Search Documents

By J. Szekely, J. W. Evans

A formulation is given for radiant heat loss from the surface of molten steel held in a ladle and numerical solutions are presented for the resultant integrodif-ferential equations. The results are shown on plots of the net rate of heat loss against time, with the geometlry, emissivities, thermal properties of the walls, and Preheat as parameters. It was found that the rate of the vadiant heat loss from the exposed metal surface was comparable to the conductive losses from the Portion of the metal in direct contact with the walls. The radiant heat loss was markedly affected by the geometry and by the thermal properties of the walls the net radiant heat loss from the steel could be drastically reduced by providing a top cover and also by the provision of preheat. The results of this work are thought to be relevant to heat loss calculatious concerned with vacuum degassing and with operatzons in which molten metals are held in ladles. WhEN molten steel is held or transferred in ladles heat losses inevitably occur. The accurate assessment of these heat losses is of importance in process design considerations, as the temperature of the metal may have to meet rigid specifications in certain stages of the processing sequence. As shown in Fig. 1, the principal mechanisms responsible for heat loss are: i) Conduction into the walls and ii) Thermal radation from the top metal surface (possibly augmented by natural convection) The conductive heat loss may be readily calculated as much information is available in the literature on both the general theory1'' and on its particular applications to ladle heat loss calculations. Evaluation of the radiant component of the heat loss is less straight-forward. In two recent papers it has been shown that the presence of a slag layer 2 to 3 in. thick would prevent any significant heat loss for periods up to an hour,5'" however, should bare metal be exposed, constituting the radiant surface, substantial heat losses could occur. This latter case is of considerable practical interest in various degassing operations and in the vacuum processing of certain specialty steels, where the top surface of the metal is not covered by a protective slag layer. Under these conditions a substantial radiant flux is emitted by the top metal surface; part of this flux leaves the system, part of it falls in the ladle walls. The radiant flux incident on the ladle walls is in part absorbed and conducted away, and in part reflected and re radiated. The purpose of the paper is to present a general formulation of the problem, the resultant solution of which should enable computation of the net radiant heat loss from the metal surface. The principal variables, the effect of which will be investigated, include initial metal temperature, geometry, thermal and radiative properties of the wall, and various modes of preheat. FORMULATION Consider a cylindrical enclosure, shown in Fig. 2, with a diameter D, height H, and wall thickness W, the cover at the top of the cylinder having a wall thickness L. If the temperature of the base (representing the top surface of the metal) is kept constant, say, Tb, the problem is to calculate the net rate of heat loss from the base as a function of time, geometry, the initial temperature distribution, and the thermal properties of the system. As customary, the formulation will consist of the mathematical statement of the conservation of thermal energy within the system.

Jan 1, 1970

Jan 1, 1882

By Cyril Stanley Smith

Although alloys of copper and silicon were examined several years ago,' and their excellent mechanical properties were shown, it was not until C. B. Jacobs 2 introduced manganese in small quantities to the alloys that they became of commercial importance. A few years ago The American Brass Company took over the patents and commenced to manufacture the alloy under the name "Everdur." The present study of the constitution of the ternary system was undertaken in order to reach a fuller understanding of the behavior of the alloy. Review of Previous WORK on the BinaRy Systems There have been no papers published dealing with the constitution of the ternary system, although some tests of the mechanical properties have been described," which indicate that there is a change in solubility with temperature. Copper-silicon System The copper-silicon system has been studied in detail by the author and is described in two papers published in 1928.V he portion of the diagram up to 8 per cent. silicon, as determined by this research, is reproduced in Fig. 1. The author's previous papers include a complete review of the work of other investigators and it is not necessary to deal further with this system here. Copper-manganese System The copper-manganese system has been investigated by several workers, notably Lewis,5 Wologdine,6 Sahmen7 and Schemtschuschny,

Jan 1, 1930

By David R. Mitchell

IF you are the owner of a mine, or a mine executive, or just an ordinary miner, and have a son about to go to college, do you urge him to take up mining engineering or do you try to dissuade him from such a course? If you live in the East, or the Middle West and your interest has been in coal rather than metal mining, the chances are that your young hopeful will be urged to do almost anything else rather than follow in father's footsteps.

Jan 1, 1939

By George C. Stone

WHEN George C. Stone, a Director of the Institute, and so well known to our Members in connection with the Institute's many activities was abroad in 1.919, he secured an interesting collection of these coins, which appeared in Zinc, a publication by the New Jersey Zinc Co. Regarding this collection of coin, Mr. Stone says: "During the war, all gold and most of the silver disappeared, making small change very scarce. As the French Government was fully occupied by the war, it allowed various Chambers of Commerce and other bodies to issue money, both paper and coins. Many of the latter were made of zinc, and I secured several while in Paris. We had all heard of the Belgian and German zinc coins, but I imagine few knew how many different kinds there were. The accompanying plates show both sides of those I got. I took all that the dealer had; but he said that there were a number of others in existence. The coins in the bottom line were issued by the Germans in Belgium during the war and all are still in common use. The first two in the next to the bottom line are German. All of the others were issued by Chambers of Commerce or corporations. A few have been nickel plated; these look and wear much better than the others. "Coins" made of pasteboard were also issued by similar bodies, also notes.

Jan 1, 1920

By Elliot Rexford

The quality of aggregate materials is of major importance in governing durability and permanence of concrete structures. The problem of selecting suitable aggregate materials is two-fold. Geological factors include the type and character of the aggregate source, presence of known or suspected reactive constituents, and presence of thermally incompatible materials. Laboratory investigations include petrographic studies, soundness and reactivity tests, and tests of thermal properties. The importance of each factor in the selection of satisfactory aggregate material is considered in detail.

Jan 3, 1950

By Eugene Guccione

For at least a decade, the energy crisis was accurately predicted by a small number of industry people who were ignored until last year, when they suddenly found themselves accused for their "lack of planning" and "greed." With the worsening shortage of natural gas and oil, the current scramble is for alternate energy sources-which means: a big rush into coal and uranium mining. (Some big plans are also on the drawing boards regarding geothermal steam, oil shale, tar sands, and even solar energy. But developing such new industries from scratch would be difficult enough even in a healthy economic climate-which is not exactly what the country currently enjoys.)

Jan 8, 1974

By Robert M. Dreyer

Population growth in industrialized economies constitutes an automatic stimulus for expansion of the construction and chemical processing industries, which are a big market for industrial minerals. Of the total value of mineral production in the United States, excluding fuels, about 70 % results from the production of industrial minerals. The value of industrial mineral production rose more than 10 % between 1961 and 1962. A similar growth has occurred during 1963. During the decade 1952-1962, the production of industrial minerals increased in value by 98%, in contrast to an increase of 60% in the value of the gross national product. The accompanying table shows the percentage change in the production of various industrial minerals from 1952-1962, as well as from 1961-1962.

Jan 2, 1964

By Ashok K. Sinha

During the course of an in~*estigation into the occurrence of ordered AB3 structures, the following new phases have been found —CrRh3 (AuCu3 type), CrCo3 (MgCd3 type), HfCo4 (Ths Mn23 type), and WPt, MoPh type). The composition of the TiPt3-x phase (TiNi, type) is close to Ti23Pl77. The alloy chenzistry of transition rnetal AB3 structures is rezliewed in the light of electron concentration correlations of hex-agonality recently obtained for quasi-binary alloys. The relatizte colurne contraction in the AB3 structures increases with increasing difference in volume of the conzponents. A family of ordered close-packed layered structures is formed by stacking identical layers of composition AB, in various sequences, such that the coordination is twelvefold throughout and there are no A-A contacts. Previous work' on quasi-binary AB3 alloys has led to the conclusion that the stacking sequence of the AB, structures changes with increasing radius ratio RA/RB from a purely cubic, through different mixtures of hexagonal and cubic stacking to a purely hexagonal stacking. However. for binary AB3 alloys, a correlation between the type of the crystal structure and the position of the components in the various volumns of the periodic table has been noted.2-5 It has been noted6 that this correlation appears to hold even though the radius ratio RA/RB may vary over a considerable range with the location of the components in the three long periods. Another study7" of several quasi-binary systems led to the conclusion that an increase in hexagonality of the stacking is associated with increase in the electron concentration e/a. as defined by the average per atom of the total number of electrons outside the inert gas shells. In apparent conflict with this conclusion, it is known that seven binary alloy structures isotypic with TiNi3 which is 50 pct hexagonal occur at a higher electron concentration (e/n = 8.5) than that (e/a = 8.25) for the 100 pct hexagonal MgCd3 type structure present in seven binary AB3 alloys. Table 111. In the present work, an investigation into the occurrence of binary AB3 structures in transition metal alloys was made, and a survey of binary AB3 structures is presented. EXPERIMENTAL The starting materials were pure metals of 99.9 wt pct purity. The alloys were arc-melted under partial pressure of argon and annealed in sealed silica capsules lined with molybdenum foil under argon at- mosphere. The total weight loss upon melting and subsequent annealing was always less than 1 pct and hence the alloys will be referred to by their intended (unanalyzed) compositions. Wherever the constitution permitted. the alloys were given a homogenizing treatment at 1200°C (3 days) prior to annealing. Unless otherwise stated all alloys were annealed at 900°C for 1 week and water-quenched. Sometimes the final annealing treatment was carried out on powders to accelerate the attainment of equilibrium. X-ray powder patterns were taken using a Guinier-de Wolff focusing camera (CuK, radiation) or an asymmetrical focusing camera (Co or CrK, radiation). For lattice parameter determination. internal silicon standards were employed. The intensity calculations were made using a Fortran IV program written by Jeitschko and parthe.9 RESULTS Twenty AB3 and three AB4 alloys were investigated. Table I lists the crystallographic data on some of the intermediate phases encountered in the present work. Table II contains the X-ray data for HfCo, (Th,,Mn,, type). The positional parameter, x. was assumed to be 0.378. the value for Th6Mnn2310 The X-ray pattern of ZrCo, was very similar to that of HfCo, and the previous structure determination of ZrCo, by Kuzma el al." was confirmed. Ordering in the alloy CrCo could be ascertained by the presence of only one weak super lattice line (101). the others being too weak presumably owing to the small difference in the scattering powers of chromium and cobalt. This line was observed in the X-ray pattern of powder from the massive sample annealed at 830°C (7 days) after the powder had been reannealed at 600°C (24 hr). The diffraction pattern of the powder similarly reannealed at 830°C (24 hr) contained only the lines due to a mixture of hcp and fcc Co(Crj solid solutions. Therefore, it appears reasonable to assume that O2 and/or N2 contamination which would be less likely to occur during the 600°C anneal was not responsible for the observed weak reflection. Also. this reflection cannot be identified with any of the strong lines of the neighboring s phase which is present in the Co-Cr system at higher chromium contents. The composition corresponding to the TiNi3 structure observed by Raman et al.12 in the two-phase alloy Ti,zt,, has been established in the present work as being between There was satisfactory agreement for the low-angle lines (up to d = 1.997A) between the observed diffraction pattern of TiCua and that calculated assuming the ZrAu, structure. as recently proposed by Pfeifer-et a1.I3 However. some of the superlattice lines. e.g., at d = 1.937 and 1.919A. predicted by the ZrAu, structure were not actually observed eve? though neighboring lines. at d = 1.947 and 1.986A. of comparable calculated intensity were present. The ZrAu

Jan 1, 1970

By Robert Maes, Robert de Strycker

The Fe-Ni-As phase diagram has been established by the study of about a hundred alloys, by microscopic observation, and by thermal analysis, with arsenic contents up to 50 pct. The iron and nickel arsenides present extensive solid-solution fields, owing to the substitution of nickel by iron and vice versa; the extent of the solubility field of each compound has been determined with an accuracy of ±1 pct. In the investigated range of compositions, the solidification reactions were established, and the temperatures of the invariant reaclions detevmined with a preciston of iZ°C in the most favorable and ±5°C in the least favorable cases. The isothermal lines of the liquidus surface have also been drazum, with an accuracy estimated at i5°C. Reactions in the solid state, which take place for the formation or the decomposition of certain phases , were investigated in detail. ThE constitution diagram of the Fe-Ni-As system is fundamental for the understanding of the properties of nickel speiss; these by-products of the extraction of certain nonferrous metals indeed often contain the three elements iron, nickel, and arsenic as main constituents. The Fe-Ni-As system has already been the object of earlier investigations. In 1932, Guertler and Savels-berg' have presented some elements of the ternary phase diagram, for arsenic contents up to 55 pct (all percentages in this paper are given in weight percent), including the vertical section FezAs-Ni&s2. This investigation is, however, incomplete and certain anomalies suggested the necessity to verify the results published by these authors: the section Fe2As-Ni5AsZ, for example, is presented as quasi-binary, with a field of complete miscibility in the solid state, even though these compounds do not have the same structure. Recently, ~useck' established an isothermal section at 800°C in the Fe-Ni-As system by X-ray diffraction and microscopic examination of water-quenched alloys. These techniques are sometimes inaccurate for the determination of the fields where alloys are liquid at the investigated temperature, and they may lead to erroneous conclusions when a compound exists at the investigated temperature but is not stable at room temperature and cannot be maintained by quenching. LIMITING BINARY PHASE DIAGRAMS The Fe-As constitution diagram has been the object of several investigations which have been reviewed by Hansen and Anderko.3 For the Ni-As phase diagram, a recent study has been effected by Yund.4 In this system, Heyding and calvert5 have determined the existence of a compound of unidentified structure at arsenic contents slightly higher than those corresponding to Ni5As2 and at temperatures lower than about 200°C; by analogy with iron and cobalt arsenides, this compound could correspond to the formula Ni2As, as suggested by Kulle-rud; although this is not definitely established. In the region of arsenic contents from 35 to 55 pct, Fried-rich7 detected anomalies in the solidification reactions; an interpretation of these anomalies was given by Hansen ,8 which assumed that the solidification reactions in practice are not in equilibrium, but are meta-stable. The main features of the Fe-Ni constitution diagram are the existence of a complete miscibility field, at least at high temperatures, for the fcc phase (which will be designated by My in the remainder of this work) and of a limited solubility field for the bcc phase (designated by Ma). EXPERIMENTAL METHODS The fundamental technique used in this investigation was microscopic observation, which allowed the determination of the reactions occurring during solidification of the alloys, and possible reactions in the solid state.

Jan 1, 1968

By B. T. Wykoff

This paper describes an important function of mining in Southeast Missouri. The practice is a necessary procedure to prevent disintegration of the pillars. Although the technique is peculiar to this district, it might have application in other mines using room and pillar method.

Jan 8, 1950

By N. J. Grant, D. S. Bloom

THE development of high temperature, high stress alloys had proceeded with such rapidity during the war, and for a short time afterward, that our knowledge of the constitution of the alloys had become seriously inadequate. To interpret correctly alloy behavior it is not only necessary to recognize the phases present, but also to know the properties of the phases under all varieties of conditions and treatments. Chromium in these high temperature alloys holds the unique distinction of being the only one element which must be present when an oxidizing or generally corrosive atmosphere is present and when a long life is desired in service. Carbon and nitrogen must also be considered where chromium is present. Carbon is always present, either as an impurity in the raw alloying elements, or as a deliberate addition agent to increase the strength. Nitrogen is generally picked up from the atmosphere during melting or may be added as an alloying element. The effect of nitrogen additions is not too dissimilar to that of carbon additions. As such, chromium carbides and nitrides become of great interest since they are present in a very large number of alloys, including alloy steels, stainless steels, super alloys, and the like. In the chromium-carbon system there are three accepted, carbides: Cr,C, Cr7C8, and Cr3C2. The existence of one more carbide, a still higher carbon form CrC, has been advanced. The phase diagrams of chromium and carbon as published by Friemann and Sauerwald² and by Tofaute, Kuttner and But- tinghaus³ -do not extend beyond the carbide Cr3C2, which contains 13.3 pct carbon; but Hatsuta has extended the diagram up to 20 pct carbon, and in doing so hypothesized, with the use of some questionable experimental results, the compound CrC. This carbide would contain 18.75 pct carbon, 81.25 pct chromium, by weight. It is further known that as the chromium carbides increase in carbon the acid resistance increases but the oxidation resistance decreases4,5 This is of great importance in high temperature alloys where time-temperature stability, as well as oxidation resistance, is of prime importance. The possible existence of a carbide of the formula CrC thus becomes of prime importance and it was considered important to recheck the chromium-carbon binary constitutional diagram for such a compound. In view of the wide spread of values listed for the melting point of chromium (1500° to 1850°C) and 1930°C8, it was considered .that the liquidus temperatures might well be redetermined more ac-

Jan 1, 1951

By John T. Eastlick

The Banner mining district is about 70 miles northeast of Tucson in the southern part of Gila County, Arizona. Production from the district, valued at about $26 million, is chiefly from copper-silver-lead zinc ores. The stratigraphic section consists of Precambrian conglomerates, quartzites, dolomites, and limestones, Cambrian quartzites; Devonian limestones; dolomites, and shales; Mississippian limestones; Pennsylvanian limestones and shales; and Cretaceous volcanic and sedimentary rocks. Deformation of these rocks presumably started near the end of the Cretaceous, and extended into the late Tertiary. The sedimentary rocks were folded, faulted, and intruded by fine grained diorite, quartz mica diorite, and dacite porphyry. At least four distinct stages of mineralization are recognized. In the first stage of contact metamorphism and the second stage of hydrothermal alteration, favorable zones were prepared for ore deposition. Metallization occurred in three of the mineralizing stages. Magnetite, pyrite, and hematite were deposited near the end of the second stage of hydrothermal alteration. The third stage included the main deposition of sphalerite, chalcopyrite, bornite, and galena. In the fourth and final stage, minor amounts of sulfide minerals were deposited with a late anhydrite and quartz gangue. The ore deposits in the form of veins and veinlets, pipes, irregular massive replacements, and bedded replacements are localized by the extent and distribution of metamorphic and hydrothermal alteration, by the proximity to the intrusive contacts, and by the effects of structural development. Oxidized ores of copper, lead, and zinc constituted the principal production of the district prior to 1940, but, for the most part, supergene enrichment was of minor economic importance. The ore bodies of the district are in the mesothermal class of deposits, occurring as normal metasomatic replacement and vein types.

Jan 1, 1968

By Edward C. Mack, Ronald G. Stovash

INTRODUCTION Ronald G. Stovash General Superintendent Consolidation Coal Company Shoemaker Mine Moundsville, West Virginia Consolidation Coal Company's Shoemaker Mine is located in West Virginia's Northern panhandle near Wheeling, adjacent to the Ohio River. Steam coal is mined from the Pittsburgh #8 seam which averages 65 in. in thickness. The 10 in. of draw rock directly above the coal is taken on advancement, but remains when longwalled. The top consists of up to 12 in. of lower quality coal, and immediately over that, up to 10 ft of multi layered shales, coal, and bone. The cover ranges from 300 to 800 ft of shales and limestone. Two longwalls operate in the mine. The first longwall started in April 1975 and is retreating its eighth panel. This wall was the first to use shield supports in the United States. The second longwall started in September 1979 and is currently retreating its first 7,000 ft panel.

Jan 1, 1981

By R. F. Mehl, C. S. Barrett, A. H. Geisler

THE mechanism by which the super-saturated solid solution of 20 per cent silver in aluminum decomposes has been reported in two previous publications. 1,2 The analysis of streaks in Laue photograms showed that thin platelike particles (the so-called Guinier-Preston aggregates) form upon {111} matrix planes in the early state of decomposition.1 The size of these particles is larger, the higher the temperature at which they form in accordance with nucleation theory;3 at all temperatures they increase in size with aging.2 When they have grown thick enough to afford three-dimensional diffraction, powder X-ray photograms show that the structure is not that of the equilibrium precipitate y but that of a transition lattice ?'. Since this is also platelike in shape and also lies upon the {111} matrix planes with the {110} direction in the matrix parallel to the {11.0} direction in ?', it seems likely that the original platelet particles are merely ?' in an early stage of formation, and thus finely dispersed. The atomic spacing and pattern on the {00.0} plane in ?' are identical with those on the {111} matrix plane to which it lies parallel, and since comparable directions in the two planes are parallel, the lattices are thus coherent at the interface; an analogous coherence has been found in aluminum-copper alloys.3 The structures ?' and y are both close-packed hexagonal and are oriented alike; they differ only in interatomic distances. Consequently, ? ' is regarded as y strained from its ordinary dimensions by the lattice coherency between it and the matrix.2 The lattice movements that transform the matrix to the equilibrium precipitate appear to be very simple.2 The mechanism of precipitation in this system is simpler and is more precisely known than that in any other system,2,4 hence the system should be a profitable one for the difficult task of correlating property changes with structural alterations. The present report provides additional studies on powder X-ray diffraction from alloys of 10 per cent, 20 per cent and 30 per cent Ag, and presents the correlation of crystallographic changes with changes in microstructure, Brinell hardness and electrical resistivity of the three alloys. PREPARATION OF SAMPLES AND EXPERIMENTAL PROCEDURE The preparation of the 20.2 per cent Ag alloy has been described.2 Alloys containing 9.9 and 29.7 per cent Ag were prepared from 99.97 per cent Al and 99.99+ per cent Ag using a similar procedure. Rolled

Jan 1, 1943

By T. M. Williams

DURING the year just ended we have had three great fires in the mines in the Wilkes-Barre district. One at the Empire Colliery, one at the Prospect shaft, and the other at the Baltimore old mine. It is proposed in this paper to give a brief history of the fire at the Empire Colliery, and the methods employed in extinguishing it. The fire was first discovered breaking out in the air-stack, alongside what is known as the " Kidder Plane," about one o'clock on the morning of December 31st, 1873. Subsequently it was ascertained that the fire originated in the return airway somewhere near the steam boiler, located inside the mine, near the head of No. 5 slope. The coal from this slope was hoisted to the shaft gangway, at a point nearly four thousand feet distant from the foot of the shaft. As there were from four to five hundred mine cars hoisted per day from this slope the steam boilers were located at this place. The mines being of considerable extent required a large volume of pure air for ventilation, and no fan having been erected at this slope at the time, the heat from the boiler was made use of to assist ventilation, by conveying the return air from No. 5 slope into the large airway made from these boilers to the surface through the old "Kidder slope" to the stack where the fire was first discovered. The length of this slope or airway was about one thousand feet, with a sectional area of about sixty feet. The quantity of air passing through it must have been over sixty thousand cubic feet per minute

Jan 1, 1875

By H. Rosenthal, A. L. Jamieson

THE action of mercury on stressed brass to produce cracks was known before Moore, Beckinsale and Mallinson1 showed that actual season cracking did not occur spontaneously but could be induced by ammonia. These investigators studied other substances, including diphenylamine, without finding that anything other than ammonia could cause season cracking. Grimston2 reported season cracking in cartridge cases stored in wooden boxes wetted with dilute sulphuric acid pickling solution. Season cracking associated with sulphur dioxide, water vapor and air has been reported by Johnston,3 although he reported that trimethylamine and pyridine did not cause cracking. Jevons4 has ascribed season cracking of brass in certain instances to trimethylamine, "aldehyde amine," "ketone amine" and pyridine, but no experimental work was done evidently to prove this definitely. Pyridine was investigated by Morris,' who found it to have considerable cracking power. In the present investigation, the object was a qualitative evaluation of a number of representative amines with respect to their ability to cause season cracking. Thus it was desired only that an appreciable vapor pressure of each amine be obtained in order to make the test as severe as possible, without attempting to test equivalent concentrations for comparative purposes. METHODS Specimens Two types of specimen were used: I. Unannealed 70-30 brass cups formed from 0.040-in. thick sheet. Height of cup was 1 3/8 in. and diameter was 1 7/8 inches. 2. First draw pieces of caliber .50 cartridge cases in the unannealed condition (70-30 brass). The cups were representative of a thin wall and thin base specimen, whereas the draw pieces have a thick base (1/4 in.) and a thick wall (approximately 3/32 in.). Both types of specimens contained high residual stress and cracked in less than one minute in a solution of I per cent mercurous nitrate and I per cent nitric acid provided that this was preceded by a 30-sec. pickle in 40 per cent nitric acid. Specimens were prepared as follows: (I) degreased in trichlorethylene, (2) rinsed in H20, (3) pickled 5 min. in 10 per cent by volume H2SO4 (1.84 sp. gr.), (4) rinsed in H2O, and (5) dried. Amines Tested In selecting the amines, representatives of the three series of amines and one series of substituted amines were chosen. The aliphatic series was represented by the methyl and ethyl primary, secondary and tertiary amines. These are the simplest aliphatic amines. For the aromatic series, the phenyl primary, secondary and tertiary amines were selected as being the simplest. The heterocyclic series was represented by pyridine, which is a simple heterocyclic base (tertiary amine).

Jan 1, 1944

By C. W. Phillips, D. N. Frey

A commercial Ti-Fe-Cr alloy, Ti-150, exhibits a martensitic transformation on cooling and two nucleation and growth reactions, one above and one below the Mg-Mf region, on isothermal holding below the single-phase ß temperature range. The reactions were followed by metallographic, X-ray diffraction, and microhardness methods. THE rapidly expanding engineering application of titanium and its alloys makes increasingly urgent an adequate knowledge of the effect of heat treatment on this material. The work herein reported is an attempt to determine certain aspects of the behavior of a commercially available alloy, Ti-150, during heat treatment. The alloy, with a nominal composition of 2.7 pct Cr, 1.3 pct Fe, 0.25 pct 0, 0.02 pct N, and 0.02 pct C, was received in the as-rolled condition as a 3/4 in. round. Slugs 0.11 to 0.12 in. thick were cut under a coolant using a silicon carbide wheel. Preliminary work established that the alloy consists of two phases, a (hexagonal close-packed) and /3 (body-centered cubic), at temperatures below 1750" to 1775"F, and of only /3 phase at higher temperatures. The slugs were heated for 1 hr in air at 1800°F to form a single-phase /3 matrix, then transferred to molten tin (1250° to 1650°F) or lead (1150°F and below) for isothermal holding. Holding temperatures ranged from 700° to 1650°F, times from 0.001 to 23 hr. The treated slugs were then sectioned, one part for metallographic examination and diamond pyramid hardness, the other, after deep etching to remove the high oxygen surface,' for comparative lattice parameter determination and X-ray phase identification. Hardness measurements were taken on the lightly etched surfaces of the metallographic specimens; a 1000 g load on a 136° diamond pyramid was used. Five impressions on each sample were made and the average of the hardness calculated. The use of microhardness measurements to follow the course of an isothermal transformation reaction is undesirable because of the possibility of wide differences in microconstituent hardness.' They were used in this case, however, because of the small amount of material available. At the higher transformation temperatures, where the above-mentioned objection was apparent, the readings were proportioned to correspond to the estimated ratio of transformed and untransformed constituents present. At lower temperatures, resulting in much finer microconstituents, the microhardness measurements were more uniform. The standard deviation of the mean of five impressions calculated from these latter values was 4.2 DPH. Employing 2a limits (probability 0.95) the experimental error of the hardness measurements averages was 8.4 DPH. The etchant used was composed of one part glyc-erol and one part 48 pct hydrofluoric acid." Of a number of etches tried, this one appeared most satisfactory. All micrographs were taken at 500X magnification and with oblique lighting to permit easier identification of the acicular structure resulting from rapid cooling. No advantage was gained by using polarized light for metallographic examination. Phase identification and lattice parameter measurements were made with a North American Philips high angle spectrometer in conjunction with a recording potentiometer. Considerable difficulty was encountered with some of the lattice parameter measurements because of the extreme broadness of the few diffraction lines obtained from samples consisting mainly of strained, untempered, quenched structures.

Jan 1, 1953

By B. Wilhelmi, W. H. Somerton

Simultaneous measurement of pore and elastic properties of socks under a wide range of triaxial stress conditions may be made with equipment and methods developed in this paper. Tests were run on three outcrop sandstones at several confining pressures and axial stresses up to approximately 80 percent of failure stress. The greater reduction in porosities and permeabilities occurred in the hydrostatic loading portion of the stress cycle, but substantial reductions in both properties did occur upon application of deviator (triaxial) stress. Triaxial elastic moduli were calculated from strain gauge measurements. Both Young's moduli and shear moduli were found to increase with increasing confining pressure. Poisson's ratios increased with axial stress but showed no consistent change with confining pressure. Only very general relations were observed between pore and elastic properties. The lesser decrease in porosity and permeability at higher stress values is related to increase in rigidity of rocks at higher stresses. INTRODUCTION Many investigators have studied the effects of hydrostatic stress on the properties and behavior of rocks. A few have studied the effects of triaxial stress fields on individual physical properties of rocks. To our knowledge no one has measured simultaneously pore and elastic properties of rocks under a wide range of triaxial stress conditions. This is the purpose of this work. Rocks exist in the subsurface under what Jaegerl refers to as "polyaxial" stress conditions (all principal stresses unequal). When two of the three principal stresses are equal, this is referred to as triaxial loading. The triaxial method of loading is most commonly used in modern testing work because experimental difficulties in measuring physical properties of rocks are greatly reduced over polyaxial testing. Although triaxial loading may not reproduce subsurface conditions precisely, subsurface stress conditions are never known precisely anyway. Triaxial testing would seem to be more realistic than testing under hydrostatic loading (all principal stresses equal) for application of results to subsurface problems. The objectives of this work were threefold: (1) to develop methods of measuring simultaneously pore and elastic properties of rocks under triaxial stress conditions, (2) to determine whether changes in these properties are of sufficient magnitude to be considered in subsurface calculations and (3) to attempt to relate changes in pore properties and elastic properties since they will have been measured at the same time under identical loading conditions. REVIEW OF EARLIER WORK PORE PROPERTIES Several investigators have studied the effects of stress on the physical properties of rocks. Fatt and Davis2 showed the reduction of permeability of rock with hydrostatic loading. McLatchie et al.3 and Knutson and Bohor4 related permeability reduction to compessibility of reservoir rock, again under hydrostatic loading. Wble,5 and later Redmond,6 evaluated the effects of applied radial pressure on conductivity, porosity and permeability of sandstones. In this latter work, no axial stress was applied. Dobrynin7 reviewed much of the previous work done . on the effects of overburden pressure on physical properties of rocks. He concluded that changes in physical properties are controlled to a large extent by pore compressibility of the rock. Several sets of curves developed from empirical relations are presented. These curves permit estimation of change of properties with net overburden pressure, knowing the pore compressibility and porosity of the rock. Net overburden pressure is defined as (Pe - 0.85 Pi ) where Pe is the

By C. N. J. Wagner, E. N. Aqua

Dilute Fe-Si alloys (0 to 5 wt pet Si) were cold-worked by making filings at room temperatuve. The analysis of the broadening of the X-vay powdev pattern peaks yields anisotropic particle sizes normal to the (110), (100), and (112) planes which are a consequence of deformation faults (probability a) and twin faults (probability p). The combined fault probability (1.5a +ß) increases from 0.01 in pure iron to 0.02 in Fe-5 pct Si. The root mean square stvains vary with crystallographic ovientation due to elastic anisotropy of the alloys, and increase from about 0.0035 in pure iron to 0.005 in Fe-5 pct Si measured in the [100] direction. Assuming that deformation and twin faults occur with equal probability, the X-ray data would imply that the stacking-fault energy does not change upon alloying. THE crystallographic aspects of the plastic deformation of dilute Fe-Si alloys has been studied many times since the observation of glide band structures by Barrett et a1.l These glide bands were much straighter than the wavy bands observed by Gough2 in unalloyed iron nearly 40 years ago. This difference in the morphology of the slip band structure has been verified many times, most recently by replication electron microscopy3 and dislocation etch-pitting methods.4,5 These observed differences in deformation behavior have been considered to result from the degree of cross slip that occurs in pure iron and in the Si-Fe alloys. The lowered tendency for cross slip would result from a lowering of the stacking-fault energy of iron by the silicon alloying addition. Experimental evidence for this lowered stacking-fault energy in the Si-Fe alloys, obtained with transmission electron microscopy, is the observation of dissociated dislocations in Fe-6 pct si6 and Fe-3 pct Si alloys,7 and the observation of sharply defined cellular substructures in Fe-3 pct si6,7 compared to the more diffuse substructure in zone-refined iron.' The activation energy for recovery of cold work is greater in the Si-Fe alloys than it is in pure iron, indicating that cross slip has become a more difficult process.9 The purpose of this investigation is to determine the change in stacking-fault probability from the broadening of powder pattern peaks in dilute silicon-in-iron solid solutions, when cold-worked at room temperature. The knowledge of the stacking-fault probability and the dislocation density, both of which can be deduced from line-broadening analysis of two orders of reflections from (110), (200), and (112) planes, will permit us to calculate the change in stacking-fault energy upon alloying silicon into iron. Previous X-ray investigation of cold-rolled Fe-5 wt pct Si (100)[001 ] single crystals did not reveal any line broadening, whereas cold-rolled Fe-3.1 wt pct Si (001) [110] and (001)[100] single crystals10 showed line bro2dening as a consequence of small particle sizes (-200A) and root mean square strains (-0.25 pct), which are comparable to those found in cold-worked iron filings.11 EXPERIMENTAL PROCEDURE A series of five Fe-Si alloys containing nominally 1 to 5 wt pct Si and pure iron were cold-worked by making filings at room temperature. The actual silicon content deviated at the most by +0.1 pct which is of no significance in the present study. The carbon contents of these materials were less than 0.02 pct. The X-ray diffraction patterns were measured with molybdenum, cobalt, and iron radiation using a GE and a Philips diffractometer. The (110)-(220), (200)-(400), and (112)-(224) pairs of reflections were

Jan 1, 1968