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REPORT OF PRESIDENT C. F. RAND FOR THE YEAR 1917 The noteworthy occurrences during 1917 were the creation of Engineering Council; the completion of the addition to the Engineering Societies Building. and the occupation by the American Society of Civil engineers of the space thus provided for it; the addition of 67,000 vol-

Jan 3, 1918

C. E. Dewey, Georgetown, Colo. (communication to the Secretary) : In his remarks on crushing-machinery, Mr. Douglas says (Twins., xxii., p. 322): "To insure a smaller and more uniform size of particles in the crushed material, the Dodge crusher still communicates motion to the upper extremity of tile movable jaw, which oscillates on fixed pivots projecting from its lower extremity!' The notion that, in order to obtain a fine and uniform product from a rock-breaker, the movable jaw must be pivoted at its lower extremity, seems to obtain generally among mill-men, as well as among manufacturers of machinery. My experience with machines of both types does not confirm this belief. It is true that, to obtain a uniformly fine product from a jaw-crusher, the stroke at the lower extremity of the crushing-surface must be short; but that the movement at that end must be less than at the other or receiving-end is, I think, an erroneous assumption. Figs. 1 and 2 are intended to illustrate the two types of machine. It is found in practice that the capacity and the nature of the product of either machine, as usually constructed, are governed by the opening, C D, and the length of stroke of the movable jaw at D. This being the case, machines of either type, of the same width of crushing-surface, running at the same speed, and having the same adjustment as to opening and stroke at D, should give, when fed

Jan 1, 1895

By A. Gittens

In two recent papers stevens13,14 has compared the methods used by various investigators to calculate the contribution of grain boundary sliding to the total creep strain. In previous work Gittins15 has shown that the strain due to grain boundary sliding Egb may be estimated from the lateral, d, and vertical, v, displacements of a longitudinal marker line as it crosses a grain boundary. He obtained the formula, where nL is the number of grains per unit length measured on the specimens before creep, and \p and ?2 are, respectively, the angle between the grain boundary and the stress axis in the plane of the surface and normal to the surface (see Ref. 13, Fig. 1). The subscript L indicates that observations are made in a longitudinal direction parallel to the stress axis. It was generally found more convenient to measure the grain size of a specimen before creep; this was necessary to characterize the specimen. Stevens13,14 however prefers to define Egb in terms of NL, the number of grains per unit length after creep. Since nL - NL(l + €1) where cr is the total strain, Eq. 1 11 becomes The quantities d and ?, can be determined directly from the marker lines, while v and ?2 are found by sectioning normal to the surface. In the interior when symmetry considerations suggest that v = d and ?1 - ?2 the strain due to grain boundary sliding may be estimated from a suitable internal longitudinal marker line by the equation To determine cgb at the surface using either Eqs. |1| or [2] requires a large number of observations, particularly if many estimates of cgb are required, and also it is impossible to determine the variation of cgh with creep strain on the same specimen because the specimen must be sectioned to determine ?2. Gittins15 found that for a number of materials the sliding vectors d and v were related to each other so that provided one was measured the other could be estimated. Also during creep, grain boundaries tend to migrate to meet the surface at angles close to 90 deg,16 so that the term nL(v/tan?2)L was comparatively small when 4,- 90 deg. By determining the frequency distributions of ?2 on control specimens this term can be estimated without sectioning the creep specimen. In this way an empirical equation based on Eqs. |1| and |2| enables cgb to be determined with reasonable accuracy with fewer observations of the angles and sliding components. For B brass, the relationship between the sliding vectors indicated that ceb = 0.85nLVL . In Table I of Stevens paper this equation is stated to be incorrectly derived. However it should be pointed out that this is an empirical equation derived from Eq. |1|, based on a knowledge of the relationship between d and v and on the frequency distributions of ?1 and ?2 for a particular material under given experimental conditions. It was used only when these relationships were known, to reduce the number of observations required to estimate cb. Therefore the comment "derivation incorrect does not apply. Gittins did in fact make use of Eqs. |1| and 131. Author's Reply I must apologize to Dr. Gittins for the inadvertent misrepresentation of his work. Other slight errors in Table I have been pointed out to me. Langdon (No. 12 Table I), Gifkins (No. 7, Table I), and possibly other workers did not measure the number of boundaries per unit length after creep (A') but the corresponding quantity bejove creep (n). As Dr. Gittins points out, a completely analogous set of equations to those given in the paper can be derived by the same method: using the number of boundaries per unit length before instead of after creep. The basic equations corresponding to Eqs. [2] and 171 of the paper, from which all the others can be derived, are

Jan 1, 1968

By Irving Crosby

ELECTRICAL prospecting by potential methods has been applied to mining problems for some years and determinations of the depth to bed rock have been made, but so far as is known it has not been used previously in the solution of civil engineering problems, such as investigating the foundations of dams. During the past winter and spring the senior author has been engaged as consulting geologist in studying the site of a large darn on the upper Connecticut River and has had the satisfaction of introducing electrical prospecting to foundation problems. The valley across which the dam is to be built is underlaid by a deeply buried preglacial gorge which is filled with glacial deposits. An extensive drilling campaign was in progress, but the work was unusually slow and expensive on account of the number of boulders in the overburden. The necessity of speeding up the work was pressing and it was decided that much of the needed information could be obtained by geophysical methods. After investigating the various methods and conferring with the company engineers and with the consulting engineer, Albert Crane, a contract was made with the Schlumberger Electrical Prospecting Methods, and an observer with apparatus was sent to the dam site the first of April, 1928. The problem was to determine the depth to rock at various points in order to prepare a contour map of the bed-rock surface and outline the buried gorge in the vicinity of the dam site. Over one hundred determinations of depth have been made and the bed-rock topography, is now known in considerable detail. In addition, some information has been obtained about the nature of the overburden. The drilling has been continued; in fact, two additional drills have been put to work, and the electrical determinations have been checked at several points. At one of these the depth to rock given by the electrical work was 142 ft. and the drill found rock at 147 ft., an error of less than 4 per cent. The electrical work has also been checked by the geological study, and it has been found that when the electrical determinations are in agreement with the geological expectations they are probably reasonably accurate. When the electrical interpretation of the sub-surface topography is incon-

Jan 1, 1928

By L. L. Swift

AT the present time there are four base metals being used for automotive bearing alloys. Of course there are numerous variations in the amounts of alloying elements added to each base metal and nearly all of these alloys have the conventional, if not classical, duplex structure; that is, they are composed of a hard constituent embedded in a soft matrix. The well-known theory is that the former will wear well, while the latter will be plastic enough to allow the bearing to be broken in and conform to the contours of the shaft. The requirements of the modern bearing have been most aptly described by W. M. Corse: In order to meet the engineering demands of today a good bearing metal must be able to carry the weight of the shaft and stand up under steady or suddenly applied loads, or even blows in some types of service. A certain amount of plasticity is desired to compensate for minute irregularities in the shaft or bearing surface, and to permit yielding, thereby avoiding dangerous stresses in bearing and shaft and preventing overheating and rapid wear of parts. Less plasticity is required in a bearing metal if the surfaces of bearings and journals are machined accurately, aligned, and kept in alignment. It is desirable, of course, that a bearing metal have a low coefficient of friction. Under most operating conditions the friction depends on the unit pressure of the bearing, the speed, the temperature, and the properties of the lubricant. A good bearing metal must have a low rate of wear to reduce the necessity for frequent replacements, and adjustment of the bearings. It must wear more rapidly, however, than the journal or shaft running on it, because replacement of the journal or shaft is more difficult and costly than replacement of the hearing., The hardness of, the bearing alloy is a property closely related to several of the foregoing. With a duplex microstructure, the measurement of hardness with any of the usual commercial devices means little. The Bierbaum method of measuring the hardness of the individual constituents was developed to, fill this need. MICROCHARACTER The Bierbaum microcharacter2.3 measures the scratch-hardness of a solid by pulling a weighted diamond point over the surface. The diamond point is ground. so that it is the corner of a cube, and mounted

Jan 1, 1938

By Francis Foley

WITH the possible exception of high-speed tool steel, the service demanded of rock-drill steel is probably more precarious than that of any other tool steel. Unaided by the helpful influence of alloys and dependent solely on the efficiency of the heat treatment applied for its ability to stand up under the abuse to which it is necessarily subjected, rock-drill steel is worthy of intensive study. For its heat treatment the smith has his fire, an oil fire perhaps, and a quenching bath; he judges' the temperature by his eye. There are shops where excellent drills are produced by this method, but there are more where the product varies between very good and very bad. Pyrometers with specially designed equipment are used in but few cases. But the responsibility for rock-drill failures does not rest entirely on the smith. Little has been published concerning the efficiency of drill steel, though the Canadian Mining Journal' published the breakage record of a large number of hollow drill steels. This record indicates that most of the breaks occur during the early life of the steel and that as a given batch of steel is used, its percentage of breakage decreases. This fact, the article points out, is at variance with the much-talked-f theory concerning failure from crystallization and fatigue. It seems to point to the fact that the greater part of drill-steel failure from breakage is traceable to faulty manufacture, resulting in defects in the bore of the hollow steel from inclusions of slag or oxides, etc. As this defective material meets with early failure, it is weeded out. In addition, some breakage may be caused by a lack of proper condition with respect to heat treatment of the steel as furnished by the manufacturer. In the article mentioned, the breakage of 1 ¼ -in. (3.17 cm.) hollow steel is given as 4.62 per cent. for the early period of use, with a decrease to 3.35 per cent. and 2.67 per cent. With time in use. For 1-in. (2.5 cm.) hexagonal hollow steel, the figures for breakage are 0.18 per cent. and 0.06 per cent.; attention is called to the "enormous decrease in breakage by the use of smaller diameter drills." The figures are given as so many "drills sharpened," but there is no way of determining the percentage of

Jan 6, 1921

By David R. Poirier

THE activity of carbon in Fe-C-Cr liquid solutions has been measured by Richardson and Dennis,1 Fuwa and chipman,2 and Goto et aL3 Fuwa and Chipman2 have presented their data along with data of Richardson and Dennis1 and utilized an interaction parameter. However, the interaction parameter is only valid for dilute solutions of carbon, because, as indicated, the same interaction parameter does not apply to more concentrated solutions of carbon (i.e., the effect of chromium on the saturation of graphite in liquid iron). Ohtani4 has attempted to account for the effect of carbon concentration on the interaction parameter; however even his analysis does not apply to the saturation data. Also, the effect of temperature on interaction parameters must be taken into account. Therefore, in any process where the concentration of carbon and/or the temperature changes (such as solidification), the use of an interaction parameter is not adequate to know the activity of carbon. The purpose of this communication is to make use of the existing data on the effect of chromium on the activity of carbon in liquid iron solutions in such a way that the activity can be described as a function of both composition and temperature. The method is an extension of Rist and chipman's5 analysis for the binary Fe-C solutions. As in Rist and Chipman's analysis, the activity coefficient is assumed to obey the relation: log y1 = at(l -X1)2 + It [1]

Jan 1, 1969

By R. H. Fillnow, D. J. Mac

IT has been demonstrated that alloys in systems structurally analogous to steel undergo reactions during heat treatment similar to those of steel, and yet very little work has been done on such systems, particularly from the standpoint of isothermal transformation. The literature shows that most of the isothermal work has been done on copper-alu-minum alloys.'-3 One paper has been reported on a eutectoid copper-silicon alloy,' and one on iron-nitrogen alloys.' There are no published reports of previous investigations on the isothermal transformation of a eutectoid beryllium bronze. At least two papers have been reported on isothermal age-hardening phenomena in beryllium-copper alloys of lower beryllium content.5,6 No information on eutectoid transformations in this alloy is given in Rimbach's book, "Beryllium." ' This paper reports the results of an investigation on the isothermal transformation characteristics of a eutectoid beryllium bronze. Materials Used and Procedure The eutectoid beryllium bronze used in this investigation was centrifugally cast at the Ampco Metal Co., Inc.. Milwaukee. Wis. A master beryl-lium-copier alloy, purchased from the Brush Beryllium Co., was used to make the beryllium addition to the copper. The alloy was melted under a protective carbon cover and Centrifugally cast into a graphite mold preheated to 920°F. Some trouble with segregation of beryllium in the melt was encountered but was eliminated by violent stirring during melting and pouring. Since very thin .specimens were used for the various heat treatments, only one casting of the four prepared was necessary for the complete isothermal study, thus eliminating any discrepancies caused by a change in composition. The analysis of this casting was 94.035 pct copper and 5.965 pct beryllium. A slight trace of iron was found. The castings were sawed into specimens approximately 3/32 in. in thickness. The specimens were first given an "austenitizing" heat treatment at 788°C, well within the single phase beta region, in a vertical tube furnace. The specimens were then quenched individually into an adjacent molten salt bath and held there for a definite time, after which they were quenched into water at room temperature. Temperature was held to ± 2°C in the salt bath. No homogenizing treatment was given the specimens other than the soak at 788°C. Despite the fact that this was a cast alloy, no evidence of segregation or coring was found in the microstructure of any specimen, either as cast or as heat-treated. Upon completion of the heat treatment, the speci-mens were subjected to metallographic examination

Jan 1, 1951

By D. L. Martin, E. R. Parker

IN a previous paper, one of the authors observed that the rate of cooling from the anneal prior to testing greatly influenced the life of copper under sustained load at 200°C. Furnace-cooled bars of oxygen-free copper (with, and without silver) had a life four to twenty-five times that of the water-quenched specimens. The addition of 0.054 per cent silver to the oxygen-free copper increased the life at a stress of 20,000 lb. per sq. in. from about 2 hr. to 50 hr. Fractures in these bars were intercrystalline. An explanation was advanced to account for the profound influence of cooling rate on the rupture properties at 200°C. The suggestion offered was that at the high annealing temperature the minor constituents are distributed at random. By water quenching, this condition is maintained at room temperature, whereas furnace cooling permits some segregation at the grain boundaries. The higher concentration of the minor constituents in the grain boundaries results in a strengthening, so that a longer life at a given stress and temperature results. Small amounts of cadmium or manganese have also been found to increase the life of copper at 200°C., and to a much greater extent than silver .2 The increase in the long-time strength of copper resulting from small additions of cadmium or silver appears to be related, indirectly at least, to the higher softening temperatures of such alloys. The elements, such as silver or cadmium, which greatly increase the rupture life of copper also cause large increases in the softening temperature. As little as 0.05 per cent of cadmium or silver is sufficient to raise the softening temperature more than 100°.3,4 The effects of cooling rate and of minor constituents on the rupture properties are of considerable fundamental as well as practical interest; therefore a more detailed study of their nature was conducted and is reported in this paper. EXPERIMENTAL PROCEDURE Materials The materials studied in this investigation may conveniently be classified in two groups: one consisting of a wide variety of commercial coppers, and the other composed of special high-purity, laboratory-prepared coppers. The commercial materials were tested to determine whether or not the effect of cooling rate occurred with all coppers, whereas the high-purity coppers were investigated in order to establish a basis for evaluating the effect of minor constituents on the rupture properties. In Table I are given the analyses of the coppers tested. The samples I to 6 are commercial materials and were obtained for the most part from stock supplies.*

Jan 1, 1943

By Parke A. Hodges

CHROMIUM, one of the most vital of the strategic metals, has constantly increasing importance as research expands potential uses in alloy steel metallurgy. All signs point to a steadily growing use for chrome ore, and the general subject has received a great deal of attention recently.1 A relatively little known country, Southern Rhodesia produced a total of 5.949 million tons, or 18.6 pct of the total world chrome output, between 1906 and 1950, according to figures from the U. S. Dept. of Commerce. According to U. S. Bureau of Mines figures, Southern Rhodesia produced 291,525 tons in 1950 and 300,267 tons in 1951, or approximately 13 and 11 pct, respectively, of world production for the two years. In 1953 the Rhodesian Vanadium Corp. produced about 85,000 tons of which probably 7,000 tons were concentrate. Production by other companies was high. Large in themselves, the figures assume even greater significance because most of this output is of metallurgical grade.

Jan 8, 1954

APRIL BEGAN with increased disorder in the Ruhr and some blood-shed. The war cloud in the East disappeared, however, with the signifi- cance by the Turks of their intention to return to Lausanne to negotiate a treaty of peace with the Allies. The French occupation of the Ruhr continued during April without there being any spectacular develop-ments. Of course there was surliness on the part of the Germans. In the meanwhile the statesmen on both sides were intimating what they might give and what they might take, sounding the sentiment of their respective populaces. The British Government found that its revenue for the last fiscal year has been greatly in excess of expenses. The surplus was applied to reduction of the debt. A consequence of this development has been a reduction in British taxes for the ensuing year, which has naturally created a much better feeling in Great Britain. On the other hand the unemployment situation in Great Britain caused increasing alarm. At the begin-ning of April about 1,500,000 men were out of work and the thought was developing that this might be not merely a temporary emergency, but a long continuing condition. The uneasiness of the workers themselves began to be exhibited in increasing strikes and threats of strikes. There were important domestic events during April. The six miners who were on trial in Illinois for the Herrin massacre were acquitted, following which the State dropped further prosecutions on the ground that Williamson County is so thoroughly under labor domina-tion that justice could not be had there. The Supreme Court of the United States on Apr. 10 handed down a decision that an act of Congress fixing minimum wages for women in the District of Columbia was unconstitu-tional, being interference with the freedom of contract included within the guarantees of the fifth amendment. Advances of wages became more general during April. The leading event under this head was the action of the United Steel Corporation putting into effect an.11 per cent. increase in the wages of common labor on Apr. 16, by virtue of which the rate per hour was raised from 36 c. to 40 c. This was dictated by competitive conditions, the labor difficulties of the steel industry being due less to a scarcity of men than their disinclination to take jobs in that industry while the building and other industries were paying as high as 60 c. per hour for similar work.

Jan 5, 1923

By Akio Suzuki, P. G. Wahlbeck

AS a part of a study of the vaporization of transition metal-chalcogen systems, the vaporization reactions for the Ti-Se system have been studied. In order to establish vaporization reactions it is important to determine the identity of vapor species in equilibrium with the condensed phases. In some cases, it is possible to deduce the identity of vapor species through observations of composition change of the condensed phase with which the vapor is in equilibrium. Determination of vapor species in equilibrium with condensed phases should precede vapor-pressure measurements and is necessary for proper thermodynamic analysis of vapor-pressure data. Bear and McTag-gart' reported that vacuum heating ot TiSea at 950°C produced a residue with a composition of 1.7 Se/Ti atomic ratio units. Analyses of condensed phases existing for the Ti-Se system have been performed by Bernusset,2"4 Gron-vold and Langmyhr,5 Hahn and Ness,' and Ehrlich.~ Results and conclusions of two types of experiments are described herein: 1) experiments where samples of known composition were vaporized followed by chemical analysis of residues and 2) experiments where the vapor species were identified by means of a mass spectrometer. Experimental Section. Sarnple Preparation. Samples of TiSe2 were prepared in a sealed, evacuated quartz ampule by heating to 1000°C stoichiometric amounts of selenium of 99.999+ pct purity obtained from the American Smelting and Refining Co. and titanium of 99.2 pct purity obtained from A. D. Mackay, Inc. After heating, the sample was ground and reheated to insure homogeneity. Samples containing less selenium than TiSez were prepared by mixing amounts of titanium powder and TiSez appropriate for the desired composition; the titanium and TiSez mixture was heated in the same manner as described for TiSe2. Analyses of titanium selenide samples contained in quartz crucibles were performed by gravimetric oxidation in oxygen at 800°C; the products of the oxidation were solid TiOz and gaseous Se02. The mass of the original sample and the mass of TiOn determined the Se/Ti atomic ratio. The sample of TiSen used in these experiments had a composition of 2.04 Se/Ti atomic ratio units. The compositions for all samples reported were analyzed by this method. Va/!orization Experiments. Samples of titanium selenides were vaporized in tungsten Knudsen crucibles. Some vaporization experiments were carried out in glass vacuum lines followed by chemical analyses of residues, and some vaporization experiments were performed with a Bendjx mass spectrometer as described previously.8

Jan 1, 1967

By F. B. Foley

With the possible exception of high-speed tool steel, the service demanded of rock-drill steel is probably more precarious than that of any other tool steel. Unaided by the helpful influence of alloys and dependent solely on the efficiency of the heat treatment applied for its ability to stand up under the abuse to which it is necessarily subjected, rock-drill steel is worthy of intensive study. For its heat treatment the smith has his fire, an oil fire perhaps, and a quenching bath; he judges the temperature by his eye. There are shops where excellent drills are produced by this method, but there are more where the product varies between very good and very bad. Pyrometers with specially designed equipment are used in but few cases. But the responsibility for rock-drill failures does not rest entirely on the smith. Little has been published concerning the efficiency of drill steel, though the Canadian Mining Journal1 published the breakage record of a large number of hollow drill steels. This record indicates that most of the breaks occur during the early life of the steel and that as a given batch of steel is used, its percentage of breakage decreases. This fact, the article points out, is at variance with the much-talked-of theory concerning failure from crystallization and fatigue. It seems to point to the fact that the greater part of drill-steel failure from breakage is traceable to faulty manufacture, resulting in defects in the bore of the hollow steel from inclusions of slag or oxides, etc. As this defective material meets with early failure, it is weeded out. In addition, some breakage may be caused by a lack of proper condition with respect to heat treatment of the steel as furnished by the manufacturer. In the article mentioned, the breakage of 1/14-in (3.17 cm.) hollow steel is given as 4.62 per cent. for the early period of use, with a decrease to 3.35 per cent. and 2.67 per cent. with time in use. For 1-in. (2.5 cm.) hexagonal hollow steel, the figures for breakage are 0.18 per cent. and 0.06 per cent.; attention is called to the great decrease in breakage by the use of smaller diameter drills. The figures are given as so many drills sharpened, but there is no way of determining the percentage of

Jan 1, 1922

By D. A. Woodford

A number of observations have now been reported where the steady-state creep rate is apparently linearly dependent on the applied stress at high temperature and low stresses. This results in a creep rate greater than that predicted by extrapolation of high-stress data and has obvious practical implications. However, some of these observations are open to question. For example, the analysis by Harris and Partridge17 of the data of Greenfield et a1.18 was dependent on strain rates which, according to the original authors, were too low to be measured. Dr. Bernstein appears to have demonstrated a linear stress dependence at low stresses in two zirconium alloys. There are, however, a number of discrepancies in his treatment of the data and the subsequent theoretical analysis which require clarification. 1) It is incorrectly stated that steady-state conditions are revealed by a slope of unity on a plot of log i vs log (time). This objection is trivial if the author meant to say a slope of zero, although it is unclear how subsequent extrapolation was made to determine the steady-state creep rates at low stresses for the zircaloy-2. If the plot used was actually log c vs log (time), it is unlikely that a slope of unity would represent a constant creep rate. A plot of log (c - co) vs log (time), where c0 is the extrapolated intercept sf the steady-state creep rate on the strain axis, would have a slope of unity during steady-state creep. However, eo cannot be determined unless is is already known. 2) The author chooses to interpret his results based on the equation: where A, and B, are structure-sensitive parameters, Ql and Q, are the activation energies for the particular creep process, and n describes the sensitivity of the creep rate on stress. The first term represents a slip creep process and the second a diffusion creep process. However, it is stated later that "two distinct processes acting in parallel are involved". Eq. [I] surely represents two processes in series since each reacts to the total applied stress and t, is the sum of the individual creep rates. If the processes are acting in parallel, then the effective stress in each would be less than the applied stress. The component stresses would be given by sl + s2 = a but it is not clear how the magnitude of either, or the corresponding stress exponent, could be determined.

Jan 1, 1969

By R. C. Hall

We are pleased to confirm some of the mechanical data presented by Dr. Detert on the 18 pct Ni marag-ing steel.15 Bar 3 in. in diam and containing 0.02 wt pct C, 18.5 Ni, 8.9 Co, 5.1 MO, 0.55 Ti, 0.05 Al, and balance iron has been examined in our laboratory. Cylinders 0.5 in. high and 0.4 to 0.5 in. in diam were cold-compressed from 3 to 40 pct reduction in height. Table VI shows some typical data; deformation in-

Jan 1, 1968

By R. E. Reed-Hill

Recently Levine applied the Conrad-Wiedersich17 equation where H is the activation enthalpy, v the activation volume, T* the effective shear flow stress, T the absolute temperature, and ? the strain rate, to an analysis of titanium single-crystal data. The activation energy as a function of testing temperaturs obtained from specimens oriented for single (1010) prismatic slip is shown in Fig. 12. This diagram indicates a different linear dependence of H on T in the temperature interval from 220° to 300°K than from 0° to 220°K. Levine interpreted the break in this curve as indicating a change in the thermally activated mechanism controlling the flow stress. The purpose of this communication is to point out that the data in Fig. 1 is not consistent with the concept of a flow stress controlled by a simple thermally activated mechanism between 220° and 300°K. The Conrad-Wiedersich relation assumed that the strain rate can be expressed by:

Jan 1, 1968

By B. A. Cheadle, C. E. Ells

The ovienlalion of hexagonal a-zirconium crystals in cold-drawn Zircaloy-2 tubes and in both as-extruded and heat-treated Zr-2.5 wt pcl ND tubes has been rrleasured using the inverse Pole - figure technique. Uniaxial tensile tests hare shown the Zil-caloy-2 lubes to hare highly anisotropic delovmation behavior whereas heat-treated Zr-2.5 wt pet Nb tubes are nearly isotropic. The differences in deformation behavior are esbloilred from the observed textures of the tubes and the deformation systems known to oberate in Zircnloy,-3. Tlze vcsults lead to an explanation of the high effective strain observed fov the Zircaloy-2 tubes as colrzpared to heat-treated Zr-2.5 wt pet Nb tubes in restrained end burst tests at 280° to 300°C. THE Zr-2.5 wt pct Nb alloy. when heat-treated by quenching from temperatures slightly below the (a + p)/P phase boundary and subsequently aged at 500°C, has tensile strengths about 50 pct greater than those of 20 pct cold-worked Zircaloy-2.1 There is. therefore, considerable economic incentive to replace Zircaloy-2 with the heat-treated alloy in some in-reactor applications. notably for pressure tubes, where strength is a prime consideration. However, when tubes of Zr-2.5 wt pct Nb fabricated by extrusion and drawing prior to heat treatment were subjected to restrained end-burst tests at 300 °C. the circumferential expansion at failure1 was only 10 pct that of cold-drawn Zircaloy-2 tubes in similar tests,2 Table I. This result was not predicted from uniaxial tensile tests in which the ductilities of the two materials were quite similar.' The detailed requirement for ductility in pressure vessels has not yet been worked out. and comparison of the relative merits of cold-worked Zircaloy-2 and heat-treated Zr-2.5 wt pct Nb is further complicated by the irradiation-induced loss of ductility and hydrogen pickup each will undergo from reactor operation.1,2 Nevertheless. the lower circumferential expansion of the Zr-2.5 wt pct Nb tubes raised serious doubts on the advisability of their use as pressure vessels. For this reason, an investigation to determine the cause for different ductilities of the two types of tubes was initiated. From a study of uniaxial tensile properties and crystallographic orientation it has been found that the fracture ductilities observed in the burst tests can be related directly to the crystallographic ori-

Jan 1, 1965

By Orville A. Derby

In view of the recent important discussions before this Institute on the genesis of metalliferous deposits, certain features in the occurrence of gold which seem to be more clearly developed in Brazil than elsewhere can hardly fail to be of interest. As the observations here recorded have necessarily been of a somewhat cursory character, they will be presented in the form of brief notes, without any attempt to draw conclusions as to their genetic significance. Gold in Gneiss.—The statement made by me many years ago† that in the districts of Campanha and S?o Gongalo, in southern Minas Geraes, gold occurs in gneiss, can now be reaffirmed in the most positive manner, on the strength of a recent examination of fresh material, confirmed by the testimony of an experienced mining captain from the Morro Velho mine, who, being skeptical on this point, made a prospectingtour in the district. The specimens examined, though so far decomposed as to be readily disaggregated, were clearly of

Jan 1, 1903

By L. L. Swift

.It the present time there are four base metals being used for automo-tive bearing alloys. Of course there are numerous variations in the amounts of alloying elements added to each base metal and nearly all of these alloys have the conventional, if not classical, duplex structure; that is, they are composed of a hard constituent embedded in a soft matrix. The well-known theory is that the former will wear well, while the latter will be plastic enough to allow the bearing to be broken in and conform to the contours of the shaft. The requirements of the modern bearing have been most aptly described by W. M. Corse: In order to meet the engineering demands of today a good bearing metal must be able to carry the weight of the shaft and stand up under steady or suddenly applied loads, or even blows ill sorne types of service. A certain amount of plasticity is desired to compensate for minute irregularities in the shaft or bearing surface, and to permit yielding, thereby avoiding dangerous stresses in bearing and shaft and pre-venting overheating and rapid wear of parts. Less plasticity is required in a bearing tuetal if the surfaces of bearings and journals are machined accurately, aligned, and kept in alignment. It is desirable, of course, that a bearing metal have a low coeffi-cicnt of friction. Under most operating conditions the friction depends on the unit, pressure of the bcaring, the speed, the temperature, and the properties of the lubricant. A good bearing metal must have a low rate of wear to reduce the necessity for frequent replacements, and adjustment of the bearings. It must wear more rapidly, however, than the journal or shaft running on it, because replacement of the journal or shaft is more difficult and costly than replacement of the bearing.' The hardness of the bearing alloy is a property closely related to several of the foregoing. With a duplex microstructure, the measurement of hardness with any of the usual commercial devices means little. The Bierbaum method of measuring the hardness of the individual canstituents was developed to fill this need. MICROCHARACTER The Bierbaum MicroCharacter~,~ measures the scratch-hardness of a solid by pulling a weighted diamond point over the surface. The diamond point is ground so that it is the corner of a cube, and Mounted

Jan 1, 1939

By L. L. Swift

.It the present time there are four base metals being used for automo-tive bearing alloys. Of course there are numerous variations in the amounts of alloying elements added to each base metal and nearly all of these alloys have the conventional, if not classical, duplex structure; that is, they are composed of a hard constituent embedded in a soft matrix. The well-known theory is that the former will wear well, while the latter will be plastic enough to allow the bearing to be broken in and conform to the contours of the shaft. The requirements of the modern bearing have been most aptly described by W. M. Corse: In order to meet the engineering demands of today a good bearing metal must be able to carry the weight of the shaft and stand up under steady or suddenly applied loads, or even blows ill sorne types of service. A certain amount of plasticity is desired to compensate for minute irregularities in the shaft or bearing surface, and to permit yielding, thereby avoiding dangerous stresses in bearing and shaft and pre-venting overheating and rapid wear of parts. Less plasticity is required in a bearing tuetal if the surfaces of bearings and journals are machined accurately, aligned, and kept in alignment. It is desirable, of course, that a bearing metal have a low coeffi-cicnt of friction. Under most operating conditions the friction depends on the unit, pressure of the bcaring, the speed, the temperature, and the properties of the lubricant. A good bearing metal must have a low rate of wear to reduce the necessity for frequent replacements, and adjustment of the bearings. It must wear more rapidly, however, than the journal or shaft running on it, because replacement of the journal or shaft is more difficult and costly than replacement of the bearing.' The hardness of the bearing alloy is a property closely related to several of the foregoing. With a duplex microstructure, the measurement of hardness with any of the usual commercial devices means little. The Bierbaum method of measuring the hardness of the individual canstituents was developed to fill this need. MICROCHARACTER The Bierbaum MicroCharacter~,~ measures the scratch-hardness of a solid by pulling a weighted diamond point over the surface. The diamond point is ground so that it is the corner of a cube, and Mounted

Jan 1, 1939