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By W. R. Hibbard

T has been proposed1 on the basis of slip and flow I- that the ideal deformation texture of cold rolled face-centered cubic metals is (110) [112]. As pointed out recently by Brick,' this theory does not account for the difference between the pole figures for cold rolled copper and 70-30 alpha brass, which develop strikingly different spreads from the ideal orientations. It does suggest that the pole figures might be similar for these two metals if they are rolled sufficiently. This has been found to be the case for cold drawn wire.' Experimental Procedure: Four inch sections of cast cakes of copper and 70-30 alpha brass were obtained through the courtesy of the Bridgeport Brass Co. Pieces from these cakes were cold straight rolled 99.993 pct reduction in thickness with the assistance of the Remington Arms Co., Bridgeport, Conn., and by the use of pack rolling. Pole figures were made using the X ray camera and techniques described by Brick.' These pole figures were not significantly different from those previously published for the same materials rolled 98 pct. Eight thicknesses of this strip were then pack rolled. This material failed completely and extensively in tension as shown in fig. 1, developing wavy transverse fractures and bulges. No further work could be done on these samples. Summary: Within the range of this experiment, no attainable amount of cold rolling would cause the pole figures of cold rolled copper and 70-30 brass to become similar, in spite of the fact that such a similarity is predicted by theory.' References W. R. Hibbard. Jr. and M. K. Yen: Trans. AIME (1948) 175, 126. Met. Tech. Feb. 1948. TP 2334. ²R. M. Brick: Trans. ASM (1949) 41A, 99. 3W. R. Hibbard, Jr.: Trans. AIME (1949) 185, 598, Jnl. of Metals, Sept. 1949. "R. M. Brick: Trans. AIME (1940) 137, 193. 'R. M. Brick, D. L. Martin and R. P. Angier: Trans. ASM (1943) 31, 675.

Jan 1, 1951

By Carl Zapffe

Because no rock outcrops exist in the Cuyuna district, it is necessary first to make a magnetic survey with a dip needle, or possibly with a sun-dial compass, and determine the area or belt of magnetic variations and the maximum lines of magnetic attraction. A dip-needle survey is quicker to make, is sufficiently accurate, and will suffice. Regardless of how poorly defined the magnetic attractions may be, it is important that they be determined. Even if drilling has developed ore on an adjoining property, the survey should not be omitted. Iron-bearing formation is indicated by the magnetic attractions, but whether or not ore exists must be determined by drilling. The maximum line of magnetic attraction offers the best place to begin drilling. If no magnetic attraction exists, nearby developments are the only guide; and if these also are lacking, drilling is governed by guess. Test-pitting is not employed in exploratory work because the surface is too deep. Tunneling cannot be used because the topography is not suitable. Exploration shafts are a waste of time and expense, because from every standpoint drilling with churn and diamond drills is the most applicable method for exploratory work. Light drilling equipment only is needed. Rarely have heavier drills been required, for seldom do holes exceed 400 ft. in depth, and about 100 ft. of this is in glacial drift which is easy to penetrate. The deepest hole is 1023 ft. Because of the steep inclination of the strata and the narrowness of the orebodies, many angle holes have been drilled, mostly at 60' to 70" from the horizontal and against the dip of the formation. Angle holes are most advisable. If after initial drilling the beds are of shallow dip, vertical holes or holes of any angle can be used. The total cost of drilling a property is much greater if only vertical holes are used because more holes must be drilled to obtain the requisite information than when angle holes are used. Many tests for variation in angularity of a finished hole have seldom shown more than 2'; therefore, such tests may with safety be abandoned. Because the orebodies are generally about 100 ft. wide and cross a 40-acre tract at a slight angle, and as the dips are usually about 70"

Jan 1, 1925

By R. H. Singleton

ThE purpose of this investigation was to determine the effect of cerium upon the nonmetallic inclusions found in cast and wrought steel containing various amounts of sulfur, oxygen, and nitrogen. Interest of the Physical Metallurgy Laboratory of the Watertown Arsenal Laboratories in this type of research was stimulated by the reports from industry that rare-earth metals imparted beneficial effects upon the mechanical properties of steel, but that the mechanism was not understood. Berry and Dorvel' found that misch metal improved the impact properties of aluminum-killed cast steels. They reported that the rare earths modified the intergranular-film type nonmetallic inclusion, present with aluminum as the sole deoxidant, to a randomly distributed globular type. Lilliequist and Mickelson2 observed the improvement of ductility and toughness of quenched and tempered cast steels through rare-earth additions. They also observed the change from angular to duplex inclusions when rare earths were present. They con-

Jan 1, 1960

By Harvey S. Chase

During the recent great depression in iron, little has been done in the magnetic separation of iron-ores; and previous to the present decade the art was in its infancy, so that there were few, if any, successful separators on the market, and but scanty practical data could be obtained as to the industry itself. Moreover, the recent development of the great Mesabi Bessemer beds, coincident with the intense depression in business, has discouraged active attempts to solve the problems presented in the crushing and separation of the refractory magnetites of the South. Experiments have been carried on, however, upon a practical scale in separating these ores magnetically, at the well-known Cranberry mines, in Mitchell county, N. C., with results which are encouraging. The magnetites of the Blue Ridge, in the South, have been known, and the soft ores of the region have been used in Catalan forges, since very early times. The original settlements in East Tennessee were made along the Watauga river by Daniel Boone, William Bean, John Sevier, and other stalwart pioneers; and this valley lies parallel with the " Cranberry " lead, which is undoubtedly the most celebrated and the most extensive deposit of workable magnetic ore in the Southern States. This lead I have personally traced along the outcrop, be-

Jan 1, 1896

By E. M. Wise

IT is known qualitatively that the recrystallization behavior of platinum is dependent upon the amount and particularly the nature of impurities present, the amount of prior cold-work and the annealing time and temperature, but published data are limited. A study of the effects of cold-work and annealing temperature on the hardness of a sample of very pure platinum was undertaken to supply part of this information. CONCLUSIONS 1. The platinum used in the experiments had a probable platinum content of 99.99+ per cent, and had the following mechanical properties in the completely softened condition: Vickers hardness number, 39.4; ultimate tensile strength, 19,340 lb. per sq. in.; proportional limit, very low; elongation, 37.5 per cent in 2 inches. 2. The effect of cold-rolling on the hardness is shown in Fig. 1. The hardness increases rapidly up to 10 to 15 per cent reduction and more slowly up to about 75 per cent reduction, beyond which it increases more rapidly. 3. The recrystallization temperatures for a 15-min. anneal, after cold-rolling 19, 39.5, 50.8, 66, 80.5 and 89.5 per cent reduction in thickness, are approximately 765°, 700°, 635°, 600°, 545° and 425°C., respectively. 4. The recrystallized grain size of this platinum is a function of the percentage of cold reduction, being larger the lower the percentage of cold-work. 5. Little or no grain growth resulted from subjecting recrystallized samples to higher temperatures or annealing for longer times.

Jan 1, 1940

By T. Sterry Hunt

I have in a previous communication called the attention of the Institute to the geognostical relations of the crystalline iron ores belonging to the Eozoic racks of North America, at which time I noticed (1) those associated with the gneisses of the Laurentian series, (2) those of the crystalline schists of the Huronian, as seen in Northern Michigan and in many localities along the Appalachians; (3) those of Southeastern Missouri associated with petrosilex porphyries and schistose rocks, and presumed to be nearly of the same age with those of the Huronian schists; and (4) the highly titaniferous ores of the Norian or Labradorian series from Essex County, N. Y., and from various parts of Canada. It may here be remarked that, although the presence of titanium is most marked in the Norian ores, this objectionable element is sometimes found in the schistose ores of the Huronian, and to a lesser extent in certain Laurentian magnetites. The ores of each of these geological divisions have their individual peculiarities, which serve to distinguish them to such a degree that the magnetites and specular ores of the Laurentian are as dissimilar to those of the Huronian as are the crystalline silicated rocks of the two series. As it happens that these mineralogical dissimilarities correspond to diflerences in composition and in adaptability to different processes of manufacture, which, in the present condition of the iron industry, are objects of special consideration to metallurgists, it will be seen that these geognostical distinctions become of great practical importance. During the past year I was desired by the Geological Commissioners of Pennsylvania to devote a few weeks to certain geological studies in the eastern part of the State, in the course of which I was enabled to make, with regard to its crystalline iron ores, some observations to which I desire to call the attention of the Institute. I may mention, in passing, that the great South Mountain belt, from the Schuylkill to the Delaware, is composed of Laurentian rocks, in which are found the characteristic ores of the series like those of the Highlands of New Jersey and New York, and of the Adiron-

Discussion of the paper of W. H. Gunniss, presented at the Butte meeting, August, 1913, and printed in Bulletin No. 81, September, 1913, pp. 2309 to 2310. PROF. J. W. RICHARDS, South Bethlehem, Pa. :-In regard to the physical nature of quartz for making silica brick, is the coarse-grained preferable ? E. P. MATHEWSON, Anaconda, Mont. :-A dense quartz is preferable. The quartzite is the actual material used by the Anaconda Company. The sandstone referred to, the foreign quartz, was a very pure sandstone and bad hardly any impurities in it, and the brick made from that particular material, while apparently beautiful while coming out of the kiln, and true, immediately on heating in the furnace buffed up half an inch and were cracked open.

Jan 11, 1913

By Thomas M. Brown

The method usually employed in accurate determinations of sulphur in pig-iron and steel is to treat a weighed sample of borings in a flask with muriatic acid, and to pass the gaseous products through an alkaline solution of lead or silver, which precipitates all the solphur of the sulphuretted hydrogen in the form of sulphide of lead or silver. The sulphide thus formed is subsequently oxidized by aqua regia, bromine, or other oxidizing agent, and the sulphuric acid formed precipitated in the usual way by chloride of barium. I have substituted for the alkaline metallic solution, a solution of permanganate of potash in the strength of one gramme of permanganate to 200 cubic centimetres of water, and find that it gives results quite as accurate as those obtained by using an ammoniacal solution of silver. By the employment of the permanganate it will be readily seen that there is considerable saving of time and work. In order to test the accuracy of the method, six samples of pig-iron borings were weighed out (about six grammes each) and treated identically

By Joseph H. Taylor

The Ducktown district is in the extreme southeastern corner of Tennessee, its principal railroad point being Copperhill, on the Blue Ridge division of the Louisville & Nashville Railroad, midway between Knoxville, Tenn., and Atlanta, Ga. The ore deposits were discovered about 1849 and development work was begun in the early fifties. Only the "black copper" ores, products of secondary enrichment, from beneath the gossan outcrops and overlying the massive sulphide deposits, were then mined and smelted for their copper content. Upon their exhaustion, attention was directed to the treatment of the pyritic ore remaining, resulting in the devising of a process consisting of open-heap roasting, followed by blast-furnace smelting, which was practised until 1903, when semi-pyritic smelting was adopted. In 1908, the companies operating in the district, on account of litigation brought about by alleged smoke damage to forests and vegetation in the adjoining counties of Georgia, were compelled to erect enormous acid plants to prevent the escape of the sulphur dioxide produced in the smelting operations. The utilization of this sulphur dioxide in the manufacture of sulphuric acid as a byproduct has added to the revenues of the companies, and at the same time has furnished a valuable source of supply of sulphuric acid to the fertilizer trade of the South, and more recently to the manufacturers of eyplosives for use in the production of war munitions. The steadily increasing demand for sulphuric acid for the manufacture of fertilizers and explosives, together with the decreasing imports of pyrites, from which the acid is generally produced, now makes it imperative that greatly extended resources of pyrite be developed. While the Ducktown deposits do not predominate in pyrite, they do contain an inexhaustible supply of pyrrhotite, admixed with pyrite, which can be satisfactorily employed to supplement or substitute for pyrite in acid making.

Jan 1, 1918

By H. W. Knott, M. H. Mueller, P. A. Beck

The rolling and recrystallization textures in 300°C rolled uranium sheet were investigated using a Geiger counter diffractometer with the modified Schulz reflection technique. Seven sections of sheet material were used in order to obtain sufficient data for quantitative pole figures by the reflection technique. A special integrating specimen table was used for obtaining and recording the data automatically. The rolling texture was described in terms of several "ideal orientations" in which the stronger orientations have either the (1103 or (010) poles in the vicinity of the rolling direction. The recrystallization texture of the sheet uranium was also described by several "ideal orientations" which are somewhat different, except in one case, than the as-rolled "ideal orientations." RESULTS of an X-ray study of the deformation texture in rolled uranium rods were reported by Harris' in which a concentration of (010) and (110) poles was found in the rolling direction. More recently Seymour," Mitchell 'and Rowland,3 and Adam and Stephenson4 reported results obtained on uranium sheet rolled under various conditions of tem- perature and amount of reduction. Since the results of Seymour as opposed to those of the two other groups of investigators are not in full agreement, it seemed justifiable to publish the present data, obtained concurrently with the previously mentioned investigations.'-' The results with rolled and re-crystallized uranium sheet were also included in the paper, since they appear to be more complete than the only previously published texture data on recrystallized sheeL3 In the present investigation great care was taken to maintain complete separation of the reflections from different crystal planes, even in cases where the 20 angles differed from each other by less than

Jan 1, 1956

By A. Spilners, M. Simnad

The rates of formation of the different oxides on molybdenum in pure oxygen at 1 atm pressure have been determined in the temperature range 500° to 770°C. The rate of vaporization of MOO, is linear with time, and the energy of activation for its vaporization is 53,000 cal per mol below 650°C and 89,600 cal per mol at temperatures above 650°C. The ratio Mo03(vapor.lzing)/MoOS3(suriace) increases in a complicated manner with time and temperature. There is a maximum in the total rate of oxidation at 6W°C. At temperatures below 600°C, an activation energy of 48,900 cal per mol for the formation of total MOO, on molybdenum has been evaluated. The suboxide Moo2 does not increase beyond a very small critical thickness. At temperatures above 725°C, catastrophic oxidation of an autocatalytic nature was encountered. Pronounced pitting of the metal was found to occur in the temperature range 550° to 650°C. Marker movement experiments indicate that the oxides on molybdenum grow almost entirely by diffusion of oxygen anions. USEFUL life of molybdenum in air at elevated temperatures is limited by the unprotective nature of its oxide which begins to volatilize at moderate temperatures. Although the oxide/metal volume ratio is greater than one, the protective nature of the oxide film is very limited. Gulbransen and Hickman' have shown, by means of electron diffraction studies, that the oxides formed during the oxidation of molybdenum are MOO, and MOO,. The dioxide is the one present next to the metal surface and the trioxide is formed by the oxidation of the dioxide. Molybdenum dioxide is a brownish-black oxide which can be reduced by hydrogen at about 500°C. Molybdenum trioxide has a colorless transparent rhombic crystal structure when sublimed, but on the metal surface it has a yellowish-white fibrous structure. It is reported to be volatile at temperatures above 500" and melts at 795°C. It is soluble in ammonia, which does not affect the dioxide or the metal. In his extensive and classic investigations of the oxidation of metals, Gulbransen2 has studied the formation of thin oxide films on molybdenum in the temperature range 250" to 523°C. These experiments were carried out in a vacuum microbalance, and the effect of pressure (in the range 10-6 yo 76 mm Hg), surface preparation, concentration of inert gas in the lattice, cycling procedures in temperature, and vacuum effect were studied. The oxidation was found to follow the parabolic law from 250" to 450°C and deviations started to occur at 450 °C. The rates of evaporation of a thick oxide film were also studied at temperatures of 474" to 523°C. In vacua of the order of 10- km Hg and at elevated temperatures, an oxidation process was observed, since the oxide that formed at these low pressures consisted of MOO, which has a protective action to further reaction in vacua at temperatures up to 1000°C. Electron diffraction studies showed that, as the film thickened in the low temperature range, MOO8 became predominant on the surface. Above 400°C MOO, was no longer observed, MOO, being the only oxide detected. The failure to detect MOO, on the surface of the film formed at the higher temperatures does not militate against the formation of this oxide, since according to free energy data MOO3, is stable up to much higher temperatures. At the low pressures employed, this oxide would volatilize off as soon as it was formed. Its vapor pressure is relatively high and is given by the equations" log p(mm iig) = -16,140 T-1 -5.53 log T + 30.69 (25°C—melting point) log p(mm He) = -14,560 T-1 -7.04 log T+1 + 34.07 (melting-boiling point). Lustman4 has reported some results on the scaling of molybdenum in air which indicate a discontinuity at the melting point of MOO, (795°C). Above the melting point of MOO,, oxidation is accompanied by loss of weight, since the oxide formed flows off the surface as soon as it is formed.5,6 Qathenau and Meijering7 point out that the eutectic MOO2-MOO3 melts at 778C, and they ascribe the catastrophic oxidation of alloys of high molybdenum content to the formation of low melting point eutectics of MOO3 with the oxides of the melts present. Fontana and Leslie -explain the same phenomenon in terms of the volatility of MOO,, which leads to the formation of a porous scale. Recent unpublished work by Speiser9 n the oxidation of molybdenum in air at temperatures between 480" and 960°C shows that the rate of weight change of molybdenum is controlled by the relationship between the rates of formation and evaporation of MOO,. They have measured the rates of evaporation of Moo3 in air at different temperatures and estimated an activation energy of 46,900 cal. This compares with the value of 50,800 cal per mol obtained by Gulbransen for the rate of sublimation of MOO, into a vacuum.

Jan 1, 1956

By H. T. Clark

NO previous determinations of the deformation or recrystallization textures of titanium or of titanium-base alloys have been reported in the literature. The room-temperature structure of titanium is hexagonal close-packed with a c/a ratio less than 1.633. It would be expected, therefore, to have a rolling texture similar to that of other hexagonal close-packed metals, namely (0001) [1010]. Burgers and Jacobs1 have shown that zirconium, a metal isomorphous with titanium in its structure and similar in many of its properties, has such a texture with a scatter of the basal plane toward the transverse direction. This scatter is in the opposite direction from that found in magnesium by Bakarian2 but similar to that reported by Smigelskas and Barrett3 or beryllium. The rolling and annealing textures reported here for high-purity iodide titanium are significantly different from the . textures of any other hexagonal close-packed metal. All titanium used during this investigation was prepared by the iodode process." The annealed hardness of this material varied from 73 (material used for sample No. 2) to 97 Vickers hardness number. An estimate of the chemical composition of this grade of titanium has been reported by Finlay and Snyder.5 With one exception, shown in table I, the as-deposited titanium was cast into 10 to 20 g ingots in an electric arc furnace in purified argon before being rolled to sheet. The cast ingots were forged and ground until their cross-section was approximately rectangular, annealed 1 hr at 700°C in vacuum and cold rolled. Rolling was carried out in a two-high, 4 in. diam mill, using reductions no greater than 10 pct per pass. The direction of rolling was reversed after each pass, and, in order to avoid temperature effects, the sheet was allowed to cool after each pass. Unless the rolled sheet was sufficiently thin for X-ray penetration (about 0.004 in.), it was reduced to this thickness by pickling. Because of the possibility of introducing twinning or other deformation during grinding, no attempt was made to maintain uniform thickness of the sample during pickling by intermediate grinding or sanding operations. Those samples to be used for determining the annealed texture were recrystallized by vacuum annealing the cold-rolled sheet for 1 hr at 500°C. These thin samples were held between thick titanium sheets during annealing to prevent distortion. Table I outlines the rolling and annealing schedule of those samples for which photograms or texture patterns are shown. X-ray Techniques The usual techniques for determining textures were employed during this work. Molybdenum radiation was used for the transmission exposures and copper radiation for the glancing angle ones. Since titanium fluoresces under these conditions, it is necessary to employ a filter between the sample and the film. The Kß radiation filters are very satisfactory for this purpose. Sufficient grains having favorable orientation were present in both the cold-worked and in the cold-worked—500°C annealed samples to provide satisfactory patterns with the samples stationary. Because of the difficulties of comparing intensities of transmission photograms with those obtained

Jan 1, 1951

By Byron W. Cheever

In working up the process which I described at the Chicago Meeting, May, 1884 (p. 163 of the present volume), for the estimation of phosphorus in iron and steel, I employed samples of steel obtained from one works only, and of a given brand. Since then I have had frequent occasion to test the process on other steels, and find that it works equally well. But some steels present certain colors which may mislead the operator; and I therefore propose a slight change in the directions formerly given. On the second page of my paper, in the second paragraph, I would substitute the following modified directions: Place the flask under the hydrant, till the solution is perfectly cold ; then add, gradually, strong ammonia, with constant stirring, till the solution is changed into a pasty mass and the ammonia is in slight excess; then add cautiously HNO3 (1.40 specific gravity)

Jan 1, 1885

IT is not very necessary for those who work ores to return the litharge to lead, because they use litharge in place of lead ore and they use it the more willingly when it still contains some trace of silver. For the cupeling hearth can never be so well made or so cleanly operated that some little bit of silver does not remain in it, and some particle of it is also necessary by its very nature. But for one who has to use very much lead at one time, like someone who smelts sweepings or cements, or for someone who wishes to bring his operations to a conclusion and withdraw his investment, it is possible to have the lead again. In order to do this, the litharge is taken and ground. Cupeling hearths are washed in addition to being ground. Then these powders are made into a paste by wetting them with salt water, and they are made into large

Jan 1, 1942

By J. Chipman, N. J. Grant, J. C. Fulton

This paper contains data on the distribution of silicon between liquid iron-silicon-carbon alloys saturated with respect to graphite and CaO-SiO2-Al2O3 slags under 1 atm of CO at 1600°C. The ranges of slag compositions studied were extended from the dicalcium silicate saturated liquidus composition up to silica concentrations at which Sic appeared as a stable phase. IN blast furnace operation it is not to be expected that slag and metal reach equilibrium with one another. Nevertheless, the silicon content of the metal varies with slag composition and with temperature in a manner which would be predicted from equilibrium considerations. Similarly, the distribution of sulphur between slag and metal does not attain an equilibrium state, yet the influence of slag composition is strongly analogous to its effect on the distribution equilibrium. The desulphurizing power of metallurgical slags has been shown to be highly dependent upon the FeO content of the slag. Moreover, the rate of removal of sulphur from slags is influenced by the oxygen potential of the slag-metal system. Thus it was shown by Grant, Kalling, and Chipman1 that the presence of MnO in slags which are low in FeO causes a marked slowing down of the transfer of sulphur from metal to slag. This led to the hypothesis that the slow removal of sulphur by blast furnace slags of more acid composition might be due in part to the effect of SiO2 on the oxygen potential of the system. This was verified in the work of Grant, Troili, and Chipman,' who found that the desulphurizing power of the more acid blast furnace slags could be markedly improved by an increase in the silicon content of the underlying metal. Their explanation of this improvement was that the higher silicon content of the metal decreased the rate of transfer of more silicon and, along with it, of oxygen from the slag to the metal. The slowness of the transfer of sulphur from metal to slag was the result of the slow reduction of SiO2 from slag to metal. Attempts to study the rate of sulphur removal had in the past resulted in very slow rates corresponding to the rates of silica reduction. It has become evident on the basis of these studies that further experimental studies on the rate of removal of sulphur must take these factors into consideration if there is to be a clear understanding of the rate of sulphur transfer under conditions simulating those existing in the blast furnace. It will be necessary, at least in a part of such study, to employ combinations of slag and metal in which the disturbing effect of silica reduction has been eliminated; in other words, to employ slag-metal combinations which are already in equilibrium with respect to the transfer of silicon. In preparation for such studies of desulphuriza-tion, a preliminary program of research on the distribution of silicon between slag and metal has been undertaken. This will ultimately include a comprehensive survey of the effects of temperature and slag composition on the equilibrium distribution of silicon between slag and metal. The present paper is a report on experimental methods employed and on

Jan 1, 1954

By Michael R. Wilder

This paper discusses the two major problems of computerization currently confronting the coal mining industry, specifically, user education and standardization of software practices. Each problem has a unique set of criteria that require addressing individually and collectively. This paper addresses these problems and additionally, a plausible method of overcoming these problems.

Jan 1, 1983

By AIME AIME

MINING men in general- are a roving lot but not so Selwyn G. Blaylock. Immediately after graduation from McGill in 1899 he went to the Trail smelter and he is there today though he spent three or four years of his early professional life at other British Columbia mining centers. Either he sensed the great possibilities of the company of which he is now vice-president and general manager, or it sensed his; more probably both. Certainly the association was a happy and fortunate one.

Jan 1, 1937

By L. W. Eastwood

PART 1. EFFECT OF HEATING RATE UPON RECRYSTALLIZED GRAIN SIZE OF ALUMINUM AND ALUMINUM ALLOYS AMONG those concerned with the annealing and heat-treating of aluminum and aluminum alloys, it is well known that after cold-working a coarser grain is usually produced by slow heating than by more rapid heating. Consequently, for the control of the grain size produced by annealing or heat-treating cold-worked aluminum and aluminum alloys, the heating rate is of considerable practical importance. References in the current literature on the effect of heating rate are numerous, but it appears neither necessary nor desirable to give here a review of the former work done on this subject. It became evident during some preliminary work on the recrystalliza-tion of aluminum and aluminum alloys that the effect of heating rate depended upon the type of microstructure of the metal. This observation led to the following study of the relationship of the type of microstructure of the alloy to the effect of the heating rate.

Jan 1, 1939

By Ben-Zion Weiss, Melvin R. Meyerson

FATIGUE crack propagation in some aspects can be viewed as being a result of localized plastic deformation concentrated near the tip of the crack.' Deformation is influenced by microstructure which in turn can affect the fatigue crack growth significantly. To study the effect of localized microstructural changes on fatigue crack propagation, cantilever-type notched specimens were subjected to cyclic bending at constant load amplitude. The extent of fatigue crack propagation was obtained by measuring the length of the crack by periodic observation with a microscope on the polished side of the sample,2"4 and these data were used in preparing the curves in the figures which follow. Figs. 1 (solid lines) and 2 show experimental results obtained in austenitic type 302 stainless steel containing higher than standard carbon (0.24 pct C) and 310 stainless steel. Both steels were homogenized for 8 hr at 1120°C and then water-quenched in order to prevent the precipitation of carbides. Fig. 3 shows experimental results obtained on 9440 low alloy steel in the normalized condition and in the quenched and tempered (580°C) condition. Indications of microstructural influence can be seen in scattering of the experimental data. The degree of scattering depends on both the microstructure and the amount of cyclic stress applied to the sample. For microstructures which are more easily deformed plastically, e.g., normalized or annealed as compared with hardened and tempered structures, the scattering is greater. Similarly, higher stresses produce greater scattering in the results, regardless of whether the cause of the stress increase is due to initial loading conditions or the growth in crack length. Scattering is believed to be a result of partial redistribution in the stress field around the tip caused by plastic deformation. This opinion is borne out by much smaller scattering of experimental results in the austenitic 302 high-carbon (0.24 pct C) steel. In this steel, plastic deformation in the neighborhood of the crack causes partial mar-tensitic transformation of metastable austenite,5 which in turn restrains further plastic deformation. As a result, the stress redistribution around The tip is reduced. Partial martensitic transformation was confirmed

Jan 1, 1969

Dr. Healy's paper presents a concise state-of-the-art description of mechanistic, thermodynamic models available today for design, interpretation, and trouble-shooting flocculation processes and problems. Coagulation by manipulation of inorganic electrolyte concentrations is controlled largely by adjustment of electrostatic repulsive forces, guided by well understood theory. For simple solids in simple electrolytes, existing models are capable of predicting the influence of potential determining ion and one dominant, non-reacting, symmetrical electrolyte concentration on floc stability quantitatively. Concentration changes required to coagulate and disperse can be estimated. Convenient, easily understood means are available for summarizing the effects of key variables, (e.g., pH, ionic strength) on dispersion stability, and estimating tolerance to unintentional changes (Matijevic coagulation domain diagrams). These models have not been developed to the point that mixed unsymmetrical electrolytes can be easily handled. They are capable of describing two- solid heterocoagulation, but not “n-solid” heterocoagulation. In combination with recently developed computer codes for simultaneous computation of solution equilibria, ion exchange and electrical double layer properties (1,2), these models .should be capable of describing simple clay coagulation systems. This has not been done. Models developed for polymer flocculation are valuable interpretive tools, have some qualitative predictive value, but are less potent in quantitative needs. Most real systems probably involve more than one mechanism of floc stabilization. Little has been done toward developing combined models, even in the simplest systems.

Jan 1, 1979