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By Oscar E. Harder, H. A. Grove

It is now just a quarter of a century since Fred W. Taylor§(23) pub-lished his classical paper On the Art of Cutting Metals, describing his researches in which he, in cooperation with Maunsel White, had developed what is essentially the modern method of heat-treatring high-speed steels. Regarding this research, Dr. Sauveur,(22) in his address on Steel Wizards, Past and Present, at the annual banquet of the American Society for Steel Treating in Philadelphia in 1920 said, "The discovery of high-speed steel, or if you prefer, of the treatment imparting high-speed properties to certain steels by Taylor and Maunsel White I am inclined to consider as our one epoch-making contribution to the metallurgy of steel." It was at about that same time (1900) that Taylor exhibited high-speed steels, heat-treated by the improved process, at the World's Exposition in Paris and attracted much attention by showing that the steels would operate at such feeds and speeds that the tips of the tools were visibly red hot. This observation must have started metallurgists to wondering regarding the relative hardness of the various steels at red-heat temperatures. Considerable work has indeed been done in an effort to measure the hardness of high-speed steels and related materials in the red-heat range, using various methods. The result's, however, have been only partly satisfactory, owing to experimental difficulties. The present investigation had as it's immediate inception an address by J. V. Emmons, of the Cleveland Twist Drill Co., to the Columbus Chapter of the American Society for Steel Treating in 1931, in which he deplored the fact that comparatively little was known with regard to the hardness of high-speed steels at elevated temperatures, in spite

Jan 1, 1933

By R. J. Brison, W. C. Bleimeister

The International Salt Company has long been interested in finding an efficient process for the removal of impurities from rock salt, and particularly from the rock salt produced at the Detroit mine. Methods which have been used previously at the Detroit mine included both hand sorting and differential crushing in a Bradford breaker with rejection of the oversize. Neither of these methods was adequately effective. The development of a new process for removal of impurities from rock salt has been described in the preceding article." Basically, the process consists of exposure of crude rock salt to radiant heating which selectively heats the impure particles. Subsequently the heated particles are removed by adhesion to a heat sensitive-coating on a conveyor belt. This method was found to be effective in improving both the quality and appearance of rock salt by the rejection of the dark, impure particles.

Jan 8, 1960

By H. T. Mercer, A. C. Paulson

The composition of steel and the theory of its heat treatment have been so ably discussed elsewhere that it is unnecessary to go into the subject here. The purpose of this paper is to describe briefly the method of treating drill steel at the Copper Range mines, giving some of the troubles encountered and the manner in which they were overcome or corrected. To study the matter properly, it was necessary to devise a system of records that would show the actual underground performance of the drills. To illustrate this system, the records of the Champion mine are used, as it is at this mine that most of the work along these lines has been done. Reports from each drill machine are made daily by the shop and mine, and tables compiled from these reports show the footage drilled, steel broken, drills received and sent out at the shop, drills sharpened, and bits cut off. These data show what each machine or party is doing and whether the miners' supply of drills is kept up to date. There have been times when the supply of drills has been short and time lost by the miner in looking for drills. The daily records show the number and condition of drills on hand at all times. Under the old method of sharpening, the drills were heated in a coke furnace, the proper degree of heat being judged by color. Then they were sharpened in a machine, reheated in a second coke furnace where the proper heat was again determined by color, and quenched in water. While this method was fairly successful in the hands of a careful workman and for the solid steel used in the old piston drill machine, the introduction of the faster water machine, using hollow steel, produced changes both underground and in the shop. Much more was expected of the hollow-steel and hammer-type machine, with its improved method of rotation, but troubles due to breakage, burnt bits, uneven tempering, etc., at once appeared.

Jan 1, 1922

By H. T. Mercer

THE composition of steel and the theory of its heat treatment have been so ably discussed elsewhere that it is unnecessary to go into the subject here. The purpose of this paper is to describe briefly the method of treating drill steel at the Copper Range mines, giving some of the troubles encountered and the manner in which they were overcome or corrected. To study the matter properly, it was necessary to devise a system of records that would show the actual underground performance of the drills. To illustrate this system, the records of the Champion mine are used, as it is at this mine that most of the work along these lines has been done. Reports from each drill machine are made daily by the shop and mine, and tables compiled from these reports show the footage drilled, steel broken, drills received and sent out at the shop, drills sharpened, and bits cut off. These data show what each machine or party is doing and whether the miners' supply of drills is kept up to date. There have been times when the supply of drills has been short and time lost by the miner in looking for drills. The daily records show the number and condition of drills on hand at all times. Under the old method of sharpening, the drills were heated in a coke furnace, the proper degree of heat being judged by color. Then they were sharpened in a word drill-sharpening machine, reheated in a second coke furnace where the proper heat was again determined by color, and quenched in water. While this method was fairly successful in the hands of a careful workman and for the solid steel used in the old piston drill machine, the introduction of the faster water machine, using hollow steel, produced changes both underground and in the shop. Much more was expected of the hollow-steel and' hammer-type machine, with its improved method of rotation, but troubles due to breakage, burnt bits, uneven tempering, etc., at once began to appear.

Jan 8, 1920

By G. F. Sager, B. J. Nelson

Magnesium alloy forgings offer higher and more uniform mechanical properties than heat treated magnesium alloy castings and are used principally for light weight parts that may be stressed in fatigue or subject to impact loads, or where space limitations do not permit the use of the necessarily bulkier magnesium alloy castings. Compositions and Properties of Magnesium Forging Alloys The nominal compositions and properties of the principal commercial magnesium forging alloys are given in Table 1. The two that are most commonly used are AMC58S and AM65S. The former has the highest strength and is, therefore, employed for heavy duty applications. However, the forging of this alloy and of AMC57S ordinarily requires the use of slow speed hydraulic presses. The forging alloy AM65S combines good, although somewhat lower, mechanical properties with excellent forging characteristics. This alloy can be forged on hammers, upsetters, rolls, and mechanical presses, as well as on hydraulic presses. These characteristics make it particularly useful for many applications. Manganese Segregation in AM65S The alloy AM65S contains 5 pct tin, 3 1/2 pct aluminum, and a small amount of manganese, the manganese being added to insure satisfactory resistance to corrosion. Some manganese segregation was occasionally encountered in this alloy. In many applications, such segregation is of no particular consequence, but when forgings are acid dipped prior to the application of various chemical coatings, the segregated particles of manganese constituent may stand in relief. The resultant surface roughening may impair appearance and is undesirable in forgings employed in the textile industry, where very smooth surfaces are essential to avoid the catching and breaking of fine threads. An effort was therefore made to determine the cause of manganese segregation in this alloy and find a method for its elimination. Radiographic examination of a series of cast ingot sections and extruded samples of the AM65S type having manganese contents ranging from zero to about 0.7 pct revealed no appreciable manganese segregation when the manganese was less than about 0.4 pct. A small amount was observed with a manganese content of 0.46 pct and considerable with manganese contents of 0.6 pct or higher. Attempts to eliminate the manganese segregation by variations in the melting and casting conditions were unsuccessful and it soon became apparent that the trouble was attributable to the fact that the manganese contents that caused segregation were in excess of the amounts that would remain in solution at temperatures encountered in the melting and/or casting operations prior to the complete solidification of the ingots. A knowledge of the amounts of manganese that would be soluble in molten alloys of the AM65S type at various temperatures was obviously desirable. The liquid solubilities of manganese in binary Mg-Mn alloys and in Mg-Al-Mn and Mg-Zn-Mn alloys have been determined by Tiner and others,* but no data on the solubility of manganese in molten magnesium alloys containing tin and aluminum are given in the literature. For this reason, an investigation to determine the solubility of manganese in a magnesium alloy containing 5 pct tin and 3.5 pct aluminum (AM65S type) was undertaken.

Jan 1, 1950

By AIME AIME

No democracy such as ours, can ever be prepared for war, because we could never conceivably be the aggressor. The aggressor prepares in secret, designs his new tactics, and invents and makes new equipment and selects the time to strike. If a democracy prepare done year and the war came later, all that it had one would have to bed one over. All that England has today in the way of effective armament has been invented, designed, made, and the crews trained since the war began, because the totalitarian aggressor introduced new types of equipment and new techniques.

Jan 1, 1941

By G. A. Vissac

MoIstuRe in coal must be considered as an impurity, just the same as ash, from the standpoint of utilization of the coal. Being incombustible, it reduces directly the heating value of the coal, and in addition absorbs heat for its evaporation. Its presence means useless expenditures in handling and transportation. In coke plants, extra moisture reduces capacity and may cause damage to brick work and equipment. Accordingly, the removal of extra moisture can be considered just as important as the removal of other impurities, such as ashes, in the modern coal preparation plant. Moisture, which can be removed by heating the coal up to a temperature of 100°C, may be retained in various forms: 1. As a film, on the surface of each coal particle, and in the interstices between particles, retained by capillary forces. 2. Or "occluded" inside the coal particles. This occluded moisture may be either free moisture (as in a sponge), or hygroscopic moisture which varies with atmospheric conditions, (also called "regain"). These latter forms of moisture are particularly common in "young" coals (subbituminous and lignites); bloom coals (seam outcrops); fusain; and carbonized products. In our study of coal drying, we shall consider only the removal of free moisture, exclusive from hygroscopic moisture. Dewatering If we reserve the name of drying to the removal of water by evaporation, we must consider the initial phase of the mechanical removal of free moisture as a distinct operation covered by the term dewatering. In all cases the free water carried over the surface of the coal particles or in their interstices, or in their pores, is retained by capillary forces. Dewater-ing is accomplished by breaking or counteracting these capillary forces; removal of as much water as possible by dewatering methods is usually advisable, as the cost of these operations is generally much less than by evaporation. The most common methods of me-chanical dewatering are: 1. "Pressure piling," which reduces the interstitial spaces, accomplished in dewatering bins or over dewatering screens. 2. Or dynamic methods, such as used in centrifuges or over vibrating screens. We shall only mention the " preferential wetting" method, in which surface water can be displaced by hydrocarbons, as offering possibilities, but which, to our knowledge, has not reached yet a practical development. But we must point out that the capillary forces retaining water on the coal surfaces, decrease considerably with increased temperatures. This is the principle used in all modern dishwashing machines; by using very hot water, dishes are extracted almost dry. In line with this development, we favor the type of dryers including a dewatering section; as the coal enters the dryer and is gradually brought up to higher temperatures, its dewatering ability is increased and advantage can be taken of this conditioning, resulting in increased drying efficiencies and reductions in drying costs. Heat Drying In the final phase, the remaining moisture must be evaporated. Coal and water must be brought up to the chosen temperature of evaporation, and heat must be supplied to fill the requirements of the latent heat of evaporation of the water to be removed. Accordingly, drying becomes largely a problem of heat transfer, and drying methods can be classified accordingly, namely: 1. Radiant transfer. 2. Transfer by surface contact and conduction. 3. Transfer by hot gas contact. The first method is not applicable to coal drying; the second method is used in the old type rotary dryer. The third method, the most commonly used in modern coal dryers, will be the only one considered here; and, of course, we shall deal with continuous types of dryers only. The mechanism of complete drying is really very complex-—several phases are involved: 1. The constant rate period. 2. The uniform falling rate period. 3. The varying falling rate period. As most of our practical coal drying problems deal with wet coals (over 6 pct of moisture), and do not require complete drying (under 1.5 pct), we shall deal with the first condition only, namely the constant rate drying. Dryer Calculations Instead of presenting the algebraic formulas, we believe a concrete example will provide a clearer illustration. Assume a feed of wet coal at the rate

Jan 1, 1950

By H. E. Wheeler

THE work described was carried out during 1917 and 1918 at the testing laboratory of Watertown Arsenal at the instigation of the Nitrate Division and later with the concurrence of the Cannon Section of, the Ordnance Department, U. S. A. The experiments follow three principal lines of work: First, the effect of nitrogen under pressure on steel containers of various compositions at a red heat; second, the effect of decomposing ammonia on various alloy steels, iron, and non-ferrous alloys; third, a new theory of the erosion of guns in respect to the effect of nitrogen in steel. PART I In the Haber process for the manufacture of ammonia from its elements, it is necessary to have nitrogen and hydrogen of 1500 lb. per sq. in. (105.5 kg. per sq. cm.) at a temperature of 500 to 600° C. The steel containers for these gases gave trouble by failing without apparent cause. When the General Chemical Co. began to develop its method for the production of ammonia, it experienced the same difficulty and, knowing that the Haber process had solved the difficulty by the use of alloy steels, it made several small steel bottles of different compositions and kept them filled with these gases at this pressure and temperature until they failed. The time of service varied from a few days, for the plain steel casting, to two years for a chrome-vanadium forging. Four of these steel bottles were sent to this laboratory for investigation; they were a plain carbon-steel forging, a nickel-steel forging, a chrome-vanadium steel forging, and a chrome-steel forging. The time of service was as follows: plain carbon steel, 4 mo.; nickel steel, 6 mo.; chrome-vanadium steel, over 2 yr.; chrome steel, 4 mo. When these containers were cut open and the cross-section surface polished, they showed an inside zone with a different luster from the rest of the metal. Upon etching, this zone was almost unaffected while the rest of the steel etched normally.

Jan 4, 1920

By John Blatchford, William T. Hall

The product obtained by roasting stibnite is likely to contain some unoxidized antimony trisulphide and a mixture of antimony trioxide and antimony tetroxide. It was desired to determine, as accurately as possible, the condition of the antimony as well as the total quantity present. Attempts were made to separate the trisulphide and the two oxides by methods based upon their varying solubilities in different solvents, but no satisfactory results were obtained in this way. It was found, however, that by determining the total antimony content, the antimony present as trioxide, and the antimony present as trisulphide, a good idea of the chemical composition of the roasted product could be obtained. The total antimony was determined by dissolving the sample in concentrated hydrochloric acid, reducing the antimony entirely to the trivalent condition by means of hydriodic acid and eventually titrating the antimony back to the pentavalent condition by means of iodine in the presence of sodium bicarbonate1* The details of the procedure are as follows: Weigh out 0.25 gram of the roasted product into a trapped flask (Fig. I), add 4 grams of powdered tartaric acid, 2 grams of potassium iodide and 40 c.c. of concentrated hydrochloric acid. Boil the solution gently f;r 5 min. and then cool to room temperature by shaking the flask while holding it under running water. Then, very carefully discharge the iodine color by the cautious addition of 0.05-normal sodium thiosulphate solution, adding a little starch toward the last. Nearly neutralize the acid with ammonia solution, but leave the solution distinctly acid. Pour the slightly acid solution into 200 c. c. of water containing an excess of sodium bicarbonate and titrate to a permanent blue color with standard 0.1-normal iodine solution.

Jan 1, 1916

By John A. Dunn

Continued increase in electric power requirements for mining, brought on by higher capacity mining machines and total mechanization, emphasizes the importance of proper power system design and planning. How effective a mine operates to produce quality coal at low cost depends to a great extent on how well its power system is planned and how well it is maintained. To be planned well it must be adequate to serve all the needs of the mine, it should be safe, there should be a margin for expansion, and it should be easily maintained. In planning a power system for mining coal it is helpful to establish a reliable base for estimating loads. Since most mines are served electric power by utility, power bills for similar mine loads are useful in setting up a base for estimates.

Jan 12, 1964

By J. Fred Johnson

COROMANT is the trade name of the alloy-steel drill rod tipped with a chisel-type tungsten-carbide bit manufactured by Sandvik Steel Works Co., Ltd. Other names, such as Swedish or air-leg method of drilling, are used in various localities. Coromant drilling in Sweden was the natural sequence of the adaptation of tungsten-carbide inserts to the already established routine of drilling. By the middle thirties the percussion drill had reached practically its highest attainable efficiency as a drilling machine. Since then improvement has been in metallurgy of component parts to increase life or lessen weight, in the development of pneumatic and automatic feeds, in the use of jumbos to more quickly and easily handle machines, and in changes in drill rods and bits. By 1937, drilling in the United States and Canada was done by relatively heavy mounted drifters with positive hand or automatic feeds. In Sweden, on the other hand, emphasis had been placed on light equipment and drifting was done with pneumatic bars and reverse-feed stopers. In 1938, one of the most prominent American drill manufacturers developed an air-leg for successfully drilling the extremely variable but relatively soft iron ores of some of the northern Michigan mines. Also in 1938, a comparative Swedish test, also in soft iron ore, of a 50-lb jackhammer mounted on an air-leg, against a 100-lb reverse-feed drifter on a pneumatic bar, showed the net drilling time was increased by the air-leg set-up from 51 to 71 pct, in drilling 6-ft rounds in a 6 1/2x6 1/2 ft drift. Miners were becoming scarce in Sweden even at that time and, since the lighter equipment made the work easier and more attractive, the airleg was then made use of in some types of soft rock. In 1940, for instance, a large tunnel for a hydroelectric plant was driven with this equipment. By 1943, when tungsten-carbide inserts came into the picture in Sweden, a great many of the kinks in percussion drilling with this hard-metal had been worked out in Germany under the stress of war conditions. However, only 10 pct of the drilling machines manufactured in Sweden were jackhammers for use on air-legs and only the one manufacturer made air-legs in the United States. American practice had largely supplanted integral forging of drill bits by the detachable steel bit. Canada and South Africa were using the one-pass throwaway bit but Sweden was still using the same old integral forged bit. After a long study of the trend toward simplicity

Jan 1, 1952

By Lester W. Strock

METALLURGISTS handling lead and zinc ores have long been familiar with the spectrograph as a routine analytical tool, as its earliest regular use by American industry was in controlling impurities of zinc metal and its alloys. This application has been extended to other metal industries on an extensive scale, accompanied by refinements of procedure to such an extent that a large part of some metals produced, especially magnesium, aluminum and steel, are checked only by spectrographic methods for conformity to specifications. The spectrographic analysis of ores and other poorly conducting powdered solids presents difficulties not encountered with metallic samples, which can be arced or sparked as self-electrodes or can be readily dissolved, so that their solutions can be analyzed, as in the American Society for Testing Materials standard methods for zinc and zinc-base alloys. Spectra of powdered solid samples can be prepared by using carbon electrodes provided with a crater of suitable size, into which the sample is packed. Ore samples and many other powdered solid materials usually analyzed in the chemical and metallurgical laboratory are more complex and varied in composition than samples of metals produced in large tonnages. More preliminary work therefore is usually necessary in devising a spectrographic method for analyzing a given type of powdered sample than for analyzing metal samples, in order to use that method with confidence. The knowledge that the standard samples and unknowns produce equivalent line intensities at equal concentration is the fundamental basis of any quantitative spectrographic method. On the other hand, powdered samples have an advantage over metals in that any desired number of chemical compounds can be mixed dry in any desired ratio to produce a synthetic standard. Experience has shown, however, that spectra of elements in finely divided compounds introduced into a standard in preparing a synthetic ore sample do not always behave in the electric arc in a manner that produces spectral line intensities similar to those observed at the same concentration in a natural mineral. In ore samples minor elements frequently are contained in the crystal lattice of larger particles of an abundant ore mineral. Their dissociation and volatilization from the sample into the arc then proceeds differently in the standard and sample, with resultant differences in intensity. During the past 10 years I have devised and applied several quantitative spectrographic methods for determining various elements in rocks and minerals in connection with studies on their geochemistry,1 but the incentive has gradually changed since the summer of 1940 to the specific practical problem of searching for domestic sources of rare and strategic metals. The

Jan 1, 1945

By Clarence G. Merritt

Stainless iron, as mild stainless steel is usually called, an alloy ranging from 11.50 to 15.00 per cent chromium with carbon under 0.12 per cent, has been considered to be not appreciably affected in respect to corrosion resistance by heat treatment. This metal, while one of the most widely used of the "straight" chromium stainless alloys, has failed in many applications because of insufficient information regarding heat treatment. These failures have been attributed to many possible causes from an inherent lack of resistance to corrosion and misapplication to mlysterious electrolytic effects or comparatively minute non metallic inclusions. Many uses for a steel with such excellent physical properties as are latent in this alloy have been lost on account of corrosion failures which could have been avoided by applying proper heat treatment. The alloy has not received the recognition or attention it should because of the fact that the details of its metallurgical behavior were not thoroughly understood. Response to heat treatment of the steel is well known as regards tensile properties,1-2 but its application has been for improvement in tensile characteristics or on account of machining considerations rather than for corrosion prevention. The potential user of this steel has not been clearly advised in papers, either technical or commercial, that have been written about it in the last 10 years or more, of particular features that are of prime importance in developing the excellent properties of this metal. The data to be presented in this paper are concerned mainly with the effect of heat treatment on the corrosion resistance, but a study has also been made of the concurrent microstructural changes and an explanation developed for the phenomena revealed, as well as a correlation to the other physical properties—hardness, tensile characteristics and impact strength. Stainless steel, largely used for cutlery purposes, an alloy of approximately 13.00 per cent Cr with 0.30 per cent C;, must be hardened and the surface prepared by polishing or pickling for best resistance to staining and corrosion. Monypenny reports that a loss of hardness is

Jan 1, 1932

By John M. Lovejoy

FEDERAL regulation of the petroleum resources of the nation has long been an interesting topic for discussion. A plan to accomplish Federal control has now taken definite form. At the request of the President of the United States, a bill to be known as the Petroleum Conservation Act of 1939 has been presented to Congress-H. R. 7372, offered by Representative Wm. P. Cole, Jr., and more usually known as the Cole bill. It is an act ostensibly designed to conserve our petroleum resources, through regulation of production practices. Hearings are being held currently by a subcommittee of the Interstate and Foreign Commerce Committee, in compliance with the request of the President to report the bill early in the next session of Congress.

Jan 1, 1939

By J. Sibakin, R. D. Hindson

In order to devise a practicable soaking pit schedule for use at The Steel Co. of Canada Ltd.'s Hamilton Works, soaking pit heating temperatures, sooking times, pit capacity, and safe maximum mill drafts were correlated with fluctuations in the current or load of the bloom mill driving motor. Other variables such as total delays in the pit, rolling schedules, mill delays, and track times were also investigated. IN order to show an easily applied and accurate means of establishing soaking pit heating temperatures, soaking times, pit capacity, and safe maximum mill drafts, these various factors are correlated herein with fluctuations in the current or load of the bloom mill driving motor. Rolling practices have a considerable influence on the production capacity of a blooming mill. The maximum values of the torque, in particular, are of importance, since even instantaneous current peaks lead to the tripping of the motor by the overload relay and result in loss of mill time. The establishment of safe maximum drafts and accelerations for ingots of different sizes and of a soaking pit practice which would ensure a consistent and satisfactory plasticity of the metal is of considerable importance for increasing the efficiency of both the blooming mill and the soaking pits. The Bloom Mill Dept. of the Hamilton Works, The Steel Co. of Canada Ltd., is equipped with one 44 in. mill driven by a 7000 hp motor with the setting of the overload relay at 22.0 ka. The speed of rotation of the motor is regulated after the Ward-Leonard system. There are three basic speeds of 9.5, 28, and 47 rpm and a further possibility of increasing the speed by weakening the field. This last possibility is hardly ever used during practical operations. The rolling program of the blooming mill is varied, both in the size of the ingots to be handled and in the steel grades. The total tonnage handled by the mill is about 2,000,000 ingot tons per year. At the time of the investigation, the Bloom Mill Dept. was equipped with 22 soaking pits (6 regenerative, 14 bottom-fired, and 2 one-way top-fired pits) with a total bottom area of 2770 sq ft. The pits are fired with a blast furnace-coke oven gas mixture having a calorific value of 155 Btu per cu ft. The foregoing figures show that the production program was such as to impose the necessity of a most efficient usage of the available equipment. For this purpose, the operations of the 44 in. mill and of the soaking pits were investigated, and the results of the investigation were used as a basis for a revised soaking pit schedule and drafting practice. The plasticity of an ingot of a certain chemical composition when being rolled is determined mainly by the following factors: I—the ingot size, both thickness and width; 2—the length of the gas soak; and 3—the surface temperature. The first two factors determine the uniformity of the temperature distribution over the cross-section of an ingot. The third factor introduces the level of the heating of an ingot. The torque produced by an ingot being rolled is determined by the area of the metal displaced, its plasticity, and acceleration values. On the other hand, with shunt motors the torque is determined by the current. This can be assumed to be correct with only a small degree of error for compound motors with a relatively small effect of the series windings as long as the velocity is not regulated by weakening the field. Since the spread is relatively unimportant when compared to the width of an ingot and since it is also reduced several times during rolling by edging passes, the draft alone and not the area of the metal displaced may be taken into consideration with ingots of a similar size. It is therefore possible to determine the main features of the heating and drafting of an ingot by measuring the current and acceleration of the mill motor. After the acceleration has been taken into account, the amount of current will be an indication of how the motor responds to a heating and/or drafting practice and these practices can be adjusted in order to get the desired result. As peak currents are more likely when heavier ingots are rolled, the rolling of plate and slab ingots was investigated. Conditions prevailing when smaller ingots are rolled can be deduced from the results obtained on heavier ingots. All measurements were made when plain carbon grades under 0.15 pct C were rolled. The motor current, the voltage across the armature, and the rpm were recorded simultaneously on synchronized charts, Fig. 1, which moved with the speed of 6 in. per min. Each draft was recorded by a special observer. The rpm curve made it possible to establish the acceleration at any given moment. For purposes of correlation, the maximum current during a pass and the corresponding acceleration were used. The charts made it possible to establish the position of the roller's lever at any given moment as well as the total time of a pass. The slab ingots were divided into three groups (28x35, 28x45, and 27Mx53 in. ingots) and each group was investigated separately. Since they account for most of the current peaks, only flat passes were used for purposes of correlation, a total of 1373 having been investigated.

Jan 1, 1956

By H. A. Schlesinger

Various studies have estimated that for the next few decades, about half of all new power plants will be nuclear. The other half will be fueled with coal. Pending legislation on air pollution control would require all new coal-fueled power plants to install stack gas scrubbers or other technology to reduce sulfur oxide (SO,) emissions. These regulations would require flue gas desulfurization (FGD) or other technology for SO, reduction even on lower sulfur western coals. Among the options for FGD are single or dual alkali throw away processes using lime or limestone as the major reagent. These processes are currently more economically attractive than recovery processes, such as magnesium oxide and Wellman- Lord, that produce a salable product such as sulfur or sulfuric acid. One of the major problem areas with the throw away processes is disposal of the thrown away solid wastes, primarily calcium sulfite (CaSO3) and calcium sulfate (CaS04). Coal ash also must be disposed of, even if SOx reduction is not required. This paper addresses the alternatives for handling and disposal of throw away lime, limestone, and dual alkali process solid wastes. Advantages, disadvantages, and the economics of various methods are discussed. Both large central station power plants (500-1000 MW capacity) and smaller industrial power plants (up to 100 MW capacity) are considered. High sulfur eastern coals (53% S) and lower sulfur (3 1% S) western coals are considered.

Jan 1, 1981

By G. Pizzi, G. M. Ciucci, G. L. Chierici

The use of the material balance equation to estimate the volume of hydrocarbons originally present in a reservoir, whose producing mechanism is partly due to water drive, has been discussed in the literature by several authors. There is no general agreement upon the possibility of obtaining reliable results by this method. Gas reservoirs in contact with an active aquifer are considered in this paper. Theoretical considerations based on the cybernetic principle of uncertainty (which states that the internal structure of a system cannot be uniquely determined from its observed external behavior) lead to the conclusion that the volume of gas originally present in a reservoir of this type cannot be uniquely determined from its past history. The range of values which encompasses the actual value of the reserves varies from case to case and must be determined by either numerical or analogical methods. Results obtained for six gas fields are reported. All these fields were produced with small fluctuations in their production rates, as is common practice for gas reservoirs; no gas storage fields were considered. Results obtained show that reserves values in a range of 1 to 2, associated with appropriate aquifers, allow the matching of the reservoir past history with mean-square deviations less than the experimental errors involved in pressure and produclion measurements. Similar results have been found in several other partial water drive gas reservoirs. From these results it is concluded that gas reserves cannot be uniquely determined from the past performance of partial water drive reservoirs, at least in cases where the reservoir has been submitted to small fluctuations in the production rates, and pressure data of normal accuracy are available. INTRODUCTION A number of authors have analyzed the problem of estimating the reserves originally present in a partial water drive reservoir from its past pressure-production performance. Literature which deals with this subject can be grouped, according to their conclusions, as follows. 1. A reliable value for the reserves can be obtained even if reservoir data (pressure and cumulative production) are affected by errors within the normal range.'-' 2. A reliable value for the reserves can be obtained only if reservoir data are very accurate'- or if past production performance has been subjected to abrupt variations in the production rate."' 3. No unique value for the reserves can be obtained from reservoir past production performance. This conclusion has been based upon theoretical considerations" and verified in several field cases. The purpose of this paper, which deals only with partial water drive gas reservoirs, is to test the above conclusions against actual field cases. Some theoretical considerations on this problem are also presented. THEORETICAL CONSIDERATIONS As the behavior of a gas reservoir communicating with an aquifer depends on both the aquifer and the reservoir characteristics, the physical system to be studied is the combined gas reservoir plus aquifer. The information which is available for studying the performance of such a system is the well production rates and bottom-hole pressures, all given as functions of time. The external behavior of the reservoir-aquifer system is therefore described by 2n input variables (Gp, Wp,) and n output variables (p,), n being the number of wells in the reservoir. In reservoir engineering it is common practice to consider the reservoir as a whole, disregarding the internal distribution of pressures and of producing wells. This practice is equivalent to substituting the above multi-variable system with a single-variable system, where the average reservoir pressure is the only output variable and the cumulative production G,(t) and W,(t) are the input variables. The internal structure of such a system, defined by initial gas reserves G, aquifer shape and dimensions, boundary conditions and petrophysical parameters distribution throughout the aquifer, is unknown. Therefore, from a cybernetic point of view the system is a "black-box It has been demonstrated" that for a blackbox the indetermination principle holds. Accordingly, the number of different internal structures (or set of parameters) which can account for the observed external behavior is infinite. As a consequence, the initial reserves cannot be uniquely determined from the reservoir past performance. When W,(t) is known, the determination of G from

By F. G. Cottrell

About a year and a half ago, at the San Francisco meeting of the American Chemical Society, in connection with the excursions to local smelting-works, I had occasion to show some lantern-slides illustrating the recent commercial development of electrical methods for precipitating the suspended matter from smelter-smoke, the underlying phenomena of which were clearly brought to the attention of the technical public by Sir Oliver Lodge as long ago as 1884. In the .Journal of Industrial and Engineering Chemistry, August, 1911, most of these views were reproduced, together with an account of the work from its beginning up to July, 1911. To-day I wish particularly to show you some of the further developments of the work since that time; but in order to make these clear they will be prefaced by a brief abstract of the article above referred to. The removal of suspended particles, from gases, by the aid of electric discharges is by no means a new idea. As early as 1824 we find it suggested by Hohlfeld ' as a means of suppressing ordinary smoke, and again a quarter of a century later by Guitard.2 These suggestions, which do not seem to have stimulated any practical study of the question, were soon entirely forgotten, and only brought to light again by Sir Oliver Lodge: many years after he himself had independently rediscovered the same phenomena and brought them to public attention4 in a lecture before the Liverpool Section of the So-

Jan 1, 1913

By D. J. Schmatz

DISCUSSION OF RESULTS The qualitative correlation between low-temperature ductility and prior high-temperature creep strain in nickel obtained in this investigation confirms the result obtained on high-purity brass by Chen and Machlin. However, the quantitative effect is much smaller in nickel. Comparison can be made on the basis of a prior high-temperature strain that is a certain percentage of the total high-temperature elongation to rupture. In the research of Chen and machlin, the prior high-temperature strain of 1/2 pct equaled 8.5 pct of the total high-temperature elongation at rupture. For nickel, in our experiments, 8.5 pct of 21.2 pct equals 1.8 pct. For eh = 1.8 pct, the loss in ductility in percent equals x 100 = b.5 pct. That is, for equivalent bo Formation of Beta Manganese-Type Structure in Iron-Aluminum-Manganese Alloys D. J. Schmatz IRON-aluminum alloys have gained much interest in the past few years for use as a base material for elevated-temperature alloys because of their excel- high-temperature strain the loss in low-temperature ductility is 8.5 pct for nickel as compared to 60 pct for pure a, brass. It is also interesting to note the observation that in nickel the low-temperature fractures, even at the most extreme high-temperature pre-strain, were partly trans crystalline and partly intercrystalline. In the case of a brass, these fractures were completely intercrystalline. According to the data on the percent of the grain boundary area that is cracked, at 22 pct high-temperature elongation, about 12.5 pct of the grain boundary area does not carry load. Thus, the inter-crack areas are carrying a stress that is about 11 pct higher than the nominal stress. A simple model predicts that the overall elongation, which is primarily the elongation in the bulk of the specimen, will correspond to the nominal stress when the stress in the intercrack area equals the tensile strength. Quantitatively this model predicts the equation The form of this equation will agree with that found if the strain-hardening exponent, n, equals unity. Actually this model is too gross an approximation to yield good quantitative results. The question naturally arises as to whether in ordinary hot-working, such as hot-rolling, intercrys-talline cracks are introduced that affect the low-temperature properties. It appears that the answer is that such a possibility cannot be overlooked, if the hot-working induces tensile stresses at temperatures above the equicohesive temperature and if the material tends to be notch sensitive at low temperature. ACKNOWLEDGMENT This research was supported by the Aeronautical Research Laboratory, Directorate of Research, Wright Air Development Center, United States Air Force. REFERENCES lC. Zener: Fracturing of Metals, 1948, Cleveland, ASM. 'H. C. Chang and N. J. Grant: Mechanism of Intercrystalline Fracture. AIME Trans., 1956, voL 8, p. 544; lownal of Metals, May, 1956. 'E. S. Machlin. CreepRupt ure by Vacancy Condensation, AIME Trans., 1956, vol. 8, p. 106; lownd of Metals, February, 1956 'C. Chen and E. S. Machlin: On a Mechanism of High-Temper at ure Inter-crystalline Cracking, lownd of Metals, July. 1957. p. 829. Alloys lent oxidation resistance. Binary alloys of aluminum in iron are ferritic and consequently have poor hot strength. Alloys of iron-aluminum-manganese were made in an attempt to produce an austenitic alloy containing sufficient aluminum to retain the oxidation resistance of binary alloys of iron-alumi-

Jan 1, 1960

By Henry Rawdon

ANY laboratory corrosion test, as judged from the practical point of view, is valuable only to the extent that it foretells what will, in all probability, occur in service. Such a test is most properly to be considered as a "pilot test, " that is, a test which indicates the direction along which action may be expected to occur rather than as a truly quantitative test which would be expected to tell just how and to what extent the action would proceed. It is generally recognized that laboratory corrosion tests should be chosen with particular reference to the character of service expected for any particular type of metal, so far as it can be foreseen. Even when this requirement has been fulfilled, however, the question whether the actual service behavior of the material is in accordance and general agreement with predictions based upon such laboratory tests is always a pertinent one. The information available in the technical literature bearing on the correlation between the service behavior of metals from the corrosion standpoint, and the results obtained with the same metals in laboratory corrosion tests is very meager, indeed. The results which have been obtained in weather-exposure tests of sheet duralumin which form the body of this discussion are presented here for their bearing on this particular phase of the problem of the corrosion resistance of duralumin. Although the exposure tests described have not been completed, in the sense that all of the tests, in the series initially laid down, have been accomplished, still the general trend shown by the results is so clear that a number of definite conclusions at this stage (subject, of course, to possible modification in the light of later results) are believed to be warranted. The tests reported upon here form one phase of the much broader study of this subject which has been under way for several years in which the National Advisory Committee for Aeronautics, the Bureau of Aeronautics of the Navy Department, the Army Air Corps and the Bureau of Standards have cooperated. Without the very helpful cooperation of the manufacturers in furnishing the

Jan 1, 1929