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By W. D. Sylwestrowicz

In tests on polycrystalline copper and aluminum, the ratio of the yield stress to modulus of elasticity was found to be strongly dependent on tempemture. Also, it was shown that the change of the yield stress with temperature of a material at a given temperature and deformed to a given yield stress, but not necessarily to the same strain, does not depend on previous mechanical thermal history. Likewise, for a material at a given temperature and deformed to a given yield stress, the rate of work hardening is independent of the temperature of prior stressing. It has been shown by Los and Orowan1 and by Dorn, Goldberg, and Tietz2 that the temperature dependence of the yield stress-strain curves of crystalline materials reflects two effects: not only does the yield stress of a material in a given structural state depend on the temperature, but the structural state (and the corresponding strain hardening) after a given amount of plastic straining also depends on the temperature at which the pre-straining has been carried out. Thus, for instance, if a specimen of a ductile metal has been strained along the stress-strain curve 1 at room temperature to point A, Fig. 1, and then the straining continued in liquid nitrogen along curve NR, the yield stress A' immediately after lowering the temperature is lower than the yield stress A" of a specimen that has been strained by the same amount in liquid nitrogen (along curve 3). AA' represents the effect of the temperature change upon the yield stress of the specimen pre-strained at room temperature; A' A" is the excess strain hardening acquired if the pre-straining has been carried out in liquid nitrogen instead of at room temperature. The dependence of the yield stress (i.e., of the structural state acquired during preceding straining) upon the conditions (speed, temperature) of a pre-straining is the reason for the nonexistence of a so-called "mechanical equation of state" for plastic deformation. A 'mechanical equation of state" is a relationship of the form F(s,E, e, T) = 0, or s = f(E, E, T) [1] It was first suggested by Ludwik3 that plastic deformation might obey such an equation; this, however, was conclusively disproved by experiments of Kochendorfer.4 Additional disproofs were given in

Jan 1, 1959

By Hubert D. Keiser

AN observation that is finding fresh confirmation in the leadership of the Allied Nations is "When the need arises, a man will rise to fill it." Much the same can be said of industrial advances in the current emergency. Events and circumstances have created needs for new materials and stimulated the inventive genius of man to fill them. The timely development of fibrous-glass manufacture, in relation to present war needs, is a case in point. HISTORICAL SUMMARY It is probable that the first glass fibers produced by the hand of man were made about 4000 years ago. Successful production of glass fibers for manifold industrial and military uses, on any scale that could begin to meet present needs, has a history spanning a scant four years. The American processes that brought this young industry into being were developed between the years 1931 and 1937; research and manufacturing efforts were consolidated to create a commercially satisfactory operation as late as November 1939. In the 40 months that have elapsed since then, the industry has achieved commercial importance, supplied immense quantities of materials for pre-war industrial expansion to meet "defense" and Lend-Lease needs, and now has reached such importance that it has come largely under the control of the War Production Board for equitable distribution of its major products among 13 claimant agencies. It is worthy of note, however, that the Bureau of Ships, Navy Department, began exploratory use of fibrous-glass products in 1932, within one year after the date of the first experimental trials of the new process. This early recognition of the military importance of fibrous glass gave impetus to further research work. The foregoing rapid scanning of historical development must be filled in, lest the impression be created that glass fibers were suddenly created out of thin air, with no antecedent trials, failures, and partial successes. The actual history of glassmaking is lost in antiquity. Probably some nomadic tribesman found molten glass beneath the bed of a hot campfire built upon sand of the proper composition. If his curiosity led him to poke the glowing, viscous pool with a green-wood stick or some handy weapon, it is probable that he drew a glass fiber on the end of his implement. Molten glass has much the same consistency as honey or molasses; it strings out tenuously. Thus, it is quite possible that the first form of glass shaped by man's action was a glass fiber. Artisans in glass, throughout the long history of glassmaking as an art, drew fibers from fine rods for many decorative applications, including "spun glass" decoration in beautiful stemware and the charming millefiori (glass flowers encased in solid glass), and even to create the blood vessels in glass eyes to match a bleary mate.

Jan 1, 1943

By J. T. Norton, N. J. Grant, A. M. Gervais

An investigation of the creep deformation of coarse grained specimens of high purity aluminum in the temperature range 800' to 1150°F, permitted the formulation of a theory explaining the formation of kink bands. The X-ray Laue back-reflection technique was used in conjunction with metallographic studies to determine the crystallographic elements involved in kinking and to measure the rotations of the bands. THAT metals deform by the formation of kink bands was first shown by Orowan1 in 1942. He manually compressed cadmium single-crystal wires, the basal planes of which were parallel to the wire axis and to the direction of compression. He found that kink bands formed quite suddenly. Similar experiments were performed by Hess and Barrett2 on zinc with a hydraulic testing machine to permit slower more careful compression. They observed that kink bands formed progressively with increasing compression. Recently Washburn and Parker3 observed the formation of kink bands in zinc single-crystal specimens during tension creep experiments. Each of these authors observed the formation of kink bands but did not make a complete analyses of the crystallographic relationships. In addition to these studies on hexagonal metals, extensive investigations of kink bands formed during deformation of aluminum in tension at room temperature have been reported. Two types of deformation bands have been observed during the deformation of aluminum at room temperature. These are: 1—kink bands: these exhibit a sharp curvature of the lattice along certain surfaces, and 2—bands formed by secondary slip along certain regions. As has already been shown by Honeycombe,4 it is important to point out the difference characterizing the two types of deformation bands. In the first case. for moderate deformation, only one system of slip planes normally is active; in the second case, however, two slip systems are active in the deformation bands. The latter have a rumpled surface because of the action of the two slip systems. In the present work only the first type of band was studied and to avoid any confusion the term kink band will be used exclusively in the discussion which follows. Honeycombe' observed that very narrow kink bands (width, 0.01 mm) formed along the (110) planes during the deformation of high purity aluminum at room temperature. He observed narrower ones in commercially pure aluminum and found also that their width decreased with decreasing temperatures. Chen and Mathewson5 reported the formation of kink bands during tensile testing of single crystals of high purity aluminum at room temperature and pointed out that some rotation occurred about a [211] direction. The influence of the bending moment on the formation of kink bands was illustrated by the experiments of Rohm and Kochendorferl0 who used a Polanyi apparatus to obtain pure shear during tensile testing of high purity aluminum single crystals. Under such conditions only one slip system was active and no kink bands were observed; consequently, no noticeable asterism was detected after deformation. The influence of the bending moment will be discussed later. Calnan8 gave a detailed account of the work performed on kink bands obtained during deformation of aluminum at room temperature. Because no explanation of the process of kink band formation in creep was given in the previous investigations and because some of the above observations are vital to the following discussion the brief review of the literature has been given. It is proposed in the present work to provide an explanation of kink band formation during creep deformation at elevated temperatures. Results and Discussion Kink bands were observed to form during tensile creep testing of high purity (99.995 pct) aluminum specimens, having a very large grain size, in the temperature range 800" to 1150°F. These observations were made in grains which occupied the whole cross section of the specimen. The specimens were originally round (diameter, 0.187 in.; gage length, 1 in.) and had parallel flats milled to permit easier metallographic and X-ray observations. The final

Jan 1, 1954

By AIME AIME

IN furtherance of the policy of acquainting those members of the Institute who live at a distance from New York with all the details of administration, the thirty delegates sent by the local sections and the technical divisions were invited to attend the meeting of the Directors on Tuesday evening as well as the Directors' dinner immediately preceding. Including the Directors and officers, new and old, the members of the Papers and Publications Committee and the section delegates, more than 70 sat down at the dinner table in the Engineers Club. The attendance at the business meeting that followed was not quite so large, doubtless for the reason that the ladies' fashion show, held in connection with the informal dance, offered attraction that eclipsed that of watching the wheels of Institute business go around.

Jan 1, 1930

By W. C. Roberts-Austin

The subject with which the Council of the American Institute of Mining Engineers has entrusted me is one of much interest. It has been so admirably treated in America by Prof. Carl Barus* that I should have hesitated to deal with it had not the adoption of pyrometric methods in England recently occupied much attention, especially in relation to metallurgical industries and research. I shall endeavor to show what is the present state of our knowledge of practical pyrometry by briefly tracing the history of the efforts which have been made to measure high temperatures. This paper will, therefore, be limited to the consideration of those forms of appliance which have either marked distinct stages of advance, or have remained in use with more or less modification through a considerable range of time. The earliest pyrometers were essentially thermoscopes, and although their graduation presented great difficulties, their importance as affording a means for the measurement of high temperatures has been recognized for centuries. It would be difficult to illustrate this better than by a brief record of the testimony which has from time to time been offered by those who have had to apply the heat of furnaces in research or in industry, and it is mainly for the sake of the light incidentally thrown on the progress of both that the following historical notes are offered. In the eighth century, Geber, the chemist, wrote a treatise on furnaces, and showed that he was familiar with many and varied means of applying heat; but he points to the difficulties that are met with in conducting operations at high temperatures, which he attributed to inability to measure heat, his actual words being: " sed quoniam non est res ignis, quae mensuari possit." t

Jan 1, 1894

By Earl S. Bardwell

The structural relations existing between cuprous oxide and copper were first systematically studied by Heynl; who suggested that a study of the microstructure of refined copper might be substituted for the analytical methods in vogue for determining the oxygen content of copper coming from the refining furnace. Hofman, Green and Yerxa,2 in their paper A Laboratory Study of the Stages in the Refining of Copper, working along the lines suggested by Heyn, showed that a study of the microstructure could be made to yield a correct estimate of the oxygen content of refined copper. In order to determine the oxygen content of the specimen of refined copper under examination a photomicrograph was first made. From the relative areas of copper and eutectic, the percentage of cuprous oxide and the corresponding percentage of oxygen were then readily calculated. It was found that the values for oxygen thus obtained corresponded closely with the analytical results. With the idea of utilizing this method of determining the oxygen content of each charge dipped from the refining furnaces at the Boston & Montana Reduction Plant, the physical testing laboratory was equipped with suitable apparatus for carrying out the work. It may be of interest to describe certain of the methods which have been worked out in this connection and give such data as have been obtained bearing on the effect of the oxygen content of refined copper upon its conductivity. Apparatus.—For the benefit of those who may be unfamiliar with metallographical apparatus and methods and may be interested to know what equipment is required, a few words with regard to the apparatus are in place at this point.

Jan 1, 1914

By J. C. Bayles

An obstacle to the more careful and satisfactory study of metals has been the difficulty in harmonizing the results of chemical and physical tests. These give us records of observations made from different and often widely separate points of view, and while it is true that they furnish bases for more or less accurate triangulations into the realm of speculation, it is doubtful if, with only the laboratory and the testing machine, our investigations would not move in parallel lines, leaving between them an unexplored field in which must probably be sought the information which shall connect the results of chemical and physical tests, and give to both a practical value which neither has yet been found to possess. The use of the microscope in the study of metals is not a new thing, but it is only lately that it has begun to attract the attention it merits or to show results of tangible value to the metallurgist. Among recent valuable contributions to the literature of this subject, I have been especially interested in the work of Mr. A. Martens, of

Jan 1, 1883

By O. S. True, C. H. Herty

It is well known that manganese will desulfurize molten iron through the formation of manganese sulfide, which, being only slightly soluble in the metal, rises to and enters the slag where it remains as such (mixer slag) or is converted partly or wholly to calcium sulfide (basic open-hearth slag). The reaction by which manganese sulfide is formed is Mn + FeS = MnS + Fe. This reaction is generally considered to be reversible, although McCancel states that such is not the case. The experimental work was carried out to confirm the results of Roh12 as to the reversibility of the reaction. Six trials are herein considered. In each 200 gm. of electrolytic iron free from manganese and sulfur were melted in a pure zirconia crucible in a carbon resistance electric furnace. To the melted iron in runs 2, 3 and 4 metallic manganese and manganese sulfide were added to give 1, 2 and 4 per cent. manganese respectively, with 0.50 per cent, of sulfur in each. In runs 5, 6 and 7, metallic manganese and iron sulfide to give the same proportions of. manganese and sulphur as in runs 2, 3 and 4, were added. The melts were held molten in the furnace for an hour and then cast into small ingots. The results of these melts are as follows: Ingredients of Charge Analysis or InRot ManOaneBe, SulfUR, ManOaneBe. SULFUR, Run Material Charged PeR Cent. PeR Cent. Per Cent. PeR Cent. 2 MnS + Mn............... 1.0 0.452 0.636 0.367 3 MnS + Mn............... 2.0 0.50 1.57 0.310 4 MnS + Mn............... 4.0 0.50 2.81 0.230 5 FeS + Mn................ 1.0 0.50 0.647 0.397 6 FeS + Mn................ 2.0 0.50 1.45 0.374 7 FeS + Mn................ 4.0 0.50 2.73 0.195

Jan 1, 1925

By J. T. Eash, N. B. Pilling

As a group, the alloys of iron, nickel and carbon are, in application, one of the most versatile of the ferrous alloy family, and while many investigations have been made of their properties and structure only a few attempts have been made to show the microstructural relation over a wide range of composition. It is neccssary at once to be clear about the kind of structural relation with which we are concerned. The equilibrium diagram provides quantitative data regarding structural make-up and its variation with temperature, but equilibrium structures often are far different from the technologically significant ones. This is particularly true of steels and cast irons, and some of the most important cornponents of their structure may have no place in the diagram of equilibrium. The fugitive phases that result from transFormation are dealt with in a highly detailed and descriptive manner in. the S-curves originated by Bain. The present effort lies in a still different field, which is to portray the relation between sweeping changes in composition and in resultant structure, under controlled but nonequilib-rium conditions of thermal treatment. The Guilletl diagram presented in 1903 was the initial attempt at such a correlation and frequent references to this diagram can be found in the literature even though later work has shown it to require considerable modification. Kase2 published in 1925 a diagram that was based upon observations of furnace-cooled melts: At low carbon contents this diagram agreed fairly well with experience in showing pearlite to exist in alloys containing up to 6 per cent nickel, and completely austenitic steels at 24 to 28 per cent nickel. At high carbon contents, however, irons were indicated as being martensitic at around 2 per cent nickel and austenitic at 12 per cent nickel; these interpretations are open to serious question. Based upon experience with steels and cast iron, Wickenden3 suggested a diagram that agreed fairly well with Kase's in the steel range but which presented a wide departure from it in the higher-carbon, high-nickel regions. In its broad picture, the Wickenden diagram is an approach to "practical" structures. Reference may be made at this point to the efforts of Marsh5 to construct an iron-nickel-carbon equilibrium diagram by the coordination of scattered data, which are described at length in the monograph cited. None of these preceding attempts has appeared to meet the need for an exposition of the structural sequence that is encountered in traversing the nickel-steel nickel-cast-iron range under what might be called ordinary departures from equilibrium. ExperimentaT. Conditions Since the intent has been to establish structures developed under arbitrary conditions, experimental details have perhaps more than usual importance. Three of these conditions should particularly be noticed: (I) the material was cast and not subjected

Jan 1, 1942

By J. T. Eash, N. B. Pilling

As a group, the alloys of iron, nickel and carbon are, in application, one of the most versatile of the ferrous alloy family, and while many investigations have been made of their properties and structure only a few attempts have been made to show the microstructural relation over a wide range of composition. It is neccssary at once to be clear about the kind of structural relation with which we are concerned. The equilibrium diagram provides quantitative data regarding structural make-up and its variation with temperature, but equilibrium structures often are far different from the technologically significant ones. This is particularly true of steels and cast irons, and some of the most important cornponents of their structure may have no place in the diagram of equilibrium. The fugitive phases that result from transFormation are dealt with in a highly detailed and descriptive manner in. the S-curves originated by Bain. The present effort lies in a still different field, which is to portray the relation between sweeping changes in composition and in resultant structure, under controlled but nonequilib-rium conditions of thermal treatment. The Guilletl diagram presented in 1903 was the initial attempt at such a correlation and frequent references to this diagram can be found in the literature even though later work has shown it to require considerable modification. Kase2 published in 1925 a diagram that was based upon observations of furnace-cooled melts: At low carbon contents this diagram agreed fairly well with experience in showing pearlite to exist in alloys containing up to 6 per cent nickel, and completely austenitic steels at 24 to 28 per cent nickel. At high carbon contents, however, irons were indicated as being martensitic at around 2 per cent nickel and austenitic at 12 per cent nickel; these interpretations are open to serious question. Based upon experience with steels and cast iron, Wickenden3 suggested a diagram that agreed fairly well with Kase's in the steel range but which presented a wide departure from it in the higher-carbon, high-nickel regions. In its broad picture, the Wickenden diagram is an approach to "practical" structures. Reference may be made at this point to the efforts of Marsh5 to construct an iron-nickel-carbon equilibrium diagram by the coordination of scattered data, which are described at length in the monograph cited. None of these preceding attempts has appeared to meet the need for an exposition of the structural sequence that is encountered in traversing the nickel-steel nickel-cast-iron range under what might be called ordinary departures from equilibrium. ExperimentaT. Conditions Since the intent has been to establish structures developed under arbitrary conditions, experimental details have perhaps more than usual importance. Three of these conditions should particularly be noticed: (I) the material was cast and not subjected

Jan 1, 1942

By Robin O. Williams

AN investigation has been made of the Ni-Cr system for the purpose of elucidating certain points, namely the nature of aging in both terminal solid solutions and the nature of the phase diagram. Information pertaining to solubilities and precipitation has been obtained. Experimentation Five alloys, Table I, were arc melted in a cold copper crucible using electrolytic chromium and car-bony1 nickel, both dry hydrogen treated. These 100 g buttons were homogenized 24 hr at 1300°C in dry hydrogen and air cooled. Powders were prepared by filing or pulverizing and subsequent heat treatment was done in vacuum or helium using titanium chips as a getter. Powder of —80 mesh was filed from the 60 pct Ni alloy quenched from 1000°C and was sealed in silica under vacuum using a 250 °C outgassing. After aging as indicated in Table I1 the lattice parameters were measured on the quenched samples using the standard cos" 6 extrapolation. These parameters are considered accurate to roughly 0.0001A. In all cases chromium lines of 2.8812 ± 0.0005Å at 30°C were found. Drastic quenching from sufficiently high temperatures produced very sharp body-centered-cubic lines in the first four alloys without indications of transformations. Temperatures to 1250°C were used. Solid samples less than 1/16 in. thick were quenched in water without transformation and the powders could be adequately quenched in small helium filled thin wall silica tubing using a water quench. For those powder samples which were quenched from the two phase field the relative intensity of the body-centered-cubic lines and the face-centered-cubic lines were estimated and extrapolated to give the indicated solubility data in Fig. 1. The data for the two higher alloys were somewhat limited, the plotted points being the lowest temperature where no nickel phase was found. Neither filing, abrading, pulverizing, nor cooling to —190°C produced any new diffraction lines for solid samples quenched from the single phase region, nor did the character of the body-centered-cubic lines change Single phase body-centered-cubic powders likewise did not change on cooling to —190°C. Also, samples which had some precipitation due to inadequate quenching showed no additional changes under these conditions. The first change apparent by X-ray diffraction form samples quenched almost fast enough to prevent precipitation was the diffuseness of the body-centered-cubic lines, particularly on the low angle side, For slower cooling rates the diffuse face-centered-cubic lines appeared. Work on the large grained castings showed profuse streaking through some of the Laue spots while oscillating patterns showed broad body-centered-cubic and face-cen-tered-cubic lines as well as some new lines. For the 23.6 pct Ni alloy the new lines corresponded to 2.16, 1.96, and 1.86A and were more similar in character to the face-centered-cubic lines than the body-centered-cubic lines. Samples which were air cooled gave only face-centered-cubic and body-centered-cubic lines which were still broad. One pattern indicated that face-centered-cubic (111) plane was parallel to a body-centered-cubic (110) plane. For those samples which were examined by light microscopy there were details which were not resolved. However, varied and beautiful structures were obtained. Fig. 2 is of an alloy quenched in a helium filled silica tube from the single phase region and shows particles associated apparently with dislocations which are arranged in low angle boundaries. Finer, general precipitation has also taken place within the grains. Figs. 3 to 5 show the variety of structures produced in these alloys on continuous cooling. It appears that there are four distinct modes of precipitation as evidenced by these, figures. Annealing these structures at higher tem-peratures in the two phase field gives structures as shown in Fig. 6, which shows nickel plates in the chromium matrix which reprecipitated nickel on a much finer scale of the final quench. Lower annealing temperatures and shorter times naturally give finer plates of the nickel-rich phase. Samples of the first four alloys were annealed for appreciable times between 900º and 1250°C and gave structures like Fig. 6. The relative amounts of the two phases were measured and extrapolated to give solubility data as indicated in Fig. 1. The point at 1250°C was deduced from data of Oxx.1 These and most of the other samples were checked for ferromagnetism but none was apparent. In fact, it appeared that the magnetic susceptibilities were not more than three times that for paramagnetic chromium. Discussion In Fig. 1 it is seen that the solubility of nickel in chromium can be represented by a slightly curved line on the usual log X vs 1/T plot, These data are believed to be accurate to roughly 5 to 10º. There is only fair agreement with the data of Taylor and

Jan 1, 1958

By Frederick Laist

THE ore from the Butte mines of the Anaconda company is quite siliceous; that is, it contains considerably less iron than is needed for the fluxing of the silica. The direct smelting of this ore, therefore, requires the addition of considerable fluxing material. The only flux available in sufficient quantity at Anaconda is limestone containing no metallic minerals. This necessarily makes the direct smelting of the ore so expensive that it is more profitable to subject the ore to a preliminary treatment by concentration. However, as the losses in the concentrator were very high, compared with the losses in the blast furnaces, it was found, by calculation, more profitable to send ores containing more than a given percentage of copper to the blast furnaces, in spite of the higher costs of treatment. The dividing point was dependent on various factors, the chief of which was the prevailing market price of -copper. It was customary, therefore, to segregate the ore as mined into two classes. Ore in the first class generally contained 5 per cent. or over of copper;: this was sent directly to the blast-furnace department. Second-class ore contained less than 5 per cent. of copper, and averaged around 3 per cent.; it went to the concentrating department. With the introduction of the flotation process, it was found possible to maintain an average recovery, as concentrates, of 96 per cent. At the same time, the cost of reverberatory smelting was very materially decreased by the use of pulverized coal. These two changes in practice made the blast furnaces unable to compete with the reverberatory furnaces on a cost basis. The distinction between first-.and second-class ore was therefore abandoned, and the ore was treated by concentration. Obviously, on ores as high in iron as the Butte ores, the concentrator, produces a product that is self-fluxing; in fact, it is possible to produce a

Jan 1, 1920

By M. Muskat, H. G. Botset, R. D. Wycoff, M. W. Meres

The subject of the flow of homogeneous fluids—gases alone or gas-free liquids—through porous media may be considered at the present time to be fairly well completed. That is, analytical, graphical, numerical, or experimental methods are now available for obtaining detailed descriptions of the behavior of such homogeneous fluid systems of any reasonable geometry. Thus, satisfactory empirical techniques are now well established for the determination of the permeability of porous media for homogeneous fluids, the numerical magnitude of this permeability uniquely and completely describing a porous medium as a carrier of a homogeneous fluid. Considering this constant as known, the treatment of a wide variety of specific problems involving either the flow of gases or liquids has been carried through to satisfactory conclusions. Beginning with the simple case of strictly radial two-dimensional flow of a liquid or gas into a well under steady-state conditions, generalizations have been developed to apply for systems where the flow is not strictly radial, due either to a lack of uniformity in the reservoir pressures at points distant from the well or deviations from circularity of the external boundary whereby the fluid is being supplied, and finally, to the lack of complete penetration of the well into the producing strata. Satisfactory descriptions are now available for cases where gravity is acting as the driving agent inducing the flow of liquid into the well, either alone or as a supplement to the effect of pressure. The effect of acid treatment on limestone wells has been given a reasonable interpretation on the basis of the fundamental theory of the flow of homogeneous fluids through sands, as have the important features of the problem of water-coning. Then, too, systems in which the outlet of the fluid from the underground reservoir is of a predominantly multiple character may be now considered as in the domain of

Jan 1, 1937

By S. Stutz

Coal, like most other minerals, only exceptionally occurs in a sufficiently pare state to he directly available for general manufacturing purposes. And even where this is the case, the small coal or slack is usually more impure than the lump coal, as the slate, clay, etc., from the roof and bottom of the vein become mixed with it in the handling it undergoes. These impurities often exceed ten or more per cent. in addition to the impurities of the coal itself. The most common impurities of the coal are slate, or shale, clay, and sulphur. The latter occurs in different forms, but moat frequently as bisulphide of iron, or iron pyrites, and as sulphate of lime, or gypum. In both cases the impnrities add greatly to the amount of ash, and where they are present in considerable quantities the raw coal, and still more the coke made from it, is unfit for the manufacture of iron. Coke will coutain on an average at least fifty per cent. more ash and sulphur than the ram coal from which it is made. To the manufacturer of iron every additional per cent. of ash which his coal or coke contains is a source of additional expense, seemingly small, and yet very important in the aggregate. In the blast-furnace, for instance, the ash must be heated up to the melting-point, and, since it is composed largely of refractory substances, the consumption of carbon in melting it will be equal to at least one-half of its weight; that is, a certain part of tile coke is consumed for the melting and fluxing of the ash and is lost. Besides this, it is well enough known to the iron-master that coke containing lees ash makes the &lag or cinder more liquid and less incliner1 to stick to the walls of the furnace. Fuel containing much sulphur produces generally a white iron, poor in carbon, while from the same ore arrd flux, with a pure fuel, a good foundry iron might be obtained. The work of separating slate, sulphur, etd, from the coal has as yet only been successfully accomplished by the washing process. This process depends for its success on the differences in the specific

Jan 1, 1881

By A. H. Geisler, F. Keller

Although the subject of precipitation from solid solution appears to be one of the more profitable fields in metallurgy for study with the electron Microscope, few comprehensive studies have yet been made. Occasionally electron micrographs have been published that illustrated alleged precipitation in various alloys, but frequently the apparent size, shape and distribution of the particles do not fully agree with those expected from theory or from observations of the Precipitate when the particles have grown to a size resolvable with the light microscope. The presence of a Widmanstatten pattern for submicroscopic precipitate particles has been demonstrated for only a few aged a1loys.l The initial problem has been the development of suitable techniques for applying the transmission-type instrument to a field that has been inherently associated with reflection-type microscopes. The various techniques have been the subjects of numerous publications, and instead of describing them individually here it will sufficc to say that the oxide film method has proved to be the most satisfactory method yet found for studying the microstructure of aluminum alloys with the electron microscope. This method has the definite characteristic advantage that the actual surface layer of the specimen is examined and not a plastic or silica replica. Doubtless suitable methods for forming and removing the oxide film could be developed for alloys of other metals. The purpose of this report is to point out the characteristics of the oxide film method that have been observed during the studies of numerous aged aluminum alloys and to present the results of these studies. Preparation OF Specimens The oxide film method for preparing specimens of aluminum alloys for examination in the electron microscope has been described in detail previously,¹,² Briefly, the procedure consists of preparing the metallographic specimen, forming the film by anodic oxidation and removing the film from the prepared surface of the oxidized specimen, The specimen is polished accordillg to the usual procedure for microscopic examination.³ he specimen may then be etched to remove flowed metal but etching to attack the alloy constituents or to leave them in relief as in the replica processes is not necessary. Electrolytic polishing is not generally recommended, Deep-etched specimens are used frequently, however, since they provide information that is not revealed by polished specimens and frequently present the same information more clearly than do the polished specimens, The surface preparation of specimens to be deep-etched is not important, since specimens that have been subjected to the first wet PoliShing operation are generally used, but frequently the as-rolled surface is Suitable. These specimens are then etched using a suitable macroetching reagent.

Jan 1, 1947

By F. Keller, A. H. Geisler

Although the subject of precipitation from solid solution appears to be one of the more profitable fields in metallurgy for study with the electron Microscope, few comprehensive studies have yet been made. Occasionally electron micrographs have been published that illustrated alleged precipitation in various alloys, but frequently the apparent size, shape and distribution of the particles do not fully agree with those expected from theory or from observations of the Precipitate when the particles have grown to a size resolvable with the light microscope. The presence of a Widmanstatten pattern for submicroscopic precipitate particles has been demonstrated for only a few aged a1loys.l The initial problem has been the development of suitable techniques for applying the transmission-type instrument to a field that has been inherently associated with reflection-type microscopes. The various techniques have been the subjects of numerous publications, and instead of describing them individually here it will sufficc to say that the oxide film method has proved to be the most satisfactory method yet found for studying the microstructure of aluminum alloys with the electron microscope. This method has the definite characteristic advantage that the actual surface layer of the specimen is examined and not a plastic or silica replica. Doubtless suitable methods for forming and removing the oxide film could be developed for alloys of other metals. The purpose of this report is to point out the characteristics of the oxide film method that have been observed during the studies of numerous aged aluminum alloys and to present the results of these studies. Preparation OF Specimens The oxide film method for preparing specimens of aluminum alloys for examination in the electron microscope has been described in detail previously,¹,² Briefly, the procedure consists of preparing the metallographic specimen, forming the film by anodic oxidation and removing the film from the prepared surface of the oxidized specimen, The specimen is polished accordillg to the usual procedure for microscopic examination.³ he specimen may then be etched to remove flowed metal but etching to attack the alloy constituents or to leave them in relief as in the replica processes is not necessary. Electrolytic polishing is not generally recommended, Deep-etched specimens are used frequently, however, since they provide information that is not revealed by polished specimens and frequently present the same information more clearly than do the polished specimens, The surface preparation of specimens to be deep-etched is not important, since specimens that have been subjected to the first wet PoliShing operation are generally used, but frequently the as-rolled surface is Suitable. These specimens are then etched using a suitable macroetching reagent.

Jan 1, 1947

By John T. Norton, Robert J. Anderson

The purpose of this paper is to report evidence, regarding metal structures, that is contradictory to the amorphous-metal hypothesis of Beilby, and particularly evidence that is opposed to the proposition that a vitreous amorphous layer is produced by polishing a piece of metal. According to the theory of Beilby, which has been developed by Rosenhain and others, polishing a piece of metal greatly affects the condition of the metal at or near the surface polished, making that surface entirely different in character from the metal beneath. A vitreous amorphous surface film is said to be formed. The polishing process, on the basis of Beilby's explanation, is well known and does not require discussion here, but it is advisable to seek the precise meaning of the term "amorphous." According to Beilby, "amorphous means non-crystalline in the most intimate sense of the word; the molecules arc not marshalled in crystalline order and orientation." According to Rosenhain, the amorphous condition is that assumed by a metal when the crystalline arrangement is completely broken up so that the atoms exist in a state of disorderly arrangement similar to that which exists in the liquid state. Thus, from the point of view of the phase rule, the "amorphous phase" is regarded as being identical with the liquid phase. Amorphous metal is often likened to an undercooled liquid. A crystalline substance is one in which the atoms are arranged in space according to some definite repeating geometrical pattern. The existence of amorphous metal has not been definitely proved. The evidence offered here that amorphous metal probably does not exist is of a direct nature and is afforded by x-ray diffraction effects given by a number of metals and alloys when polished, cold-worked, and annealed. Considerable of the experimental work was carried out with substantially pure aluminum and the aluminum alloy duralumin, but many of the observations made on these materials were checked by similar observations on copper, iron, tin, zinc, lead, mild steels, and

Jan 1, 1925

By H. S. George

A method of illumination that enhances the value of microscopic study of opaque materials, as in metallography. By simulating natural lighting, structures. That possess relief are given a natural appearance. An example is included of the revelation of a hitherto invisible microconstituent. Erroneous interpretation is avoided. For example, etching figures in ferrite, heretofore considered to be pits, are revealed as pyramids, standing in bas-relief. Suggestions on technique are given, for, while the method is obvious, practice and attention to detail are requisite. ON one occasion when it seemed desirable to reveal under the microscope not only the metallic structure of an alloy, but certain small non-metallic inclusions, that are ordinarily obliterated by etching, it was discovered that, by partly eclipsing the illuminating pencil of light rays, the residual light was thrown on the object from one side and the structure was brought out in relief. At the same time, the non-metallic inclusions were retained in clear view. In this first demonstration of lighting obliquely through the objective a card was thrust part way into the light beam between the arc iris, and the light filter; the shadow of the card on the filter served to locate its position. Next several stiff-paper disks of various diameters were mounted on flexible wires some plasticine on the other end of the wires made it easy to adjust and maintain a disk at any desired position in the light beam. To facilitate manipulation, an assortment of disks, was mounted on a wheel, as shown in Fig. 1. The purpose of partly eclipsing the light beam was discussed in an earlier paper.1 There it was pointed out that the usual methods of illuminating opaque objects for microscopic examination lend an, un-natural appearance to, the view, while the new method, which has been termed conical illumination, revels the true relationship of constituents by simulating natural lighting.

Jan 3, 1924

By John Norton

IN recent years, the damping capacity of metals has come to be recognized as an important index of certain types of structural change. In a number of instances, this property has proved to be particularly sensitive, but insufficient work has been done to permit a general inter-pretation. There is considerable question at the present time as to just what factors are responsible for the internal dissipation of energy when a metal is carried through a cycle of stress, and these factors must be ascertained if the value of the damping method as a metallurgical tool is to be determined. Since internal stresses are among the chief causes of dissipation of internal energy, or damping capacity, it was thought that a study of the changes in damping during the recovery and recrystalliza-tion of a cold-worked metal might throw some light upon the subject, particularly if the damping changes were correlated with other properties that are better understood. Probably more work has been done on the recrystallization phenomena of alpha brass than on any other metal, so this was chosen as the material for the present investigation. Damping measurements on brass have been made by Förster and Köster.1 They showed that the annealing of a brass that had been cold-drawn to 50 per cent reduction produced a rapid fall in the damping, a flat minimum occurring at approximately the temperature of recrystal-lization. The damping remained at a low value until grain growth was well under way and then it increased rapidly with increasing grain size. Köster and Rosenthal2 continued the work in greater detail. They pointed out that the damping decrease does not correspond to the hard-ness drop but occurs at a lower temperature, suggesting that the relief or redistribution of internal stresses has a large effect while the actual recrystallization effect is small. They also show the increase in damping at the higher annealing temperatures. Their curves are reproduced in Fig. 1.

Jan 1, 1940

R. W. Raymond, New York City: In connection with the subject of multiple tuyeres, my attention has been drawn to the practicability of gaining, without the multiplication of tuyeres, the advantages which that measure is intended to secure ; and learning that this had been attempted in the invention of the Gaines radial-discharge or fan-shaped tuyere, I wrote to Messrs. Gustafson Brothers, of Sequachee, Tenn., who manufacture that tugere, for information concerning the invention itself and its performance in practice. To their courtesy I am indebted for most of the facts given below. I present these statements without expressing any personal opinion on the subject (having no personal knowledge of it), for the purpose of bringing this device to the notice of members, and calling forth both criticism and testimony concerning it. Admitting that definite advantages are to be secured by the multiplication of tuyeres, we must still confess that this change involves considerable expense in the increased number of blastpipes, tuyeres, coolers, connections, and pipes for water-circulation. There is, moreover, a serious question involved in the weakening of the furnace-wall by extra perforations. This consideration applies with special force to furnaces already built without reference to such an increase of tuyere-openings. Ledebur, in his Handbuch der Eisenhüttenkunde, says on this point (I translate from the edition of 1893, page 365): "A limit to increase in the number of tuyeres is given, in any case, by the circumstance that the perforation of the wall weakens it; in other words, that there must be left between the tuyeres a mass of masonry sufficient to carry the parts above. In most cases an appropriate number may be secured by giving to the furnace as many openings as there are meters in its circumference at the tuyerelevel. For instance, for a hearth-diameter of 2.5 meters, i.e., a circumference of 7.7 meters, seven or eight openings might be made, of which, however, one would

Jan 1, 1899