Search Documents

By W. D. Forgeng, D. Beregekoff

In the routine examinatlion of a wide variety of metal specimens it is sometimes necessary to have special methods of polishing in order to retain and reveal certain details in each specimen. Among such special cases is the retention of graphite in malleable and gray cast irons, the preservation of all types of non metallic inclusions in both hard and soft steels, obtaining a scratch-frec surface with soft metals, and avoiding the usual relief effects with very hard specimen. such as tool metals c3o1ltaining various carbide and nitride phases. It, is the purpose of this paper to give an account of some of these special polishing methods in use at the Union Carbide and Carbon Research Laboratories. The polishing procedures outlined have been found to give uniform results. It is obvious that only general rules and the most important working details can be given here. Following these rules, the polisher can obtain satisfactory results if he possesses the necessary patience and has a sincere desire to give as nearly perfect a finish as possible to his work. Procedure The specimen is flattened with considerablecare on a file or sharp cutting sanding belt, since the initial production of a flat surfacc greatly facilitatcs subscqucnt polishing. The polishing motors have two speed., 600 and 1200 r.p.111. ,It higher speeds specimens arc likely to he over-Ileated, therefore the high speed is used only when a saving of time is important. The following abrasive papers are used consecutively: Yo. 2, So. 1, No. 0, No. 00 and No. 000. The final wet polishing is done oil a cloth-covercd metal disk. Woolen broadcloth of the best quality and capable of resisting severe pressure is most commonly used on the last lap. . polishing felt of the type used for polishing optical glass has been found equally satisfactory and is much stronger than broadcloth. For retaining inclusions and graphite, a hard cloth with very little residence, such as

Jan 1, 1939

By Alwyn Birchmore Cox, Ian William Wark

Sodium sulfide is used extensively to increase the recovery of oxidized copper and lead minerals by flotation, particularly when using xanthates as collectors. It is generally assumed that the sodium sulfide converts a film of the oxidized mineral to the sulfide, and that the xanthate, while not a very effective collector for the oxidized minerals, is a good collector for the sulfide. On the other hand, Taggart and his collaborators1 claim that unless sulfide minerals are oxidized they cannot adsorb xanthates and do not float. Gaudin2 states that amyl xanthate, used in conjunction with sodium sulfide, gives better results than ethyl xanthate. Rabone3 and Mayer-Schranz4 agree that excess of sulfide functions as a depressant. Owing to the greater solubilities of the oxidized minerals than of the sulfides, the consumption of sodium sulfide is greater than that of most other flotation reagents, up to 10 lb. per ton of ore being used in some plants. Luyken and Bierbrauer5 recommend a water washing to remove soluble heavy metal salts; by this means sulfide consumption may be reduced. It was desirable to determine the limits of the sulfide concentrations between which contact is possible at surfaces of anglesite and cerussite in xanthate solutions. Similar determinations were desirable for the sulfide minerals with which the oxidized minerals are usually associated, since conditions should be chosen, if possible, so that the two types of mineral will float together. Because of the formation, especially in acid solutions, of hydrogen sulfide and of the hydrosulfide ion (HS-), the permissible limits of sulfide addition are obviously dependent upon the pH value. Sphalerite responds to ethyl xanthate only in the presence of an activator; for example, copper sulfate. It was necessary, therefore, to determine whether sodium sulfide interferes with the activation of sphalerite by copper sulfate. The combined effect of sulfide and copper sulfate was determined also for galena, chalcopyrite and pyrite.

Jan 1, 1939

By Oliver C. Ralston, James E. Norman

Separation of minerals by froth flotation is rightly called an art. It can truthfully be said that no two ores separate in the same way. The difference in results obtained when natural and synthetic mixtures of minerals are separated is so great that such tests frequently have been worthless in attempting to select conditions in which a natural mixture will separate. With a few rare exceptions, the natural mixture is much more difficult to treat than a synthetic mixture, and a much poorer separation is obtained. Perhaps several experimenters have wondered why 10 or 20 per cent of a mineral being floated from an ore does not float and is different from the 90 or 80 per cent that is recovered. In experimental tests on pure sphalerite, observers' have noted that varying amounts of sphalerite may be froth-floated with pine oil alone, the amount recovered in the froth depending apparently upon the source of the sulphide. The only explanation of results such as these, barring insufficiency of frother or time of flotation, is that the surface of the mineral floated is different from that of the mineral depressed. This difference often has been found to be caused by natural contamination of mineral surfaces, apparently brought about by weathering and exposure to natural solutions. There is virtually no rock that is absolutely unweathered. One of the writers had an exceedingly instructive experience in 1931 while working with United Verde copper-zinc iron sulphide ore in Arizona. Nonselective flotation of chalcopyrite and sphalerite away from some of the pyrite was all that could be accomplished. All known depressants produced only slight effect. Sodium cyanide showed some effect, but so much had to be used that only a small amount of chalcopyrite could be

Jan 1, 1939

By W. F. Holbrook, C. E. Wood, E. P. Barrett

The high-frequency laboratory induction furnace with a rotating liquid crucible enables research workers to conduct certain investigations heretofore very difficult or impossible to realize because vessels are not obtainable that are capable of resisting the physical conditions or the chemical actions to which they are subjected. Applications for patents covering commercial uses of centrifugal liquid crucibles were filed in the United States in 1919,' in France in 1925, in the United States and Germany in 1926,2 and in France in 1927.3 In 1928, Schuette and Maier,4 of the Bureau of Mines, reported the construction of a whirling table beneath a high-frequency induction furnace. Shape and Size of Centrifugal Liquid Crucibles When a vessel containing a liquid is rotated, the inner surface of the liquid takes the shape of a paraboloid under the simultaneous action of centrifugal force and gravity. The internal dimensions of the paraboloid rotating liquid crucible are governed by the diameter of the container and its speed of rotation. Melted Wood's metal was poured into cylinders 2 1/2 in. in diameter, which were rotated at 180, 300, and 468 r.p.m. When the metal was solid, a slurry of plaster of Paris was added, and rotation continued until the plaster had set. Fig. 1, a photograph of sections of the cylinders, shows the effect of speed of rotation of the containers upon the shape of the inner surface of the rotating liquid crucibles. Types of Furnaces Three types of high-frequency induction laboratory furnaces using liquid-metal crucibles were designed and constructed by the Blast

Jan 1, 1939

By A. Hultgren, G. Phragmén

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

Jan 1, 1939

By L. H. Levenson, Charles S. Barrett

Plastic flow in metal crystals and the changes in orientation resulting from it are generally understood to take place by the following fundamental mechanisms: (1) slip on crystallographic planes, (2) homogeneous crystal rotation resulting from the slip, (3) bending of the 1attice between the planes of slip, and, under certain circumstances, (4) twinning. This paper and a preceding one on iron subjected to uniaxial compression1 concern two additional processes that must now be added to this list: (5) the formation of deformation bands, and (6) the bending and rotation of these bands. The present investigation yields a new understanding and definiteness to the common terms so loosely used when speaking of cold-worked metals —('grain fragmentation," "elongated grains," and "deformation twins," "deformation bands," "etch bands," or "X-bands." Bands have been noted on the polished and etched surfaces of cold-worked metals by various investigators for more than 25 years, ‡ yet their nature and their significance have been so little understood that they are not treated in the most comprehensive modern texts on the deformation of crystals. The experiments in this series show that they are one of the fundamental processes in the deformation of metals, of importance in the development of preferred orientations, in work-hardening (since they have the effect of reducing the effective grain size and interfering with slip), and in the recrystallization process. The present experiments were performed on the same stock of material that was used in the earlier compression experiments1—hydrogen-purified mild steel in which the carbon content had been reduced to the limit detectable under the microscope and in which single crystals could be grown by a strain-anneal treatment.2

Jan 1, 1939

By Leo P. Tarasov

Magnetic torque studies of ferromagnetic single crystals have been carried out in a number of laboratories during the last decade&apos;s2 and some work has been reported on polycrystalline material showing preferred orientation. Goss3 used the method extensively in developing electrical sheet with desirable magnetic properties, but he used it as a control rather than as a means of studying the texture. Bozorth4 made a quantitative correlation of a torque curve he obtained from some cold-rolled iron with the texture as determined from X-rays, but did not extend his studies beyond the one specimen. Other studies, which have been reported from time to time2,5 have also been incomplete in the sense that no effort was made to study a whole series of samples, differing only in degree of cold reduction or in the annealing temperature, in order to ascertain the effect of such treatments on the texture as revealed by torque measurements. It is the purpose of this investigation to make such a study, mainly in order to see how useful the method can be made when used under favorable circumstances and to find what kind of a correlation can be expected between magnetic and X-ray studies of texture. Before proceeding further, it is desirable to say a little about single crystals, so as to make clear the concepts involved in magnetic torque measurements. Magnetic Torque Method It is fairly well known nowadays that single crystals of ferromagnetic substances have directions of easy magnetization and of hard magnetization. In Fig. 1 are reproduced typical magnetization curves for a single crystal of iron, which show that in a < 100 > direction saturation occurs at low fields compared to those required to saturate the same crystal in a <110> or a <111> direction. (The magnetization intensity I is defined by the equation B = H + 4pI.) At fields high enough to

Jan 1, 1939

By J. B. Austin, R. L. Rickett

Measurements of the rate of decomposition of austenite at constant temperature are commonly represented by plotting the percentage transformed on linear coordinates against time on either a linear or a logarithmic scale, a method that yields a curve that in shape resembles an integral sign (Fig. 1). A graph of this kind is not always convenient because extrapolation to the beginning or end of the transformation, or even intebrpolation, may be uncertain unless there are a large number of observations, which seldom happens; furthermore, the degree of consistency of a set of measurements is difficult to judge from such a curve. It is desirable therefore to find some mode of plotting, or even better to find a standard variety of graph paper, that gives a straight line instead of the integral shape. The straight line has many advantages; the number of readings required to fix the position of the curve is greatly reduced, interpolatiorr is easy and rapid, extrapolation can be carried out with greater confidence and, finally, the consistency of the measurements is readily estimated from the scatter of the points. The last advantage is particularly valuable when the data are obtained by direct microscopic examination alone, because they are influenced by the skill of the observer in estimating the relative size of areas, possibly also by undetected inhomogeneity of the specimen. A search for ways of representing the observations as a straight line yielded two methods which are described in this paper. The paper also includes an account of some interesting relations brought to light in applying these methods to the available experimental data. Usually the best way to derive such a method of plotting is to base it on established principles of chemistry and physics, as has been done, for example, for the temperature variation of the equilibrium constant of a chemical reaction. But so little is known of the mechanism of the decomposition of austenite, and so little is available in the way of well established background for changes of this kind, that it is simpler to rely upon purely empirical means. The general plan therefore is to study existing data with a view to finding some function of the direct observations that will

Jan 1, 1939

By Walter Crafts

Structural steels containing chromium have become widely used in the last 20 years. In the earlier part of this period the major applications were in chromium-molybdenum aircraft tubing and similar special high-strength steels. During the past 10 years there has been a notable expansion in the use of chromium-bearing steel for structural purposes when welding was utilized for fabrication. The chromium-bearing steels introduced by Saklatwallal (chromium-copper), Kinzel2 (chromium-manganese-silicon), and Schultz3 (chromium-copper) are being extensively used at the present time. General Effects of Chromium Chromium is so widely known for its carbide-forming tendency that its capacity to stabilize oxygen, nitrogen, and phosphorus is often overlooked. In low-carbon steels of the structural type these so-called secondary characteristics become more prominent. For this reason also, chromium in structural steel is definitely a toughening agent. As the carbon content is increased, the more widely known hardening effect becomes more evident. In low-carbon steels chromium increases the notched-bar impact strength substantially. This property persists at subzero temperatures and is utilized for low-temperature service in chromium-copper steel.4 Chromium also reduces any tendency to strain-aging embrittlement. In addition to improving the toughness of steels with the usual impurities, chromium has the specific property of counteracting the brittleness induced by high phosphorus.5,6 In steels low in carbon and alloys, chromium has an almost negligible effect on tensile strength, and a hardening influence is noticeable only in the stronger steels. The ductility of welds adjacent to the base plate is also improved by chromium, both in the range of foolproof welding steels having strengths of less than 80,000 lb. per sq. in. as well as in the higher strength steels.

Jan 1, 1939

By R. E. Head

Some mixtures of sulphide and oxide ores from the Tintic district in Utah are of a sufficiently good grade to be shipped to the smelter without beneficiation. In mining this type of ore, however, a material tonnage of ore of a similar composition but of lower grade is obtained. It is a question of economics whether such ore should be shipped with a certainty of a small return or concentrated if that would yield a sufficiently increased return to amortize plant construction and upkeep and yield a higher rate of profit than at present. It may be assumed that the tonnage of this borderline ore is constantly increasing and that eventually it will attain such proportions as to justify plans for milling on a relatively large scale. Under existing conditions, the producer of mixed sulphide and oxide ores is not greatly concerned about the physical characteristics of his ore or of its mineralogical complexities, since his contract with the smelter calls for payment on the basis of chemical analysis. When concentration is contemplated an entirely different picture is presented. Percentages of valuable metal content must then be con-sidered in terms of minerals, for it is in the form of minerals that recoveries are made and losses sustained. In describing the performance of a given flotation mill and reagent combination, it may be stated as a generality that a specific percentage recovery of valuable elements is made. Technically, however, the concentrator is really constructed and the reagents are selected to recover the valuable minerals. These considerations must be given prominence in discussing borderline ores from the Tintic district because of their physical characteristics and mineralogical composition. Because of these peculiarities they may be justly termed complex, since their lead, silver, and copper contents are each represented by two or more minerals of different chemical composition and presenting widely divergent physical properties. This paper sets forth the results of a microscopic study of a type of borderline ore from the Tintic district that is now being treated by direct smelting. A

Jan 1, 1939

By J. M. Morris

The point to be made most clear in this paper is the economic value of flotation in the Benguet mill flow sheet. It is rather a statement of effect with no attempt at a technical explanation of the cause. Certain well-known, easily understood reagents, mechanisms and principles have been adapted to the conditions at Benguet, and have proved to be more successful than was demonstrated in the laboratory. The mechanical and metallurgical development of this particular operation was arrived at by trial and error, with fortunately very little error. Changes were slow, of necessity, which in the end proved a blessing in that time was afforded for observation and analysis of the disturbing factors; and as a result each change was a definite step towards higher efficiency. Many of these steps were unpredictable from laboratory work because of the varied and differing characteristics of ores met with in daily operation of the mill, which were practically impossible to reproduce on a laboratory scale. The Benguet mill receives daily ores that differ as much as if they were delivered from three different properties. There is first the surface and upper-level zone, which produces an oxidized secondary ore containing considerable iron oxide, manganese oxide and some organic matter. Formerly, most of this ore consisted of very soft fill with some hard rock mixed in. It also contained an unusual amount of iron and aluminum sulfate, which formed hydrates upon entering the alkaline cyanide solution and caused excessive frothing. When flotation was introduced in the Benguet mill the general characteristics of this upper-level ore had changed considerably, in that it was practically all newly mined, fairly hard ore. It still contained many of the same disturbing elements, but was somewhat simpler to treat than formerly. The small proportion of fines is still troublesome in flotation, and plant practice probably does not show more than 80 per cent extraction on this small portion of the ore. No definite figure on this is available, as this particular ore is delivered at irregular intervals

Jan 1, 1939

By H. P. Allen

The Achotla mill of the Cia. Minera de Penoles is of special interest in that it is one of the few still employing the chloridization process. The ore milled comes from the Suriana mine and consists of both oxide and sulphide, from neither of which can the gold or silver be extracted by a simple cyanide treatment. The mill was built in 1927, after several years of study in the development of the process1, and operated from December of that year until October 1930. Operations were resumed in February 1935, and have been continuous since, treating approximately 5000 tons per month, while the mine is getting up to full tonnage of 6500 tons per month. Transportation of Supplies The property is in Guerrero, Mexico, some 175 km. by airline southwest of Mexico City. The mill site is at Temisco (Fig. I), 8 km. from the Balsas River and 4.8 km. by aerial tram from the mine. At Temisco are the general office, shops, warehouses and laboratory serving both mine and mill. Here sufficient water is available either from a small creek running through the property or from the Balsas River, also convenient and ample storage space for the tailings. With the exception of the mine timber and a few native building materials which may be obtained locally, all supplies for both mine and mill are brought down the Balsas River from Balsas, the terminal of a Mexican National Railway line out of Mexico City. The method of transportation on the river is interesting. Rapids with very fast water are numerous, prohibiting the use of mechanically propelled boats. Those used resemble large, flat-bottomed rowboats some 22 ft. long by 8 ft. wide (Fig. 2). They are manned by two oarsmen sitting in the bow, each handling one large oar, and usually another man in the stern who, with his oar, assists in steering the boat, especially when the rapids are run. From 3 to 7 tons of freight are carried on each boat, depending upon the stage of the water, which governs also the time

Jan 1, 1939

By R. E. Head

Under existing economic conditions, the treatment of gold ores occupies an outstanding position in metallurgical activity. The increased price of gold has automatically brought about a reclassification of old dumps and low-grade orebodies, and many that formerly were considered valueless are now being vigorously investigated and worked. This situation has developed problems that have taxed the ingenuity and ability of metallurgists to the utmost. Some gold ores give a high extraction of gold by standardized methods of treatment; other ores of apparently similar character yield but a relatively small percentage of their gold when treated by the same processes. Surface Contamination The experience gained by microscopic study of numerous gold ores and tailings has shown that there are pronounced differences in the physical characteristics of the minerals composing them, more especially of the gold. Repeated studies of tailings from flotation and cyanidation of gold ores has established the fact that surface contaminations on gold particles are often directly responsible for high gold losses; comparison of gold particles isolated from flotation concentrates and the resulting tailings have showed that the clean gold has been recovered and the tarnished or contaminated gold invariably lost in the tailing. Obviously, it is not possible to make such a comparison of gold ores treated by cyanidation, as the clean gold has been taken into solution; but when the gold found in cyanide tailing has a tarnished or coated surface, one may infer, with a reasonable degree of certainty, that the clean gold has been extracted. This premise is supported by experimental evidence obtained by isolating particles of tarnished gold and exposing them to cyanide solution in small parting cups. In one such experiment, tarnished gold particles picked from a cyanide tailing showed but slight evidence 01 dissolving at the end of 27 days. In this test, a cyanide solution of 1.6 11). per ton was used and the leach solution was decanted arid renewed every

Jan 1, 1939

By Orson Cutler Shepard

The term "electrocapillary amalgamation" is used in this paper to designate amalgamation processes that depend upon electrocapillary phenomenon; i.e., the action of an electric current upon the surface tension of mercury at the contact with aqueous solutions. Electro-capillary amalgamation is selected as a name for these processes because the electrocapillary phenomenon has been found to be the effective agent in the use of sodium amalgam, as well as in the various processes using an electric current from a source outside of the amalgam. Amalgamation processes that depend upon supplying an electric current to the amalgam from an outside source, such as batteries and generators, have previously been called electrical amalgamation processes. There has been a tremendous amount of experimental work done on amalgamation processes involving the use of an electric current, as shown by the large number of patents issued on these processes: the earliest in 1885 and the latest in 1934l. Regardless of all the experimental work, the fundamental principles causing the operation of electrocapillary amalgamation processes have not been described. The explanation usually given is that an electric current keeps the amalgam bright and clean. Patent No. 328532 states: It is well known that when amalgam plates are used for collecting gold and silver from their ores the surfaces of these plates are liable to become tarnished or sickened by certain substances contained in the ores or in the current of water which is employed to carry the ore over the plates, and that in this condition they are unfitted for amalgamating the particles of gold and silver. To prevent this and to keep the surfaces of the amalgamation plates always bright and in a better condition for catching and amalgamating the particles of gold and silver I employ electricity in the following manner: . . . A similar explanation is given 49 years later, in patent No. 1953364: The sodium (Na) ions lose their charge at the cathode becoming sodium atoms, which do not react with the electrolyte, but follow the grounded electrical current through the mercury body producing in their passage sodium amalgam and liberate themselves in the amalgamation compartment when brought in contact with the fed

Jan 1, 1939

By Herbert Banks Johnson

During the past 10 or 12 years very little information has been made generally available concerning the commercial possibilities of separating materials by means of static electricity; and yet during that same period important improvements have been made in various branches of the science of electricity, which, when taken together, and applied to electrostatic separation, have resulted in important improvements in that art as well. For example, much improvement has been made in high-voltage electrical equipment such as full-wave vacuum-tube rectification and improved mechanical rectification. Great strides have likewise been made in the development of insulators for high-voltage work, not only in the materials used but also in the design of the insulators themselves. Again, in another field, the development of air-conditioning equipment has improved the technique of controlling the surface condition, through drying or humidifying, of the various materials that are passed through the electrostatic separator. In many authoritative publications and textbooks, the electrostatic separation process is declared to require a balance far too sensitive for general commercial application. For example, one publication1 in the past has referred to an unfavorable effect on the process caused by varying atmospheric conditions such as humidity. Some2 have even gone so far as to state that sunlight and shadows may seriously affect the separating efficiency of the process. Such statements may have been true in the early development of the art, when the source of static electricity was derived from a friction disk machine, such as the Wimshurst. The Blake Mosher equipment and the work of Huff in applying motor-generator sets, transformers and mechanical rectification overcame much of this kind of objection to the commercial application of the electrostatic separating process. Another objection made periodically is that it is generally considered necessary to feed the particles into the electrostatic field in a stream that

Jan 1, 1939

By V. R. Garfias, R. V. Whetsel

As pointed out in previous studies, estimates of petroleum reserves if they are to be of value must not only presuppose a clear understanding of what is actually meant by reserves but must be subject to constant revision to conform with changes in their component factors. When such estimates are analyzed it must be clear that it is virtually impossible to obtain comparable figures reflecting the same degree of accuracy, to represent the reserves not only in various countries, but at times even of different fields in the same country. Estimates of reserves in the United States, subject to frequent independent checks, are obviously more reliable than those furnished, for instance, by the Soviet Government, as the latter must be accepted at their face value and are open to the suspicion of being made to conform with predetermined programs of propaganda. Any tabulation of the reserves of all producing countries, therefore, gives a total that is misleading, as the component items arc not arrived at on the same basis and therefore are not homogeneous in a true sense. Only a fraction of the petroleum stored underground, usually associated with natural gas, is or can be brought to the surface, and although practically all the natural gas underground can be rccovered, in actual practice in some fields a large part of the gas that reaches the mouth of the well is wasted. It is thus estimated that in the United States only some 25 to 35 per cent of the petroleum underground in proven fields is actually economically recovered. Estimates of reserves, therefore, should make clear the distinction between the known amount of oil underground in producing fields and the portion that actually can be brought to the surface. It cannot be overemphasized that as a result of the operation of the "Law of Capture," which controls subsoil ownership in the United States on comparatively small landholdings that seldom if ever cover the entire producing area, the oil fields are not as economically exploited as some forrign fields, and that as a result (were it not for the easy accessibility of the domestic market, the largest in the world) some American production would now be unprofitable in open competition with foreign oils.

Jan 1, 1939

By Walter Miller

Developments in oil refining were so varied during 1938 that a refiner had to be alert or be left behind. The long-talked-of conversion of oil refining into a true chemical industry using petroleum as a raw material was hastened, particularly in the realm of motor-fuel manufacture, by the increased understanding and use of catalytic processes. The petroleum refiner&apos;s vocabulary has been extended to include alkylation, cyclization, aromatization, and isomerization. There are other devel: opments of a similar nature, but these are now considered commercially feasible under proper conditions. New Equipment Less expensive equipment and processes encouraged new construction and replacement. Estimates of money spent in the United States on building new plants and remodeling existing installations during 1938 place the sum at not less than $200,000,000, a noteworthy amount in a year marked by a business recession. The commercial application of small-scale catalytic polymerization of refinery gases made one of the latest advances available to the smaller operators, who usually are faced with unit installation and production costs higher than the large refinery enjoys. Competition was thereby fostered. Outstanding in this respect was the construction of two or more polymerization plants in small refineries at extremely low installation costs, with amortization measured in months instead of years. Houdry Processes Bursting like a bombshell late in the year was the disclosure of the extent of the development of the Houdry processes of catalytic cracking, viscosity breaking, gasoline treatment, desulphurization, and polymerization, said to be applicable to almost any raw petroleum stock and yielding gasoline of exceptionally high octane number. This process is claimed to be particularly adapted to once-through cracking of aliphatic hydrocarbons, and when combined with any of the conventional thermal

Jan 1, 1939

By Daniel Hanson

FoR most of their practical applications metals are required to withstand stresses of appreciable magnitude: indeed, it id because they possess the quality of resisting stress without becoming permanently deformed that they find such extensive use in the service of man. Metals and alloys must, in service, usually behave as elastic substances—or nearly so. It is not difficult to satisfy this condition at ordinary temperatures. Iron and its alloys, especially the steels, are at normal temperatures excellent elastic bodies, capable of satisfying most of the mechanical requirements of the engineer: where electrical, chemical or other properties are impor-tant, which cannot be met by steels, it is usually possible to find a non-ferrous alloy such as nickel, copper or aluminum, which will prove satisfactory. When the metals or alloys are not inherently sufficiently elastic, cold-working or heat-treatment may develop elastic properties to a sufficient extent for practical needs. By means of relatively simple, rapid tests we can measure such properties as elastic modulus, limit of proportionality and proof stress, upon which design can be based with confidence. The case of the soft metals, such as lead and tin, is well known to be exceptional. They possess no definite limit of elasticity, and the value of proof stress or tensile strength depends to a great extent on the speed with which the test is carried out. Design here must be based on other considerations than a well-established theory of the proportionality of stress and strain. It is now generally recognized that steels and non-ferrous alloys possess at temperatures not greatly exceeding that of the atmosphere, characteristics quite different from those existing at ordinary temperatures, and that they assume qualities similar to those of the soft metals. Not only have they no limit of elasticity, but the proof stress and the ultimate stress depend on the time of application of the load. Flow under load may persist for long periods of time, possibly indefinitely, and the determination of a true maximum stress becomes a matter of great difficulty.

Jan 1, 1939

By L. A. Willey, William L. Fink

TWO of the aluminum-alloy systems previously studied—the aluminum-titanium and the aluminum-chromium—exhibit a peritectic reaction at the extreme aluminum end of the diagram. Preliminary work indicated that the aluminum-zirconium and certain other aluminum systems were similar in this respect. The present paper, the twentieth of a series from the Aluminum Research Laboratories, reports the results of a recent investigation of equilibrium relations in aluminum-zirconium alloys of high purity, which confirm the preliminary observations. Previous Investigations There has been only one investigation of the aluminum end of the aluminum-zirconium system. Sykesl prepared and studied alloys containing 0 to 70 per cent Zr. The lowering of the freezing point of aluminum by the addition of zirconium was found to be very little, if any (less than 2" C.). He placed the solid solubility of zirconium in aluminum at room temperature between 0.57 and 0.97 per cent. A few other investigators have attempted to determine the composition of the intermetallic compounds occurring in this system. Honigschmid2 obtained the compound ZrAla as a by-product during the preparation of ZrSi2. He made no attempt to prepare other aluminum-zirconium compounds. Weiss and Newmann3 prepared an alloy by heating aluminum with a double fluoride of potassium and zirconium. When this alloy was treated consecutively with caustic soda and hydrochloric acid, there was a residue, which contained approximately 72 per cent Zr and 28 per cent A1 (Zr3AI4). Marden and Rich4 prepared an alloy in the same way, treated it with caustic soda, and obtained a residue of silver-white crystals, which contained 70 per cent Zr and 30 per cent A1 (Zr3A14). Alloys Materials Used.—Electrolytically refined aluminum was employed for thc preparation of all alloys used in this investigation. The chemical

Jan 1, 1939

By Alden B. Greninger

That metallographic structures analogous to the martensite of steel may be found in certain copper-aluminum and copper-tin alloys has been known for many years; similar structures recently were found in certain copper-zinc a1loys.l In all three of these alloy systems the martensite structures result from transformation of the metastable fi phase when the speed of cooling from the B range is sufficiently high to suppress decomposition into equilibrium phases. In the normal decomposition of solid solutions into equilibrium phases, diffusion is needed to bring about the necessary changes in concentration, and the rate of reaction falls almost to zero at temperatures slightly above room temperature. The rates of reaction for martensite processes, however, are not dependent upon temperature; the transformation does not require rendjustments of concentration. For example, the martensite transformation in 60:40 (B) copper-zinc does not begin until the temperature has dropped to about minus 30" C., and then continues down to minus 130" C. and probably even at lower temperatures.&apos; Furthermore, martensite processes apparently proceed only while the tempcrature is falling, within the proper range, and cease completely while the temperature is held constant ;$ and they cannot be suppressed by extremely rapid cooling although the rate of cooling for some alloys may be increased to over 10,000 times the critical cooling velocity. Isaitschew, Kaminsky and Kurdjumow2 account for these observed behaviors of rnartensite processes by postulating that the mechanism 6I... consists in a regular rearrangement of the lattice in such a way

Jan 1, 1939