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By G. H. Matheson, J. M. W. Mackenzie

The flotation rate of coal has been studied using a continuous laboratory flotation cell and a multiple exposure photographic technique. The effects of particle size, reagent additions and cell turbulence on the flotation rate of coal have been investigated. The results have been analyzed in terms of current theories of particle bubble encounter and adhesion. The rupture forces which occur during particle bubble encounter have been shown to have an important effect on the flotation rate of coarse coal particles. The flotation of coal is a time dependent process, and in order to obtain a complete understanding of the operation it is necessary to determine the kinetics of the process. In coal flotation, the flotation rate and the associated values of cell productivity in terms of tons per kilowatt-hour and tons per cubic foot of cell volume are of greater importance than in most other mineral flotation operations. The reasons for this are associated with the low unit value of coal and the relatively high cost of coal flotation compared with other coal cleaning processes. An important aspect of coal flotation kinetics is the design of coal flotation cells. The cells used in many coal cleaning operations are often replicas of those used for the treatment of sulfide ores and are not necessarily suitable for the treatment of coal washing pulps, which usually contain a higher percentage of coarse and floatable material than the sulfide pulps for which the cells were designed. This disadvantage of many coal flotation cells has been recognized by Russian engineers who, by the addition of baffles to their subaeration coal flotation cells have increased the cell capacity by 100%. Investigation of the variables which influence flotation kinetics and cell productivity are, therefore, important to the coal industry where flotation is the only accepted method of cleaning the fine (-1/2mm) coal. The kinetics of the flotation process have been investigated in detail by Schumann10 who developed a continuous flotation cell which permitted the study of flotation under steady state conditions. This technique has been used by Gaudin et a1.,6 Brown and Smith and recently by Jowett and Savfi.7 The latter authors have developed a refined mathematical treatment for interpreting the results of continuous laboratory tests. Attempts have also been made to study flotation kinetics using conventional batch testing techniques. The experimental difficulties, however, and the problems of determining the order of the flotation rate process have made this technique of dubious value. A summary of the proposed rate equations for batch testing and the difficulties associated with this technique is given by Brown and Smith. 2 The experimental techniques described above are concerned with the rate of production of froth product. However, several authors, notably Sutherland, 11 Bogdanov1 and Philippoff, 9 have analyzed flotation

Jan 1, 1963

By G. W. Healy, W. Craft, D. C. Hilty

By means of a theoretical extension of the Cr-C temperature relation in molten chromium steels to low chromium contents and by a correlation of the ratios of chromium to iron in the slag and metal, a method has been developed for estimating the amount of metallic oxidation during the oxidizing period of a chromium steel heat. Application of this method has indicated that due to temperature limitations metallic oxidation may be excessive for very low carbon steels charged with more than a small amount of chromium. IN the melting and refining of chromium steels the oxidation of carbon to a low level is accompanied by the oxidation of chromium and iron in considerable amounts. For the subsequent recovery of chromium and associated iron from the slag, the amounts of metal oxidized must be known for efficient reduction and control of composition. Further, in order to arrive at an accurate understanding of the process, so that chromium-bearing scrap can be used effectively, information is required on the relation between composition of the charge and weight of metal oxidized to reach the desired carbon content. Crafts and Rassbach1 recently developed an empirical relation between chromium, iron, and manganese oxidized per ton of steel charged, and final carbon content and temperature. This relation did not show any dependence on amount of chromium charged. However, it was felt that such a dependence might be present, so a further analysis of the data was undertaken. Cr-C Relation at Low Chromium Levels Crafts and Rassbach's results were based on temperatures estimated from the Cr-C relation previously established experimentally by Hilty,2 and on a single temperature observation (immersion thermocouple) on a heat made at low temperature from a charge of carbon steel scrap containing only a small amount of residual chromium. The temperatures estimated from the Cr-C relation were for heats charged with chromium-bearing scrap and which contained substantial amounts of chromium (2 to 10 pct) at the end of the oxidizing period. No data, other than that from the low temperature heat just mentioned, were available for the low and intermediate chromium ranges. In order to extend the range in which temperature may be estimated, the Cr-C relation requires further consideration. The Cr-C relation, expressed as suggests that carbon is zero at zero chromium in the bath. This is obviously absurd, because as chromium approaches zero the carbon content must approach the limit established by the Fe-C-O equilibrium. It is evident, therefore, that the Cr-C relation as defined by Eq. 1 is not valid below some minimum chromium content that may vary with temperature. On the other hand, it is probable that any such limiting chromium content is less than 4 pct at 3200°F, since the experimental data from which the Cr-C relation was derived included several observations at that level with no deviation. In any event, it is apparent that further evaluation of the results presented by Crafts and Rassbach is dependent upon a means for estimating the Cr-C temperature relation in the low chromium region. From the observations of Chen and Chipman9 and thermodynamic data given in Basic Open Hearth Steelmaking,4 the following relation can be calculated for melts containing small amounts of chromium and carbon assuming a carbon monoxide pressure of 1 atm: % Cr -21,250 K' = (%C)2; logK1 == —t— +13.88 [2] Moreover, by plotting Eq. 2 for any given temperature on cartesian coordinates, it can be extrapolated graphically to the limiting carbon content at zero chromium for the specified temperature without serious complications. By means of Eq. 2 and its extrapolation, the Cr-C temperature relations originally established experi-

Jan 1, 1954

By C. Altstetter

THE work herein reported is restricted to the carbides which occur in quenched and tempered AISI 43XX steels with carbon contents up to 0.40 pct and silicon additions of up to 3 pct. In view of the instability and extremely small size of the carbides formed at low tempering temperatures, the technique for successfully preparing specimens for X-ray diffraction will be outlined. The alloys listed in Table I were obtained through the courtesy of the United States Steel Corp. in the form of 1/2-in. rounds forged from 100 lb. induction furnace heats (except for 4337 which was a commercial heat). The stock was normalized and then swaged and drawn to 15 mil wire with anneals at 1200F between passes. The wire was austenitized for 45 min in evacuated vycor capsules and quenched into iced brine with simultaneous smashing of the capsule. Tempering was done in air with a water quench after tempering. The carbides were extracted in a simple cell using a solution of 1M KC1 and 0.5 pct citric acid with an initial current density of 0.1 amp per sq cm. One end of a short length of wire was immersed in the solution, and the current at constant voltage was noted as a function of time. After about an hour the current dropped sharply because of the decrease in specimen cross-section. At this point it was found that the dissolution could be stopped and that the very fine wire which then resulted was just large enough to permit handling of the extracted precipitate still clinging to it, yet so small that it diffracted and absorbed only a negligible amount of the X-radiation. This rod of residue with a convenient handle of undissolved wire was rinsed in distilled water. alcohol, and acetone. Then it was dipped in a thin solution of cellulose-acetate cement and dried in vacuum. The resulting specimen was straight, uniform in density, easily handled, but most important, was completely sealed and never exposed to air. Furthermore, the residue had never been subjected to strong acids or rough handling such as in the extraction-replica technique or in the complete extraction to a powdered residue. It was found that improperly coated specimens were pyrophoric, turning to oxide with a dull red glow as they were exposed to air and yielding patterns of Fe2O3 and Fe3O4. The steels containing 3 pct Si were especially difficult to prepare for this reason. The specimens were put in a 57 mm Straumanis camera with double pinholes or slits and irradiated with filtered-chromium radiation. Readable patterns were obtained in less than an hour. A preliminary finding of some note was that for both tempered and as-quenched specimens of steels 4337 and 4337 (1.5 Si). M23C6 patterns were found along with the patterns of other constituents of the residues. This result was somewhat surprising in that previous investigators had reported that this carbide did not appear in a 0.38 pct C, 0.48 pct Mo steel1 or in chromium steels of less than about 10 pct Cr.2 Although the total amount of carbide-forming alloying elements is less than 2 pct, due to their mutual interaction and the action of the plastic deformation in promoting equilibrium, this carbide was able to form even in the steel containing 1.5 pct Si. M23C6 was not detected in the 4337 (3.0 Si) steel and the lower-carbon steels were not investigated in this condition. It is very likely then that the steels studied herein underwent a fourth stage of tempering during the anneals at 1200°F. This result has significance in that even a small amount of undissolved M23C6 in a low-carbon, low-alloy steel would exert a large effect on its hardenability. Its presence would also influence the mechanical properties by decreasing the carbon content of the matrix. Annealing in vacuum for 1 to 4 hr in the austenite field removed all traces of MZ3C+ The results on carbide precipitation during tempering, summarized in Table I, are in agreement with those of Klingler et al.3 for the higher carbon steels. For the AISI 4337 steels it is noteworthy that in the steels with added silicon the E carbide persists to longer times and higher temperatures and that silicon delays the formation of cementite. The results for the lowzr-carbon steels parallel those of the higher-carbon grade. The appearance of E carbide in the AISI 4315 is significant. There is considerable disagreem-nt in the literature as to whether this carbide forms in the tempering of steels containing less than about 0.2 pct C. Following the detection of E carbide in a 0.18 pct C plain-carbon steel,4 its occurrence in a steel containing chromium and molybdenum should be expected. The fact that the low-carbon steels have the same carbide-precipitation sequence as the high-carbon steels has bearing on the larger problem of the exact tempering reactions in all steels. Following the suggestion of Roberts et al.,' the first stage has been generally assumed to result in a metastable equilibrium of c carbide and martensite of about 0.25 pct C. From this it was concluded that a steel having less than 0.25 pct C should then be under-saturated with respect to c carbide and should not precipitate this carbide upon tempering. In view of the experimental findings of c carbide in steels hav-

Jan 1, 1962

By P. B. Elkin, K. C. Ten Brink, Allen D. Garrison

It is the purpose of this article to present the results of an investigation of certain clay and shale suspensions having viscosities that are materially influenced by fluid motion, and to discuss the bearing of these results upon the choice of policy in the control of drilling fluids. A previous article described the design and the characteristics of an instrument adapted to measure the viscosity of plastic suspensions during continuous uniform motion and at a variety of speeds.' It has long been recognized that the viscosity of a clay suspension depends on the past history of the fluid motion. Since an abundance of literature is available on this phenomenon,2 it is not necessary to describe it in more than general terms. It is usually observed that rapid motion reduces the viscosity of a clay suspension, and that some time is required for the viscosity to fall to its equilibrium value after the steady motion is started. On reducing the speed of motion to some lower value, the viscosity again rises, but it also requires some time to attain a steady viscosity value at the slower rate of motion. Thus clay suspensions are usually observed to be increasing in viscosity as time passes when the measurement has been immediately preceded by fluid motion that was more rapid than that employed in the measurement. And it is usually observed that the viscosity falls as time passes when the measurement has been preceded by more quiescent conditions. Reed,3 and Broughton and Hand4 have reported a condition of observation of clay suspensions in which the viscosity was observed to fall during the first few moments of steady motion, and rise thereafter. The characteristics of the new instrument are particularly well adapted to studies of this kind. With it we have been able to observe all of the phenomena described above, and it is important to understand their nature because they all occur at some time during normal drill-

Jan 1, 1940

By K. C. Ten Brink, Allen D. Garrison, P. B. Elkin

It is the purpose of this article to present the results of an investigation of certain clay and shale suspensions having viscosities that are materially influenced by fluid motion, and to discuss the bearing of these results upon the choice of policy in the control of drilling fluids. A previous article described the design and the characteristics of an instrument adapted to measure the viscosity of plastic suspensions during continuous uniform motion and at a variety of speeds.' It has long been recognized that the viscosity of a clay suspension depends on the past history of the fluid motion. Since an abundance of literature is available on this phenomenon,2 it is not necessary to describe it in more than general terms. It is usually observed that rapid motion reduces the viscosity of a clay suspension, and that some time is required for the viscosity to fall to its equilibrium value after the steady motion is started. On reducing the speed of motion to some lower value, the viscosity again rises, but it also requires some time to attain a steady viscosity value at the slower rate of motion. Thus clay suspensions are usually observed to be increasing in viscosity as time passes when the measurement has been immediately preceded by fluid motion that was more rapid than that employed in the measurement. And it is usually observed that the viscosity falls as time passes when the measurement has been preceded by more quiescent conditions. Reed,3 and Broughton and Hand4 have reported a condition of observation of clay suspensions in which the viscosity was observed to fall during the first few moments of steady motion, and rise thereafter. The characteristics of the new instrument are particularly well adapted to studies of this kind. With it we have been able to observe all of the phenomena described above, and it is important to understand their nature because they all occur at some time during normal drill-

Jan 1, 1940

By R. R. Webster, H. T. Clark

The side-blown converter has been investigated as a possible commercial process for the production of low nitrogen steel. During this work, two converters of 3-ton and 22-ton capacity were operated on a pilot plant basis for a total of 214 heats. The steel made in these converters was low in nitrogen and possessed good cold working properties. Some problems of converter operation remain to be solved. IN plants operating with a high iron capacity, sev-eral different refining methods are used in the conversion of the molten pig iron to steel. These include various ore practices in stationary and tilting open-hearths, the duplex process employing the Bessemer converter and open-hearth, and the Bessemer process. At J&L, a considerable part of the iron produced is handled by the Bessemer process, either alone or in conjunction with duplexing, and therefore an appreciable portion of the steelmaking research effort has centered about the method. This paper covers research work on the development of the side-blow converter for the commercial production of low nitrogen ingots and includes descriptions of the operation of a 3-ton and a 22-ton experimental converter at the Aliquippa Works. The refining of iron to produce steel requires the removal of a large portion of the carbon and silicon and the control of manganese, phosphorus and sulphur which are present in the iron in varying amounts. The first large-scale means of refining iron was the acid Bessemer process which was brought into use almost 100 yr ago. This method, using compressed air as the refining medium, accomplishes substantially complete removal of carbon, manganese and silicon. Phosphorus and sulphur are not affected but, by choice of an iron composition sufficiently low in these elements, a commercial product can be produced. Since the process will handle large tonnages rapidly, operates without external fuel and with a minimum of additional equipment, it quickly became the major tool in the early expansion of the steel industry. Later, the basic open-hearth process, by affording control of phosphorus and sulphur and by consuming the large quantities of steel scrap that were becoming available, forced the acid Bessemer process into a secondary position in the industry. During the past two decades the demand for steel to be used in cold forming and drawing operations has gradually increased. Bessemer steel, because of its work hardening and aging characteristics, is not as suitable for these applications as basic open-hearth steel, consequently the decline of the process was accelerated. More recently, because of changing economic conditions, this long range trend appears to have been arrested or perhaps reversed. Ingot production data for recent years furnishes only an incomplete picture of the importance of the converter in the American steel industry; open-hearth furnaces utilize large tonnages of blown metal for which no published statistics are available. Metallurgical Aspects The fundamental difference between Bessemer and open-hearth steels apparently lies not in the method of manufacture but, rather, in the differences in chemical composition of the two steels. It is further believed that the principal features distinguishing Bessemer from open-hearth steel are the higher nitrogen and phosphorus contents of the former. Evidence supporting this position is supplied by tests on laboratory induction furnace heats that were made to contain varying amounts of phosphorus and nitrogen but were otherwise similar to normal low carbon silicon-killed steels. Fig. 1, 2 and 3, summarizing the test results, are taken from G. H. Enzian's paper titled, "Some Effects of Phosphorus and Nitrogen on the Properties of Low Carbon Steels."' Fig. l indicates that phosphorus has a marked effect on the cold work embrittlement of steel as shown by the work brittleness test of Graham and Work.' In the low nitrogen steels, which as a group have the better cold working properties, the effect of phosphorus variations is the more pronounced.

Jan 1, 1951

By P. Chiotti, E. R. Stevens

The electromotive force between pure magnesium and Mg-Zn alloys in a fused KC1-LiCl-MgC12 cell was measured over the temperature range 360° to 730°C and for alloy compositions of 0.052 to 0.635 atom fraction magnesium. The calculated activity coefficients of magnesium in the liquid alloys may he represented by the relation These data and the phase diagram were employed in calculating the standard free energy of formation for the compounds MgZn, MgZn2, and MgZn2, In the temperature range from 25° to 590°C the relation ZINC-rich magnesium alloys have been shown to be very effective in reducing various solute chlorides or oxides from fused salts such as KC1-LiC1 eutectic. Such reactions are of interest in the developinent of pyrometallurgical methods for reprocessing nuclear reactor fuels.' As the conceniration of the magnesium is increased beyond 5 to 10 wt pct the extent to which solutes, such as yttrium, lanthanum, cerium, and other rare earths, can be reduced or removed from the salt decreases. This effect is due to the resulting change in the activity of the solutes in the Zn-Mg alloy as well as the change in the activity of both the zinc and mag- nesium. The purpose of the present investigation was to determine the thermodynamic properties of the Zn-Mg system which, in addition to yielding information on the alloying behavior of these two elements, would permit a more quantitative understanding of the above reactions. Since this investigation was initiated several publications have appeared in the literature giving results on the thermodynamic properties for the liquid alloys of this system. 2-4 Kozuka, Moriyama, and Kushima3 measured the vapor pressure of zinc over four different alloy compositions by a carrier-gas technique. Eremenko and Tukashenko2 and Terpilowski4 measured the electromotive force between pure magnesium and various alloys in a fused salt cell. Earlier work has been summarized by Hultgren, Orr, Anderson, and Kelley.5 In the present investigation electromotive-force measurements were made on a cell of the type The temperature range covered for the lower-melting alloys was roughly 375° to 730°C. These data were employed in calculating the thermodynamic properties for the liquid alloys and in conjunction with the phase diagram,' reproduced in Fig. 1, were used in calculating the standard free energy of formation of the compounds MgZn, MgZn2, and Mg2 Zn11. The results obtained are compared with available data from the literature. MATERIALS AND EXPERIMENTAL PROCEDURES Materials employed were: Bunker Hill slab zinc, 99.99 pct pure; Ames Laboratory magnesium containing 13 ppm N, 195 ppm C, and trace amounts of calcium, copper, nickel, and silicon; reagent grade KC1, LiC1; and high-purity MgC12 obtained from Dow Chemical Co. The electrolyte consisting of KC1-LiCl eutectic (44.4 wt pct LiC1) to which was added 15 wt pct MgCl2, was dried in a quartz tube by heating to 340° C under vacuum for a period of 4 to 5 hr, and then passing HC1 through the salt as the temperature was slowly raised to above the melting point of the salt. After about 3 hr the HC1 was shut off and the system flushed with argon and then vacuum applied for 1 hr. The salt was finally siphoned through a sintered glass filter and cast into a Pyrex container which was sealed and

Jan 1, 1965

By C. D. Stahl, E. E. Templeton, R. F. Nielsen

It has been customary, in predicting saturation changes, to use the Leverett fractional flow formula", obtained by eliminating the unknown pressure gradient from the generalized Darcy equations for the separate phases. The formula presents difficulties in the case of counterflow, since the "fractional" flow may be negative, greater than unity, or, in the case of a closed system, infinite. Recently, it has been shown by several authors that the corresponding equations (with capillary pressure and gravity terms) for actual flow of the phase may be used just as well. These equations are in agreement with Pirson's1 statement that, if the two mobilities differ considerably from each other in a closed system, the flow is largely governed by the lower value. The present study was undertaken because of an apparent lack of experimental data on gravity counter-/low with which to test the theory. A 4-ft sand-packed tube in a vertical position was employed. Electrodes for determining saturations by resistivity were spaced along the tube, one phase being always an aqueous salt solution. Air, heptane, naphtha, or Bradford crude oil was used for the other phase. A reasonably uniform initial saturation was set up by pumping the phases through the system, alter which the tube was shut in and saturation profiles obtained at definite intervals. Cumulative flows over certain horizontal levels were obtained by integration of the distributions; hence, differentiation of the cumulative flows with respect to time gave instantaneous flow rates. To compare experimental and theoretical flow values, capillary pressures were assumed given by the final saturation-distribution curve. The upper part corresponds to the "drainage" region and the lower part to the "imbibition" region, where trapping of the nonwetting phase occurred. While calculations indicated that the capillary pressure saturation function and, probably, the relative permeability saturation functions changed during the segregation, the relation of the measured rates to saturation distributions are in general accord with the frontal-advance equation. It appears that the Darcy equations, as modified for the separate phases, are generally valid for counterflow due to density differences. The usual method of predicting saturation changes, which involves a continuity equation and the elimination of the unknown pressure gradient from the flow equations, should therefore be applicable. However, the need for advance knowledge of drainage and and imbibition "capillary pressures" and relative permeabilities during various stages presents difficulties. INTRODUCTION The present study was undertaken because of a seeming lack of experimental data relating to vertical counterflow of fluids of different densities in porous media. In particular, it was desired to determine whether data obtained from these laboratory tests were in accordance with certain mathematical treatments of counterflow which have been proposed. The gravity "correction" has been incorporated into the flow equations (and, hence, into displacement theory) nearly as long as both have been used. field4 and laboratory5 data have generally borne out the validity of the theory as applied, for instance, to downward displacement by gas, with all fluids moving downward. However, the modifications for counterflow have only recently been pointed out. 2-3 It has been customary to use fractional flow rates instead of actual flow rates in displacement calcuIations. In the case of counterflow, this results in negative values, values greater than unity and, when rates are equal and opposite, in infinite values. As pointed out by Sheldon, et a1,3 and by Fayers and sheldon,2 actual flow rates may be used just as well. The fact that these may be of opposite signs for the two fluids does not present any difficulty.

By B. M. Larsen, T. E. Brower

IN two previous papersl,2 dealing with the carbon-oxygen reaction, and the simultaneous content of each, in liquid steel in the furnace, we have made use of the quantity 0[O], defined as the excess oxygen beyond what would be in equilibrium with carbon then present if the pressure of carbon monoxide were I atm,; that is, if [C] X [O] is taken as 0.00222, 0[O] = [O] - 0,00222/[C] where [O] is the percentage of oxygen by weight as measured by the method described earlier.' This quantity 0[O] proves to be substantially independent of carbon content over the range 0.08 to 1.2 per cent, as well as of the basicity of the slag, and is nearly always within the limits 0.015 to 0.025 per cent when the bath is boiling normally and is in what we have termed a steady state. Apparently it must be at least about 0.014 per cent before boiling occurs; but this threshold value seems to depend upon the ease of bubble formation at the metal-hearth interface, hence upon the condition of the surface of the hearth. In any case, 0[O], on the average, changes considerably following any disturbance of the bath, as by addition of ore. The present paper deals with the average changes in ?[O] level following addition of Spiegel or crop ends, or after procedures to promote stirring, or by tapping of the steel from the furnace. The observations were made on a large number of commercial heats, and consequently are subject to the influence of various disturbing factors; the results have the compensating merit of showing the consistency obtainable under the limitations imposed by practical operation. VARIABILITY OF EXCESS OXYGEN IN NORMAL OPEN-HEARTH OPERATION The preceding general statements refer to the average value of ?[O] particularly in heats that are boiling actively; on individual heats, which are less active, there may be a variable time lag between the disturbance and its effect, which complicates the interpretation of what is going on. For instance, if in the normal refining process boiling is sluggish, the slag usually is gaining oxygen from the gas phase above it, or from added ore, faster than it is losing oxygen to the metal; yet when the bath starts to boil vigorously, the opposite condition may prevail for some time. The consequence of this lag is a variation of ?[O], the interpretation of which in a single heat may not be immediately obvious, This condition is illustrated in Figs. I and 2. In Fig, I, ?[O] at the beginning of the test period was near the lower limit of its usual range (dashed lines) in the steady state as a consequence of the lime boil, which had ended about as indicated. The bath is now cold, carbon drop is slow, and the first small ore feed causes only a small rise in 0[O]; as the temperature rises and as lime dissolves in the slag, and the bath becomes more active, the

Jan 1, 1946

By G. L. Kothny

DEVELOPMENTS of well-surveying instruments, coring and core orientation, were in an advanced state when drilling for oil began-these developments actually originated with the mining industry.1 Surveying of oil wells was not generally used in the United States until Alexander Anderson2 disclosed that the majority of wells drilled with rotary tools were crooked, with average horizontal drifts of about 516 ft. for holes 5000 ft. deep and about 793 ft. for holes 6000 ft. deep. This disclosure brought about the development of many additional instruments for surveying oil wells during the progress of drilling and after their completion. Surveying of boreholes, during the process of drilling at regular depth intervals, became a standard practice in the petroleum industry. Some producing states even established laws making check surveys mandatory, during drilling and under certain conditions also after completion. The surveying of boreholes also brought about changes and improvements in drilling practices. It provides information for the guidance of the hole while drilling, and for plotting the course as the work progresses, enabling the driller to take corrective measures immediately and with the least expense. The reasons for drilling straight holes are too well recognized to warrant any full discussion of them here. Straight holes are less costly to drill, because [ ] they reach the object on the shortest course. Table I shows the horizontal drift and loss in vertical depth for various angles of inclination. It is not surprising, therefore that many drilling contracts for oil wells today limit the drilling contractor to a maximum inclination off the vertical of 2° or 3°. In the mining industry the reasons for drilling straight holes are still more serious. A crooked hole may miss an ore body underground or provide incorrect information regarding an ore body. TYPES OF SURVEYING INSTRUMENTS The surveying instruments used in oil-well drilling may be classed in two types: I. Inclinometers, recording inclination only.

Jan 1, 1946

By E. A. Steigerwald, G. L. Hanna

The influence of work-hardening exponent on the variation of fracture toughness with material thickness was studied for high-strength steel, aluminum, and titanium alloys. The results indicate that, when materials are compared at similar fracture toughness to yield strength ratios, the material with the lower work-hardening exponent undergoes the transition from flat to slant fracture at a larger thickness than material with a high work-hardening exponent. In the thickness range where complete slant fracture is obtained the reverse is true and a lower work-hardening exponent results in a lower fracture toughness. The influence of work-hardening exponent on fracture toughness is, therefore, dependent on the particular fracture mode. In the transition region a low work-hardening exponent is beneficial for fracture toughness while in the 100 pct slant region it is detrimental. THROUGH the use of fracture mechanics analyses, the influence of geometric variables on the crack propagation resistance of structures can be interpreted with reasonable consistency. However, in order to gain a more complete understanding of the fracture process, the influence of material parameters on crack propagation must be defined and coupled to the macroscopic fracture mechanics approach. The work-hardening exponent, which characterizes specific material behavior, may serve as an effective parameter to allow some degree of coupling to be accomplished. In the extension of a crack in a specimen of suitable dimensions the propagation process occurs in a stable manner when the crack extension force is balanced by the resistance to crack extension, which exists in the material at the crack tip. As the applied stress, and therefore the crack extension force, on the specimen increases, the resistance also increases primarily because the effective plastic zone at the crack tip, which is the main energy absorption process, becomes larger. Since the work-hardening rate of a material influences the stress-strain relationship, it will also influence the energy absorption process in the plastic enclave at the crack tip and hence should have an effect on crack propagation. A number of studies have been made correlating the strain-hardening exponent or the strain to tensile instability with the ability of a material to resist fracture. Gensamer1 concluded that a low-strain-hardening exponent would result in a steep strain gradient at the base of a notch. He reasoned that a large work-hardening coefficient would result in high-energy ab- sorption due to the increased area under the stress-strain curve. Larson and Nunes2 experimentally observed in Charpy tests on steels heat-treated to below 200,000 psi yield strength that the energy to failure in the fibrous mode, i.e., above the brittle-to-ductile transition temperature, was logarithmically related to the strain-hardening exponent. In order to avoid the complicating effects present in studying materials which undergo a brittle-to-ductile transition, Ripling evaluated the notch sensitivity of a variety of fcc metals with varying work-hardening exponents.3 The results indicated that the relative notch sensitivity, as determined from tests on specimens with a sharp notch, decreased with increasing values of strain hardening. Although the energy required for ductile or fibrous fracture increases with increasing work hardening, high-strength steels often exhibit improved crack propagation resistance when heat-treated to obtain low values of strain hardening.4,5 An analysis of whether low strain hardening is beneficial or detrimental to crack propagation resistance must depend on the particular fracture criterion involved. At temperatures where the material is relatively ductile and the development of a critical strain is required for fracture, high strain hardening increases the energy required to produce failure. In the transition region and below, however, a critical stress law appears to be valid6 and a low rate of work hardening may produce superior resistance to semibrittle crack propagation. The experimental program is aimed at studying these possibilities and determining the specific influence of strain hardening on the crack propagation resistance of several high-strength materials. MATERIALS AND PROCEDURE The alloys, chosen as representative of various classes of high-strength materials, are summarized in Table I. The heat treatments evaluated along with the smooth tensile properties are presented in Table 11. Pin-loaded sheet tensile specimens were employed to determine the smooth tensile properties. A strain gage extensometer (measuring range 0.200 in.) was used at a strain rate of 0.02 in. per in. per min. The work-hardening exponents were determined from the stress-strain curves generated in the smooth tensile tests and the assumption that the portion of the stress-strain curve beyond the yield point can be described by the power relationship: where a is the true stress, P is the true plastic strain,

Jan 1, 1969

By Frank H. Kingdon

and eventually we would have trouble. That is, these little localized overstresses may not be important if the structure is loaded a few times, but may be important if the structure is loaded many thousands of times. The existence of localized stress has been demonstrated by direct experimentation with delicate extensometers by the elaborate investigations of Coker. Localized stresses four, five, and six times those that we would get by the ordinary laws of mechanics exist in most of our structures. These stresses, ordinarily, under steady load do no damage but if they are repeated many times may start progressive failure. So far, we have seen no failure that could not be explained by localized high stress at a nick, a crack, a point where one heat treatment stopped and another began, or where there was local faulting, or any one of a dozen causes. In the case of drill rods, the actual distribution of stress must be different from that which any mathematical analysis could predict. It would seem that the spread of damage from the localized overstresses, so far as we can see now, explains the phenomenon known as fatigue. The Ideal Drill Steel By Frank H. Kingdon The essential qualities of a drill steel are: (I), It must be easily forged; (2), the forged bit end must permit easy heat treatment to obtain hardness to resist chipping; (3)) the bar or body must be stiff to resist bending or twisting and yet tough to resist shock and vibration, with resulting breakage, (4), the forged shank end must be easily heat treated to obtain hardness with great toughness. Minor requirements are that the bit and the shank are in alignment with the body; that the shank is of the proper shape and length and the shank collar or lugs of the proper diameter and length; that the hole is free from obstruction; that the striking end of the shank is flat and square; that the bit is of the proper shape, with the cutting and reaming edges formed full and to the required size; that the reaming edges are concentric with the axis of the steel, and that there are no sharp corners at the shoulder where the bit blends into the body. The essential qualities of a bit, are: That its shape be such that maximum cutting speed can be maintained for as great a distance as possible before wear of the gage and cutting edge reduces the speed of penetration to a point where a change of steel is made necessary; that the size or diameter of the drill hole corresponding to the gage of the bit can be maintained with the least possible reduction as the depth of the hole increases, and that the bit can be correctly and readily formed and heat treated. The following features of bit design require attention: Shape,

Jan 1, 1922

By J. R. Long, E. T. Hayes, R. S. Dean, F. S. Wartman

THE production of titanium in 15-1b. lots and with a purity sufficient to be consolidated into ductile metal, as described in a previous paper,1 has provided adequate material for a study of the : physical properties of titanium and a more thorough examination of its working qualities. Data on the physical properties reported in that paper were obtained on metal fabricated by a fixed procedure, standardized for the purpose of control of the reduction, and are representative only of material fabricated under those conditions. There are many possible variables in the working schedule, which will have significant effects on the properties of the finished material; and since the previous working methods were not necessarily the best, an investigation of the fabrication of titanium by other methods was undertaken. In this work the consolidation of the powder by pressing and sintering was conducted essentially as outlined in the report cited' and all efforts were centered on fabrication methods for those powders and the properties produced by them. Hardness, density, microstructure, and tensile properties were determined at various stages in the working and annealing; and resistivity measurements were made on a few bars and drawn wire. [ ] CONSOLIDATION OF THE POWDER The screen analysis of the available titanium powder is given in Table I. No attempt was made to alter the size distribution from that noted because this powder, although coarse by normal powder-metallurgy standards, produced acceptable compacts suitable for the present work. Because of their large specific surface, finer powders are more contaminated by oxygen and produce harder compacts, which are difficult to work. The powder as produced is soft, compresses in a normal fashion, and exhibits very little tendency to adhere to the die surfaces. Unlike aluminum and magnesium powders, it can be readily pressed without the use of die lubricants. When compacted at so tons per

Jan 1, 1946

By D. S. Hutton, W. C. Leslie

Thermal etch patterns developed on poly crystalline 3.5 pct Si-Fe by heating in hydrogen or in argon have been examined. The most prominent feature of the etching is the development of striations on grains with (100) planes near the plane of the surface. These striations are probably produced by the resoution of a random, high-energy plane into (100) facets of lower energy. THE thermal etching of iron and iron-base alloys has a long history. The phenomenon was observed by Osmondl more than 70 years ago. The literature on thermal etching between that time and 1951 was reviewed by Olney,2 and a briefer review appeared in 1958. 3 The only articles which have been found dealing with the thermal etching of silicon iron are those of Dunn and Lionetti4 and of Dunn, Daniels, and Bolton,5 and they reported only grain boundary etching. EXPERIMENTAL PROCEDURES A cast 3.5 pet Si-Fe alloy was given a metallo-graphic polish and etch, then placed in flowing purified hydrogen for 6 hr at 2200°F. The same specimen was later repolished and etched to remove the thermal etching. The specimen was then held in flowing purified argon at 2200°F for 72 hr. In both instances the specimen was rapidly cooled by being pulled up quickly into the cold zone of the furnace. All photomicrographs shown are of the surface as removed from the furnace. Oblique illumination was essential for observation of the thermal-etching effects with a light microscope and was used for all the photomicrographs. RESULTS AND DISCUSSION Grain boundary etching, grain boundary movement, and contouring within grains are illustrated in Fig. 1. The contours within a single grain followed behind the advancing grain boundary. To determine the average contour interval, or step height, white light was used in an interference microscope. The steps were of the correct magnitude to separate while light into its spectrum of colors. A green light was focused at the top of a contoured area, shifting to red across the field. By using the difference in the dominant wave length of red and green light,6 and counting the number of steps across the area, it was possible to obtain a value of about 80A for the average step height. Laue back-reflection patterns of four grains with contour lines showed that the grains had a (100) plane slightly inclined to the plane of the surface (± 5 deg). Insofar as this could be determined from their irregular traces, the contour lines within a grain had a common direction, <100> ± 5 deg.

Jan 1, 1961

By A. L. Holley

The first session was held in the rooms of the American Philosophical Society, on Tuesday evening, February 26th. The President, Dr. T. Sterry Hunt, called the meeting to order, and after a few introductory remarks concerning the importance of theoretical and speculative science, which often involves principles of the highest economic value, and, more than all that, serves to enlarge our conceptions of the universe, and ennoble us, by the cultivation which it affords to our most exalted faculties, proceeded to discuss some points in the chemistry of the atmosphere. It is known that there is in the crust of the earth a great amount of oxidized carbon, not only in the shape of coal, but also in the graphite or plunlbago of the crystalline rocks, in the various bituminous shales or pyroschists, which are found in all succeeding rock-formations, and also in the forms of bitumen and petroleum. All the analogies of nature lead us to conclude that these various carbonaceous substances have had an organic origin, and have been generated by the deoxidation of carbonic acid, a process effected by the growing plant, and attended with the liberation of oxygen. He showed that the carbon of a layer of coal covering the whole earth&apos;s surface to the thickness of one meter, would, in its production from carbonic dioxide, liberate an amount of oxygen equal to that now present in our atmosphere. But bituminous coal contains also a large amount of hydrogen, derived from the deoxidation of water, which implies the liberation of a farther portion of oxygen. The amount from this latter source would equal, for the various coals and asphalts, from one-eighth to one-fourth, and, for the petroleums, onehalf of that set free in the deoxidation of the carbon which these hydrocarbonaceous bodies contain. From what we know of the composition of the stratified rocks, it is probable that they include an amount of deoxidized carbon and hydrogen many times greater than that contained in a layer of coal one meter in thickness, and, consequently, that the disengaged oxygen in past ages must have far exceeded that now present in our atmosphere. To this must be added

Jan 1, 1879

By Max Roesler

I. INTRODUCTION THE following article concerns the geological occurrence of the iron-ore deposits on the south coast of Cuba. The article is based on a detailed field study, made in the hope that some information would I gained which might be of value in the search for further orebodies, Or in the economic development of the ore already found. LOCATION The iron-ore deposits of the Firmeza district lie near the coast, in the southeastern part of Cuba, in the Province of Oriente. The orebodies of this district form part of a belt of deposits that extends from Sigua, 25 miles east of Santiago, to Sevilla, 5 miles east of Santiago, and lies on the seaward slope of the Sierra Maestra range of mountains.

Jan 10, 1916

By A. H. Daane, B. J. Beaudry

The Sc-Y and Sc-Zr systems were studied by thermal and X-ray methods. Both systems are characterized by complete solid solubility in the low temperature hexagonal form and in the high temperature bcc form. In the Sc-Y system, there is a minimum in the solidus at 50 at. pct and 1365°C, while the solidus in the Sc-Zr system follows a nearly straight line relationship between the melting point of scandium and zirconium. There is a minimum in the temperature of transition from hexagonal to bcc in the Sc-Y system at 43 at. pct Y and 1175°C; while the temperature of transition is raised in the Sc-Zr system to a maximum of 1415 °C at 30 at. pct Zr. INTEREST in the metals of the first transition series has usually stemmed from their useful properties; however, there is now a great deal of interest in determining the fundamental nature of these metals. Since scandium is the first of these transition metals, a study of the preparation and Properties1 and the alloying behavior of scandium2 was initiated. In a continuing study of the alloying behavior of scandium, the systems of scandium with zirconium and yttrium have been established. Extensive solid solubility in both the Sc-Zr and Sc-Y systems was expected from application of the classical rules of Hume-Rothery. Also, the modified Darken and Gurry plot as suggested by Gschneid-ner3 showed ideal conditions for solubility in the Sc-Zr system with less favorable conditions in the Sc-Y system. The effect of scandium on the transformation temperature of zirconium and yttrium was of interest, since a recent empirical observation by Uly and Burr4 predicted that the solute scandium would raise the transformation temperature of zirconium and lower the yttrium transformation. In addition to noting the validity of the above predictions, the SC-Y and Sc-Zr systems were established. EXPERIMENTAL METHODS Materials. The metals employed in this investigation were crystal bar zirconium, distilled scandium prepared by the method described by Spedding, et al.1 and yttrium prepared by the method described by Carlson, et a1.5 The major impurities present in these metals are listed in Table I in ppm. Alloy Preparation. All the alloys examined were initially formed by comelting the two metals in a nonconsumable electrode arc-melting furnace under an atmosphere of purified helium or argon. The buttons were inverted at least five times and re-melted each time to ensure homogeneity. During preparation of Sc-Zr alloys, approximately 1 wt pct was lost which was attributed entirely to the loss of scandium by distillation. When preparing Sc-Y alloys, approximately 1.5 wt pct was lost, but it was assumed that the intended composition was maintained, since the relative weight lost when arc melting the component metals was nearly the same. Samples weighing 15 to 20 g were prepared for time-temperature thermal analysis, while only 1- to 2-g samples were prepared for the optical pyrometer and X-ray diffraction studies. Thermal Methods. The solidus and the melting points of the metals were determined by an optical pyrometer method described previously.2 The temperatures at which the transformation from hexagonal to bcc occurs were determined by differential thermal analysis. Several points on the solidus and liquidus in the Sc-Y system were also determined by this method and are in good agreement with those obtained by the optical pyrometer method. The procedure followed in the preparation of samples for thermal analysis and the furnace used have been described elsewhere.2&apos;6 Since a limited quantity of scandium was available, most of the alloys were not melted during thermal analysis, thus avoiding contamination by the crucible. The alloy could then be reused and the composition changed by adding the desired quantity of solute to obtain the next alloy. Heat Treatment and X-Ray Methods. In order to ensure homogeneity, the "as arc-melted" alloys Were wrapped in tantalum foil, sealed in quartz capsules and heated at 1100°C for 15 hr and then cooled at a rate of 8 deg per min. Samples for X-ray diffraction were filed from these heat-treated alloys, sealed in 1/8 in. by 1/2 in. tantalum capsules under

Jan 1, 1963

By Thomas T. Read

Readjustment of the industrial world to a peace basis after more than 4 years of war will involve many fundamental and far-reaching changes that cannot as yet be clearly foreseen or definitely provided for. Such problems may be subdivided, in the vocabulary of war, into those involving material and those centering about personnel. Of the two, the latter group is the more difficult and obscure, as the factors involved are less clearly understood and the methods to be followed are not yet tested and standardized. When it is said that the market is weak, stocks large, and demand light, every business man understands clearly what is meant and what course he should adopt to adjust himself, so far as possible, to such conditions. But when it is said that the rapid spread of Bolshevism in Europe is a danger to industrial organization in this country, it is difficult to have any assured sense that all that the statement may mean is clearly understood or that the means to be followed to meet such a situation are definitely known. Since Bolshevism is primarily a mental phenomenon and since the rupture it brings about in industrial organization should be prevented, if possible, it is my purpose to restrict this discussion of the activities of the Committee on Industrial Organization to some of its mental aspects, as the chairmen of the sub-committees, from their special knowledge of their own fields, can best set forth recent progress in the lines with which they are especially concerned. The first requisites of success in industrial organization, as in the biological organism of which it is the social counterpart, are unity of purpose and coordinated activity. Typical good and bad examples of this&apos; are the relative parts that the United States and Russia have played in the great war. These two factors are primarily mental, and it is not difficult to view the mental aspects of all problems of industrial organization as the most important ones. Unless we can attain unity of purpose and coordinated activity in industry, the provision of comfortable homes at reasonable rent, the assurance of steady work at good wages, the elimination of industrial accidents, and provision against want in old age or in case of disability will have brought us no nearer to our real goal.

Jan 1, 1919

By A. Hultgren, G. Phragmén

Page Outline of Progress of Knowledge and Theories about Gas Evolution in Steel Ingots. and Its Influence on Crystallization and Segregation................ 134 Object of Present Investigation........................................... 148 Theoretical Discussion of Process of Solidification........................... 149 Gas Given Off from Rimming Steel during Solidification................... 149 Equilibrium Diagram of the Iron-carbon-oxygen Alloys................... 151 Solidification of Pure Iron-carbon-oxygen Alloys.......................... 157 Solidification when Carbon Monoxide Is Given Off at Constant Pressure... 157 Solidification when Gas Evolution Is Suppressed....................... 158 Schematic Application on Solidification of Rimming-steel Ingots.......... 159 Influence of Manganese, Sulphur and Phosphorus......................... 160 Experimental work..................................................... 162 Liquid Steel and the Mold Gas......................................... 162 Ingots Investigated and Methods Used.................................. 165 Ingot structure....................................................... 174 Structure of Rim Zone.............................................. 174 Structure of Core................................................... 181 Structures Obtained under Special Conditions of Freezing................ 182 Distribution of Metalloids............................................. 187 Other Observations Made............................................. 192 General Discussion of Solidification Process................................. 195 Condition of Liquid Steel before Casting................................. 195 Rimming Period...................................................... 202 Composition of Rim Zone............................................. 225 Freezing after Top Is Closed........................................... 228 Slag Inclusions and Ingot Scum........................................ 234 Reaction between Gas in Blowholes and Surrounding Solid Steel during Cooling 235 Summary.............................................................. 237 Appendix—Preparation and Etching of Ingot Sections....................... 238 References............................................................. 239 In 1934, Jernkontoret (The Swedish Ironmasters&apos; Association) appointed a committee for the study of the structure of rimming-steel ingots and the various phenomena associated with their solidification. The members of the committee, including those who have joined it later, have been: I. Bohm, B. D. Enlund, B. Kalling, M. Tigerschiöld, S. Wohlfahrt and the authors. The present paper‡ is a somewhat

Jan 1, 1939

By G. Phragmén, A. Hultgren

Page Outline of Progress of Knowledge and Theories about Gas Evolution in Steel Ingots. and Its Influence on Crystallization and Segregation................ 134 Object of Present Investigation........................................... 148 Theoretical Discussion of Process of Solidification........................... 149 Gas Given Off from Rimming Steel during Solidification................... 149 Equilibrium Diagram of the Iron-carbon-oxygen Alloys................... 151 Solidification of Pure Iron-carbon-oxygen Alloys.......................... 157 Solidification when Carbon Monoxide Is Given Off at Constant Pressure... 157 Solidification when Gas Evolution Is Suppressed....................... 158 Schematic Application on Solidification of Rimming-steel Ingots.......... 159 Influence of Manganese, Sulphur and Phosphorus......................... 160 Experimental work..................................................... 162 Liquid Steel and the Mold Gas......................................... 162 Ingots Investigated and Methods Used.................................. 165 Ingot structure....................................................... 174 Structure of Rim Zone.............................................. 174 Structure of Core................................................... 181 Structures Obtained under Special Conditions of Freezing................ 182 Distribution of Metalloids............................................. 187 Other Observations Made............................................. 192 General Discussion of Solidification Process................................. 195 Condition of Liquid Steel before Casting................................. 195 Rimming Period...................................................... 202 Composition of Rim Zone............................................. 225 Freezing after Top Is Closed........................................... 228 Slag Inclusions and Ingot Scum........................................ 234 Reaction between Gas in Blowholes and Surrounding Solid Steel during Cooling 235 Summary.............................................................. 237 Appendix—Preparation and Etching of Ingot Sections....................... 238 References............................................................. 239 In 1934, Jernkontoret (The Swedish Ironmasters&apos; Association) appointed a committee for the study of the structure of rimming-steel ingots and the various phenomena associated with their solidification. The members of the committee, including those who have joined it later, have been: I. Bohm, B. D. Enlund, B. Kalling, M. Tigerschiöld, S. Wohlfahrt and the authors. The present paper‡ is a somewhat

Jan 1, 1939