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By W. Rostoker, A. Siede

THE venerable problem of hydrogen embrittlement of ferritic iron lacks as yet a complete explanation. Possibly part of the difficulty has been the exclusive preoccupation with the total ductility prior to fracture. In the past few years it has been noted at least twice1,2 that hydrogen charged into iron has the ability to depress the upper yield point and, at room temperature, to eliminate completely the discontinuous yield phenomenon. Cracknell and Petchl rationalize that the depression of the yield stress is an example of the behavior of inhomogeneous stresses. Their explanation requires that microcracks exist in the annealed metal, and that hydrogen collect in these cavities under high hydrostatic pressure. The hydrostatic pressure of hydrogen generates localized tensile stresses in the iron which, with external loading, reach the critical stress for yield prematurely. The local plastic zones will spread across the specimen before the Lüders bands can be generated, and the yield-point elongation phenomenon is eliminated. This viewpoint will be discussed in succeeding paragraphs. Rogers,2 on the other hand, represents the depression of the initial flow stress as a result of the interaction of hydrogen with dislocations. He submits two alternative modes of interaction. In the

Jan 1, 1959

Jan 1, 1917

By Luke L. Y. Chang, Bert Phillips

A number of molybdenum oxides have been synthesized and their crystal structures have been described.' No data have been published on the stabilities of these oxides nor on the phase relations in the system Mo-0. It is probable that the tendency toward oxidation of both the metal and the oxides with low oxygen content in addition to the high volatilization rate of the oxides with high oxygen content have precluded accumulation of reliable data for establishing phase relations. These problems make experimentation difficult, but a modifi-

Jan 1, 1965

By W. H. Emerson

In the summer of 1894, a specimen of corundum from Acworth, Ga., which mas reputed to be of markedly inferior quality for the manufacture of corundum-wheels, was received by the Geological Survey of Georgia, with the request that it be analyzed, in order to ascertain whether this inferiority was associated with any peculiarity of composition. In its appearance there was nothing uncommon, though it seemed to be rather easily scratched with a knife, while, at the same time, it scratched agate easily. An analysis gave the following results: Alumina, 94.58; silica, 1.77; magnetic oxide of iron, 0.69; calcium oxide, 0.44; and water, 2.51 per cent. There is nothing unusual in this composition, except the amount of water, which is usually, in southern corundum at least, from 0.3 to about 1 per cent. Concerning this corundum, the Mineral Resources of the United States, 1893, pp. 676 and 677, Bays: "It is supposed that this variety of corundum contains a little water, as it is

Jan 1, 1900

By Frederic Benard

The electrolytic copper refinery at Copper Cliff, Ont., is operated by the Ontario Refining Co., Ltd. The associated companies behind the enterprise are the International Nickel Co. of Canada, Ltd.; The American Metal Co.; The Consolidated Mining & Smelting Co. of Canada, Ltd.; and Ventures, Ltd. The plant was the outgrowth of the rapid development of copper resources in the nickel-copper ores of the Frood and other great mines in the Sudbury district, and of the desire to have all primary production units grouped together as closely as possible. The refinery is near the intersection of the Sault Ste. Marie to Sudbury highway and the Canadian Pacific Railway. It is about one mile south of The International Nickel Company's smelter at Copper Cliff. The standard-gage track systems of the refinery and of the smelter are connected by a standard-gage timber railroad trestle that crosses the railway and the highway by means of steel girder spans. The Canadian National Railway has access to the plant by means of this trestle and the nickel company's tracks, so that the refinery has connections with both the Canadian Pacific and the Canadian National railways, as well as a direct connection with The International Nickel Company's smelter, from which the bulk of the copper to be refined is hauled by the latter's electric locomotives. Buildings The refinery (Fig. 1) covers approximately 60 acres, enclosed by an unscalable chain-link fence. The main buildings have a content of 23,000,000 cu. ft., with a total roof area of approximately 600,000 sq. ft. and near them are the substation, cooling pond and main standard-gage track system (Fig. 2). A ladder track for car storage extends 1200 ft. south of the coal-pulverizer tracks and the scale house is on this spur. The intake and pumphouse for fresh water supply are at Kelly Lake, about 3000 ft. south of the plant. Owing to the severity of the winters, when temperatures of from 20" to 40' below zero are to be expected, the building of this refinery involved a number of problems in insulation, layout, ventilation, etc., which were

Jan 1, 1934

By J. W. Eckerd, P. S. Lewis, N. H. Coates

USBM designed, constructed, and operated an 18-in.-diam fluidized-bed combustor for highly caking coals to evaluate the method for possible application to power generation. In initial tests, combustion was carried on successfully, with carbon losses as low as 0.8%+ Coal ash was not satisfactory as a bed material, but mullite proved to be acceptable. Overall heat-transfer coeffients from the bed (-20 t 50 mesh mullite) to a water-cooled tube were about 75 Btuper hr-sq ft. Fluidized-bed combustion is being investigated by the U. S. Bureau of Mines (USBM) as a potentially cheaper method of firing power plant boilers. Lower combustion temperatures in fluidized beds—only 1400" to 1800°F-—should reduce fireside deposition and corrosion and nitrogen oxides production. Fluidized-bed combustion also offers possible advantages in the use of additives to control SO, emissions and amenability to processing of high-ash, high-moisture coals without special preparation. This paper describes development of a fluidized-bed combustor and the results of preliminary tests. Equipment and Procedure Fig. 1 shows the 8-ft-high combustor. A cone-shaped plate perforated by I/8-in.-diam holes supports the fuel bed and admits the fluidizing air; water passing through the 3/4-in. pipe extracts heat from the combustion bed. Fig. 2 is a flow diagram of the system. Coal is fed pneumatically to the base of the fuel bed. Combustion products are passed through two centrifugal separators to remove most of the entrained solids, then to a water

Jan 1, 1971

By E. Gregory, A. Coucoulas

Carbm dioxide, which exists metastably as a constantly subliming molecular solid in a normal room-temperature environment, has been shown to exhibit many microstructural features which are similar to those observed in metals and ceramics at temperatures approaching their melting points. An examinution has been made of some of the factors affecting a brittleness condition known as "smzdiness" which occurs in solid carbon dioxide. It has been shown to be highly dependent on manufacturing and storage conditions and is thought to be a marked intergranu-lay brittleness which results from a combination of excessive grain growth and a concentration of gas-filled pores at the grain boundaries. In the course of an investigation carried out to explain certain physical and mechanical properties of solid carbon dioxide, observations were made of the microstructure and fragmentation of samples after fabrication and storage under varying conditions. Many similarities between the structures of solid carbon dioxide observed under ambient conditions and those existing in metal and ceramic systems at temperatures approaching their melting points have been observed. There are, however, important differences between solid carbon dioxide and the common metallic and ionic solids which result primarily from the differences in the nature of the bonding forces. Despite these differences, the relative ease with which certain microscopic observations can be carried out, may make solid carbon dioxide a useful material model for the physical metallurgist and the ceramist. It could also prove a valuable material for educational purposes where it is required to illustrate grain phenomena which normally can only be seen with the aid of a high-temperature microscope, and after prolonged chemical or thermal etching.

Jan 1, 1963

By E. C. Patton

Jan 1, 1947

By E. C. Patton

Jan 1, 1947

By Zay Jeffries

IN this paper, it is proposed to outline a method for the determination of melting points of those metals and alloys having high fusion temperatures. The application of the method as used to determine the melting points of alloys of tungsten and molybdenum will be given. It will be seen from these results that tungsten and molybdenum form a completely FIG. 1.-PARTIAL SECTION OF APPARATUS USED TO DETERMINE MELTING POINTS OF TUNGSTEN AND MOLYBDENUM ALLOYS. isomorphous series. This is also verified by the accompanying photomicrographs. Tungsten and molybdenum have been found to crystallize in the salve system, namely, isometric, and the crystal units are cubes. These determinations were made by examining etching pits in the pure metals.

Jan 7, 1916

By F. L. Ransome

The dike here described is exposed in the workings of the Wedge and Bachelor mines, on the southern side of Red Canon, north of the town of Ouray, Colorado. Its course is north 80° east, or nearly east and west, and it hades to the north about 10°. It rarely outcrops, and was nowhere seen at the surface near the mines. A specimen collected by Dr. A. C. Spencer about two miles to the westward, near the mouth of Red Creek, indicates, however, a probable exposure of the dike near this point. The Wedge and Bachelor mines lie in a nearly horizontal series of fine-grained, light-grey sandstones, alternating with beds of very fine-grained shale of the same color. The shale as encountered underground is unusually compact and massive, but weathers readily on exposure, and splits much after the manner of ordinary shale. When fresh it closely resembles some finely arenaceous limestones, but it does not effervesce with acids, and is eseentially a fine, indurated, siliceous silt. Near the surface, and near the top of the sedimentary series as

Jan 1, 1901

By Richard L. Coleman

Metallurgical testwork to develop a flowsheet is described, beginning with background information required right through to a final process flowsheet. Both laboratory and pilot plant testing are reviewed with emphasis on the former.

Jan 1, 1978

By H. N. Eavenson

In a discussion in the Transactions of the Institute (vol. Xl, page 835 et seq.) the writer gave some data about the explosions of gas and dust in the coal mines of the United States, Canada, and Mexico…

Jan 1, 1915

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

It was found that a critical boron content exists which yields the maximum boron-hardenability effect in hypoeutectoid steels, as was predicted from the mechanism proposed in a previous paper. The hardenability of boron steels with boron contents between 0.00005 and 0.0017 pct was dependent on the boron content, austenitizing temperature, quenching temperature, and austenite grain size. The effects of these variables on hardenability can be explained by the mechanism previously proposed for the boron effect. A MECHANISM has been proposed to explain the effect of boron on the hardenability of steel.' The proposed mechanism assumes that transformation particles nucleate at concentrations of lattice imperfections where the energy level is high, and

Jan 1, 1957

OUR 78th Annual Meeting was, technically and attendance-wise, one of the greatest to date. No one who came to New York's Hotel Statler had time to hear all 266 papers, or to attend all 70 sessions and 27 committee meetings, or to shake the hands of the more than 3000 engineers, educators, students and executives who attended-but no one was lost in the crowd. For crowds always dwindle down to groups of two and three and four, and those are the little sessions which make our meetings well worth attending. Herewith four pages of photographic highlights and sidelights on the February gathering.

Jan 3, 1950

By R. W. Heckel

The conzpaction of metal powders is analyzed through density-pressure curves as a three-stage process — die filling, individual particle motion, gross compact deformatim. The densification occurring during each of these stages is evaluated quantitatively. The amount of densification in the first and second stages is primarily a function of particle geometry. The densification taking place in the third stage is dependent mainly upon the material. AT the present time the densification of powders during compaction is usually described by terms such as "compactibility," "compressibility," and "compression ratio." Schwarzkopfl has proposedthat compactibility be defined as the minimum pressure needed to produce a given green strength, while compressibility be used to indicate the extent towhichthe density of a powder is increased by a given pressure. Compression ratio is generally defined as the ratio of the compact density obtained at a given pressure to the apparent density of the loose powder. 13alshina found that the pressure imposed on a compact affects the relative volume of the compact according to the following relation: hP= - LV + C [ll where: P is the applied pressure, V is the relative volume of the compact, Ratio of the specific volume of the compact to that of the material without porosity. Lisa constant described as the modulus of pressing and is determined by the slope of a plot of h P vs V, and C is a constant which is determined by the intercept of a plot of InP vs V. Several drawbacks of the Balshin analysis may be noted from Fig. 1, which is a plot of pressure (loga-

Jan 1, 1962

By L. C. Raymond

Valuations in the mineral industry differ from those of other enterprises because mines and oil wells have a definitive life so cannot be considered a perpetuity. This requires that in any mineral-property evaluation the recovery of invested capital is necessary during the life of the property. Capital writeoffs for nonextractive industries are assumed to be continuously plowed back to sustain the operation and produce yields on the capital invested. The extractive or mineral industry, however, generally attempts to return to the investor both interest and principal during the life of a property. Normally this is done currently and the dividend includes both items. Where the mineral properly possesses large reserves and the life factor approximates a perpetuity, the return on investment is generally comparable to that of industrial stocks. The valuation of a mineral property, at best, is based on educated estimates and judgment factors. This is particularly true as it relates to estimating selling prices over a long term or assessing the quality of management. Also, it is possible to make various assumptions as to rapidity of working out the deposit, varying time for start-up of operations, varying earning rates, so as to obtain different results with the same basic facts. Thus it is not surprising that two engineers, irrespective of their abilities, may not agree exactly even when given the same facts, but their results should be close enough to be used in establishing a fair value for trading purposes. The valuation is no better than the source of basic data and the soundness of judgment factors. Fundamentally the basic principles of mineral valuation are similar for base metals, sulphur, oil, or any other mineral. Each mineral, however, requires an engineer to have a knowledge of such factors as its occurrence, distribution, mining and processing methods, and marketing problems in order to gather and analyze all the facts and data that have a bearing on the earning potential of the property. PRESENTVALUEOFAMINERALPROPERTY In essence the present value of a mineral property is a sum of money in today's dollars that future earnings from the property are worth. It differs

Jan 1, 1959

Oct. 8 to 13, inclusive, 1917 COMMITTEES Committee on Arrangements H. A. BUEHLER, Chairman W. E. MCCOURT, Secretary C. J. ADAM L. L. HUTCHISON VICTOR RAKOWSKY J. A. CASELTON EUGENE MCAULIFFE J. D. ROBERTSON .F. W. DEWOLF P. N. MOORE ARTHUR THACHER E. F. GOLTRA MRS. P. N. MOORE H. A. WHEELER Committee on Ladies', Entertainment MRS. PHILIP N. MOORE, Chairman MRS.. W. E. MCCOURT, Vice-Chairman MRS. D. M. ARMISTEAD MRS. R. G. HALL MRS. A. A. BONSACK . MRS. J. W. HEGELER MRS. B. F. BUSH MRS. J. N. HOUSER MRS. G. 0. CARPENTER MRS. EUGENE MCAULIFFE MRS. F. V. DESLOGE MRS. RUDOLPH PORTER MRS. F. W. DEWOLF MRS. N. P. ROOD MRS. A. W. DICKINSON MRS. ARTHUR THACHER

Jan 12, 1917

By H. I. Aaronson

The nucleation of pearlite at proeutectoid ferrite is inhibited, to an increasing extent, at the following locations: At twin boundary-nucleated ferrite, between closely spaced ferrite sideplates, and at intragranular plates. These effects are discussed in terms of the influence of transformation strain energies and of the interfacial free energy of austen-ite:ferrite boundaries on the rate of pearlite nucleation. The growth of pearlite into the interiors of austenite grains from the region of the grain boundaries is markedly restricted when low reaction temperatures and large austenite grain sizes permit the development of interlocking networks of intragranular ferrite plates. PREVIOUS investigators have made extensive studies of the interactions which occur between the proeutectoid ferrite and the pearlite reactions from the viewpoint of the mechanisms through which pearlite interferes with the nucleation and growth of proeutectoid ferrite.1-3 In the present investigation, the processes through which proeutectoid ferrite (hereafter termed simply "ferrite") can reduce the rate of formation of pearlite have been explored in some detail. A steel with a relatively low carbon content, in which the ferrite reaction can compete successfully with the pearlite reaction over a wide range of reaction temperature, and exceptionally coarse-grained specimens, which further emphasize the role of the ferrite reaction, have been employed for most of this work. A brief examination also has been made, however, of the effects of smaller austenite grain sizes upon these processes. Experimental Procedure The steel employed had the following composition: 0.29 pet C, 0.76 pet Mn, 0.25 pet si, 0,007 pet S, and 0.005 pct P. This alloy was homogenized for 48 hr at 1250°C. The investigation was performed

Jan 1, 1959

By E. O. Chartkoff

IN 1926 one of the authors published researches on the determination and description of the iron-tungsten and iron-molybdenum systems,1 including the equilibrium diagrams. In 1929, further work was carried on, including the examination by X-rays, which is recorded here. Measurements were made of changes in lattice parameters in the solid solutions. Precipitation from the solid solution and the accompanying changes in hardness were studied as well as the formation of the intermetallic compound phases upon sintering a mixture of metal powders.

Jan 1, 1930