Search Documents

By P. V. Roundy, G. R. Mansfield

PUBLIC lands in Florida were first withdrawn from entry by President Taft on July 2, 1910, as a conservation measure because of their possible phosphate content. The reserve thus established was subsequently modified by further withdrawals and by restorations, so that on Jan. 1, 1934, it contained 66,796 acres, of which only a small part had been definitely classified. The reserved land was in scattered parcels, ranging from less than 40 acres to 320 or more, distributed in many counties. For administrative purposes and for final disposal of any of the numerous parcels, mineral classification of the land is legally necessary. In 1934 and 1935 the United States Geological Survey, under two successive grants from the Public Works Administration, prospected some 83 tracts of these lands in Polk County, comprising in all about 3300 acres, and six tracts comprising 240 acres in Citrus and Marion Counties. The tracts in Polk County were all in the so-called land-pebble field and the others in the hard-rock field. The Survey field party was under the direction of P. V. Roundy, from whose unpublished report the material in this paper is largely taken. The foreman of the prospecting crew was J. H. Wingate of Zephyrhills, Fla. The individual tracts were identified through the cooperation of the General Land Office, by transitman Hugh B. Crawford. This prospecting work fitted well the classification adopted for Public Works projects in general: it could not be done on any considerable scale under the Survey's usual appropriations; it gave employment to unemployed labor; and it may be expected ultimately to repay the Government in royalties more than the cost of the exploration. COMMERCIAL PROSPECTING METHODS Commercial methods of prospecting for phosphate in Florida have been briefly described by Mansfield.1 In the hard-rock field, where the floor of the phosphate deposit is extremely irregular, it is customary to drill as

Jan 1, 1937

By David E. Jones, Dean K. Hunt, C. Y. Chen

INTRODUCTION Of all the numerous geological hazards that threaten the well-being of urban areas in the United States, probably none is so widespread, persistent, and diversified as surface subsidence (HRB-Singer, Inc., 1977). Simply defined, subsidence is the vertical displacement or sinking of the ground surface caused by either natural phenomena or man's activities. The downward movement, however, can be accompanied by horizontal movement, strain, tilt and even by a locally upward movement. Damage to structures and the environment can result from any of these movements. Extracting subsurface materials, fluids and solids, accounts for most man-induced subsidence in the United States. Among all the mining-related subsidences, the collapse of voids created by underground coal mining has been the major cause in inflicting surface damage (Comptroller General of the United States, 1979). Subsidence from coal mining may occur within a few weeks or be delayed for years, depending upon the mineral layer's depth below the surface, the overlying rock strata's characteristics, the extent and methods of mining that were employed, and the time deterioration of pillar and mine structure. Unless underground resources are not mined or control measures are implemented to prevent or minimize damage, some degree of surface subsidence and its accompanied deleterious effects are often inevitable. The ways to control the subsidence and minimize surface damage may include: 1. Precautionary measures built into new structures or surface features. 2. Preventive works applied to existing structures or surface features. 3. Mine design incorporating special underground layouts. 4. Any combination of the above measures. Upon the enactment of Public Law 95-87, the Secretary of the Interior, through the recently created Office of Surface Mining (OSM), was authorized to promulgate rules to regulate mining reclamation including subsidence control. Proposed on September 18, 1978, these rules were finalized, following public comment and hearings, on March 13, 1979, as part of the permanent regulatory program for the regulation of surface mining and reclamation operations which include the surface effects of underground mining. On January 28, 1981, Secretary Watt of the Department of the Interior issued an order to re- quire all agencies to identify with recommendations all regulations which are believed to be excessive, burdensome or counterproductive. Also on February 17, 1981. President Reagan issued Executive Order No. 12291 requiring all Federal agencies to conduct a regulatory review to make a determination that each promulgation of a regulation is clearly within the authority delegated by law and consistent with Congressional intent (Federal Register, 1981). As a result, OSM initiated the regulatory reform to revise the permanent regulatory program. Following a brief discussion of the technical aspects and the effects of subsidence on man and his environment, this paper presents a historical overview of how rules and regulations are used to govern the subsidence related problems. The development of the regulation of subsidence under Public Law 95-87, the Surface Mining Control and Reclamation Act of 1977 (SMCRA or the Act) are also discussed, including the new regulations being developed under the regulatory reform program. SOME TECHNICAL ASPECTS Am EFFECTS OF FINE SUBSIDENCE An extensive historical review of mining subsidence is given by Zwartendyk (1971) and Shadbolt (1978). Comprehensive technical presentations have been given by Henry (1956), King and Whetton (1957), Hall and Orchard (1963). Muller, et al. (1968). Grard (1969), Voight and Pariseau (1970). Kapp and Williams (1972), Cummins and Given (1973), Brauner (1973) , and NCB (1975). A theory of surface subsidence due to underground mining was perhaps first fundamentally stated by a French engineer, Toillez, in 1838, and formulated by a Belgian engineer, Gonot, in 1839 (Goldreich, 1913, cited by Zwartendyk, 1971). Since that time,

Jan 1, 1982

By Reno Sales

THE present-day application of geological knowledge to mine opera-tions owes much to Survey activities. Early publications covering developed deposits at Comstock and Eureka in Nevada, and Leadville in Colorado, aroused great interest in mine geology among mine owners and operators. In later years personal contacts between Survey geologists, notably Lindgren, Spurr, Emmons, Weed, and Ransome, to name only a few, and mine managers, mine superintendents and mine foremen, brought directly home the importance of geological mapping and study in connection with mine operations. However, the Survey had recognized from the beginning that it was not practicable, either from the viewpoint of cost or policy, to supply direct help to the miner. The situation was met by many large mining companies through the organization of geological departments to deal with problems of geology which concerned not alone the every-day mine operation but also the life expectancy of the ore deposit. The mine owner therefore looked to the mine geologist to apply the "laws of ore deposition" in estimating the future of his mine. The examination of outside properties also became a duty of the company geologist where replacements were needed or where expansion of operations was contem-plated. And finally, out of this situation there developed the inde-pendent consulting geologist, specializing in geological examinations of prospects, mines, and mining districts, whose duties included the highly important but often difficult task of appraising ore reserves and ore possibilities. Thus, while it may be considered by many that the work of the mine geologist overlaps that of the Survey geologist, their respective fields of endeavor are not in conflict. The appearance of the mine geologist has lessened in no manner the need of intensive field and research work by the Geological Survey and related organizations.

Jan 1, 1934

By DONALD H. McLAUGHLlN

Few factors have had more influence in maintaining the strength and stability of the United States than our persistent habit of providing .checks and balances to the dynamic powers of free enterprise on the one hand and to the controls and guidance exercised by the State on the other. .Indeed, it is this same concern for matching forces against each other that has given our republic its ability -to preserve a democratic basis of life for its citizens, and yet maintain a ,government that is able to protect the rights of all and to resist and minimize the danger of excessive concentration of authority. Our current efforts to clarify the nation's mineral policies and to define more clearly the role that the governmental agencies should play in conjunction with the functions of private -enterprise again reveal the desirability and advantages of maintaining our traditional controls. At times, the equilibrium has been temporarily disturbed by too great enthusiasm for one or the other of these basic concepts. Sooner or later, however, the balance has been restored by the healthy opposition that is always created by excesses of one sort. At the current stage in our history, the swing toward undue enlargement of the powers of the State seems to have gone dangerously far and we would be untrue 'to our traditional behavior if the group that must demonstrate the virtues of free enterprise did not rally to its support with the utmost earnestness.

Jan 1, 1949

By F. W. Lee

Historical-From the beginning of time, all ingenuity of mankind has been concentrated upon the methods of finding gold and unusual deposits in the earth. An illustration (Fig. 1) from the old treatise by Agricola, "De Re Metallica," published in 1580, will serve to show the im-plicit faith of that generation in divining methods. However, it was not until 1920 that real progress was made in prospecting by using the latest advances of the physical sciences. The public interest was stimulated by the successes of these methods on the part of commercial oper-ators, and governmental agencies received many requests for information concerning their relia-bility. There were also, in the late 1920's.high- pressure mine-promotion schemes which used geophysical methods in a very questionable manner, symbolized in Figure 2 as of 1928 by an elec-trified forked stick. Authoritative information concerning such practices for public protection was needed to curb such notorious undertakings. Dr. Scott Turner, then Director of the United States Bureau of Mines, thoroughly understood the situation and was first in the governmental de-partments to recognize the possible value of a study of modern prospecting methods. The Bureau of Mines began this investigation by employing Drs. A. S. Eve and D. A. Keys of McGill University for short periods in the summer in 1927. Their first publication [see 1 of "References" at end of paper] served to illustrate the fundamental scientific principles which underlie geophysical prospecting. This was followed by a second publication [21 giving the results of field-tests. In the light of the rapid improvements during the intervening ten years, these two papers take a historical position. Later a full-time position under Civil Service was planned by the Bureau of Mines for con-tinuous investigations and research concerning geophysics and its applications to prospecting. It was Turner's idea that. since the oil-industry had been making very rapid progress with good results, if mineral mining could also benefit to the same degree, it would be of great help to that industry.

Jan 1, 1940

By J. H. Swartz

During 1938 and 1939, an extensive series of geophysical surveys, employing both resistivity and magnetic methods, have been carried on in the Hawaiian Islands by the Section of Geophysics of the United States Geological Survey in cooperation with the Division of Ground-Water of the Survey and the Division of Hydrography of the Territorial Government (see Fig. 1). During this time, surveys have been conducted on the islands of Oahu, Molokai, and Maui. Two distinct types of ground-water occurrence are being investigated: (1) The basal fresh-water lens floating on underlying salt water in obedience to the Ghyben-Herzberg principle (Fig. 2); and (2) perched ground-water (Fig. 3).

Jan 1, 1940

By William Colby

INCREASING governmental control of human activities seems inevitable. Within the present generation railroad rates and the public sale of water, gas and electricity have been subjected to rigid regulation. The field of control is slowly but surely being enlarged, and it is the object of this paper to outline in brief space this tendency toward increased governmental regulation, as far as mineral resources are concerned. Our, dual form of government complicates the problem. We must deal not only with the powers of the Federal Government, but also with those of the individual States. In order to approach this question intelligently we must have some conception of the powers and jurisdiction of the States and the United States, respectively, over mineral lands and mineral production. Starting with the Federal Government we find it never owned any public domain within the States that formed a part of the thirteen original colonies and, for historical reasons, the same is true of Tennessee and Texas. The Mid-Western States were erected out of the public domain which was acquired by the United States through cession from the original States or by purchase from foreign nations. Congress early in the last century adopted a policy of leasing public lands containing lead deposits in a portion of this Mid-Western territory, but later abandoned that policy and disposed of such public, lands, mineral and non-mineral, outright so that they long since have practically all passed into private ownership and become subject to the general jurisdiction of the respective State governments. In the great public domain lying west of the Mississippi River, and in portions of some of the Southern States, the Federal Government adopted a new mineral land policy following the discovery of gold in California. (Acts of Congress of 1866, 1870, and 1872.) The mineral lands within these States, instead of being disposed of on the game basis as agricultural lands, as occurred in the Mid-Western States, were segregated from agricultural lands and sold under special laws intended to encourage mining, giving the miner the free right to locate and work these mineral lands without paying any royalty to the Federal Government. A miner could also obtain at slight expense a complete

Jan 1, 1930

By John P. Bingham

GRACE mine and mill, owned by Bethlehem-Cuba Iron Mines Co. and operated by Bethlehem Cornwall Corp., are being developed to produce 9600 tons of 42 ½ pct Fe magnetite ore, to yield 5760 tons per day of agglomerated iron concentrates averaging 65 pct Fe. Located about 14 miles south of Reading, the property is ideally situated in relation to good highways and railroad. Three major steel plants, at Bethlehem, Steelton, and Sparrows Point, Md., are about equidistant from the mine. Discovery of the orebody resulted from an airborne magnetometer survey, completed in 1948, con¬sisting of 7000 lineal miles of flight lines spaced one-fourth of a mile apart and extending from the Delaware River on the east to Gettysburg, Pa., on the west. After examining the magnetic maps, Bethlehem's geologists made limited surface traverses over the Grace mine and Warwick area to check the location, and realtors were engaged to purchase the desired properties over and adjacent to the area showing favorable indication of ore.

Jan 1, 1957

By Harry A. Perry

The Highlad underground uranium mine is located in the southern Powder River Basin, Converse County, Wyoming. Development by Exxon Minerals Company began in 1973 and average production from the complex roll- front deposit ranges from 500 to 600 stpd. A staff of six eight grade control technicians work within the Geology Department to guide and monitor production, to minimize waste and to account production to reserve estimates. A thorough knowledge of the complex roll- front deposit aids in accounting production to reserve estimates. Grade control technicians assist the mine geologist in making geologic cross sections, in estimating reserves, and in predicting monthly and quarterly production grades.

Jan 1, 1980

By Dennis E. Stover

Grade control for in situ uranium leaching is maintaining, at desired levels, the uranium concentration in the pregnant lixiviant which feeds the extraction (ion exchange) circuit. This differs from grade control in conventional mining in that in situ grade control is imposed subsequent to rather than prior to leaching without the direct observation and control possible in conventional mining and milling. Grade control is a necessary engineering task through the entire project life, beginning with preliminary evaluation and design and ending only when the final wells are shut in. More specifically, this task is associated with designing the initial well field, maintaining productivity during well field operations, and planning well field expansions to compensate for the depletion of existing wells. Our aim during each of these phases is to maximize uranium productivity while ensuring that we are developing information necessary for future phases. Throughout this task, we remain cognizant of the fact that uranium productivity is a function of both the complex geologic and operational parameters of the project. A minimum list of significant geological factors must include the following: . Host formation mineralogy . Uranium mineralogy . Permeability . Ore quality (grade and thickness) Our concerns are not limited to average or general descriptions of these factors. The interactions among the factors as well as localized variations among them are far more important in obtaining high productivity from a deposit. For example, an ore body may display an average permeability of one darcy but have its high grade ore confined to regions with permeabilities less than 500 millidarcies. This relationship between ore grade and permeability must be understood early in the project life if the operation is to be successful. Similarly, the fundamental operating parameters for the well field include those items which enable us to distribute the lixiviant within the ore as well as the chemistry which will dissolve the uranium minerals. A minimum list of such factors will include: . Well design . Well efficiency . Well bore damage . Pattern size and shape . Oxidant type and concentration . Complexing agent concentration - pH The interactions between these variables and the complex geological variations create a situation which often defies quantitative analysis. Hence, we have adopted a statistical approach when correlating production history with these parameters and the quality of the correlations improves as the number of wells operated increases. However, the correlations are often specific to an ore body. We find that we must tailor the process to meet the unique geologic parameters of each ore body. PHASE 1: INITIAL WELL FIELD DESIGN Designing the initial well field is perhaps the most difficult phase because we have the smallest data base from which to predict performance. We will have conducted numerous laboratory tests and, perhaps, field pilot tests to select the lixiviant system and to characterize the geologic parameters. However, we will learn a great deal more about the deposit and its productivity during actual commercial scale operation. Fully acknowledging its limitations, we will, as a starting point, assume that uranium productivity will be directly proportional to the quality and quantity of recoverable reserves. Future deviations from this assumption will be plentiful and result from our limited understanding of the aforementioned interactions between and among the operational and geological factors. However, in planning the initial field, estimation of the quantity of leachable uranium present at levels above the economic grade and grade-thickness limitations is a priority task. (The concentration of uranium in the ore, the ore grade, is expressed in units of weight percent. The grade-thickness of the ore is the product of the average grade and ore thickness expressed in units of percent-feet.) These parameters provide a direct indication of the quality and quantity of ore. They are determined from gamma logging of closely spaced drill holes (50 to 100 foot centers being typical) accompanied by uranium core analysis or direct uranium assay logging. Gamma- logging measures gross gamma radiation which emanates from uranium decay products and indicates only the possible presence of uranium. Direct uranium assays are necessary to confirm this presence and the true location and quality of the reserve. From this information, an estimate of the in-place uranium reserve is formulated. Utilizing the above data, we begin to assess the quantity and quality of the leachable reserve. Analysis of self-potential and resistivity logs in conjunction with uranium logs will identify those zones which contain uranium and display apparent high permeabilities. Similarly, zones with extensive calcite cementation or dense clay sedimentation are located and uranium within such zones is excluded. (Interpretation of these logs should be confirmed

Jan 1, 1980

By J. D. Forrester

Many have been prone to credit the decline of professional interest in some branches of mineral industry education to the industrialists and other agencies who use our graduates. We hear the cry that industrial salaries are too low, opportunities for advancement do not exist, and the mineral industry specifically and generally is not interested in the engineer's efforts. Perhaps the time now has come when we should "dress-ranks," examine our practices, and publicize and encourage advanced technical training instead of laying all our troubles elsewhere. There can be no doubt but that industry is interested and stands ready and willing to co-operate. This is demonstrated by the numerous grants-in-aid and co-operative industrial projects which have been made available to those relatively few schools which have been encouraging graduate study and research. There is no dearth of research problems in any of the mineral industry fields and the sooner we realize the great opportunities for constructive, technical research in all areas of our profession the sooner we will reap the benefits of our engineering enterprises by closer liaison and broader understanding with industry. An analysis is offered here of the status of graduate work and research in various phases of mineral industry education in the United States. It is

Jan 1, 1949

By Russell B. Cornell, William B. Plank

AT the close of the academic year 1940-'41 the largest number of students ever recorded received their first or bachelor degree in the mineral technology schools of the United States. The total of men thus prepared to enter their professional careers in the mineral industries was 1601, a number nearly 12 per cent larger than two years ago and nearly 75 per cent larger than four years ago. Notwithstanding this increase in the number of graduates and as had been predicted in the preliminary report in February, there was a slight decrease in the total student population of the schools in both the United States and Canada. During the college year 1940-'41, 9133 students were enrolled in the 54 schools of the United States and 764 in six of the seven schools of Canada.

Jan 1, 1941

By Edmund Davenport

THE specific aim of this work has been to study certain forms of internal deterioration which occur in tungsten filaments when subjected to high temperatures under various conditions, and to determine the cause of such deterioration. This would naturally lead to a consideration of methods of control or means of prevention of the phenomena. The deterioration was first noticed as a peculiar condition in the grain boundaries of certain tungsten filaments which had been burned? for long periods in lamps. In these cases it was noted that the grain boundaries contained a number of minute black dots which were at first thought to be non-metallic inclusions. It was demonstrated later that these dots or pits, as they were designated, could be readily produced by burning filaments in an atmosphere of flowing hydrogen. This method was convenient and adequate for the purpose, and was adopted for most of the work discussed in this paper. The evidence accumulated to date indicates that these pits are actually small voids between the grains. The purpose of this paper is to present- the information on this interesting subject gathered during a period of about 3 years. As applied to tungsten, the subject appears to be of considerable importance, experience having shown that this pitting ?is frequently associated with poor performance of filaments in lamps. The question has arisen as to whether these intergranular pits are peculiar to tungsten, or if they occur in all metals. If they are found iii all metals, the facts will be of considerable theoretical interest, as the material at the grain boundary plays an important part in most of the current theories of the properties of metals and alloys.

Jan 1, 1927

By Davenport, Edmund S.

THE specific aim of this work has been to study certain forms of internal deterioration which occur in tungsten filaments when subjected to high temperatures under various conditions, and to determine the cause of such deterioration. This would naturally lead to a consideration of methods of control or means of prevention of the phenomena. The deterioration was first noticed as a peculiar condition in the grain boundaries of certain tungsten filaments which had been burned t for long periods in lamps. In these cases it was noted that the grain bound aries contained a number of minute black dots which were at first thought to be non-metallic inclusions. It was demonstrated later that these dots or pits, as they were designated, could be readily produced by burning filaments in an atmosphere of flowing hydrogen. This method was convenient and adequate for the purpose, and was adopted for most of the work discussed in this paper. The evidence accumulated to date indicates that these pits arc actually small voids between the grains. The purpose of this paper is to, present the information on this interesting subject gathered during a period of about 3 years. As applied to tungsten, the subject appears to be of considerable importance, experience having shown that this pitting is frequently associated with poor performance of filaments in lamps.

Jan 1, 1927

By R. S. French

THE purpose of this paper is to present data that have been obtained during the past two years concerning the effects of prior cold-work and temperature and time of anneal upon the recrystallization and grain growth of 70-30 cartridge brass. It was desirable to study certain of these phases so that an accurate picture of the principles of the subject could be shown. The work is not intended to provide explicit annealing data, but to provide material examples that may help to clarify analogous problems concerning this alloy. Specifications often set limitations upon the grain size of annealed materials because of the importance of grain size upon subsequent manufacturing operations. It was, therefore, worth while to study the variables that affect the recrystallized grain size of this material. C. H. Mathewson and A. Phillips,1 W. R. Webster,2 and others have presented annealing characteristic curves of this alloy. A recent typical curve presented by R. S. Pratt3 is shown in Fig. I. The tensile properties and grain sizes are shown as functions of the annealing temperature. Such curves serve as a useful guide in determining the physical properties of annealed material, but as they are made generally under carefully controlled laboratory conditions they do not indicate the performance of metal annealed in a mill muffle, where conditions are different and the amounts of metal require necessarily longer heating times and temperatures. Study of the effect of time and temperature upon grain growth and subsequent recrystallization was made with a coil of metal having the following analysis: 70.04 per cent copper; 0.007 lead; 0.007 iron; 0.00 tin; 0.00 silicon; 0.001 nickel; 0.000 phosphorus; balance zinc. The sample coil was obtained from metal that had been rerolled from hot-rolled mill stock, and was received at 0.228-in. gauge, soft, with a grain size of 0.125 mm. This material was then rolled 43.5 per cent to 0.125-in. gauge and annealed to a 0.053-mm. grain size. In this condition, samples were cut and used in all of the experimental work reported in this paper. TIME The first study was of crystal growth at a constant temperature over a moderate length of time. Material was cut from the stock coil at 0.129-in. size and rolled 75 per cent hard to 0.032-in. gauge. From this piece small samples were cut ½ by 2 in., suitable for grain-size determinations. Twelve samples were placed in an electric furnace uniformly across the width, approximately an inch from the floor, A thermocouple was wired to the center sample, so that the approximate metal temperature could be followed. At various

Jan 1, 1944

By William D. Manly, John Towers, Paul A. Beck

RECENT work on grain growth in high purity aluminum and in a solid solution type alloy of aluminum and magnesium' showed that the isothermal increase of the average grain diameter D with time follows the equation [D = K(to + A)-Eq I] Here [to] is that portion of the total annealing time [t], which is available for grain growth, i.e. the annealing time less the time necessary for complete recrystallization. The parameters A and n depend only on the temperature. A has the dimension of time, and is usually of the same order of magnitude as the time for recrystallization: R. In some instances R may be substituted for A in Eq I. This is the case for example at long periods of annealing or at high temperatures, where both A and R become small in comparison with t. In such instances Eq I is simplified to [D-K-tnEq2] For high purity aluminum the exponent n increases in the ratio of about 1 to 5 in the temperature range of 350° to 600°C. 70-30 brass has been long known to exhibit grain growth of the continuous type, such as occurs in pure metals. For this reason, it was of interest to determine whether grain growth in brass also follows Eq I and 2 as it does in aluminum. Isothermal grain growth data for 70-30 brass were published in recent years by R. S. French2 and by H. L. Walker3 Fig I shows a log D vs. log t plot of French's data, together with the 500, 600 and 100°C data by Walker for 42.8 pct reduction by rolling. In such a log D vs. log t plot Eq 2 corresponds to a straight line with a slope of n. As seen in Fig I, the data of French and the 600°C data of Walker can be represented by straight lines. However, the 500 and 700°C data of Walker give curved lines and the average slope of his 500°C line is very different from the slope of the line representing French's data for the same temperature. Furthermore the curvature of the 700°C line suggests a tendency for grain growth to stop after 8 hr. If confirmed, this would constitute a definite deviation from Eq 2, not explainable on the basis of the specimen thickness effect found in high purity aluminum.1 Walker's specimens were 0.125 in., i.e. 3.18 mm thick, while the deviation occurs at a grain size of approximately 0.4 mm. A further point of divergence arose recently, when J. E. Burke suggested4 on the basis of Walker's data, that, instead of Eq 2, grain growth in 70-30 brass follows the equation [D-D. =K• t,Eq3] Here D, is the grain size as recrystallized at the temperature in question. Although it was possible to show5 that, for pure aluminum, for which isothermal grain growth has been carefully investigated, Eq 3 is incompatible with the experimental facts, the situation remained somewhat obscure with respect to 70-30 brass. In view of the discrepancies between the

Jan 1, 1948

By F. G. Smith

A FEW years ago, the writer encountered a, problem that, at first, seemed to be due to peculiar conditions affecting grain growth. Large cups made from heavy metal failed in the first drawing operation in the process of making seamless tubes. The metal, as cast, appeared to be sound and strong; it rolled successfully and withstood the first cupping operation, but on the first draw it failed, with a crystalline fracture. The failure appeared in the slightly worked part of the bottom of the cup, and microscopic examination revealed exceptionally large grains. Knowing the general conditions governing recrystallization of brass, which were later published by Matthewson and Phillips, an investigation was outlined with the idea of including various conditions under which new grains might form, and which would include the effect that a previous anneal might have upon the anneal following. These conditions were produced by annealing specimens of brass at five different temperatures, indenting them with a 10-inn. ball under four different pressures, and then reannealing at each of the five temperatures five specimens each of which had been annealed at one of the five temperatures.

Jan 8, 1919

F. G. SMITH.-Probably someone will ask whether I discovered why the bottoms of the large shells broke out. I did not, as a result of this investigation. An experiment was made along the lines indicated in this paper, to determine whether abnormal grains greatly affected the physical properties of brass. Two ordinary test bars were annealed for 1/2 hr. at 750° C. and physical properties determined on one. The other was covered with indentations made with a peen hammer and then reannealed. for 5 hr. at 750° C. It was found in the tensile test to be made up of large grains 1/4 to 1/2 in. in diameter. The physical properties, however, differed from those of the first bar only as much as might be expected after a 5 hr. anneal under normal conditions. It appears then that the large grains produced in this manner do not ruin the physical qualities of the brass.

Jan 12, 1919

By M. L. Holzworth, Joseph C. Kremer, Paul A. Beck, L. J. Demer

FOR alloys which are in practice heat treated to obtain increased strength, such as steels, duralumin, copper-beryllium, and others, the treatment usually involves heating to a relatively high temperature. At such temperatures the grain size of the product is largely determined by grain growth. Even in metals and alloys annealed merely to relieve work hardening, recrystallization is generally followed by a certain amount of grain growth. Thus, effective grain size control, which is often of great practical importance in manufacturing processes, depends on the grain growth behavior of the material used. Despite its importance, grain growth has been the subject of few investigations of a fundamental nature. The term "grain growth" has been used to designate a group of related, but distinctly different, phenomena. The two most important and best known of this group are illustrated by the following example. Curve a in Fig r shows the increase of the average grain size of a copper-beryllium alloy, containing 2 pct Be and 0.15 pct Co, with increasing annealing temperature. The time of annealing was 2 hrs. The grain size was quite uniform in all specimens. The results of a similar experiment with an alloy containing 2 pct Be and 0.31 pct Co are shown by curve b. It is seen that for any annealing temperature below T. the grain size was smaller than in the previous case. Grain growth became slower with the higher Co content. This "inhibiting" effect of the higher Co addition was associated with the appearance in the microstructure of fine, light blue particles of the CoBe phase. Up to temperature T. the structure of the inhibited alloy (curve b) was just as uniform as the structures represented by curve a. However, after annealing at T, or at higher temperatures, the inhibited alloy showed some extremely large grains (much larger than the grain sizes developed by the uninhibited alloy with low Co content) mixed with the small grains according to curve b. The presence of these mixed or "duplex" structures is indicated in Fig 11 by the vertical lines branching off curve b. The type of grain growth occurring in uninhibited Cu-Be alloys (curve a) has has been most frequently and best investigated in brass. This type has been designated as "normal grain growth," while the grain growth phenomena occurring in inhibited materials were, at times, referred to as "abnormal grain growth." However, since the latter term has been applied occasionally to the phenomenon of critical recrystallization, which also results in large grains although by an entirely different mechanism, in the present paper a different nomenclature has been adopted in order to avoid confusion. Typical of the grain growth in uninhibited metals and alloys is the continuous

Jan 1, 1947

By Floyd C. Kelley

THE literature of the last decade is rich with information relating to the cause and means of control of grain growth in pure metals, but is deficient concerning the role diffusion plays in grain growth, although during this period many new products that depend on diffusion for their properties and success have been developed. Among these are cementation products, produced by calorizing, chromizing, and carbonizing, or by mixing, pressing, and sintering powdered metals such as Syke's iron-molybdenum die material, Genelite, and Elcon Metal (copper, tungsten) etc. This is a fertile field for new developments, but before it can be utilized to the fullest extent there must be a thorough investigation of the processes by which diffusion and grain growth take place. Grain growth plays no small part in the process and certainly the physical properties of these products depend largely on the grain size and state of equilibrium produced. The field of investigation does not end here, but may be extended to the effect of diffusion on impurities, segregations and dendrites in the broad field of ferrous and non-ferrous metallurgy. A number of years ago the author investigated several of these cases and noted, with striking regularity, the pronounced effect of diffusion in promoting recrystallization and grain growth. An example of this phenomenon is given in his paper on chromizing1 which contained photomicrographs of large radial or columnar crystals produced by diffusion of chromium in the solid state. Another manifestation of this effect was discussed by Austen,2 who showed the part hydrogen plays in the decarburization of steel and the effect of diffusion upon the grain structure. DIFFUSION OF METALS IN IRON It seems to be a general law, whenever two metals are brought into intimate contact at a temperature at which diffusion takes place, that a comparatively rapid, or abnormal, grain growth results. The grains

Jan 1, 1928