattice imperfections where sites of suitable size are present. Boron will decrease the energy of these local areas by occupying these sites. This mechanism accounts for the large increase in hardenability observed with small amounts of boron. The loss of the boron hardenability effect and the boron precipitate formation are explained on the basis of increased concentration of boron at the grain boundaries either with increasing boron content of the material or with increasing temperature. COMMON alloying elements affect both the nucleation and growth rates of the austenite decomposition reactions.' This effect is largely a result of the slow diffusion rates of these elements. Although a small addition of boron markedly increases the hardenability of steel, the diffusion rate of boron, which is of the same order of magnitude as that of carbon, can hardly account for this effect. An addition of boron in the range of 0.001 to 0.003 pct is about as effective as an addition of 0.30 pct Mo, 0.40 pct Cr, or 1.25 pct Ni in increasing the hardenability of a 0.40 pct C steel;' however, increasing the carbon content of the steel decreases the effectiveness of the boron addition."' The difficulty in understanding why so small an addition of boron can replace much larger quantities of the more strategic alloys, together with the erratic behavior sometimes encountered in boron-treated steels, has interfered with their general acceptance by industry. In the belief that an understanding of the mechanism by which boron increases the hardenability of steel should lead to a more general acceptance of boron-treated steels, a research investigation to determine this mechanism was undertaken at Battelle Memorial Institute under sponsorship of Wright Air Development Center. Experimental Work In order to study the effect of boron on the transformation of austenite to ferrite and bainite, a group of steels was made with a basic composition similar to that of the SAE 8600 series. This base composition was chosen because it has sufficient hardenability to permit accurate measurement of the times required for transformation to start at various temperatures. The chemical analyses of the steels used in the first part of this investigation are listed in Table I. These steels were made as 200 lb heats in an induction furnace. The furnace charge was Armco ingot iron with the alloying elements added as ferroalloys. After the alloy additions were made, the heat was deoxidized with 0.125 pct Al. A 100 lb ingot was cast and an addition of 0.003 pct B, as ferroboron, was made to the metal remaining in the furnace. This metal was cast into a second 100 lb ingot. The ingots were forged to 11/4 in. diam bar stock from which end-quench hardenability specimens were obtained. Part of this material was further reduced by hot rolling to lx¼ in. bar stock from which specimens were obtained for isothermal transformation studies. Studies of Nucleation and Growth: End-quench hardenability tests were performed on these steels, using an austenitizing temperature of 1600°F. The hardenability curves, shown in Fig. 1, indicate that boron treatment resulted in considerable increase in hardenability of the steels. Any such change in hardenability must result from a change in the transformation rate of the austenite, and these rate changes can be established readily by isothermal transformation studies. Isothermal transformation studies were conducted on these steels as follows: specimens were austeni-tized at 1600°F for 15 min, transferred to a lead bath operating at a constant subcritical or intercritical temperature, held for various lengths of time, and water quenched. The specimens were sectioned for metallographic examination to determine the amount and the type of transformation products present. In order to determine the effect of boron on the formation rate of ferrite, isothermal transformation tests were made on the 0.20 pct C steel in both the boron-treated and boron-free condition at an intercritical temperature of 1375°F where ferrite is the only decomposition product of this low carbon austenite. The results of these tests are shown in Fig. 2, where the percentage of ferrite formed is plotted as a function of time at temperature. It is apparent that boron markedly decreased the transformation rate of austenite to ferrite at this temperature.

Jan 1, 1956