Search Documents

By J. Weertman

An explanation is advanced for the recent results of Barrett and Sherby on the high-temperature creep of fee metals. Their measurements indicate that metals with a low stacking fault energy creep at a much slower rate than metals with a high stacking fault energy. The explanation is based on the assumption that the rate of core diffusion is much smaller in partial dislocations than in perfect dislocations. An experiment is suggested to test this assumption. The explanation also requires that the jog density is small on widely split dislocations. SHERBY and Barrett1,2 recently established an important result in the field of high-temperature steady-state creep. They have shown that fee metals whose dislocations split into partial dislocations separated by a wide stacking-fault ribbon creep at a much slower rate than fee metals whose dislocations are not split appreciably. The creep rates in the two cases may differ by a factor as high as 6000. (For the purpose of comparison, the test temperature of each metal was chosen so that its rate of self-diffusion was equal to a standard value. Similarly the stress levels were such that the ratio of the stress to an appropriate elastic modulus was the same for each metal. In all cases the stresses were sufficiently low that the steady-state creep rate was proportional to the stress raised to a power.) It is the purpose of the present paper to attempt an explanation of this interesting and significant result of Sherby and Barrett. The activation energies of high-temperature creep of the metals tested by Sherby and Barrett (aluminum, nickel, copper, and silver) were equal to their self-diffusion activation energies. Hence it appears reasonable to assume that this type of creep is controlled by a dislocation-climb process, which in turn is controlled by the diffusion of vacancies to or from dislocation lines. (It will be assumed that the diffusion of interstitial atoms is unimportant in the climb process. The analysis could be repeated for the case in which interstitial atoms are important.) In prior papers374 I have treated dislocation climb by using the assumptions that core diffusion is extremely fast down a dislocation and that a dislocation always maintains an appropriate vacancy concentration in its immediate vicinity. In this

Jan 1, 1965

FREderick H. Davis, Electrical Engineer of the Westinghouse Electric and Manufacturing Co., in charge of the plant at Bodie, Cal. (communication to the Secretary): I beg to offer, to complete the information conveyed in Mr. Leggett's paper, the following report of tests of the electrical efficiency of the power-transmission he has described:

Jan 1, 1895

By A. J. Garnier, N. H. van Lingen

Rock downhole is known to be lesc. drillable than when brought to the surface. This must be ascribed mainly to the presence under downhole conditions of a pressure differential across already made chips, which hinders their being lifted. The pressure differential has partly a static and partly a dynamic origin. Balling-up of bits is another consequence of this pressure differerztial. Reduction in penetration rate owing to an increase in the strength of the rock is governed by the difference between the mud pressure and the pressure of the for/nation pore liquid. Rotationally symmetric geostatic stresses have 170 effect on drillability. Fracture of rock when drilling will be brille in most cases. The above is supported by laboratory drilling experiments with drag bill and roller bits an elevated mud, pore, and confining pressures On rocks differing in strength and permeability. INTRODUCTION In oil well drilling drillability of rock is found to decrease with increasing depth of the hole. Naturally deep rock will be more compacted and, therefore, harder to drill than shallow rock of the same type. However, apart from this the drillability of a sample of deep and compacted rock brought to the surface is generally much higher than in its original location downhole. In view of the economic implications of this reduction in drillability, it seems worthwhile to analyze its causes. The origin clearly has to be sought in the difference of environment. The only conceivable factors would seem to be the presence of mud under pressure, the pressure of the formation pore liquid, and the overburden of the rock. Down the borehole the rock is compressed triaxially by mud pressure and overburden. It is well known that the strength of rock is increased when confined by external pressure1. Various authors have, therefore, ascribed the difference in drillability mainly to the strengthening of rock by triaxial compression. Another factor, mentioned by Bobo and Hoch5, is that forces. including "pressure differential forces", tend to hold a dislodged particle in place. However, the conditions determining their magnitude are not clarified nor is their effect on drilling rate assessed. In the laboratory, drilling experiments on pressurized samples of rock yielded evidence that pressure differential forces holding the chips down are the major factor in reducing rate at depth. This paper describes the experiments and shows how the results enable both a qualitative and a quantitative interpretation of the factors determining the effect of chip hold-down on drilling rate. The implication with respect to balling-up and jet action is also discussed. The greatcr part of the experiments were performed in the pressure vessel shown in Fig. 1. The spacc between the sample of rock and the vesscl is divided by "0" rings into three separate chambers. The rock sample is confined laterally by pressurized oil in thc middle chamber. Penetration of oil into the sample is prevented by partly jacketing it with brass foil. Thc pressure of the drilling fluid in the hole can be adjusted via the upper chamber. Permeable rock specimens arc water saturated before being drilled. With a properly plastering mud as drilling fluid the pressure of the pore water can be adjusted independently via the lower chamber.

By A. J. Opinsky

ThE superior performance of nonsag tungsten wire in lamps has been ascribed to the large-grained micro-structure that can be developed in it. The orientations of these large grains have been studied several times; most published data1-' appear to be similar to those plotted in Fig. 1. These new data were obtained by X-ray back-reflection Laue technique from all of the large grains occurring in thirteen different wires that had been heated at the lowest possible temperature for the formation of large grains. Here the wire axis is plotted in terms of the principal directions of the cube. Rosi decided that the preferred orientation of the large crystals could be described by a single ideal orientation, (531), being parallel to the wire axis.' Rieck2,3 and Mannerkoski' have essentially confirmed this finding. Opinsky, Orehotsky, and Seigle argued that the data suggest that (211) is parallel to the wire axis instead of a single ideal orientation.5 This {211} contains the (531) ideal orientation and would appear to be a more general case. Ahlborn and Wassermann report that their orientation data stretch from ( 110) through (531) to (311) 8 This is part of the locus of (211). All these investigators have determined the orientations of the large grains by back-reflection Laue techniques. They have all obtained essentially similar results. On the other hand, Swalin and Geisler, who obtained their data by neutron diffraction, indicated that the preferred orientation of the large grains in doped wire is (110) .7 These findings cannot presently be reconciled with the pole density data described in the previous paragraph. Rosi1 and Rieck2 have advanced arguments about how their orientations could occur. Nevertheless, the crystallographic link between the (110) (cold-worked) fiber texture and the preferred orientation of the large grains has remained missing. This link can be provided through the concept of coincidence-type boundaries. Such boundaries separate two grains that have a certain number of common lattice sites. Coincidence relationships that result from rotations about low index directions are given by Brandon et a1 .' What is desired is a calculation of those orientations that bear a coincidence relationship with the (110) fibers of the cold-worked matrix. This situation arises in the following fashion. Heating the tungsten wire for a combination of time and temperature falling short of the formation of the nonsag structure yields a structure that is still fibrous in nature and the preferred orientation remains (110). During grain growth, the growing grain is in contact with these fibers. It is hence possible that the entire process may begin by the passage of a coincidence boundary into a (110) fiber. The calculations were carried out analytically and checked graphically. Following Brandon et a1.,8 coincidence relationships from 1 in 5 to 1 in 19 have been considered. The results of the calculations are given in Fig. 2. Of the coincidences examined, some of those occurring upon rotation about ( 110) come closest to the experimental points in Fig. 1. Nineteen of the twenty-three data points in Fig. 1 can be attributed to the ideal orientations A, B, C, and D in Fig. 2. As determined analytically, three crystals lie within 4 deg of point A, four lie within 21/2 deg of point B, eleven lie within 5 deg of point C, and one lies within 1 deg of point D-a total of nineteen. The off-lying points are near the |110| point of the triangle.

Jan 1, 1968

By Mark J. Klein

The creep of 043 was studied over the temperature range 1650" to 3200°F and over the stress range 3000 to 44,000 psi. The steady-state creep rate over this range of stress and temperature can be expressed by the equation where A is a constant, is the stress, and is -0.8 x 103 psi-'. Over a narrow range of stress variations c0 a and for this proportionality n varies from 3 to 30 in accordance with the relation n = aB. Above about 2400° F, H, the apparent activation energy for creep, is 110,000 cal per mole, a value about equal to that estimated for self-diffusion in this alloy. Below 2400°F, H increases with decreasing temperature reaching a value of -125,000 cal per mole at 1700° F. In this temperature region, H appears to be a function of the interstitial concentration of the alloy. MOST of the detailed creep studies of dispersion strengthened metals have been concerned with metals having fcc structures. However, there are a number of important refractory alloys with bcc structures that derive part of their high temperature strength from an interstitial phase and whose creep behavior has not been well defined. This paper describes the creep behavior of the bcc alloy, D43, over the temperature range 1650" to 3200°F (0.4 to 0.7 Thm) and over the stress range 3000 to 44,000 psi. In addition to colum-bium, this alloy contains 10 pct W. 1 pct Zr, and sufficient carbon (-0.1 pct) to form a carbide dispersion throughout the matrix of the alloy. The effects of variations in temperature and stress on the steady-state creep rate of this alloy are presented in this paper. EXPERIMENTAL PROCEDURES Creep tests were made in a vacuum of 106 torr under constant tensile stress conditions using a Full-man-type lever arm.' Creep specimens were machined from 0.020-in. D43 sheet (grain size -5 x l0-4 in.) processed in a duplex condition (solution annealed -2900°F, 40 pct reduction in area, aged 2600°F). The specimens were tested in this condition without further heat treatment. Specimen extensions over 1-in. gage lengths were continuously recorded using a high temperature strain gage extensometer. Differential temperature and stress measurements were used to determine temperature and stress dependencies of the creep rate. Activation energies were calculated from the changes in strain rate induced by abrupt shifts in the temperature during constant stress creep tests. The 100°F temperature shifts used in most of the activation energy determinations required 15 to 90 sec depending upon the temperature at which the shift was made. The dependence of strain rate on stress was determined by measuring the change in strain rate for incremental stress reductions during constant temperature tests. It has been shown that columbium-base alloys such as D43 are susceptible to contamination by gaseous interstitial elements during vacuum heat treatments.' In this regard, it is unlikely that these alloys can be heat treated without some loss or gain of interstitial elements despite the precautions taken to control the heat treating environment. However, several factors suggest that changes in interstitial concentrations of the specimens during testing did not affect the results presented in this paper. First, the dependence of the creep rate on the stress or temperature determined during the course of a single creep test showed no variations with the duration of the test. A variation would be expected if a loss or gain in interstitial concentration during the course of the test affected results. In addition, precautions taken during this investigation to minimize interstitial contamination by wrapping the gage lengths of the specimens with various foils2 (Mo, Ta, W) did not produce a detectable change in the stress and temperature dependencies relative to the unwrapped specimens. The averages of duplicate analyses for carbon and oxygen in several specimens determined before and after creep testing are listed in Table I. The combined nitrogen and hydrogen concentrations which were ordinarily less than 50 ppm did not change in a detectable way with creep testing. The analyses show that only minor changes in carbon concentration occurred during creep testing except for specimen 4. This specimen which was tested at 3100°F lost a significant amount of its carbon concentration to the vacuum environment. Specimen 1 gained 100 ppm of O, while specimens 2, 3, and 4, which were tested at progressively higher temperatures, lost increasing portions of their initial oxygen concentrations during testing. RESULTS AND DISCUSSION The Temperature Dependence of the Creep Rate. The apparent activation energy for creep, H, was de-rived from creep curves similar to that shown in Fig. 1. Steady-state creep was rapidly attained at the beginning of the test and with each change in temperature. This behavior suggests that the alloy rapidly attains a stable structure with each shift in temperature or that the structure is constant throughout the test. Since the dispersion will tend to stabilize the structure, the latter is probably the case. The activation energy was found to be independent of the direction of the temperature shift and the magnitude of the shift (50" or 100°F). Although H was approximately independent of the strain, there was a tendency for it

Jan 1, 1970

By Norman B. Pilling

The technical difficulties hampering the metallographic analysis of silicon steels are chiefly the result of the extreme corrodibility of these alloys. The addition of silicon to iron in increasing quantities, up to about 6 per cent., rapidly increases the susceptibility of the alloy to chemical attack, not only in acid solution, but in water. This renders the preparation of metallographic sections very difficult, because of a non-selective attack upon the finely polished surface by the water used as a lubricant in polishing. This water attack masks the true structural details revealed by suitable etching reagents. It is thus necessary to use alcohol as a polishing lubricant in the last stages of preparation and to avoid all etching reagents having an aqueous base. A specific reagent for the identification of iron carbide in ferrous alloys, and the one hitherto used almost' exclusively by metallurgists, is an alkaline aqueous solution of sodium picrate, which stains this constituent selectively. Its application to silicon steels has not proved successful, as its distinctive selective action is more or less completely hidden by the general attack of the aqueous solvent on the silico-ferrite, greatly accentuated by the fact that this reagent must be used at its boiling temperature (105' C.). Thus, a powerful metallographic aid to the study of the higher silicon alloys, such as transformer steels, is lost. A new reagent has been developed for the purpose of overcoming this difficulty. It is with some hesitation that the list of etching reagents, already overburdened, is increased, but the properties of this new reagent are advantageous in several ways and a definite field for it may be found in the metallography of ferrous alloys. The reagent consists of a dilute solution of nitric acid and methyl alcohol in nitrobenzol. It is a great advantage to secure an anhydrous solution, as a tendency toward acidic etching has been traced to small amounts of water. A convenient method of preparation is to make an anhydrous stock solution of nitric acid in methyl alcohol in the proportion 20 per cent. acid by weight (12.5 per cent. by volume). The alcohol can

Jan 1, 1924

By R. W. Raymond

In my former paper (Bans., xii., 410) I quoted the ruling of Judge Hallett, of Colorado, in the "Iron-Smuggler" case, tried before him in June, 1882. Under his charge, the jury in that case found for the defendants, practically declaring that the deposit on the outcrop of which the Iron Silver Mining Company's claim was located was not a " lode," or else that the portion of it within that claim was not the apex. The case was appealed, and the decision of the Supreme Court, given in February, 1886, is reported in 116 U. S. Reports, p. 529. It simply declares that there is nothing in the charge of Judge Hallett to warrant the setting aside the verdict. The definition of a legal lode given in that case, and quoted in my paper at the page above-named, is perhaps the best of several which Judge Hallet has pronounced. That is to say, his earlier definition, that " a lode or vein is a body of mineral, or mineral-bearing rock, within defined boundaries in the general mass of the mountain," is here accompanied with further explanations, which relieve it from the requirement on one hand, that the body shall be continuously ore-bearing if it he only well-defined, and, on the other hand, that the boundaries shall be well-defined if the ore-bearing body be proved to exist. So far as this particular case is concerned, the approval of this ruling by the Supreme Court merely prevents any re-hearing as to the face. Undoubtedly, the evidence was conflicting; and the jury chose to believe, for the purpose of that occasion, the " experts " who

Jan 1, 1887

By Edward W. Parker

One of the most important features of the coal-mining industry of the present day is one that is common to the majority of industrial enterprises—the substitution of mechanical methods for hand-labor.

Jan 1, 1900

ALABAMA Aldrich -Thomas, D A Altoona -Cain, J Anniston -Cowie, L K Walmsley, W N White, H E Ashland -Sturdevant, J C Bankhead -Connaway, M B Bessemer-Ball, E M McKenzie, W C, Jr Mitchell, F R Morgan, C Thompson, N E Birmingham -Abbott, C E Adams, J H

Jan 1, 1923

By E. P. Pfleider, E. G. Malmlow, F. Landau

Friction drive hoists, long popular on the Continent, are now being installed in the U. S. and Canada by the Swedish firm of ASEA. Invented by C. F. Koepe and used first in 18.77, the principle is the same as that in elevator installations throughout the world. Inherent advantages of this system of hoisting were not fully developed until the recent introduction of the multiple-rope principle and design of concrete tower installations. Operators have a choice of independent operation of single skips and cages using counterweights, or use of skips or cages in balance. Also, hoisting control may be automatic, push button, or manual.

Jan 1, 1955

By F. C. Langenberg

DURING the course of some magnetic investigations which the authors have under way, six bars of 0.43-carbon steel were tested, a permeameter designed after the Hopkinson yoke type being used. The results obtained were of some interest and although far from complete serve at least to show the necessity for a careful investigation of the previous history of the samples under study as well as the chemical composition. A steel of given chemical composition may assume a great variety of structures, depending on its treatment. Professor Sauveur has devised a very clear and effective means of illustrating this point: The accompanying microphotographs show some of the possible structures assumed by a 0.30 carbon steel (Fig. 1). It is now a well-established fact that a structural change is accompanied by changes in the tensile strength, elastic limit, hardness, etc., and it seems reasonable to assume also, a change in the magnetic properties. Six bars of a 0.43-carbon steel were used, all the bars being taken from the same rod and treated as follows: Bar 1. Heated to 1,100° and cooled in the furnace. Bar 2. Heated to 1,000° and cooled in the furnace. Bar 3. Heated to 900° and cooled in the furnace. Bar 4. Heated to 1,000° and cooled in air. Bar 5. Heated to 900° and cooled in air. Bar 6. Untreated. The bars were then turned to 13 mm. diameter and tested by the Hopkinson yoke method. After testing, three specimens were taken from each bar, one from each end and one from the middle. The homogeneity of the. bars was tested in this manner and in no instance could any difference in structure be detected between the three specimens.1

Jan 2, 1915

By John T. Ryan

DEFINITE improvement in its accident fatality rate in the coal-mining industry was recorded during 1941, based on preliminary figures for the period from January through October. Total production during this ten-month period was approximately 91 percent of the total production in all of 1940. The ten-month accident rate for both bituminous and anthracite mining in 1941 was 2.15 killed per million tons of coal mined, compared with a rate of 2.66 for the full year of 1940. The bituminous rate decreased from 2.55 in 1940 to 1.99 in ten months of 1941, and the anthracite rate from 3.62 to 3.53 in similar periods. The decrease is more apparent for the bituminous branch of the industry, as the high figure in 1940 was due to seven major disasters which brought death to 276 men. The same number of major explosions during ten months of 1941 caused only 64 lives to be lost. The severity of the explosions has been lower this year but a definite need still exists for reduction in this type of accident.

Jan 1, 1942

EUGENE WESLEY SHAW, ? Washington, D. C.- (Written discussion?).-Paraffin earth is of especial interest because of the apparent difficulty of determining its chemical nature. I have submitted specimens to three chemists at different times with suggestions as to special tests that might he made. The results are indicated in the following reports:

Jan 1, 1919

By Hugh D. Pallister, Richard W. Smith

The Alabama flake-graphite industry has flourished only in times of war when importations of foreign graphite for crucible use have been greatly curtailed or cut off. World War I was a boom period and in 1918 some 30 plants produced 7,795,475 Ib. of flake graphite. The industry languished following the war and no graphite was produced from 1929 to 1939. The Federal Bureau of Mines began investigating the Alabama graphite deposits in 1940 and worked out modern recovery methods that were applied to production during part of World War 11. A prospecting program disclosed reserves of over 25 million tons of graphtic schists. In 1942 the War Production Board authorized the enlargement of the only plant then producing flake graphite and the construction of two new plants. Production of flake graphite from these three plants in 1943 is estimated at 8,100,000 lb. Increased imports from Madagascar late in 1943 shut down one of the new plants and curtailed production at the other. Alabama flake graphite has not yet been able to compete with Madagascar graphite for use in the manufacture of any but small graphite crucibles. The future of the industry must depend on meeting the higher carbon content demanded for other uses. Introduction The flake-graphite deposits of Alabama are confined to a narrow belt extending for about 60 miles southwest from the northeast corner of Clay County across Coosa County to the edge of the Coastal Plain in Chilton County (Fig. I). The continuity of the beds is broken by a 10-mile gap between Millerville in Clay County and Goodwater in Coosa County. The Clay County beds extend about 27 miles northwest of this gap, with a width of 3 to 4 miles near Millerville and of less than a mile at the northeast end. The Coosa-Chilton are? is about 33 miles long with a fairly consistent width of 2 to 3 miles. Geologically the graphite belt lies near the northeast boundary of the outcrop of metamorphic rocks of the Ashland series, a complex group of intensely folded and faulted beds of pre-Cambrian age composed mostly of quartz-mica schist, in which the mica is predominantly muscovite; garnet-mica schist, in which biotite is more common; and hornblende schist. Flake graphite is found in commercial quantities only in the quartz-mica schist. The best graphite, both in quantity and quality, is found in schist cut by numerous small pegmatite stringers along the planes of the schistosity. The pegmatites themselves contain little graphite, but the adjacent country rock is normally rich. . The schist was derived through the recrystallization of shale during the intrusion of the pegmatites, the graphite being derived from amorphous carbon in the shale. The intrusion of the pegmatites, and therefore the size and quantity .of the graphite flakes, seems to have a structural control.

Jan 1, 1948

By Hugh D. Pallister, Richard W. Smith

The Alabama flake-graphite industry has flourished only in times of war when importations of foreign graphite for crucible use have been greatly curtailed or cut off. World War I was a boom period and in 1918 some 30 plants produced 7,795,475 Ib. of flake graphite. The industry languished following the war and no graphite was produced from 1929 to 1939. The Federal Bureau of Mines began investigating the Alabama graphite deposits in 1940 and worked out modern recovery methods that were applied to production during part of World War 11. A prospecting program disclosed reserves of over 25 million tons of graphtic schists. In 1942 the War Production Board authorized the enlargement of the only plant then producing flake graphite and the construction of two new plants. Production of flake graphite from these three plants in 1943 is estimated at 8,100,000 lb. Increased imports from Madagascar late in 1943 shut down one of the new plants and curtailed production at the other. Alabama flake graphite has not yet been able to compete with Madagascar graphite for use in the manufacture of any but small graphite crucibles. The future of the industry must depend on meeting the higher carbon content demanded for other uses. Introduction The flake-graphite deposits of Alabama are confined to a narrow belt extending for about 60 miles southwest from the northeast corner of Clay County across Coosa County to the edge of the Coastal Plain in Chilton County (Fig. I). The continuity of the beds is broken by a 10-mile gap between Millerville in Clay County and Goodwater in Coosa County. The Clay County beds extend about 27 miles northwest of this gap, with a width of 3 to 4 miles near Millerville and of less than a mile at the northeast end. The Coosa-Chilton are? is about 33 miles long with a fairly consistent width of 2 to 3 miles. Geologically the graphite belt lies near the northeast boundary of the outcrop of metamorphic rocks of the Ashland series, a complex group of intensely folded and faulted beds of pre-Cambrian age composed mostly of quartz-mica schist, in which the mica is predominantly muscovite; garnet-mica schist, in which biotite is more common; and hornblende schist. Flake graphite is found in commercial quantities only in the quartz-mica schist. The best graphite, both in quantity and quality, is found in schist cut by numerous small pegmatite stringers along the planes of the schistosity. The pegmatites themselves contain little graphite, but the adjacent country rock is normally rich. . The schist was derived through the recrystallization of shale during the intrusion of the pegmatites, the graphite being derived from amorphous carbon in the shale. The intrusion of the pegmatites, and therefore the size and quantity .of the graphite flakes, seems to have a structural control.

Jan 1, 1948

By William Romanoff

As you are no doubt aware, virgin copper, tin and zinc are strategic metals today and little, if any, is available in the manufacture of brass and bronze ingots. The source of alloys used in the manufacture of implements of war are, therefore, from ingots made almost exclusively from the refining of available scrap. It is amusing to hear of the unusual physical properties of various alloys because they mean nothing unless the foundryman is able to produce good sound castings. A discussion therefore means little unless something is said about the relative foundry practice of the various brass and bronze alloys. Among the factors that influence the quality of castings produced are: (I) improper gating, (2) wrong pouring temperatures, (3) poor sand conditions, (4) bad melting practice, (5) faulty pattern equipment, (6) metal. It seems to be the consensus of opinion that about 95 per cent of defective castings can be attributed to the first three causes. Metal while a source of trouble at times, is probably the least responsible for foundry difficulties. As you all know, a molder never makes a bad mold. His first thought is to blame the "damn" metal as this is the path of least resistance. Let's consider the "damn" metal and how it is made. In the manufacture of ingot, scrap is collected at various sources and is shipped to the refiner either directly or through the scrap dealer or broker. It is usually sorted, although not always. In working toward a specified chemical analysis, weighed amounts of various grades of scrap metals are melted, and then oxidized by blowing air through the molten bath to rid the metal of detrimental impurities or reduce them to within specification limits after which they are skimmed off with the aid of some added fluxes. The bath of metal is then poled with wood, chemically tested before and after additions are made to bring it up to required specifications, and finally poured into ingots, after which a final chemical and physical examination is made. As mentioned above, the impurities have either been eliminated or reduced to the point where they meet the specifications of all Government Agencies or Technical Societies. Therefore, why worry as to whether castings are to be made from strategic virgin metals or secondary ingots from available scrap. Tests have continuously been made and it is a proven fact that physical properties are no better from virgin metals than from secondary ingots of the same composition. It is definitely more fool-proof to make castings from secondary ingot than from virgin metals because if an error is made in weighing the copper, tin, lead or zinc of the latter, the analysis is off balance. If an error is made in weighing secondary ingots, you merely have more or less metal but the analysis remains constant. Furthermore, when pure copper is melted. it is susceptible to reducing gases as well as oxides. Secondary ingot is already alloyed with natural deoxidizers such as zinc, etc., and the volatilization of the latter also tends to eliminate reducing gases mechanically.

Jan 1, 1943

By I. N. Knapp

Foreword I HEREWITH present some notes on the use of Portland cement to cement in the casing, and for plugging, to exclude water from oil and gas wells, and the methods employed. I have used my best efforts to make each step of the operation of cementing wells perfectly clear. The information is the result of actual experience and observation. The illustrations are from original drawings made especially for this paper. Portland Cement It is not necessary to discuss here the manufacture of cement. Any established brand of the slower setting Portland cements may be purchased with the confidence that it will harden, if properly used, and exclude water from and plug wells efficiently. Setting.-By the setting of cement is meant its initial change from a soft or plastic mortar to a friable solid. After the cement has become thoroughly set it is still very weak and can be readily pulverized in the fingers. Setting is thought to be effected by the crystallizing out of the silicate and the aluminate of lime, which are soluble in water in their anhydrous form. After dissolving in the water they pass to the hydrated state, in which they are insoluble, and hence are precipitated in a crystalline form.

Jan 3, 1914

By S. Vela, R. M. McKinley, L. A. Carlton

Johnson et al. have described a new well-testing technique that measures formation flow properties between wells.' The technique, called pulse-testing, requires a sequence of rate changes in the flow at one well and measzcrement of the re.rulting pressure changes at an adjacent well with a very sensitive differential pressure gauge. This paper describes an extensive application of the technique in a producing oil field. Pulse-tests on 28 of 45 possible well pairs in the field provided a picture of the areal distribution of reservoir hydraulic diffusivity, trans-missibility and storage. The primary objective in presenting these data is to demonstrate the potential of the methcid for reservoir description. A second objective is to show in three ways the qualitative and quantitative accuracy of reservoir parameters determined from pulse-tests: (I) pulse-test data show a nonuniformity in the field, closely correlating with the oil-water distribution as given by production data: (2) pulse-test values for permeability are comparable with core va1ue.s; and (3) perhaps most important, the field responds to a conventional interference test in the manner in which pulse-test data predict it should. The pulse-testing technique by Johnson et al.' is an ideal source of data for purposes of reservoir description, for it provides a measurement of formation storage S = +ch, hydraulic diffusivity 91 = k/+cp and transmissibility T — This paper describes an application of this method in a producing oil field. Results were analyzed to give numerical values for the parameters 7, T and S. These values were compared with oil-water production data (for the effect of fluid saturation), with core data and with data from an interference test. The reservoir in which the pulse-test survey was run is the result of a structural trap formed by a fault along the east side of a north-south trending anticline. A down-structure aquifer providcs a natural flank water drive for the pool. The producing formation is a dolomitic lime- stone having mainly vugular permeability; the formation oil has a gravity of 29" API with negligible dissolved gas. The field contains 19 wells, all on pump, arranged on 40-acre spacing along the top of the anticline. Fig. 1 shows the location of all these wells except two at the south end of the field. The dashed line on the right-hand side of the figure represents the approximate location of the fault with respect to well positions. Pulse-Test Survey and Analysis of Data A pulse-test requires a pulsing well and a responding well. In the field, changes were made in the rate of flow at the pulsing well by stopping and starting the pump periodically and measuring the corresponding pressure

Jan 1, 1969

By C. Feng, C. Elbaum

AN investigation of the fracture plane of titanium, containing 0.5 wt pct to 1 wt pct 0, was recently carried out by fracturing large-grain specimens in a tensile jig at room and liquid air temperature. The experiments were carried out on strip specimens 3 to 5 mm wide, 2 mm thick and about 100 mm long. The specimens consisted of several grains, each occupying the entire cross section of the strip and extending over a length varying from 5 to 20 mm. These specimens were prepared by a method described elsewhere.' The identification of the fracture plane was possible in twelve of approximately thirty crystals investigated. In some cases severe local distortion took place near the fracture and prevented identification of the fracture plane. On, at least, three occasions the fracture propagated in a helicoidal

Jan 1, 1959

By M. E. Wadsworth, R. D. Groves, B. W. Madsen

Experimental results obtained from large-scale (7 ton), long-term (500 days) leaching of low-tenor copper sulfide ores were interpreted by a geometric model involving the movement of a reaction zone through the ore fragments. The postulated leaching mechanism involved mixed kinetics and included diffusion of the reacting species through the host rock and a chemical reaction at the surface of the mineral particles. Ore properties which were considered were Ore particle size and shape, grade of ore, and mineral content. Excellent agreement between the mixed kinetic model and the laboratory leaching results was obtained when -1/2-in. ore particles were not included in the leach. Also, a satisfactory prediction of copper recovery from +1/2-in. ore with a different particle size distribution was made; however, it was necessary to modify the shape factor in the model. Prediction of copper recovery from an ore sample which included the -1/2-in. fine fraction and leaching for 460 days was 56.5%, and the recovery from leaching was 47.0%. The presence of fines caused solution channeling and a deficiency of oxygen which inhibited the leaching rate. Also, compaction of fines around coarser particles interfered with circulation around the ore particles, and bulk solution transport probably was a rate controlling factor.

Jan 1, 1976