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By W. Rall, A. J. Birkle

The effect of fast-neutron irradiation on the micvo strcture of a common reactor pressure-vessel steel, A212 Grade B, was studied using thin-foil transmission electron microscopy. The dislocation density of the irradiated material is considerably greater than that of the nonirradiated control material. Annealing studies indicated that dislocations and hardness ill the irradiated material annealed out—as docs the radiation-induced embrittlement according to other- investigators— at temperatures STEELS in nuclear reactors are affected by neutron irradiation. In the American Society for Testing Materials (ASTM) A302B and A212B steels commonly specified by designers for reactor vessels, between 650° and 800°F. However, the dislocations and hardness in control samples cold-worked to 9 and 70 pct did not anneal out readily, and a high dis -location density was observed, even after a 1-hr anneal at 850°F. Based on the hypothesis that cllrster defects, rather than the increased dislocation density, are primarily responsible for mdicltiotz-iudziced e)nbriftlen7ent, reconzmendations are made for reducing the susceptibility to such ernbrittlement. exposures at a temperature of 550°F or lower to neutron dosages encountered during a 20- to 30-year life (-3 X 10'' nvt, >1 mev) may increase the nil-ductility transition temperature (NDT) as much as 300" or 400".'9 Therefore, to prevent brittle failures in reactor structures, extreme caution is required to reduce thermally induced stresses during all reactor shutdowns and startups when the temperature is below the NDT of the pressure vessel.

Jan 1, 1964

By S. Y. Ogawa

The effects of sulfur (up to 0.1 pet) on the deformation and fracture characteristics of iron, in cast form, were studied at strain rates up to 100 pct pcr sec and at temperatures of 1600o to -3300 oF. The effects of oxygen and manganese additions on the behavior of Fe-S alloys were studied under comparable test conditions. Brittle fracture characteristics, evident at all strain rates, resulted from the presence of the liquid iron sulfide phase at grain boundaries. Ductility could be restored in three ways: solution of the sulfide in solid y iron at higher temperatures, spheroid-zzation of the liquid sulfide, and increase. in the melting point ot the sulfide. THE literature shows that most previous studies of deformation and fracture at hot working temperatures have been based on measurements of energy absorption, reduction of height in forging upset tests, torsion tests of bar or wire samples, and so forth,' but that relatively few tension tests have been used at high temperatures and strain rates. The present work was initiated to study the ef- fects of temperature, strain rate, composition, and structure on the deformation and fracture characteristics of iron, utilizing cast specimens tested in tension. As in a previous study,' strain rates up to 100 pct per sec were chosen for the temperature range 1600° to 2400° to provide data which might be useful in the interpretation of the deformation and fracture behavior of steels under hot working conditions. The previous work was with Fe-P solid solution al10ys;2 this work is concerned with Fe-S alloys, and with the effects of oxygen and manganese additions. MATERIALS AND PROCEDURE Cast tes! specimens were employed throughout, since most of the difficulty during hot working occurs in the initial breakdown of the ingot. Alloy Systems. Ten 25 lb. heats containing sulphur were prepared. Of these, three had manganese additions, and two had oxygen additions. The sulfur content varied from 0.023 to 0.10 pct. Manganese contents were intended to be ten to twenty times the sulfur content of the particular alloy. Oxygen, being more difficult to control in small melts, was varied by the amount of solid deoxidizer added, but poor control of the oxygen content was experienced in most instances. Table I shows the chemical analyses of the heats. Melting and Casting. Electrolytic-iron chips were melted by high frequency induction in a prefired, clay-graphite crucible lined with rammed magnesite.

Jan 1, 1962

By Laurence C. Hicks

Consideration of the past work on the subject of the diffusion of chromium into iron suggested that additional information might be given by the use of X-ray spectroscopy in following the concentration changes through the diffusion zone. Grube and Fleischbeinl packed rods of electrolytic iron in a mixture of alumina and chromium. These specimens were heated in an atmosphere of purified hydrogen for varying lengths of time. After treatment the specimens were examined metallographically and showed the usual structure, consisting of a border of radially oriented columnar grains ending in a sharp boundary line. Reference is made to the fact that etching with certain reagents will attack only the material inside the border of columnar growth and also to the fact that polishing seems to develop a ridge at the position of the boundary between the etched and unetched areas. By chemical analysis of thin layers turned off on a precision lathe, the authors were able to obtain depth-concentration curves. These curves, reproduced in Fig. 1, show that in most cases a pronounced change of slope occurs, corresponding to the position of the boundary of the columnar grains. In a laler paper Grube extends his work to other systems which show the same characteristics.~ He concludes that the reason for the break in the curve is that a hindrance of diffusion occurs at the place where the regularly oriented grains of the diffusion zone meet the random grains of the interior portion, on the assumption that the diffusion velocity in one direction in a grain may be greater than in another direction, and that the grains in the diffusion zone orient themselves so as to give the maximum diffusion rate. Kel1ey" points out that Grube has failed to note that the boundary line does not consistently cross all grains and

Jan 1, 1934

By N. S. Stoloff, J. N. Mushovic

Age hardening response of a Mg-Th-Zr alloy has been studied at temperatures in the range 60° to 450°C. Transmission microscopy revealed clustering of thorium atoms at low aging temperatures, supporting a previous report of GP zone formation. Peak strengthening, which is observed at 325°C, is due to the formation of a coherent, ordered, DO19 type superlattice structure, of Hobable composition Mg3Th, as plates parallel to the matrix prism planes. These plates later reveal a Laves phase structure of composition Mg2Th. The equilibrium Mg4Th phase begins to precipitate in two different forms at an early stage, competitively with the Mg2Th plates. RECENT work on the Mg-Th system indicated that, unlike most magnesium-base alloys, complex precipitation phenomena may be occurring. The partial phase diagram of the Mg-Th system indicates that an equilibrium phase, Mg5Th, is the sole intermediate phase.' sturkey,' however, has reported, using X-ray and electron diffraction techniques, that a metastable fcc Laves phase, Mg2Th, precedes the formation of the equilibrium compound, which he identified as closer in composition to Mg4Th. Murakami et al.3 reported that the equilibrium phase precipitates preferentially on grain boundaries and dislocations in a Mg-1.7 wt pct Th alloy; Kent and Kelly4 aged a more dilute alloy, Mg-0.5 wt pct Th, for 4 days at 220°C and found similar results. In addition, they reported that a platelike phase with a structure close to that of the magnesium matrix forms perpendicular to the basal plane and is probably ordered. Research on a Mg-4 wt pct Th alloy by electrical resistance measurements and transmission electron microscopy has suggested that GP zones may form at low aging temperatures.3 However, the electron micrographs purporting to show this phenomenon were not conclusive. In view of the fragmentary evidence concerning the nature of the precipitation processes in the various Mg-Th alloys, an aging study was undertaken to clarify the characteristics of the various precipitates which form and to correlate the mechanical properties of the system with the direct precipitate-dislocation interactions. The latter results are presented elsewhere.' The purpose of this paper is, therefore, to discuss the precipitation sequence in this system. EXPERIMENTAL PROCEDURE Sheet stock (0.060 and 0.010 in. thick) of a commercial Mg-3.93 wt pct Th-0.42 wt pct Zr alloy (designated HK3lA) similar to that studied by sturkey2 was supplied through the courtesy of Dr. S. L. Couling of Dow Metal Products Co. Zirconium does not enter into any precipitation reactions,' but is present primarily as a grain refiner. The alloy was chill cast, warm rolled to 0.090 in. thick stock, and then finally reduced by a combination of hot and cold rolling. The alloy chemistry is given in Table I. This material was solution treated at 580°C for 4 hr in a dry CO2 atmosphere, and then water quenched. Material in this condition was fairly clear of precipitate particles and was fully recrystallized. Aging at temperatures less than 200°C was accomplished by immersing the alloy in a silicone oil bath; for higher temperatures, aging was done in a salt pot. Age hardening treatments were conducted at 60°, 80°, 105°, 135°, 160°, 250°, 325°, 350°, and 450°C for times ranging from 5 min to 400 hr. Hardness tests were performed on chemically polished 0.060-in.-thick blanks of solution treated material which were aged at the various temperatures for increasing lengths of time. For aging temperatures above 150°C the Rockwell Superficial 30T scale was employed, while samples hardened at temperatures below 150°C were monitored with the 45T scale. Each data point consists of at least three separate readings. Yield stresses also were measured at room temperature on both 0.060 and 0.010 in. sheet specimens aged at 325°C. The aged foils were thinned by the window method in a solution of 80 pct absolute alcohol and 20 pct concentrated perchloric acid (70 pct) maintained at 0°C. A stainless steel cathode was used and the applied voltage was 10 to 15 v. Thinned samples were rinsed in distilled water and pure methanol. After the me-thanol rinse the thin foils were quickly dried between filter paper. Foils prepared by the above method were examined in a Hitachi HU11B electron microscope operating at 100 kv. RESULTS A) Hardness. The hardness data are depicted in Figs. 1 and 2. Peak strengthening occurs at 325°C after aging about 6 min, see Fig. 1. Significant strengthening is achieved also at 350°C, but aging at 450°C produces only softening. The stepped curve at 250°C indicates that a complicated precipitation process may be occurring at that temperature. Fig. 2 suggests that at least two hardening mechanisms exist since the lowest temperature hardness peaks are displaced to the left of the peaks obtained at 135° and 105°C. A great deal of scatter is observed at long times in all cases due to magnesium surface degradation caused by the silicone oil bath. B) Identification of the Strengthening Precipitates. The structure formed atlowagingtemperatures (c10O°C) was not clearly resolvable by transmission microscopy. The only bright-field evidence for a change in structure was a mottled appearance which could be observed at extinction contours, as shown in Fig. 3(a), and the disappearance of this effect when dislocations produced under the influence of the electron beam passed through the matrix, as noted in

Jan 1, 1970

By W. M. Dressel, A. Visnapuu

The Bureau of Mines, U.S. Department of the Interior, has upgraded high-iron domestic chromite concentrate to high-chromium concentrate by a laboratory carbonyl process. The chromite concentrate product has a chromium-to-iron ratio in excess of 3:l compared with the starting concentrate ratio of 1.6:1. The high-iron chromite was first reduced to convert the iron oxides to the metal, and then treated with carbon monoxide at elevated pressures and low temperatures to convert the metallic iron fraction to iron pentacarbonyl. Carbonylation was accelerated by the addition of hydrogen sulfide in small quantities. A constant flow of carbon monoxide swept the iron pentacarbonyl formed in the reactor out through a pressure-reducing valve. The mixture of carbon monoxide and iron pentacarbonyl at atmospheric pressure was then passed through a heated section to decompose the iron pentacarbonyl to carbon monoxide and iron, whereupon the latter plated out on the heated surface. Carbon monoxide pressure, temperature, and promoter trends for enhanced carbonylation are presented.

Jan 1, 1984

By A. Dorsey Lyon

INTRODUCTION A GREAT DEAL of attention has recently been given to the metallurgy of zinc, and much of that which has been said and written on this subject has been in the nature of a criticism. For instance, we are quite accustomed to hearing it said that the metallurgy of zinc has stood still, that it is antiquated, out of date, etc. We are, however, inclined to agree With George C. Stone1 When he says that, although there have been no such spectacular and radical changes as Were worked in the metallurgy of copper and iron by the introduction of converters, there has nevertheless been a decided and marked progress in the metallurgy of zinc, and especially during recent years. However, it must be admitted that, due to the fact that the chemistry of zinc is so different from that of the other metals, the retort process is the only process by which zinc is produced commercially; and, moreover, that losses which occur in the zinc industry-that is, in the mining, milling, and smelting of zinc ore-are very great, for it is stated' that probably less than 50 per cent. of the zinc mined, even

Jan 7, 1914

By C. Willard Hayes

One of the most productive iron-ore districts of the southern Appalachians lies in the vicinity of Cartersville, in northwestern Georgia, where the ore-deposits are so directly related to the stratigraphic and structural features of the region that a description of its geology possesses economic as well as scientific interest. Stratigraphy.—The area shown on the accompanying map, Fig. 1, occupies the southeastern portion of Bartow county, Georgia. It is about equally divided between the older crystalline and metamorphic rocks which occupy the Piedmont plateau and Appalachian mountains on the east, and the Paleozoic formations which occupy the Appalachian valley on the west. The line separating these two groups of formations enters the mapped area near the northeastern corner, and, pursuing a somewhat irregular diagonal course, leaves it, as shown on the map, near the southwestern corner. This line marks

Jan 1, 1901

By J. H. Brophy, S. J. Michalik

A constitution diagram for the system Mo-Ir has been determined. The maximum solubility of iridium in molybdenum is 16 at. pct at 2110ºC and decreases to less than 5 at. pct at 1500°C. The solubility of molybdenum in iridium is 22 at. pct. Three intermediate phases appear in the system: 8 MoJr, having the p-tungsten structure; a phase, a cornplex tetragonal structure; and the hcp ? phase. Metallography, melting point determinations, X-ray diffraction and fluorescence, and electron micro-probe unalyses were employed in establishing the diagram. PREVIOUS to the present investigation, the intermediate phases in the Mo-Ir system were identified, but no detailed account of the phase diagram has been reported in the literature. Raub1 investigated alloys of Mo-Ir over an extensive range of composition between the temperatures of 800º and 1600°C. The in-termetallic compound MosIr was found to exist with nearly pure molybdenum, as the solubility of iridium in molybdenum was not detectable parametrically in this temperature range. MO3Ir was found to be iso-morphic with a ß-tungsten type structure, having a parameter of 4.959Å. An intermediate hcp phase, designated as the ? phase, ranged in composition from 52 to 78.5 at. pct at 800ºC, and from 41 to 78.5 at. pct Ir at 1200°C. Parameters noted for the ? phase were as follows: at 42.7 at. pct Ir, a = 2.771i0, c = 4.4366, c/a = 1.601; at 78.5 at. pct Ir, a = 2.736A, c = 4.378A, c/a = 1.600. Molybdenum was found to be soluble in iridium up to 16.5 at. pct Mo (83.5 at. pct Irj, with the parameter of iridium increasing to 3.845A at the solubility limit. Knapton,2 who investigated alloys between 15 and 85 at. pct Ir, essentially agreed with Raub's data, but, in addition, found a a phase in as-melted alloys near 25 at. pcto Ir. The oaphase lattice parameters were a = 9.64Å, c = 4.96Å, c/a = 0.515. The a phase was replaced by the 8 -tungsten phase on annealing at 1600°C. Knapton concluded that the a was stable only at elevated temperatures, and placed the composition of the a phase at approximately 30 at. pct Ir. The intermetallic compound Mo3Ir, with a lattice parameter of 4.965A, was included among the 8-tungsten structures reported by ~eller.' Matthias and Corenzwit,4 and Bucke15 studied the superconducting nature of MosIr, and reported a superconducting transition temperature of 8.$K. The present investigation describes the phase relationships in the Mo-Ir alloy system determined by melting point measurements, X-ray diffraction and fluorescence, and metallography. EXPERIMENTAL PROCEDURES Alloys for the determination of the phase diagram were prepared from powders. Commercial 99.9 pct Mo from Fansteel Metallurgical Corp. and 99.9 pct Ir powder from J. Bishop and Co. Platinum Works were used. The powders were weighed to nominal compositions, mixed, and then pressed, without binder, into compacts weighing 4 to 6 g. These were presintered in uacuo between 1200' and 1400°C for 1 hr, to reduce the degree of spattering during subsequent arc-melting. The compacts were arc-melted in a nonconsumable tungsten electrode furnace six times on alternate sides on a water-cooled copper hearth in an atmosphere of zirconium-getter ed argon at 500 mm of mercury pressure. In almost all cases, this procedure yielded buttons of satisfactory homogeneity. The composition of all melted buttons were confirmed by X-ray fluorescent analysis using the experimentally determined ratio of the iridium La1 line intensity to that of the molybdenum Ka1 line as a function of composition. In this determination four alloys analyzed by wet chemical methods were used as standards. An uncertainty range of ±1 at. pct has been attributed to all indicated compositions. All heat treatments and solidus measurements were carried out in tantalum resistance heating elements in vacuum conditions of 10-4 to 10-5 mm of mercury. A detailed account of this procedure has been reported by Schwarzkopf and Brophy.8 In the heat treatment and solidus measurements of iridium-rich alloys (50 at. pct Ir or greater), a tungsten lining was inserted into the tantalum resistance heating element because of a eutectic reaction which occurs between iridium and tantalum at 1948ºc.7 Heat treatments and solidus measurements carried out at compositions less than 40 at. pct Ir both with and without tungsten linings within the resistance

Jan 1, 1963

By C. G. Dunn, W. W. Martin

Various X ray diffraction techniques have been developed for determining orientations of crystals. Transmission and back-reflection Laue methods1,2,3 in particular have been found to be very useful. In many applications, however, a need still exists for a simplification of the details of analysis so that orientations can be determined more rapidly, and operators with little or no training in crystallography can be easily instructed in the necessary procedures. Filling this need in part is a system of analysis that has been in use for several years in the Metals Section of the Laboratory, General Electric Co., Pittsfield, Mass. This method is an extension of the one of Majima and Togino,4 which uses fifty-five indexed standard transmission Lauemams to cover the entire range of crystal orientations. Greater rapidity in determining the orientation of a crystal is achieved by using a slightly larger set of standard Lauegrams and by systematizing the steps followed. This system of analysis in its present form constitutes the subject matter of the present paper. Although the method uses transmission X ray Laue patterns, many of the operations are applicable to the analysis of back-reflection Lauegrams. Very briefly the method is based on the fact that Bragg and azimuthal angles for two or more identified Laue diffraction spots completely determine the orientation of a crystal, and standard Laue photographs of the Majima and Togino type provide a ready means for identifying Laue spots. After a preliminary analysis, which consists of identifying the pattern in terms of one of the standard patterns, a correctly marked Lauegram is selected to carry out the final analysis. From measured Bragg and azimuthal angles, the normals (poles) of the reflecting planes for the selected Laue spots are located on a stereographic projection and the orient.at.ion of the crystal determined (in terms of the positions of cube poles for example) by a few additional operations on a \I1ulff net. The actual procedure followed will be illustrated in detail after a brief treatment or X ray problems connected with orientation determinations and a discussion of useful principles and techniques. X Ray and Plotting Problems RELATIVE ADVANTAGES OF BACK-REFLECTION AND TRANSMISSION LAUE DIFFRACTION METHODS In the back-reflection Laue method it is easy to make a direct measurement of the tilt of a zone of Laue spots. Specimen thickness also is generally no problem. In the case of thin specimens, however, the time of exposure is less for the transmission Laue method. For example, with silicon ferrite this advantage holds up to a thickness of 0.6 mm if tungsten radiation at 40 kv peak voltage is used. Furthermore, the transmission photograph represents the entire thickness of the crystal whereas the back-reflection picture represents only a surface layer (a thickness of less than 0.05 mm for silicon ferrite), the deeper layers supplying a negligible amount to the diffraction pattern. If a crystal is distorted, the transmission Laue pattern gives more information particularly with regard to the orientation of the crystal and the overall amount of spread in orientation. Finally a 3 1/4 X 4 in. film suffices for transmission photograms; a 4 X 5 in. or 5 X 7 in. film with a central hole is needed for back-reflection patterns Not only is the manipulation of film easier because of the size of film, but

Jan 1, 1950

By M. Van Siclen

THE outstanding fact in connection with dust disease in the United States at present is the growing recognition of its seriousness by state officials and by the more progressive operators of mining, metallurgical and allied industrial plants. The same may perhaps be said of labor in some of its better organized centers, but the average independent non-union workman continues, as of yore, to suffer the toll of disability and even of death from dust inhalation without realization of the source of his ill-being. Progress in the betterment of the handling of sufferers from dust disease and of the conditions creating dust hazards in mining and allied industries is pursuing a course similar to that of the now widespread campaign against accidents, in which the risk is more obvious, more severe, and was naturally recognized sooner. The coming on of dust disease is generally relatively slow and its immediate effects not infre-quently masked by or attributed to other diseases. Marked exceptions to this general rule have occurred in districts where the dust is particularly pernicious, such as the Rand and Joplin; yet such exceptions, unhappy in themselves, opened the eyes of medical men, and of those in other localities charged with the responsibility for the welfare of industry, to the much more widespread if less spectacular hazard existing from the inhalation of dust in all rock-excavating operations and all industrial operations creating inorganic dust, whether it be crushing and grinding, sand-blast-ing, granite-cutting, or what not. Advancement to date in the United States in prevention and treat-ment has been slow, yet the record shows that quantitative methods for determining the degree of hazard and means for decreasing it were being developed as far back as 25 years ago; and that more rapid progress may be looked for from now on. In 1908, in this country, F. L Hoffman?(1) discussed the mortality from consumption in dusty trades, especially brass foundries; and in 1913 E. R. Hayhurst(2) described the effects of inhalation

Jan 1, 1933

By J. D. Wheeler, H. W. Mathews

The increased activity in West Texas, which started in 1933, has continued through 1936 at a constantly accelerated rate. During 1936 there were 1442 wells completed in the area as compared with 700 in 1935 and 468 in 1934. Of these completions, 1313 were producers with a total 24-hr. potential in excess of 1,750,000 bbl. From among the 1442 wells, eight are considered to be discovery wells for new West Texas fields. New Fields Bennett.—The Bennett field, which added Yoakum County to the oil-producing counties of West Texas, was actually indicated as an oil-producing area during 1935, but the discovery well, Honolulu Oil Corporation, Ltd. and Cascade Petroleum Company's Bennett No. l, was not given a production test until April 1936. The discovery well made 15 bbl. per hour through 3/4-in. choke with a plugged-back total depth of 5264 ft. First oil in the hole was from 5088 to 5090 ft., which is several hundred feet below the top of Permian lime. Producing limits of the field are unknown, as the second test had not reached the pay at the close of the year. Henderson.—-To date indications are that the Henderson pool, in northern Winkler County, is the most prolific area opened during 1936. This field, which lies to the north of the old Hendrick pool, is producing from the same reef-type dolomitic lime producing in the older field. The Henderson field was opened by the completion of R. H. Henderson, J. B. Walton-Humble 1-A in April 1936 for a natural flow of 2306 bbl. per day through tubing. Total depth of the discovery well is 3049 ft. Later development has indicated the productive area to be a rather narrow zone running slightly west of north. Present area of from 1000 to 1500 acres has been proved for production. Keys and Emperor.—The Keys and Emperor pools in the belt of sand pools running across Winkler County appeared for the first time on State proration schedules during 1936. This report considers these pools as links in joining the belt of sand production across Winkler County, for

Jan 1, 1937

By Rossiter W. Raymond

The 12th of April, 1877, witnessed the celebration, at Freiberg, Saxony, of an event profoundly important for the ancient mining industry of that district, and full of interest to mining engineers throughout the world—namely, the connection of the famous Roth-

Jan 1, 1879

By L. J. Boucher

The beneficiation process at Northampton is described and reasons are given for installing a flotation plant. The economics of running the plant, the difficulties of operation, and subsequent remedial action are discussed.

Jan 3, 1953

By authority of the Secretary of War, and in response to frequent requests, the following suggested list of reading is issued by the War Department for the information of civilian engineers desiring to inform themselves on military subjects: These references have been selected, first, with a view to giving to engineers unfamiliar with the art of war a general survey of that sub-

Jan 1, 1916

By W. M. Peirce, E. A. Anderson

A FEW metals have been known since the dawn of history. Many have been prepared in quantity only within the present century. Zinc falls into an intermediate category, although there is some evidence of its existence in elemental form in Greece as early as the third or fourth century B.C. Nevertheless, the first important use of zinc antedates the earliest records of civilization. This first use was in the alloy, brass, which is roughly one third zinc. This continues to the present time as one of the major uses of the metal. The first production of brass, in light of present knowledge, was perhaps one of the 'most romantic and fortuitous of technical discoveries. Copper, the major constituent of brass, had been given to man by Nature in the native state; that is, as lumps of fairly pure copper. The art of melting and working it had been learned. But zinc does not occur as the metal in Nature and even if some early metallurgist happened to heat zinc ore with a reducing agent, the reduced metallic zinc passed off as vapor and was lost. Doubtless some early coppersmith, melting copper in accidental contact with zinc ore, reduced the zinc, and the vapor was absorbed by the molten copper. Its color, hardness, and other properties were thus wonder- fully changed. And so the earliest metallic form of zinc, as nearly as we can deduce, existed in the alloy brass. Probably knowledge of the kind of rock with which to heat copper to change it to brass, the best

Jan 1, 1953

By Donald L. Katz

The equilibrium constants developed by Souders, Selheimer and Brown1' have been very useful tools in predicting vapor-liquid equilibria during the past five years. Their equilibrium constants were computed by assuming ideal solutions and recognizing the deviations of vapors from ideal gas laws. The same fundamental concepts were used by Lewis and co-workers8 for predicting vaporization phenomena by means of fugacities. The equilibrium constant is defined by equation 1: y\x =K [1] in which K = equilibrium constant, y = mol fraction of a constituent in the vapor phase, x = mol fraction of the constituent in the equilibrium liquid phase. The equilibrium constants are a function of temperature and pressure and might be considered as replacing the ratio of the vapor pressure to the total pressure of Raoult's law. They may be used to compute the vapor or saturation pressure of a liquid or the dew point of a vapor for any pressure or temperature from the analysis of the mixture much as Raoult's law is used. Likewise, the quantity of a mixture that will vaporize at any equilibrium temperature and pressure and the composition of the vapor and liquid may be calculated. The purpose of this paper is to review the available equilibrium data of interest in petroleum production, to discuss the auxiliary physical properties of the hydrocarbons, and to present typical uses of the equilibrium constants. The particular applications chosen are the computation of the results of stage separation of crude oil and natural gas, the calcula: tion of a pressure-volume curve of a crude oil-natural gas mixture, and information gleaned from a consideration of reservoir equilibria.

Jan 1, 1938

By D. T. Goettge, E. L. Robinson

The phase changes occurring in low carbon steel during hot strip mill rolling are shown to be metallurgically significant when related to commonly used temperature control points, particularly finishing and coiling temperatures. In combination, these temperatures are shown to have an important influence on the level and uniformity of hardness, grain size, and carbide characteristics of the finished hot and cold rolled sheets. PRODUCTION of wide flat-rolled products ordinarily requires a number of operations in sequence to prepare the material for shipment to the customer. Most products are tailor-made for specific end uses, with each operation contributing certain properties to the finished material. Since the characteristics imparted to the semifinished product by a given step in processing carry through to the finished product in varying degrees, it is important that the intermediate stages of production of flat-rolled strip be carried out with the same care which characterizes the last or finishing operations. The step of hot strip mill rolling is common to the production of all of the various types of flat-rolled product; therefore, the hot strip rolling is an especially important point at which to recognize and control those variables which have an effect on the surface characteristics and metallurgical properties of the finished product and which influence the ease of conducting subsequent operations. Orders entered at a producing mill usually show an end use or describe an article or part into which the ordered product is to be fabricated. Applying his experience as to the properties necessary in a finished sheet to suit the end use and to perform successfully in the fabrication involved, the metallurgist selects a steel of suitable composition and deoxidation practice, and slabs of appropriate dimensions are produced for rolling on the hot strip mill. At this stage of processing, the metallurgist faces the problem of controlling hot strip mill practice in the light of his diagnosis of the properties necessary to meet the end use, paying due attention to the accompanying problem of producing a strip which can meet processing requirements on subsequent units in the mill. It is the purpose of this paper to describe some of the factors which he must consider in solving these problems and to indicate some of the principles which guide him. Equipment, Physical Requirements of the Strip, and Temperature Measurement The metallurgist must, of course, be familiar with the physical layout of the mill, the temperature-measuring equipment available, and the physical requirements of the hot strip product before he can apply his metallurgical knowledge to the problem; hence, the first section will consist of a brief discussion of these matters. The usual hot strip mill consists of reheating furnaces, five or six roughing stands including a scale-breaker, holding table, and second scalebreaker, six-stand finishing mill, runout table with spray cooling facilities, and coilers. A schematic diagram of a typical layout is shown in Fig. 1. Slab temperatures are primarily a function of heating time and furnace temperatures, while mill speeds, spray practice, drafting practice, available water pressure, temperature of the cooling water, cross sectional dimensions of the strip, coil size, and equipment limitations, either singly or in combination, determine what rolling temperatures are practical on a given hot strip mill unit. Thus, it is possible that a set of temperatures which can be utilized successfully on one mill cannot be used on another. However, adjustments in temperatures and rolling practice can usually be made to develop the desired metallurgical properties. In addition to the metallurgical properties developed through proper temperature control, the hot strip mill must also provide strip with certain physical attributes which may be summarized as follows: Strip Cross Section—The strip contour should conform to a section which will give the best results in the cold reduction operation. This is generally recognized as a strip with 0.001 to 0.003 in. crown or shoulder-to-shoulder convexity depending on width, and freedom from concave, flat, or wedge-shaped cross sections which cause metal buildup in cold reduction. Excessive drop off in thickness at the edges can also be very detrimental in cold reducing to light gages. Gage, Width, and Camber—All of these must be controlled. For example, rundown or increasing thickness from the front to the back of the coil results in nonuniformity in the thickness of hot-rolled sheet product and in added difficulty with gage and welds in cold reduction. Similarly, excessive width variation is the cause of guide trouble and excessive edge scrap at later stages of processing, while excessive camber is the source of a variety of processing troubles. Type of Oxide—Product intended for pickling should have a predominance of the type of oxide most easily removable in sulfuric acid. It is generally recognized that this type is obtained by use of maximum table cooling water and cold coiling

Jan 1, 1957

By J. M. Adams

IT is my purpose to give some of the results obtained by an experience of nearly seven years in working ores by the method frequently called the Washoe Process, and in several mills of which I have had charge, but principally in the Owyhee Mill, at Silver City, Idaho, which had twenty '650-pound stamps, and sixteen pans. I shall discuss here merely the mechanical details for working ores generally, subdividing the subject as follows: 1. Preparation of the ore for the stamps; 2. The crushing in the battery; 3. The settling of sand or pulp in vats or tanks; 4. The treatment in the pans; 5. The results obtained in settlers, agitators, and concentrators ; 6. The straining of quicksilver, cleaning of amalgam, and retorting; 7. The saving of slimes and their subsequent treatment; 8. The loss of quicksilver. For descriptions of the various kinds of orebreakers, stamps, tanks, pans, settlers, etc., I must refer to the various works on these subjects, prominent among which are the reports of the United States Commissioner of Mining Statistics, and the volume on "Mining Industry," the third volume of the United States Geological Survey on the Line of the Fortieth Parallel through the gold and silver bearing regions of the great West, undertaken under the able guidance of Clarence King, assisted by Mr. James D. Hague and others. In this discussion it will be assumed that the general arrangement of the quartz mill is understood; and the question will be treated how to secure, from such a mill, the greatest economy in working, combined with the largest results. This place seems fittest for a single preliminary suggestion-namely, that there should be double "floors" throughout the mill, so that nothing can sift through and be lost.

Jan 1, 1874

By Ottar Dragge, C. Danielsson, Bo Kalling

THE desulphurizing of pig iron has been accomplished with a number of different additions. The oldest and still most commonly used agent is soda, the extensive use of which commenced about 1925, when it was used principally for cupola furnace iron. More recent experience' seems to show that better results can be obtained with sodium hydroxide. The well-known desulphurizing properties of lime have also been exploited in different technical processes. Another material with even more powerful effect is calcium carbide.' The desulphurizing ability of manganese, when added to the ladle in sufficient quantity, should also be mentioned in this connection. During recent years increasing attention has been paid to the desulphurizing properties of metallic magnesium." An addition of a suitable alloy of magnesium is now in use purely for the purpose of sulphur elimination. Of the desulphurizing agents mentioned, lime is by far the cheapest, provided that the reaction can be brought about rapidly and completely. Therefore, a method that makes full use of the desulphurizing ability of lime may be able to compete with other processes. A method developed at the Dom-narfvet Iron and Steel Works (Sweden) will be described, which enables pig iron to be rapidly desulphurized to very low sulphur contents by using a burnt lime powder. as the desulphurizing agent. Lime in Older Processes In cases where lime has been used for the desul-phurization of pig iron, it has generally not been used alone, but mixed with other substances such as fluorspar, to obtain the formation of a molten slag during the process. This method has been tried by Tigerschiold,' who treated the iron with a lime-fluorspar mixture, the stirring of the iron being brought about inductively with low frequency alternating current. Very good results were obtained. A process of this type has also been suggested by R. P. Heuer, U. S. A. The principles of this method, which has been tested in Great Britain by Newell. Lanener. and Parsons." re that a mixture of lime and fluoispar is added to the hot metal in the ladle, while a powerful stream of nitrogen gas is blown into the bath to produce the required intermixing. The results of the tests were unsatisfactory, however. A similar process has been developed at The Steel Co. of Canada, according to a statement by H. M. Griffith.' Here the tests were carried out in a carbon-lined ladle provided with carbon tuyeres in the side wall for blowing nitrogen into the bath. The addition consisted of about 20 lb of a mixture of burnt lime and fluorspar per ton of pig iron. Good results appear to have been achieved. The sulphur content of the pig iron is stated to have been reduced from 0.025 to 0.050 pct down to 0.006 pct. Various methods of desulphurizing pig iron have been tried using lime powder without fluxing material for fusing. Eichholz and Behrendt7 have experimented with blowing a powdered limeicoke mixture with air into the ladle. Their results were, however, not conclusive and the experiments do not appear to have been continued. Similar experiments have been carried out at Domnarfvet, using nitrogen instead of air in order to avoid oxidation. But these attempts were not particularly successful. It appears to be difficult to achieve the required agitation by this means. The strong cooling effect of the gas on the iron is also a serious drawback. A method in many respects similar to that tried at Domnarfvet was tried by Eulenberg and Krus at the end of the 1930's. Here again desulphurization was carried out with lime alone, brought into contact with the molten iron in a rotary furnace. The temperature was kept at the required level, 1400" to 1500°C, by the introduction of a pulverized coal burner in one end of the furnace. The speed of rotating was not given. A paper by Bading and Krus states that, in one of the first experiments, the sulphur content in 56 tons of pig iron was brought down from 0.186 to 0.035 pct in 117 min, but that a considerable shortening of the time would be possible. According to later reports by Eichholz and Behrendt,' it should be possible by this process to achieve a desulphurization speed of 0.35 pct S per hr for a consumption of 6 to 10 pct limestone and 2 to 3 pct coke, as fuel exclusively. The final sulphur content is, however, not stated. Domnarfvet Method After a number of different procedures had been investigated, the tests at Domnarfvet were directed to desulphurization with lime in a rotary furnace. Before going into the practical details of the method, the theoretical aspects will be discussed briefly. If the pig iron does not contain alloying elements other than carbon, the reaction can be expressed most simply by the usual equation: FeS + CaO + C = Fe + CaS + CO [I] 4H,. ~ 34,000 cal That this reaction can be carried through to a very complete desulphurization of pig iron has been shown by OelsenD in a discussion in connection with the Eulenberg and Krus' method. He mentions two laboratory tests, in one of which the sulphur content in the pig iron at 1400°C was reduced from 0.540 to 0.006 pct after treating with 3.35 pct lime. The pig iron had a low manganese content, but other analysis is th. given. Mention also should be made of the recently published investigations by Fischer and Cohnen'" dealing with the influence of the carbon content of the iron on desulphurization with lime, although in this case fluorspar was added also. The tests show that efficient desulphurization is possible with lime in the steel bath, provided that the carbon content is sufficiently high. The temperature employed in these tests was considerably higher (1620") than that normal for treatment of pig iron. The author concludes that the product S% X C% - 0.011 at the temperature in question.

Jan 1, 1952

By T. A. Rickard

The notion prevails that writing is a knack, that the skilful use of the pen is a gift of nature. This is an error. Dogberry may be responsible for it; he said: "To be a well-informed man is the gift of fortune, but to write and read comes by nature". Because Dogberry said it, we may be sure that Shakespeare thought otherwise. Ability of any sort may be partly innate, but my own observation and experience lead me to conclude that most of the easy writers have become so by constant practice. As I recall the names of men successful with the pen, I remember that most of them have written a great deal and have taken particular pains to improve their style. The suggestion that proficiency in the difficult art is a happy accident provokes a sardonic smile. The larger part of the great writing in our literature is the result of persistent effort. An easy fluency has been the undoing of many; their flamboyant and fantastic scribbling has proved as perishable as froth. This criticism applies to technical writing also; in order that a technical description or discussion may hold the interest of the reader, at least long enough to cause him to read it to the end, the writing must be done carefully and systematically; otherwise it will fail in its purpose of conveying information. Clearness is absolutely essential. "It is not enough to use language that may be understood; it is necessary to use language that must be understood."* The purpose of writing, at least of that which is meant to be read by others, is not only to express ideas but to communicate them. Lack of perspicuity may prove as %ad as

Jan 1, 1931