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By H. I. Morrison, A. J. deVilliers, D. T. Wigle, H. Stocker

INTRODUCTION At the end of 1959, high levels of radioactivity attributed to radon and its daughter products were discovered in the fluorspar mines at St. Lawrence, Newfoundland. These levels were presumed to be the cause of an unusually high incidence of lung cancer among the fluorspar miners (deVilliers & Windish, 1964) (Parsons et al. 1964). The mining of fluorspar (calcium fluoride) began in 1933 as open pit operations but converted to standard underground mining procedures in 1936. During the second world war, production was greatly expanded as a result of increased demand for fluorspar used in the production of steel. Wet drilling was first introduced into general use in 1942. Ventilation was mainly by natural draft occasionally supplemented by small blowers. The amount of ventilation varied greatly between mines as well as over time. For example, one large mine, the Iron Springs mine, had only a single small raise to the surface some 600' from the central shaft. Other mines, such as the Director mine, had a number of raises to the surface and, as a result, had far better ventilation. Mines also varied by the amount of ground-water which seeped into them. In the early 1950's, an unusually large number of lung cancer cases were diagnosed among the fluorspar miners. As a result, in 1956 and 1957, J.P. Windish of Canada's Department of Health and Welfare tested for possible causative agents in the mines. Unfortunately, radon measurements were not conducted until 1959 and 1960 when Windish tested Director mine as did the A.D. Little company in 1960. As a result of the high radon levels found, mechanical ventilation was introduced and the concentration of radon dauthers fell, on the average to well below 1 WL. During this period, lung cancer cases continued to be diagnosed with 29 lung cancer deaths recorded by 1964 and 71 by 1971. As of July 1981, 105 lung cancer cases had been identified (Hollywood, 1981). Previous reports concerning the fluorspar miners have dealt in detail with the factors in the occupational environment and discussed occupational mortality patterns. The purpose of this paper is to review further the mortality experience with particular reference to lung cancer in relation to cumulated radiation exposure and to describe briefly our ongoing study of this group. METHODS Occupational histories were prepared for men who had been employed by the mining companies at St. Lawrence during the period 1933 to 1977. The histories were compiled from company records except for the period 1933 to 1936, records for which were lost in a fire; however, the occupational histories for this period were completed by searching census records and interviewing company officials, ex-employees and others. In addition, occupational and smoking histories were also obtained for some miners during a survey conducted in 1978. Occupational records included name and date of birth as well as the type, place and hours of work by year. For each year prior to 1960, hours of work were converted to working months (1 WM = 167 hours) and were multiplied by the estimated average radon daughter concentration in working levels (WL) to yield the annual radiation exposure in working level months (WLM). Pre-1960 radiation levels were estimated on the basis of the history of mining methods employed, ventilation history of the mine, type and place of work and conditions under which the first radiation measurements were made in 1959 and 1960 (deVilliers and Windish, 1964). During the period from 1960 to 1967, the average exposure was about 0.5 WL. Beginning in 1968, radiation levels were measured more frequently, and, beginning in 1969, daily exposures for each worker were recorded based on radiation levels in the place worked on a given day. Mortality data were obtained from medical certificates of death. In a small number of cases, medically certified death certificates were unavailable. In these cases, probable cause of death were obtained from forms completed by the local clergyman (returns of death), parish records, information obtained from interviews with family members of the deceased and/or hospital information, before assigning a cause of death. Data obtained from these sources were found in Tables 1, 2 and 4, cover the time period 1933 to 1971. Data in Table 3 as well as in Figures 1 through 3 cover deaths from 1933 to 1977, and includes only those miners for whom medical certificates of death were available. Two medically certified causes of death were changed from other causes to lung cancer on the basis of pathology reports.

Jan 1, 1981

By I. L. Dillamore

I. L. Dillamore (University of Birmingham)—The different textures developed in various fcc metals have long awaited satisfactory explanation and it has now become clear that these differences are related to parallel differences in the deformation characteristics of the metals. Liu is correct, therefore, in seeking to account for the observed textures in terms of the flow mechanisms but I believe, for the reasons outlined below, that the particular interpretation of flow mechanisms proposed by Liu is open to substantial objections. By considering the forty-eight possible designations of the twelve octahedral slip systems found in fcc metals as distinct and separate deformation modes, Liu has fallen into the error of assuming that only positive glide dislocations associated with each system are present. In fact both positive and negative dislocations will be present and the only difference between for instance the systems B4 and B4' (in Liu's notation) is that under a stress of given sign the direction of motion of a dislocation is reversed on changing from B4 to B4'. For both orientations positive and negative dislocations will be present. In considering possible dislocation interactions it is, therefore, inadmissible to differentiate between R4 and R4' as Liu does. Liu considers those dislocation interactions which give the biggest reduction in energy to be the most favorable and neglects, on the grounds that they will form strong barriers to slip, interactions between dislocations with perpendicular Burgers vectors. Setting aside interactions between positive and negative dislocations of the same slip system, which must occur regardless of the combination of slip systems chosen, the biggest reduction in energy occurs for the Lomer-Cottrell interaction and it is Lomer-Cottrell barriers which are thought to provide the stronger dislocation obstacles. On the other hand the intersection of dislocations with perpendicular Burgers vectors is thought to be a low-energy process which contributes only a fairly small temperature-dependent part of the total work hardening. On this basis it seems doubtful whether the reduction in energy through possible dislocation interactions provides a reasonable criterion for choosing the operative slip systems. From the point of view of texture development it is unsatisfactory to ignore the slip rotations leading to an end position and to neglect to consider the stability of the chosen end point. It is also unsatisfactory to treat the two stress axes as interchangeable since, if the stress system is idealized as biaxial, one stress is compressive and the other is tensile. For the same reason the rotations of the two stress axes are not made compatible simply by assuming that the same slip directions are responsible for the rotations of the two stress axes. It is, in short, essential to treat the two stress axes as acting together on the same slip systems. Turning to the question of the difference between the copper-type and the brass-type texture, there now remains little doubt that the difference is attributable to differences in stacking-fault energy (y), as noted by Liu, but it is doubtful whether the temperature dependence of the texture in copper and in silver is due to increasing stacking-fault energy with increasing temperature. The results of Swann and Nutting42 cited by Liu were obtained in Cu-A1 alloys and the apparent increase in stacking-fault energy on raising the temperature may be influenced by short-range ordering. In pure metals such effects are absent and the only data available on the variation of y with temperature are those of Buhler et a1.43 for silver. They report a minimum at 200°C which does not fit the hypothesis put forward by Liu. It is much more likely that thermal activation of cross slip is important in determining which texture develops, as proposed by Dillamore and tors. These workers have proposed an explanation for the differences in observed texture among the fcc metals and the pole figures predicted consist of an orientation spread which is in better agreement with observation than the limited number of discrete orientations suggested by Liu. The theory of Dillamore and Roberts is also able to account for the differences between aluminum and copper which Liu still leaves unexplained. Y. C. Liu (author's veply)—The writer appreciates the interest of Dr. Dillamore, but must discuss some of his comments in order to avoid cross purposes. The phrase, "forty-eight slip systems," which appeared twice in the text—in the caption of Fig. 1 and the first paragraph in the Discussion—might unfortunately have led Dr. Dillamore to disagree

Jan 1, 1965

By Robert L. Slobod

In much of the work reported in the literature on long cores. true connate water value, probably have not been obtained because of insufficient flow of 011 to attain equilibrium. A -.satisfactory method for establishing connate water in long cores has been developed in which oil flow is maintained until no additiona1 water is displaced. INTRODUCTION Long cores have been used by sev-erals investigators in an effort to evaluate the efficiency of oil recovery for various producing schemes. The effects of many variables such as rate of displacement. pressure drop, volume of displacing medium, gas-oil ratio, inter-facial tension, and others have been investigated, and the merits of gas drive have been compared with water drive. In the older experiments no connate water was used. but in the more recent stndies the philosophy of the experiment calls for a core containing oil and connate water (irreducible water) as the starting point of the experiment. The method generally used to establish this condition in long cores involves dynamic' displacement wherein one or more phases are forced through the core. flow being maintained at a constant rate or at a constant pressure until a steady state is reached wherein there is no change of saturation with time. It is one purpose of this paper to point out that in much of the work reported in the literature true connate water values probably have not been obtained. The reason for this failure is pointed out. and a method for obtaining more reliable connate water values on long cores is presented. It is impossible at this time to completely evaluate the effect on the conclusions in the earlier papers resulting from the failure to obtain true connate water in the long cores, but some data are presented which indicate that serious errors may he present in many cases. MATERIALS AND APPARATUS Cores cut front outcrop sandstones (Strawn. Torpedo, and Elgin sandstones) with permeabilities of the order of 300 md were used. The major experiments were made with a core 18-in. long and 2-in. in diameter. Cores of the same diameter but only 12-in. long were used in a few tests? and in some work a core I-in. in diameter and 11-in. long was used. These materials were all somewhat bentonitic. 'To reduce the effect of such constituents, one of the cores (Torpedo No. 10) on which the most work was performed was acid extracted at the start of the experiment. Brine containing 50,000 ppm chloride and naphtha (Stoddard's Solvent) were used as the water and oil phases, respectively. The core was mounted in a rubber sleeve which forms the inner lining of a brass cylinder. In this arrangement2 the rubber sleeve is forced against the core by applying pressure to water in the annular space between the rubber sleeve and the brass cylinder wall. The core is therefore sealed in rubber so that all fluids introduced at the input end of the core flow through the core. With this equipment the core may be easily removed for inspection and analysis. Also, other cores may be introduced for study with no extra time for preparation such as is required when plastic mounting is used. When pressure or conductivity measurements are desired at intermediate points along tile length of the core, the brass cylinder comprising the outer jacket of the core holder is cut into section, of the desired length. Each section is then made up as an individual unit with its own rubber sleeve (see Fig. 1). The individual units are then butted up against a ring of plastic or other insulating material which carries an electrical contact for resistivity measurements and an opening which can be used for the measurements of fluid pressures. The individual units are forced tightly against the plastic ring separators and held in place with several tie rods. Inlet and outlet end butts of the same diameter as the core and several inches in length are provided to control the introduction and withdrawal of fluids and to complete the arrangement for sealing the core within the rubber sleeve. Fluid flow is maintained either by applying pressure to the liquid confined in a reservoir or by the use of a gear pump. The latter is preferable where continuous flow at a moderate rate over a long time interval is desired since a small volume of liquid can be readily recirculated using filters to prevent plugging of the core. EXPERIMENTAL The oven-dried core is weighed and is then completely saturated with brine

Jan 1, 1950

By J. E. Dorn, S. K. Mitra

The low -temperature tensile and creep behaviors of single crystals of copper were evaluated and analyzed in such a manner as to provide an estimate of the separate contributions of short-and long-range stress fields to strain-hardening. Furthermore, the average force-displacement diagram for thermally activated intep-section of two dislocations was estublished. This diagram plus a knowledge of the variation of dislocation spacing and the long-range back stresses with strain permits on accurate prediction of creep rates. The calculated activation energy for intersection under conditions of a constant strain rate increases linearly with the absolute tempevatus-e as required by theory. AN understanding of the detailed mechanisms for strain hardening constitutes one of the principal unsolved problems in dislocation theory. Two major models for strain hardening have been advanced in the past. The one that has received greatest attention assumes that strain hardening arises exclusively from long range interaction stresses between moving dislocations and piled-up arrays of blocked dislocations on the slip planes. This type of interaction was first announced by Taylor' who revealed that the back stress fields due to a simple uniform array of positive and negative dislocations entrapped in the deformed crystal would result in parabolic hardening. Shortly thereafter Andrade and Henderson" demonstrated that the strain hardening of fcc single crystals was not parabolic, as previously thought, and finally it was recognized that a typical stress-strain curve consisted of three successive stages of deformation, niz., the easy glide, Stage I, linear hardening, Stage 11, and the parabolic hardening, Stage 111, ranges. The objections to Taylor's somewhat na'ive model, which were presented so forcefully by cottrell; were largely removed by the more realistic details incorporated in Mott's analysis.5 But because Mott's theory for hardening via long range stress fields gave somewhat analogous results to that of Taylor's (inasmuch as it also predicted a parabolic rate of strain hardening whereas the observed rate of strain hardening in Stages I and I1 were linear), it was not widely accepted. Major consideration was therefore given to models, such as those which were advanced by Friedel and seegere that were formulated for the ad hoc purpose of yielding linear rates of strain hardening. The second major thought regarding strain hardening is based on the concept that it arises principally from short-range stress fields due to the interactions between intersecting dislocations. Cottrell and stokes7 showed, several years ago, that the constancy of the flow stress ratio at two temperatures regardless of the strain was inconsistent with the concept that strain hardening arose exclusively from long-range back stresses. The argument that strain hardening was primarily due to local interactions of intersecting dislocations was presented in considerable detail by asinski.' Extending Basinski's method of analysis of the intersection process, Mitra, Os-borne, and dorn recently demonstrated that indeed the strain hardening in aluminum single crystals arises principally from local effects coincident with intersection; however, these conclusions, too, must be modified, as will be shown later in this report. The present investigation, devoted principally to the low-temperature deformation of copper single crystals, was initiated in an attempt to ascertain whether or not the same conclusions arrived at for aluminum also apply to metals, such as copper, which have much wider stacking faults. It was soon observed that the strain hardening in copper could not be attributed exclusively to local effects between intersecting dislocations. Previously no analytical method for arriving at the possible simultaneous contributions of long-range stress fields and localized forces on intersecting dislocations was available; consequently, the separation of these two factors could not be readily accomplished. In the present report a method of estimating the separate contributions of each of these two factors to strain-hardening will be presented. The authors will show that both long-range stress fields of the type contemplated by Seeger and Friedel as well as short-range forces of the type considered by Basinski are responsible for strain hardening in fcc metals at low temperatures. This method of analysis also accounts for, in a satisfactory way, the effect of stress, temperature, and strain on the creep rate under constant stress. Furthermore, in the course of presenting their methods of analysis the authors will also reveal the rather complete agreement of their experimental data with the concepts of the theory for thermally activated intersection of dislocations. INTERSECTION MODEL As shown by seegerl0 the strain rate arising from thermally activated intersection of dislocations is given by

Jan 1, 1962

By H. N. Hall

Various factors must be considered in an engineering evaluation of gravity-drainage reservoirs. Among these are: (1) the effect of producing rate on total oil recovery; (2) the effect upon well productivity and ultimate recovery of the pressure level maintained during the producing life of the reservoir; (3) the economic advantage of full or partial pressure maintenance; and (4) estimate of the rate of gas production and injection and the possible purchase of gas under conditions of full pressure maintenance to ascertain compressor facilities needed. All of these factors can be evaluated only when a reliable method is employed for determining reservoir performance in gravity-drainage reservoirs. The purpose of this paper is to present a general method for calculating the performance of a gravity-drainage reservoir. This method is applicable for conditions of complete pressure maintenance, partial pressure maintenance and normal pressure depletion. Provisions are made to take into account variations throughout the reservoir of reservoir configuration, changes in permeability and fluid composition. Based on the method presented in this paper, an IBM 650 computer program has been developed. The past performance of an actual gravity-drainage reservoir producing under conditions of declining pressure and no gas injection was duplicated using this program. INTRODUCTION In tilted reservoirs the production of oil is influenced by drainage of oil from upstructure to downstructure locations. When this downstructure drainage of oil is sufficient to cause effective segregation of the gas and oil in a reservoir, the reservoir is usually classified as a segregation drive or gravity-drainage reservoir. (Discussion will be restricted to gravity-drainage reservoirs which have no encroachment of edge water.) The important feature in gravity-drainage reservoirs is the density difference between reservoir oil and gas. These phases tend to segregate in the reservoir with the result that in the gas cap the oil saturation is maintained at a higher level by drainage of oil from the gas-cap area. Oil can be produced from the oil zone at a low gas-oil ratio and reservoir energy is thereby conserved. The standard material balance in not adequate for predicting gravity-dramage reservoir performance because it does not take into account the difference in saturation above and below the gas-oil contact. Several authors'.' have presented methods for calculating the performance of gravity-drainage reservoirs in which reservoir pressure is maintained constant by gas injection into the gas cap. Using some simplifying assumptions, these methods can be employed with a desk calculator to give acceptable results. The problem of predicting the performance of gravity-drainage reservoirs under the conditions of declining reservoir pressure is many time more complex than that of constant pressure. fierefore, attempis to develop a method suitable for desk calculation have required excessively simplified assumptions. In the past several years, highspeed digital computers have become more widely available for reservoir engineering problems. These corn puters are well suited to problems such as the prediction of the performance of gravity-drainage reservoirs with pressure decline. Many of the simplifying assumptions necessary for hand computation can be eliminated so that a realistic approach to the gravity-drainage process can be made. CONCEPTUAL PICTURE OF OIL MOVEMENT IN GRAVITY-DRAINAGE RESERVOIRS Before attempting to develop an analytical treatment for conditions occuring in a gravity-drainage reservoir, a concept should be formed concerning the movement of fluids in the reservoir as oil is produced. A review of the literature'.' shows that it is customary to classify gravity-drainage operations into two categories—(1) with complete pressure maintenance, and (2) with declining pressure. The same line of reasoning will be followed in presenting the concept of the movement of fluids in the reservoir because it is easier to visualize the movement of fluids under conditions of complete pressure maintenance. After discussing complete pressure maintenance, an analogy will be made between that and the case of declining pressure. It should be kept in mind throughout that the final aim for the problem of solving gravity-drainage performance with digital computers will be to develop a general program for any kind of gravity-drainage reservoir. COMPLETE PRESSURE MAINTENANCE One feature which is generally common in gravity-drainage reservoirs is a gas cap located at the top of the structure. This is shown in Fig. 1(a). Fig. l(b) shows oil saturations that might occur through the reservoir. In the gas cap, oil saturation is lower than

By A. A. Venghiattis

A rational approach to the selection of the appropriate perforator to use in each specific zone of an oil well is presented. The criteria presently in use for this choice bear little resemblance with actual down-hole condilions. These environmental conditions affect the elastic properties of rocks. One of these elastic properties, acoustic velocity, is suggested as the leading parameter to adopt for the choice of a perforator because, being currently measured in the natural location of the formation, it takes into account all of the effects of compaction, saturation, temperature, etc., which are overlooked in the laboratory. Equations and curves in relation with this suggestion are given to allow the prediction of the depth of perforation of bullets and shaped charges when an acoustic log has been run in the zone to be perforated. INTRODUCTION When an oil company has to decide on the perforator to choose for a completion job, I wonder if it is really understood that, to date, there is no rational way of selecting the right perforator on the basis of what it will do down-hole. This situation stems from the fact that the many varieties of existing perforators, bullets or shaped charges, are promoted on the basis of their performance in the laboratory, but very little is said on how this performance will be affected by subsurface conditions such as the combination of high overburden pressure and high temperature, for example. The purpose of this paper is to show the limitations of the existing ways of evaluating the performance of perforators, to show that performances obtained in laboratories cannot be extended to down-hole conditions because the elastic properties of rocks are affected by these conditions and, finally, to suggest and justify the use of the acoustic velocity of rocks, as the parameter to utilize for the anticipation of the performance of a perforator in true down-hole environment. EVALUATING THE PERFORMANCE OF A PERFORATOR It is natural, of course, to judge the performance of a perforator from the size of the hole it makes in a predetermined target. Considering that the ultimate target for an oilwell perforator is the oil-bearing formation preceded in most cases by a layer of cement and by the wall of a steel casing, the difficulties begin with the choice of an adequate experimental target material. For obvious reasons of convenience, the first choice that came to the mind of perforator designers was mild steel. This is a reasonable choice for the comparison of two perforators in first approximation. Mild steel is commercially available in a rather consistent state and quality, and is comparatively inexpensive. The trouble with mild steel is that it represents a yardstick very much contracted; minute variations in depth of penetration or hole diameter and shape may be significant though difficult to measure. The penetration of projectiles in steel being a function of the Brinell hardness of the steel (Gabeaud, O'Neill, Grun-wood, Poboril, et al), it is often difficult to decide whether to attribute a small difference in penetration to a variation on the target hardness or to an actual variation on the efficiency of the projectile. Another target material which has been widely used for testing the efficiency of bullets or shaped charges in an effort to represent a formation—a mineral target as opposed to an all-steel target—is cement cast in steel containers. This type of target, although offering a larger scale for measuring penetrations, proved so unreliable because of its poor repeatability that it had to be abandoned by most designers. The drawbacks of these target materials, and particularly their complete lack of similarity with an oil-bearing formation, became so evident that a more realistic target arrangement was sought until a tacit agreement was reached between customers and designers of oilwell perforators on a testing target of the type shown on Fig. 1. This became almost a necessity about seven years ago because of the introduction of a new parameter in the evaluation of the efficiency of a perforator, the well flow index (WFI). The WFI is the ratio (under predetermined and constant conditions of ambiance, pressure and temperature) of the permeability to a ceitain grade of kerosene of the target core (usually Berea sandstone) after verforation. to its vermeabilitv before perforation. The value of this index ;or the present state if the perforation technique varies from 0 to 2.5, the good perforators presently available rating somewhere around 2.0 and the poor ones around 0.8, There is no doubt that, to date, the WFI type of test is by far the most significant one for comparing perforators. It is obvious that a demonstration of a perforator

By J. L. Gillson

Historically, rock deposits and sand deposits of titanium minerals came into production about the same time, although there may be some argument as to what is meant by production. Beach deposits of heavy minerals in India (Figs. 1-4) and Brazil (Figs. 5) were worked for monazite about the turn of century, but as there was then no market for titanium minerals, these were thrown away. The rock rutile deposits at Roseland, Va., Fig. 6, were worked to supply rutile for titanium chemicals and for coloring ceramics long before there was a titanium pigment business. The pigment industry started about the middle twenties, both in Europe and the U. S., and almost simultaneously the rock deposits at Ponte Vedra Beach near Jacksonville, Fla., were worked for titanium content. Since those days, production from both types of deposits has continued to grow at a rapid rate; many deposits of both types have been found, and reserves have grown to very large figures. In total tonnage of reserves, there is no doubt that the rock deposits are far ahead of the sand deposits; nevertheless there is a very large tonnage of commercial sands available. It is the quality of titanium mineral in the sand and the relatively lower costs of operating sand deposits that have kept them abreast, at least in annual tonnage produced, with the rock deposits. The principal titanium mineral used is ilmenite, but as soon as that mineral began to be sought as a titanium ore, it was obvious that there are ilmenites and ilmenites. Textbook ilmenite should have the composition FeOTiO2 and should analyze 52.6 pct TiO2 and 36.8 pct iron as Fe. The Indian ilmenite, for almost a generation the standard ore for manufacturing pigment in the U. S., was found to analyze about 60 pct TiO, and only 24 pct. Fe, and most of the iron is in the ferric condition. The whole process of pigment manufacture in the U. S. was built up on the use of a raw material of that grade, and the American chemical engineers who operate the pigment plants shuddered at the thought of using a rock ilmenite with 45 pct or so of TiO, and nearly 40 pct Fe. Intensive search was made around the world to find other deposits of rich black sand, like the Indian beaches, but although a few were found, there was some objectionable feature about each. A deposit in Senegal, south of Dakar (Fig. 7), was worked for a while, but an organic coating on the grains made attack by acid difficult. Modern practice would have included a scrubbing operation, in a caustic soda bath, to eliminate the organic coating. Brazilian deposits were numerous, but individually small, and shipping from them difficult. Deposits on the east coast of Ceylon had many attractive features, but the ilmenite analyzed only 54 pct TiO2 and could have been used only with a penalty. Sand deposits with 2 pct ilmenite, like those now worked in Florida, would not have been considered commercial ore, even if they had been known at that time. Most rock ilmenites are associated or mixed with hematite or magnetite, which accounts for the lower titanium and higher iron values than in the sand ilmenites. The Norwegians, English, and Germans, with cheap Norwegian rock ore at hand, learned to install in their pigment plants adequate capacity on the black side, as it is calltd, and counterbalanced the extra cost of plant, and larger amount of acid used, by the lower cost of ore. When World War II arrived, two of the largest pigment manufacturers in the U. S. had to learn how to use the Adirondack ilmenite, but one of them very gladly went back to sand ores when the Florida deposits came into large-scale production after the war. The other continues to use Adirondack ilmenite and finds it commercially attractive to do so. Rutile is not a raw material for titanium pigment manufacture by the sulfate process, since it is insoluble in sulfuric acid. In addition to its small consumption in chemicals and ceramics it began to be used in quantity in welding rod coatings. With the outbreak of World War 11, and the tremendous need for welding rods in shipbuilding and other structural steel construction, rutile suddenly became in heavy demand. The sand deposits on the eastern shore of Australia (Fig. 8A) which had been worked in a small way since 1934 were brought into production, and some stream placers in Brazil were worked and rutile concentrates shipped to American

Jan 1, 1960

By J. P. Nielsen, H. Margolin, E. Ence

The Ti-Ni phase diagram has been investigated up to 68 pct Ni with iodide titanium base alloys by metallographic, X-ray, and melting point methods, and from 68 to 90 pct Ni by examination of as-cast structures of sponge titanium base alloys. NVESTIGATION of the nickel-rich portion of the I Ti-Ni phase diagram was first reported by Vogel and Wallbaum in 1938.' This work was subsequently extended to lower nickel contents by Wallbaum' who indicated the possibility of a eutectic reaction for nickel contents below 38 pct. Long et al.3 studied the titanium-rich portion of the phase diagram and found eutectic and eutectoid reactions below 38 pct Ni. However, the temperature of the eutectic indicated by Long et al. was considerably lower than that suggested by Wallbaum. Long and his coworkers synthesized their alloys by powder metallurgical techniques and encountered oxygen and/or nitrogen contamination. Thus the diagram which was obtained did not represent binary alloying conditions. However from these results the features of the binary diagram were predicted. At Battelle Memorial Institute4 the Ti-Ni diagram was investigated up to approximately 11.5 pct Ni with sponge titanium alloys. The range of temperatures used was not sufficient to define the eutectoid temperature or composition. The data of Wallbaum2 and Long et al.8 were of particular interest for the present study, and although the work was originally concerned with the region below 40 pct Ni, the investigation was extended to higher nickel contents in an attempt to resolve the differences between these workers. Experimental Procedure Preliminary work on the Ti-Ni system was carried out with duPont Process A sponge titanium alloys to reduce the amount of subsequent work to be done with iodide titanium base alloys. The sponge titanium used contained 99.71 to 99.77 pct Ti, 0.1 pct Fe and 0.005 to 0.009 pct Ni. The iodide titanium obtained from the New Jersey Zinc Co. contained 99.9 to 99.95 pct Ti. Nickel used with sponge titanium was 98.9 pct pure. The high-purity nickel alloyed with iodide titanium was cobalt-free with approximately 0.05 pct C and was obtained through the courtesy of the International Nickel Co. The 15 g sponge titanium charges for melting were prepared by compacting in a die or by placing the weighed portions of nickel and titanium directly into the furnace. Iodide titanium charges were made by drilling holes in the as-received rod and inserting the nickel or by wrapping the nickel in sheet. Sponge titanium alloys containing from 0.2 to 90 pct Ni and iodide titanium alloys containing 0.2 to 68 pct Ni were prepared by these methods. In addition to these alloys several 1/2 1b sponge titanium alloys were supplied by the Allegheny Ludlum Co. The charges were melted in an arc furnace under an argon atmosphere. The procedures used were similar to those reported in the literature5,' and the furnace has been described.' Except for iodide titanium alloys with 40 to 68 pct Ni (see section on copper contamination), each alloy was melted for 1 min, then either turned over or broken before re-melting for an additional minute. Currents of 200 to 400 amp were used depending on the melting point of the alloy. Prior to heat treatment, alloys containing less than 14.5 pct Ni were hot-forged at 750°C. With the exception of alloys in the homogeneity range of the compound TiNi, alloys of higher nickel contents could not be hot-forged. Heat treatment of iodide titanium base alloys was carried out in argon-filled quartz capsules which were broken under water at the conclusion of heat treatment to quench the specimens. Temperatures were controlled to ±5oC and annealing times up to 48 hr were used. For melting point determination, specimens were placed in carbon crucibles which were in turn en-capsuled in argon-filled quartz capsules. The start of melting was determined by rounding of corners and by metallographic examination. Complete melting was considered to have occurred at that temperature at which the specimen assumed the shape of the crucible. Specimens were prepared for metallographic examination by mechanical polishing or by an electrolytic procedure." For alloys containing up to 80 pct Ni Remington A etch7 50 pct glycerine, 25 pct HNO,, 25 8 HF) was used. For higher nickel alloys aqua regia and Carapella's etch (5 g FeCl,, 2 ml HNO,, and 99 ml methyl alcohol) were employed. Specimens to be exposed for powder patterns were prepared by filing, by breaking specimens in a

Jan 1, 1954

By N. C. J. Ros

The paper deals with pressure gradients occurring in flowing and gas-lift wells, a knowledge of which can be applied to the determination of optimum flow-string dimensions and to the design of gas-lift installations. The study is based on a pressure-balance equation for the pressure gradient. It appears that a pressure-gradient correlation of general validity must essentially consist of two parts-—one part being a correlation for liquid hold-up and the other part being one for wall friction. Dimensional analysis indicates that both liquid hold-up and wall friction are related to nine dimensionless groups. It is shown that in the field of interest only four groups are really important. On the basis of these four groups a restricted experimental program could be selected that nevertheless covered practically all conditions encountered in oil wells. This experimental program has been carried out in a laboratory installation. Three essentially different flow regimes were found. The pressure gradients in these regious are presented in the form of a set of correlations. Comparison of these correlations with a few available oilfield data showed excellent agreement. INTRODUCTION Prediction of the pressure drop in the flow string of a well is a widely known problem in oilfield practice. Accurate data on the pressure gradient of a simultaneous flow of gas and liquid in a vertical pipe are especially useful for the determination of optimum flow-string dimensions. It is well known that with moderate gas and liquid flows such a vertical string acts as a "negative restriction". The pressure drop decreases (1) when the throughput through a given pipe increases, and (2) when at a given throughput the cross-sectional area is decreased. The reason is that, with increasing velocities, the flow becomes more agitated so that the gas slips relatively more slowly through the liquid. With the resulting increase in gas content in the string, the static head decreases. When the area becomes very small, however, the high velocities entail great wall friction, which causes an increase in pressure drop. For a given flow, therefore, minimal pressure drop is obtained by using a certain cross section. This means that, in principle, each well can be provided with an optimum flow string for minimum pressure drop and, hence, maximum possible production rate. The procedure for the selection of the optimum string has been discussed by Gilbert.' A necessary tool in the procedure, however, is accurate knowledge of the pressure gradient to be expected for various values of the governing variables. Another application of pressure-gradient data lies in the field of gas-lift practice: they provide a means of determining the optimum gas-injection rate, optimum injection pressure and optimum injection depth. Much work has already been done in the study of the pressure gradient of vertical gas-liquid flow. Poett-mann and Carpenter2 presented a pressure-gradient correlation based on measurements in wells. This correlation has been found to provide accurate predictions in high-pressure wells and in high-production wells for flow through both tubing and annuli.2-5 However, when their method is checked on low pressure-low production wells or on wells with viscous crudes, serious discrepancies are found. As we shall see in the next section, this is due to the fact that their correlation factor, representing all irreversible energy losses, is given as a function of only one correlation group. Some important variables, such as gas-liquid ratio and liquid viscosity, are not incorporated in this group so that their specific effects are not accounted for. To study also the mechanism of vertical gas-liquid flow outside the ranges covered by the Poettmann-Carpenter publication and extensions, a laboratory investigation has been carried out. This study is founded on a pressure-gradient equation that is based on a pressure balance. To reduce the number of test runs required, a dimensional analysis has been carried out, followed by a selection of relevant dimensionless groups. These groups guided a subsequent experimental study, and with their aid the experimental program could be minimized while still covering the majority of the situations encountered in oilfield practice. In this paper the choice of a formula for the pressure gradient is discussed first. This is followed by a brief description of the experimental setup. Subsequently, the dimensional analysis is discussed and the relevant dimensionless groups are selected, resulting in the experimental program required. The general relationships of pressure gradient and liquid hold-up are then described; various flow patterns and a certain flow instability (so-called "heading") are discussed and a set of correlations is presented which shows a good agreement with the measurements and a few available field

By S. Gstalder, J. Raynal

Consideration was given to simple tests which could be performed on rocks to give a measure of rock drillability. Various methods of breaking rocks were considered and the hardness test developed by Schreiner was selected for this study. The test involves application of an increasing load on the rock face through a flat-faced cylindrical punch until rupture occurs. Test results show that hardness is a good measure of the breaking strength of rocks. Useful relationships are shown to exist between hardness and other physical quantities such as specific disintegration, Young's modulus and sonic velocity. Specific disintegration (volume of rock broken per unit of work input) provides a possible means of comparing the effectiveness of other methods of rock breakage. The relationship between hardness and sonic velocity may be very significant for it may be possible to deduce rock drillability from sonic log data. provided that a mineralogical factor is taken into account. TO test further the results of the work, laboratory drilling tests were performed which closely simulated down-hole pressure conditions. Correlations of drilling results with rock hardness measurements were quite good. It was concluded that rock hardness, as measured in the laboratory or as deduced from sonic logs, could be used in relations for predicting rock drilling performance. INTRODUCTION Drillability of rocks cannot be defined in an absolute manner by a single quantity or measured by a single test. Resistance of rock to drilling depends to a large extent upon the means used for rock destruction. This complicates drillability classification of rocks for there may be as many classifications as there are methods of rock breakage without known functional relations between them. The objective of this work was to develop. in terms of rock destruction behavior, means of selecting the best drilling method for a given rock or the conditions for optimum output from a given drilling method. ANALYSIS OF ROCK DESTRUCTION TESTS Gauthier and Baron' have reviewed the many test methods which have been developed for determining the resistance of rocks to breakage. These include drilling tests, punch tests, scratch tests, resistance to shock, wear tests, etc. A standard drilling test might be to determine the time required to drill a standard depth (1/16 in.) in a rock using a bi-cone microbit (1 1/4-in. diameter) when a standard load (417 Ib) is applied at a standard speed of bit rotation (110 rpm). From the standpoint of similarity, the results of microbit drilling tests would seem to be most representative of the several methods suggested above. However, evaluation of drilling performance by this method is only qualitative and cannot be applied directly to actual drilling conditions. Punch tests basically measure rock hardness. Punches of various shapes and sizes, including small cones for Vickers' and Knoop's tests, the wedge for Epstein's test and the right circular cylinder for Schreiner's test, have been used. Results of these tests lead to a quantitative hardness classification which would seem to be related to the resistance of rock to bit-tooth penetration. Scratch tests are related to the resistance of rocks to abrasion such as would be encountered in drilling with diamonds. Either the width of the scratch obtained at a fixed load or the load required to give a scratch of a fixed width may be used to evaluate surface hardness of the rock. This should be related to the resistance of the rock to wear. The above tests, and probably many others. give relative measurements of the breakage or destruction characteristics of rocks. There is no direct relation between results of these tests and the drillability of rocks. Also, the tests each measure different quantities which have different dimensions and they do not permit direct comparison of numerical values. As one step in rectifying the above difficulties. it is proposed that the results of all test methods be expressed in terms of volume of rock destroyed per unit of work required; this is referred to as "specific disintegration". Test results may then be reported in a form which shows both a classification of rocks in regard to each method and a comparison of methods with regard to each rock. The disadvantage in using specific disintegration is the difficulty of measuring this quantity with accuracy. The volume of rock damage is difficult to measure. as is the true value of work input. Rock heterogeneity adds to the

Jan 1, 1967

By J. L. Huitt, B. B. McGlothlin

The introduction of new fracture propping agents that are brittle but much stronger than sand created the problem of what loading strength is required for a propping agent to be effective in a given formation. It is shown that the load at which the propping agent crushes should exceed the load at which total embedment in the fracture faces is possible. Simple laboratory tests to determine loading strength of the propping agent and embedment in the fracture faces, and use of these data in selecting a propping agent for a given formation, are discussed. INTRODUCTION One of the most important factors in the design of hydraulic fracturing treatments is the selection of a propping agent that can effectively provide the fracture flow capacity needed for stimulation of a well. Sand, once generally accepted as being synonymous with propping agent in hydraulic fracturing, is now recognized as having limited effectiveness in many formations because of its low resistance to crushing. Sand particles are brittle and have relatively low strength. Because of this property, sand particles are crushed in rocks that offer high resistance to the penetration of fracture faces by the proppant particles when the fracture attempts to close under the action of the overburden load. For rocks that offer a high resistance to penetration, deform able particles are more effective propping agents than sand. However, for this same type of rock, a propping agent that does not deform, yet does not crush, is often more effective. Thus, a rigid propping agent with sufficient strength to prevent crushing is desirable. A method for determining the strength required for a rigid propping agent to function effectively in given formations is discussed. BEHAVIOR OF RIGID PROPPANTS AND FRACTURE FACES RELATED STUDIES An early qualitative description of the reaction of propping sand in fractures was given by Hassebroek et al.' In discussing fracturing in deep wells, the authors mentioned that even though propping sand entered the fractures, a high flow capacity did not result due to crushing or embedding of the propping sand. Dehlinger et al.2 in discussing the reaction of propping sand surmised that, because of the hardness of sand particles, deformation occurred in the fracture faces contacting the propping sand. In later studies,3,4 methods of determining the embedment of propping sand in fracture faces of soft rock and the critical load at which propping sand is crushed by the fracture faces in hard rock were discussed. In working with de-formable proppants, Kern et al. considered proppant particles to be deformed into cylindrical disks by action of the overburden and then pressed slightly into the fracture faces by further action of the overburden. Rixie et al.'0 reported on embedment pressure and presented a method of selecting a propping agent for use in given formations. The propping agents included sand, walnut shells and aluminum pellets. All these studies have contributed materially to a better understanding of propping agent behavior; however, the strength of brittle proppants (sand, glass and ceramics) required to result in embedment rather than crushing has not been discussed. This topic will be covered in the ensuing discussion. PROPPANT PARTICLE CRUSHING—-EMBEDMENT For this discussion, a rigid propping agent is considered to be one that is brittle and fails under tensile stress when loaded to a critical value. In an earlier study4 it was shown that the Hertzian4 loading theory could be applied to a spherical brittle propping agent if the propping agent and fracture faces behaved elastically. At the failure of the proppant, the ratio of the load to the square of the diameter of the particle should be constant for a given material combination, or: Lc/dp2=C ............(1) A partial derivation of this equation from proppant and formation properties is included in the Appendix. Should a rigid particle not be crushed as a load is applied, it embeds in the fracture faces. A study3 of particle embedment in fracture surfaces has been published. The embedment can be described by an equation based on Meyer's metal penetration hardness relationships: d1/dp=B 1/2[L/dp2]m/2..........(2) In Eq. 2, B and m are constants that are characteristic of the rock; the significance of the other terms is shown in Fig. 1. A STANDARD DEFINITION FOR PROPPANT LOADING STRENGTH Eq. 1 is useful in appraising propping agent strength," but it is strictly applicable only when the area of contact between a particle and a fracture face (or loading plate)

Jan 1, 1967

By C. R. Sandberg, L. S. Gournay, R. F. Sippel

The effect of fluid-flow rate and fluid viscosity on oil-water relative permeability determinations was studied using the "dynamic flow technique." In this work relative per-nleability curves were obtained for homogeneous small core .samples from several sandstorle outcrop form-utions. Radio-tracers were used for the determination of fluid saturation and for the detection of saturation gradients. Cobalt-60 in the form of cobaltous chloride was used as a water-phase tracer in some of the experiments. Iodine-131 in the form of iodobenzene and Mercury-20-3 in the form of mercury diphenyl were used as oil-phase tracers in other experiments. Flow rates for each phase were varied within a range of 2.5 to 140.6 ml/hr. Oil-phase vis-cosities under flowing condition,> were varied from 0.398 to 1.683 cp. The relative permbilities ob-tained were found to he solely a function of saturation and independent of flow rare, provided there was no .Saturation gradient induced in the core sample by "boundary effect." Even though equilibrium with re-sped to flowing conditions was obtained at the lower flow rates, where a saturation gradient exists, this equilibrium is of a "contingent"-type rather than the "steady-state" equi-librium implicit in the relative per-meability concept. The only effect of increasing the oil or non-wetting phase viscosity was to decrease the flow rate required for the elimina-tion of the boundary effect. Fairly good agreement between experimentally determined and calculated values of the boundary effect was obtained when the non-wet-ring oil phase was the only Flowing phase. INTRODUCTION In the characterization of reservoir rock, as well as in the solution of reservoir production problems, it is most desirable to have reliablc rela-tive permeability measurements for the rock and fluids of interest. Many techniques have been developed for the laboratory determination of the relative permeability of both large and small core samples. In varying degree, difficulties attend the use of all of the methods. Each of the methods requires the metered flow of fluids of known viscosity through the core sample under conditions wherein the pressure drop in the individual flowing phases can be measured or closely approximated. Since the relative permeability is a function of the saturation and distribution of the flowing fluids, some means of obtaining such information is also required. The laboratory determination of the relative permeability of a sample should give the same relative permeability saturation relationship that would exist if the sample were in place in the oil reservoir. The attainment of this objective is complicated by the fact that the use of small core samples for laboratory measurements is usually necessary. As a result, errors in measuring the relative permeability arise from boundary effects at either the fluid input or output ends of the sample; no significant boundary effect is anticipated at the sides of the sample normal to direction of fluid flow. At the input end of the sample a boundary effect exists if the flow fluids are not com- mingled as they would be in the reservoir. At the output end of the sample a boundary effect exists as a result of discontinuity of the capillary properties of the system. Here the flowing fluids leave the small flow channels and enter a collecting system having much enlarged flow channels. Thus, there is a tendency for the wetting phase to be retained by the core sample because of the attraction of the core sample for the wetting fluid. No reference is made to these boundary effects in either Darcy's equation or in the relative permeability concept. As a consequence the saturation effect peculiar to the input end of the core sample may cause an error in the effective permeability measurement, since some portion of the core sample must be utilized for commingling of the flow fluids. At the output portion of the core sample a saturation gradient or a saturation change along the axis of flow results. Since relative permeability is a function of fluid saturation, this saturation gradient may cause a variable permeability measurement, especially since extent and character of the saturation gradient can vary with fluid-flow rate. The most convenient method of minimizing the boundary effect, especially at the output end of the sample, is to flow the fluids of interest through the core sample at such high rates that the capillary forces arc insignificant as compared to the viscous forces involved in the fluid flow. Since recent work of a preliminary nature has indicated that fluid dispersion in the porous medium increases with the flow rate, the high flow minimizes the boundary effect at the input end of the core sample by enhancing the mixing of the fluids.

By David B. McWhorter

Conventional analyses of seepage through saturated media do not apply when tailings impoundments are located above a partially saturated zone. Three stages of seepage are identified and methods for estimating the seepage rates and duration of each stage, based upon flow in partially saturated and saturated porous media, are demonstrated. The effectiveness of earthen liners is discussed and procedures for estimating the required properties of the porous media are provided.

Jan 1, 1978

By James A. Wasson

This Bureau of Mines report summarizes the application of pilot flooding in the evaluation of a potential waterflood project. Aspects of pilot flooding discussed include choice of pilot location, confined and unconfined waterfloods, operational precautions, and comparison of predicted with observed performance. Summaries of published methods of pilot flood data analysis for determination of full-scale waterflood feasibility are presented and their use illustrated for example pilot flood data.

Jan 1, 1974

By Hans W. Schreiber

Most geologic and mining engineering consulting firms* began to experience the recession with declining billing levels, number of inquiries, and proposal requests in late 1981 or early 1982. As of today, most of them have been functioning at reduced income levels for nearly a year. And while many consulting firms have apparently reached a stabilized income level, they can see little prospect for attaining normal (pre-late 1981) billing levels and income for the remainder of 1983. A few firms have escaped being affected by the recession. Such com panies almost without exception are small (fewer than 20 personnel), offer a limited range in technical capabilities, and tend to be highly specialized in a particular niche. They include those specializing in the heap leaching of precious metals ores, in ground water testing programs, and in the derivation of computer-aided programs to monitor particular mineral processing functions. Those firms affected by the economic downturn have instituted a variety of policies and undertaken actions to cope with significantly reduced incomes to bring fixed costs in line with the depressed demand for services. These changes fall into the following broad categories: • management and management practices; • markets and market definition; • marketing and the pursuit of assignments; and • administration and personnel relationships. Not all of the perceived changes have necessarily been instituted by every consulting firm, and any one appears sporadically instituted. Management and Management Practices In favorable times the managers, and often the owners of the equity, of consulting firms tend to concentrate their attention on the part of the business they find most satisfying and enjoyable. For some, this means acting as project or assignment leaders, even undertaking a specific technical aspect of the job. For others, it means constant marketing with the associated heavy travel and entertainment schedules. In unfavorable conditions, such as the current recession, managers tend to spread themselves far more thinly, expending time and effort on all facets of the business including marketing, proposal preparation and cost estimating, budgeting, general administration, accounting and cash flow monitoring, project/assignment overview, and actual client work. The manager who in favorable times concentrated on client work is now less billable. The manager who concentrated on marketing is somewhat more billable. The manager now needs to pay attention to and expend equal effort on each facet of the business just to keep all the facets in relative balance. Falling behind schedule on a client job or carrying an unduly large percentage of accounts receivable exact a cost to the firm. Clearly the absolute cost to the firm is the same whether demand for service is good or slack. But in periods of slack demand the firm is frequently less able or even unable to bear such costs. Marketing and Market Definition Markets appear to have undergone some significant changes: • Federal and state governments have assumed a greater importance as providers of work vis-a-vis both industry and private groups. • Projects with increase-in-capacity aspects have given way to projects with maintenance or reduced operating cost aspects. • Projects searching for new deposits of minerals in generally new locations have given way to projects reviewing known mineral districts or known deposits. • Industrial mineral and mining companies have exhibited a great propensity to cut back the use of consultants and to undertake as much work as possible in-house. Further-more, a number of industrial mineral and mining companies have entered the competitive arena with consulting firms, submitting proposals (usually to the federal government) in an effort to keep their staffs intact and occupied. In response, consulting firms have reevaluated their capabilities by reviewing old work and reassessing personnel. The purpose is to broaden the services offered and the potential client base, thus redefining the available market. For example, a firm specializing in assessment of technical and cost parameters of a deposit would normally assist a prospective lender in judging the deposit's suitability for project financing. That same company could easily expand into the field of analyzing production costs for an individual operation -something that is needed in periods when lower prices reduce profit margins. Similarly, a firm that has confined such economic assistance to commercial banks could expand to provide its expertise to other lending and even equity buying in-stitutions such as insurance companies. Marketing and the Pursuit of Assignments With few exceptions, consulting firms have significantly increased their

Jan 2, 1983

By J. M. Manka

American mining companies operate many drum hoists that hoist from various depths with varying payloads. This paper will review the procedure of selecting optimum wire rope constructions for these existing hoisting installations. Selection for proposed installations along with recommended hoisting parameters will also be presented. To achieve this optimum rope performance, preventative and corrective maintenance procedures will be reviewed along with examples of rope problems and their causes.

Jan 1, 1992

By J. J. Jakosky

The strategic importance of the metallic minerals in our industrial economy, and the declining rates of discovery have focused attention on means of exploration for new mineral deposits. A consideration of exploration techniques leads to an attempt to evaluate the effectiveness of geo- physics as a tool for mining exploration. One means of evaluation will be to compare the use of geophysics in petroleum exploration with its possible uses in mining.

Jan 1, 1949

By Dean H. Ambrose

Computer programs are presented that provide mine electrical systems based on computer modeling for design and safety analysis suitable for large or small computer systems and handheld calculators. Bureau of Mines research has resulted in load-flow, fault, grounding, reliability, short-circuit, transient, and cable ampacity computer models that enable mine power system engineers to analyze their system or to design a system. This report describes the capabilities of the program.

Jan 1, 1984

By Kush Patel

This paper presents methods currently available for the evaluation of bulk explosives and discusses the results of the evaluation of bulk explosives using each of the methods. Through the preliminary experimental analysis, wet chemistry and the Bulk Explosive Analyser were found as methods most suitable for the evaluation of bulk explosives. This paper also presents data obtained from the experimental comparison of the wet chemistry method and the Bulk Explosive Analyser.

Feb 1, 2020

By R. M. Goldhoff, J. W. Spretnak, R. Speiser

IT has been observed by Grange and Garvey' that the homogenization of boron-treated steels could lead to complete elimination of the hardenability effect caused by boron. The experimental conditions leading to this conclusion involved the heating of steel specimens with and without boron at 2350°F for 24 hr. To prevent oxidation and decarburization, the specimens were encapsulated under vacuum in silica tubes. This observation of permanent deterioration of boron effect was noted in both a 0.63 pct plain carbon steel and a 0.25 pct C low alloy steel, both of which had been treated with ferroboron and homogenized at 2350°F for 24 hr. In another series of boron-treated steels which had been homogenized for shorter times, the effect was to reduce, but not completely eliminate, the boron effect. Under these circumstances, it was presumed that longer heating times would cause permanent deterioration of the boron effect in this series of steels also. Since the characteristic grain boundary constituent could not be formed in any of these steels after homogenization, it was concluded that possibly boron was being converted into an ineffective form through chemical combination resulting from prolonged heating at high temperatures. Assuming the validity of this observation, a series of experiments to establish the relationship between temperature of homogenization and kinetics of deterioration was contemplated. Initially an attempt was made to reproduce the results just described. For this purpose commercial lots of AISI 8640 and AISI 86B40 steels were used. The analyses of these steels appear in Table I. Hardenability evaluation was on the basis of the hardness of normalized sections. Grange and Garvey' pointed out that these steels are air hardening to some extent and such a technique can be used. For these tests the specimens were held for 20 min in a salt bath at 1600°F and then cooled in still air. Several evacuated silica capsules containing pairs of the test steels were made up and heated for 24 hr at 2350°F. A number of failures occurred among these capsules, but evaluation of the specimens successfully treated indicated a complete deterioration of the boron effect. However, examination of the surface of the treated specimens showed that some reaction, probably with the silica tube, had taken place, since none of the specimens was bright. One further test was made at 2350°F for 12 hr, using a pair of specimens wrapped in tantalum foil prior to encapsulation. These specimens appeared bright after treatment, and their hardenability evaluation showed that no deterioration had taken place. Since these steels are extremely sensitive to de-boronization at high temperatures and particularly at long times of holding, the experimental observations raised some doubt as to the real occurrence of the permanent deterioration effect. To resolve this question an experiment was undertaken in which the high temperature portion of the treatment was completed in vacuum. For this purpose a molybdenum wound resistance furnace capable of maintaining good vacuum was used. All the pertinent accessories to this furnace were machined from molybdenum stock in order to withstand the high temperature involved in the experiment. With this equipment a temperature of 2400 °F was obtained and held under a pressure of 5x10-" mm Hg for 24 hr. A specimen of each of the two test steels was suspended in the furnace and both were heated simultaneously. Temperature was measured with a standardized Pt—Pt-13 pct Rh thermocouple, whose millivoltage at 2400°F was extrapolated from the standardization equation, good up to 2200°F. The complete evaluation of these specimens is shown in Table 11. The hardness values attained by each steel after normalizing, both before and after the prolonged high temperature treatment, remain the same. A microscopic study of the decomposition products present in the microstructures of specimens at various points in the heat treatment correlated with the hardness values observed. It seems that no permanent loss of boron hardenability effect occurs, at least in these Grainal-treated steels, when deboronization is circumvented. Acknowledgments This work was conducted under the sponsorship of the Aeronautical Research Laboratory, Wright Air Development Center, under Contract No. AF 18(600)-94, and their support and permission to publish is gratefully acknowledged. A note of thanks is also extended to the Republic Steel Corp. for supplying the materials used in the work. References ' R. A. Grange and T. M. Garvey: Factors Affecting the Harden-ability of Boron Treated Steels. Tro.ns. ASM, 1946, vol. 37, p. 136.

Jan 1, 1957