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By M. J. Marcinkowski, A. S. Sastri

A detailed compressive stress-strain analysis and transmission electron microscopy investigation has been made of the deformation behavior occurring in a 50 at. pct Ni-Ti (hypoeutectoid) alloy and a 54.5 at. pct Ni-Ti (hypereutectoid) alloy. In the case of the hypoeutectoid alloy, three stages of work hardening are observed. Stage I occurs at a very low stress and is associated with plastic deformation via martensite formation. Stage 11 is characterized by very rapid work hardening and is due to difficulties in causing further deformation in the fine martensite aggregate produced in Stage I. Stage III which occurs at very high stress levels is characterized by smaller work hardening rates and is due to the plastic deformation arising from alternate reconversions of the original martensites to martensites of varying orientation. Rapid quenching of the hypereutectoid alloy leads to very high yield strengths and is related to a fine precipitate dispersion that such treatment brings about. The present investigation represents the final phase of a three-part study directed toward an understanding of the solid-state transformations in near equi-atomic Ni-Ti alloys as well as the deformation mechanisms associated with these alloys. In the first part,"2 to be henceforth referred to as I, it was found that alternate simple shears on {112} planes and in (111) directions convert the parent B2 structure in the equiatomic NiTi alloy into two distinct close-packed monoclinic martensites. All of the marten-sites were of this type, whether they were formed by cooling or by plastic deformation, whether induced to form in bulk samples or in thin foils, or whether examined in the electron microscope at room temperature or below. On the other hand, in the second part of this investigation,3 to be reffered to as 11, it was shown that upon slow cooling to about 640°C. alloys in the neighborhood of NiTi which possess the B2 structure transform eutectoidally into their equilibrium phases Ti2Ni and TiNi3. However, preceding the formation of these equilibrium phases a series of metastable intermediate phases are formed. This paper will set as its goal the elucidation of the remarkable deformation behavior exhibited by NiTi. In particular, Buehler and Wiley4 have found equiatomic NiTi to be surprisingly soft, while Buehler et al.5 have shown this alloy to possess a memory effect: i.e., upon bending at room temperature it will revert to its original shape when heated to above about 50°C. In I it was shown that NiTi was soft in the sense that the yield stress was low; nevertheless, the alloy work-hardened at an extremely rapid rate to very high stress levels. On the other hand, the hypereutectoid alloys with somewhat higher nickel, say 54.5 at. pct (60 wt pct) have enormously increased yield strengths compared to those of the equiatomic alloys. In order to determine the atomistic processes giving rise to the above behavior, it was decided to examine samples that were wafered from bulk specimens deformed in compression to various strains using the techniques of transmission electron microscopy. EXPERIMENTAL TECHNIQUE All of the alloys used in the present investigation contained either 50 at. pct Ni (55.06 wt pct) or 54.5 at. pct Ni (60 wt pct) and were arc-melted in the form of a finger using the same techniques described in I and II. The finger was capsulated in a stainless-steel jacket and swaged at 850°C into rods. Compression specimens 0.300 in, long and 0.200 in. in diam were machined from these rods. In order to completely re-crystallize the samples and remove residual stresses, all of them were capsulated in evacuated quartz, annealed for 1/2 at 1050°C. and then furnace-cooled. Compression tests were carried out in an Instron tensile testing machine covering a range of temperatures from —196° to 200°C using procedures described previously.6'7 In all cases crosshead speed was 0.02 in. per min. Wafers 0.015 in. thick were spark-cut from the cylindrical samples at 45 deg to the compression axes after they had been deformed to the desired strain. These specimens were then spark-planed to about 0.005 in. and then electrochemically thinned for examination by transmission electron microscopy as described in I.

Jan 1, 1969

By Edward Wisser

THE Pachuca silver district, situated about 100 kilometers northeast of Mexico City (Fig. 1), covers roughly the southeastern half of the Sierra de Pachuca. The latter is a mountain range with northwest trend, and forms a part of the northeastern rim of the topographic basin known FIG. 1.-LOCATION OF PACHUCA DISTRICT AND OTHER MINING CAMPS. as the Valley of Mexico. The length of the Sierra proper is about 50 km., its greatest width about 9 km., and it rises to a maximum of 600 meters above the general level of the basin floor. The Pachuca district consists of two contiguous subdistricts, the Pachuca area and the Real del Monte area. The center of the Real del

Jan 1, 1936

By Arthur H. Leigh

Anode mud, the residual material collected from the bottom of the electrolytic cells during the refining of copper is leached, roasted, fire-refined and cast into Dore1 metal anodes. Dore1 metal is a gold-silver-copper alloy containing 80 percent silver. The metal is processed electrolytically using the Moebius system to refine silver and separate gold, platinum and palladium. The Moebius cell cathodes receive a deposit of silver crystals which are melted and cast into 1000 ounce silver bars with 999 Fine minimum purity. Gold mud is collected in fabric bags and cast into gold anodes for further refining in the Wohlwill cells. Wohlwill cells are unique in that gold, the noble metal, can be put into solution electrolytically without the use of aqua regia. Gold is collected on high purity gold foil cathodes and cast into 400 ounce bull ion with 999.7 Fine minimum purity. Platinum and palladium remain in the electrolyte progressively increasing in concentration and are finally separated and purified by precipitation.

Jan 1, 1973

By J. B. Novak

The program describes preventive maintenance practices and controls applicable in situations where maintenance actions are triggered primarily by breakdown or part failure and specification and documentation of detailed maintenance practices are minimal or nonexistent. The presentation describes requirements of organization structure, program administration, implementation and operation, type of benefits expected, and actual benefits derived in selected areas. The principle objectives of the program are to provide quick, inexpensive, and effective controls over maintenance practices and requirements and to establish a nucleus of controls that subsequently can be expanded to cover all maintenance activities.

Jan 1, 1973

By C. D. Woodward

THE subject of electric signals for the despatching off mining cages through shafts has received cousiderable attention recently from various mining companies. The Anaconda Copper Mining Co. has found it necessary to develop a system that is reliable, safe and simple in operation, and easy to repair. The movement of all mine cages or skips is under the direction of a station tender, who rides on the cages when men or supplies are being lowered or raised. When ore is hoisted, he is stationed at a skip pocket for loading and despatching the skips. For the station tender's use, two signal systems are installed in each hoisting compartment, and he is the only employee authorized to use them. One system is known as the "AC" or Station bells, as it is operated from the 110-volt, 60-cycle, power service; the other system, called the "DC" or shafts bells, takes its energy from closed-circuit primary batteries. As a supplement to the two main signals, a buzzer system is installed. The general arrangement is similar to "the main signal, except that there is a mine buzzer at each station. When a signal switch connected into the buzzer system is pulled down, all buzzers are operated, thus notifying the station tender that he is wanted at some particular level. Placed on the station posts, and within easy reach of the men on the cages, are the signal pull switches for the main signals. The station, or "AC," pull switches are furnished with a short rope as shown in Fig. 1, while the shaft, or "DC," pull switches are equipped with ropes that extend down the shaft past the next station. To avoid all confusion in the use of the three signal systems, a standard arrangement has been adopted in all mines for the location of the pull switches. Fig. 2 illustrates the position of the pull switch at the various mine stations for the main signal systems, but it does not show the buzzer pull switch; this is fixed to the roof timbers about 25 ft. back from the shaft. If the skip pockets are a considerable distance below the station, a pull switch for each main shaft compartment is connected to the "AC" system and placed at this point. However, if the distance is short, a light cord is attached to the station pull switches and dropped down to the skip pocket.

Jan 2, 1922

By C. Laird, C. E. Feltner

May different kinds of dislocation structures have been observed in strain-cycled metals and alloys. In order to understand their pattern and causes, an experimental program has been carried out to determine the influence on the dislocation structures of the three variables: 1) slip character of the material, 2) test temperature, and 3) strain amplitude. The results show that at high strain amplitudes cell structures me formed when the slip character is wavy, and that these are progressively replaced by uniform distributions of dislocations as the stacking fault energy is decreased. At lower strains, dislocation debris is formed which consists primarily of dipoles in wavy slip mode materials and multipoles in planar slip mode materials. Temperature merely acts to change the scale of the structure, smaller cells, and clumps of dislocation debris being associated with lower temperatures. It is shown that the results for many metals fit this pattern, which Parallels that occurring in unidirectional deformation. DISLOCATION structures produced by cyclic strain (fatigue) have been examined in a number of metals by transmission electron microscopy. These studies have produced a variety of interesting and often seemingly conflicting results. For example, different investigators have reported such structural features as cells.le4 bands of tangled dislocations,4'5 dense patches or clusters of prismatic dislocation loops, planar arrays,4'10 and various combinations or mixtures of these different structures. Most of these observations have been made on materials which were initially annealed and cyclically strained at low amplitudes resulting in long lives. Recently we have reported observations of the dislocation structures produced in copper and Cu-7.5 pct Al cycled at large amplitudes, resulting in lives of less than 104 cycles.4 These results, examined in combination with those in the literature, have suggested that a common or consistent structural pattern exists. Variations in this pattern appear to be determined chiefly by the three variables, namely, the slip character of the material,4,11 test temperature. and the strain amplitude. To verify this interpretation, we have studied [he influence of the above three variables (in different combinations) on the resultant structures in cyclically strained metals. Copper, fatigued at room temperature, was chosen as a reference state to which all other observations can be compared. The effect of slip character has been investigated by employing fcc metals of different stacking fault energy. Thus aluminum which has a more wavy slip character than copper, and Cu-2.5 pct A1 having a more planar slip char- acter, have been examined. The aluminum samples were fatigued at 210°K thus making their homologous temperature equal to that of copper at room temperature. The influence of temperature has been evaluated by examining the structures in copper at room temperature and 78°K. Finally the effect of strain amplitude was studied by looking at the structures at amplitudes giving lives ranging from 104 to 107 cycles. All of the specimens were examined at the 50 pct life level at which stage the structures have reached a stable configuration.12 I) EXPERIMENTAL PROCEDURE Strip specimens, 0.006 in. in thickness, were prepared from base elements of 99.99 pct purity or greater. Specimens were fatigued by cementing the strips to a lucite substrate which was subjected to reverse plane bending. This method of testing has been described e1sewhere.7 After fatiguing, specimens were thinned and examined in a Philips EM 200 which was equipped with a goniometer stage capable of ±30-deg tilt and 330-deg rotation of the specimen. On the basis of separate calibrations,13 allowances were made for the relative rotation and inversions between the bright-field images and the diffraction patterns. II) RESULTS AND DISCUSSION The life behavior of the materials under different test conditions is shown in Fig. 1 in the form of plots of total strain range vs cycles to failure. Comparisons of structures produced in the different materials were made at amplitudes which produced equal numbers of cycles to failure. The influence of strain amplitude on the structures produced in the reference state material (copper tested at room temperature) is shown in Fig. 2. At the 104 life level the structure produced comprises cells similar to those previously observed.3,4 They are approximately 0.5 p in diam and the cell walls are generally more regular or sharper than those produced by unidirectional deformation.14 At the 10' life level the

Jan 1, 1969

By I. L. Dillamore

I. L. Dillamore (University of Birmingham)—The different textures developed in various fcc metals have long awaited satisfactory explanation and it has now become clear that these differences are related to parallel differences in the deformation characteristics of the metals. Liu is correct, therefore, in seeking to account for the observed textures in terms of the flow mechanisms but I believe, for the reasons outlined below, that the particular interpretation of flow mechanisms proposed by Liu is open to substantial objections. By considering the forty-eight possible designations of the twelve octahedral slip systems found in fcc metals as distinct and separate deformation modes, Liu has fallen into the error of assuming that only positive glide dislocations associated with each system are present. In fact both positive and negative dislocations will be present and the only difference between for instance the systems B4 and B4' (in Liu's notation) is that under a stress of given sign the direction of motion of a dislocation is reversed on changing from B4 to B4'. For both orientations positive and negative dislocations will be present. In considering possible dislocation interactions it is, therefore, inadmissible to differentiate between R4 and R4' as Liu does. Liu considers those dislocation interactions which give the biggest reduction in energy to be the most favorable and neglects, on the grounds that they will form strong barriers to slip, interactions between dislocations with perpendicular Burgers vectors. Setting aside interactions between positive and negative dislocations of the same slip system, which must occur regardless of the combination of slip systems chosen, the biggest reduction in energy occurs for the Lomer-Cottrell interaction and it is Lomer-Cottrell barriers which are thought to provide the stronger dislocation obstacles. On the other hand the intersection of dislocations with perpendicular Burgers vectors is thought to be a low-energy process which contributes only a fairly small temperature-dependent part of the total work hardening. On this basis it seems doubtful whether the reduction in energy through possible dislocation interactions provides a reasonable criterion for choosing the operative slip systems. From the point of view of texture development it is unsatisfactory to ignore the slip rotations leading to an end position and to neglect to consider the stability of the chosen end point. It is also unsatisfactory to treat the two stress axes as interchangeable since, if the stress system is idealized as biaxial, one stress is compressive and the other is tensile. For the same reason the rotations of the two stress axes are not made compatible simply by assuming that the same slip directions are responsible for the rotations of the two stress axes. It is, in short, essential to treat the two stress axes as acting together on the same slip systems. Turning to the question of the difference between the copper-type and the brass-type texture, there now remains little doubt that the difference is attributable to differences in stacking-fault energy (y), as noted by Liu, but it is doubtful whether the temperature dependence of the texture in copper and in silver is due to increasing stacking-fault energy with increasing temperature. The results of Swann and Nutting42 cited by Liu were obtained in Cu-A1 alloys and the apparent increase in stacking-fault energy on raising the temperature may be influenced by short-range ordering. In pure metals such effects are absent and the only data available on the variation of y with temperature are those of Buhler et a1.43 for silver. They report a minimum at 200°C which does not fit the hypothesis put forward by Liu. It is much more likely that thermal activation of cross slip is important in determining which texture develops, as proposed by Dillamore and tors. These workers have proposed an explanation for the differences in observed texture among the fcc metals and the pole figures predicted consist of an orientation spread which is in better agreement with observation than the limited number of discrete orientations suggested by Liu. The theory of Dillamore and Roberts is also able to account for the differences between aluminum and copper which Liu still leaves unexplained. Y. C. Liu (author's veply)—The writer appreciates the interest of Dr. Dillamore, but must discuss some of his comments in order to avoid cross purposes. The phrase, "forty-eight slip systems," which appeared twice in the text—in the caption of Fig. 1 and the first paragraph in the Discussion—might unfortunately have led Dr. Dillamore to disagree

Jan 1, 1965

By Alec M. Crowell, Harry P. McClintock

Production of oil and gas condensate from the 45 oil and gas fields of South Arkansas increased for the eighth consecutive year, the production for 1943 being 27,605,647 bbl. Six new pools were discovered during 1943, bringing the state's crude oil and condensate reserve to 475 million barrels, a net increase of 70 million barrels for the year. The gross increase in proven reserve was 98 million barrels, from which, of course, is subtracted production of approximately 28 million barrels to reach the net figure of 70 million barrels. There were 35 more wildcats in 1943 than in 1942, and 29 more wells were drilled in fields of the state. Sixteen companies operated exploratory crews during the year for a total of 677 crew weeks, divided as follows: 563 weeks seismograph, 111 weeks gravity and 3 weeks core drill. There was a decided increase in gravity work and a decrease in seismic work. The year started with 15 seismic crews and ended with 5 seismograph and z gravimeter crews. Geologically, it is interesting that the number of wells bottomed in Gulf, Comanche, and Jurassic strata were near equal for the year 1943. During 1942 Jurassic was much higher than the other two. However, Jurassic still led in wildcats for the year 1943. Abandoment of wells in the stripper areas of the state reached about the same figure for the year 1943 as for the year 1942; that is, 145 wells were permanently abandoned. However, 243 wells were drilled in 1943, as against 184 for the previous year. The completions for the year were divided into 103 dry holes, 137 oil and condensate wells and 3 dry gas wells. Among new developments perhaps the most significant was the pressure-main-tenance project for the Midway field of Lafayette County, which is utilizing fresh water as the maintenance medium. This is the first fresh-water pressure-maintenance operation during primary production of an oil field in the United States. The operator of the project, Barnsdall Oil Co., estimates that the ultimate recovery of oil from this field will be increased from 32.5 to 65 million barrels. The Midway pool is of the dissolved-gas type, but a similar project is getting underway for the Magnolia field, Columbia County, a pool of the gas-cap and water-drive type. Dual completion of wells, on concurrent production from two productive zones through a single well bore, became common practice in South Arkansas during the year. As the year ended, some 50 wells had been dually completed and it was estimated that the first 37 of these wells represented a saving of more than 2 1/4 million dollars and a saving in steel of 7000 tons. The majority of the wells dually completed were those reaching depths in the neighborhood of 9000 ft. below the surface and initially productive there. Selective completion at lesser depths in the same well bore proved mechanically feasible and economically sound. The year was marked by the successful completion and placing into operation of three large natural-gas desulphurization

Jan 1, 1944

By Harry P. McClintock, Alec M. Crowell

Production of oil and gas condensate from the 45 oil and gas fields of South Arkansas increased for the eighth consecutive year, the production for 1943 being 27,605,647 bbl. Six new pools were discovered during 1943, bringing the state's crude oil and condensate reserve to 475 million barrels, a net increase of 70 million barrels for the year. The gross increase in proven reserve was 98 million barrels, from which, of course, is subtracted production of approximately 28 million barrels to reach the net figure of 70 million barrels. There were 35 more wildcats in 1943 than in 1942, and 29 more wells were drilled in fields of the state. Sixteen companies operated exploratory crews during the year for a total of 677 crew weeks, divided as follows: 563 weeks seismograph, 111 weeks gravity and 3 weeks core drill. There was a decided increase in gravity work and a decrease in seismic work. The year started with 15 seismic crews and ended with 5 seismograph and z gravimeter crews. Geologically, it is interesting that the number of wells bottomed in Gulf, Comanche, and Jurassic strata were near equal for the year 1943. During 1942 Jurassic was much higher than the other two. However, Jurassic still led in wildcats for the year 1943. Abandoment of wells in the stripper areas of the state reached about the same figure for the year 1943 as for the year 1942; that is, 145 wells were permanently abandoned. However, 243 wells were drilled in 1943, as against 184 for the previous year. The completions for the year were divided into 103 dry holes, 137 oil and condensate wells and 3 dry gas wells. Among new developments perhaps the most significant was the pressure-main-tenance project for the Midway field of Lafayette County, which is utilizing fresh water as the maintenance medium. This is the first fresh-water pressure-maintenance operation during primary production of an oil field in the United States. The operator of the project, Barnsdall Oil Co., estimates that the ultimate recovery of oil from this field will be increased from 32.5 to 65 million barrels. The Midway pool is of the dissolved-gas type, but a similar project is getting underway for the Magnolia field, Columbia County, a pool of the gas-cap and water-drive type. Dual completion of wells, on concurrent production from two productive zones through a single well bore, became common practice in South Arkansas during the year. As the year ended, some 50 wells had been dually completed and it was estimated that the first 37 of these wells represented a saving of more than 2 1/4 million dollars and a saving in steel of 7000 tons. The majority of the wells dually completed were those reaching depths in the neighborhood of 9000 ft. below the surface and initially productive there. Selective completion at lesser depths in the same well bore proved mechanically feasible and economically sound. The year was marked by the successful completion and placing into operation of three large natural-gas desulphurization

Jan 1, 1944

By John S. Johnson, Thomas Fraser

SIZING is the process of separating mixed particles into groups of particles all of the same size, or into groups in which all particles range between certain definite maximum and minimum sizes. In coal preparation, sizing is generally accomplished by passing the coal over screens. Separation by differential settling in air or water currents has been adapted to the special field of separating very fine sizes, and these processes are in commercial use to a relatively small extent in the coal industry. Separation with screens is a very old industrial practice. Agricola described the use of screens for ore treatment in the middle ages. In the literature of the British coal industry references were made to the screening of coal as early as 1589, but the practice of extensive sizing for the market did not become general until the last half of the nineteenth century. In America, the practice of sizing developed first in the Pennsylvania anthracite region, beginning with the use of rakes in the mine working places to recover coarse coal. This mining procedure left the fines in the mine. Preparation outside the mine started with the installation of stationary cast-iron plates with 4 to 6-in. square holes. The run-of-mine coal was dumped upon the platforms, the large pieces of rock were picked out by hand, and the large lumps of coal were broken with hammers. The term "breaker," which still applies to the anthracite-preparation plant, originated with this practice, but the term is no longer descriptive of the entire function of the plant. In 1884, the first power-operated anthracite coal breaker was erected by Gideon Bart at his colliery at Wolf Creek near Minersville, Pa. This plant utilized a system of rolls for breaking the coal and revolving screens for sizing. The plant was driven by a steam engine. It could handle coal at the rate of 200 tons a day. By 1860, revolving screens were in wide use in the Pennsylvania anthracite field. Shaking screens were introduced in the Pennsylvania anthracite region in the 90's and they rapidly displaced the lower-capacity revolving screens.

Jan 1, 1950

By Chas. A. Dobbel

The Chief Consolidated properties are situated in the Tintic mining district of Utah, being included in Juab and Utah Counties, about 70 miles south of Salt Lake City. The drilling referred to in this paper has been carried on in the Chief Consolidated No. Pmine, the Gemini mine, and the Eureka Hill mine at Eureka, the Grand Central mine, above Mammoth, and the Apex Standard mine just south of Dividend. The occurrence of ore through the district is typically in lenses on bedding or breaks, and in connecting pipes, without accurate geometrical trend so that the ratio between the total length of development in drifts and crosscuts to the square feet of ore exposed is very high. A section of one of the western channels (Fig. 1) through the Tintic district, shows, roughly, the irregularities calling for excessive development work, so typical of the Tintic mines. This irregular trend of the ore constantly calls for excessive cutting up of the whole area for offshoots and the connecting links always present. In the planning of prospecting and development, no regular system may be laid out without overlooking some orebodies or segments of orebodies. It was with these facts in mind that Cecil Fitch, the general manager of the Chief Consolidated Mining Co., decided that some method of drilling was the more feasible way of successfully cutting up and bringing about the discovery of ore believed to exist; yet this drilling had to compete with a great margin of cost over crosscutting, as a crosscut in the Tintic district, even though barren, brings out geologic facts that, in many cases, are worth the price of the working itself. Diamond drills met with the success that might be expected in a district that has a reputation for the Gear and loss of diamonds; after 6 or 8 months, this method was discarded on account of the high costs. Simultaneously, a small churn drill outfit was set up underground but a few shifts proved its inapplicability. At the same time, the ordinary hammer drill was used to drive prospect holes with jointed steel. Just what equipment to develop for this work with the hammer drill involved much experimenting, as nothing was found in the literature

Jan 1, 1925

By G. A. Moore, D. W. Williams, C. E. Sims

During the past several years the steel casting industry has made studies of heavy castings in which the test bar has been taken from heavy sections rather than from attached or separately cast coupons. It has been noted that the ductility properties of these heavy sections are often lower than those normally expected. Such lowered ductility is usually accompanied by a spotty test bar fracture and the ductility values often can be greatly improved if a low-temperature aging treatment is given to the casting. A loss of ductility of this type is considered "abnormal," since it is not accompanied by an increase of tensile strength or hardness, and "temporary" when the ductility can be restored by aging, The cure of such an abnormal condition represents a real improvement in the quality of the steel. Some hundreds of previous investigations, largely qualitative in nature, have established beyond reasonable doubt that hydrogen is normally present in newly manufactured steel and that this gas, in small amounts, can cause a temporary ab- normal loss of ductility. The commonly observed association of high gas content and low ductility has given strong evidence for the presumption that hydrogen, possibly assisted by other gases, is the primary cause of the low ductility observed. Accordingly, the Steel Founders' Society of America has, since Nov. I, 1944, sponsored investigations at Battelle Memorial Institute whose primary objective is to obtain quantitative information on the relation of the amount of hydrogen and nitrogen in steel, together with associated methods of steelmaking and treatment, to low-ductility effects and porosity. In order that these investigations might proceed on a quantitative basis, hydrogen analyses of a precision considerably higher than any previously reported in the literature were necessary. 'The method chosen was selected entirely on the basis that it had the highest probability of freedom from uncontrollable errors and will be described in detail in another publication.' Briefly, the method used consisted of the hot extraction of solid pieces of steel weighing from 45 to 50 g in a highly evacuated quartz tube maintained at 1050°C (1925°F) for a period of approximately 40 hr. The greatest precautions were taken to eliminate blanks and insure a sound gas-collection system. vacuum and temperature conditions were maintained automatically. Mercury-filled risers were used for the introduction of samples in order that the System could be degassed thoroughly in

Jan 1, 1949

By C. E. Sims, G. A. Moore, D. W. Williams

During the past several years the steel casting industry has made studies of heavy castings in which the test bar has been taken from heavy sections rather than from attached or separately cast coupons. It has been noted that the ductility properties of these heavy sections are often lower than those normally expected. Such lowered ductility is usually accompanied by a spotty test bar fracture and the ductility values often can be greatly improved if a low-temperature aging treatment is given to the casting. A loss of ductility of this type is considered "abnormal," since it is not accompanied by an increase of tensile strength or hardness, and "temporary" when the ductility can be restored by aging, The cure of such an abnormal condition represents a real improvement in the quality of the steel. Some hundreds of previous investigations, largely qualitative in nature, have established beyond reasonable doubt that hydrogen is normally present in newly manufactured steel and that this gas, in small amounts, can cause a temporary ab- normal loss of ductility. The commonly observed association of high gas content and low ductility has given strong evidence for the presumption that hydrogen, possibly assisted by other gases, is the primary cause of the low ductility observed. Accordingly, the Steel Founders' Society of America has, since Nov. I, 1944, sponsored investigations at Battelle Memorial Institute whose primary objective is to obtain quantitative information on the relation of the amount of hydrogen and nitrogen in steel, together with associated methods of steelmaking and treatment, to low-ductility effects and porosity. In order that these investigations might proceed on a quantitative basis, hydrogen analyses of a precision considerably higher than any previously reported in the literature were necessary. 'The method chosen was selected entirely on the basis that it had the highest probability of freedom from uncontrollable errors and will be described in detail in another publication.' Briefly, the method used consisted of the hot extraction of solid pieces of steel weighing from 45 to 50 g in a highly evacuated quartz tube maintained at 1050°C (1925°F) for a period of approximately 40 hr. The greatest precautions were taken to eliminate blanks and insure a sound gas-collection system. vacuum and temperature conditions were maintained automatically. Mercury-filled risers were used for the introduction of samples in order that the System could be degassed thoroughly in

Jan 1, 1949

By Brian F. Dyson

The surface tensions at 1550°C of some Fe-S alloys (in the range 0.008 to 0.052 wt pct S), Fe-Sn alloys (0.31 to 48.4 wt pct Sn), Fe-P alloys (0.038 to 2.38 wt pct P), Fe-Cu alloys (2.15 to 22.8 wt pct Cu), and Fe-1 pct C-S alloys (0.005 to 0.076 wt pct S) along with the surface tension of the base iron have been measured by the sessile-drop method. A mean value of 1754 dynes per cm was found for the surface tension of the base iron. Sulfur was found to be highly surface-active, the surface-tension results being in quantitative agreement with existing data. Tin and copper were found to be less surface-active than sulfur while phosphoms was completely nonsurface-active. The surface tensions of Fe-1 pct C-S alloys were found to be lower than those of the Fe-S alloys containing the same sulfur content. This was shown to be a mmzifestation of the increase in the thermodynamic activity of suZfur by carbon. It is only in recent years that attempts have been made to measure the surface tension of liquid iron of known high purity.1-3 Earlier measurements4-7 were made on liquid iron containing variable amounts of what are now known to be surface -active solutes. The exact value of the surface tension of liquid iron is still, however, open to some doubt. Halden and Kingery' reported a value of 1720k 34 dynes per cm at 1570°C, Kozakevitch and Urbain8 gave 1790k 25 dynes per cm at 1550°C, while Van-Tszin-Tan et al. obtained a value of 1865k 37 dynes per cm at 1550°C. The first systematic investigation into the effect of controlled solute additions on the surface tension of iron was made by Halden and Kingery.' They showed that sulfur and oxygen were highly surface-active, whereas nitrogen was only slightly active, and carbon inactive. A subsequent investigation by Kingery indicated that two other group-6B elements, selenium and tellurium, were also surface-active. This highly surface-active nature of sulfur and oxygen has recently been substantiated by Kozakevitch and Urbainla and Van-Tszin-Tan et al. l1 Kozakevitch and Urbainl2 have also conducted an experimental survey of the effects of a number of metals on the surface tension of liquid iron. Their surface-active nature was, in all cases, less than that of the group 6B elements. The present investigation was undertaken to study in more detail the surface tensions of dilute Fe-S alloys and to measure the surface tensions of binary alloys of iron containing phosphorus, copper, and tin. The effect of sulfur additions on the surface tension of Fe-1 pct C alloys was also determined. EXPERIMENTAL PROCEDURE The sessile-drop method was employed in the present investigation. An apparatus was built similar in principle to that described by Humenik and Kingery.lS It consisted of a horizontal silica tube, which could be evacuated to pressures less than 10-5 torr, with its central portion surrounded by a water jacket within which was a high-frequency coil. This generated heat in a tantalum susceptor placed inside the silica tube, which in turn radiated heat to the specimen mounted on a recrystallized alumina plaque. Temperatures were measured by an optical pyrometer and photographs of the molten drop were taken on a fixed-focus plate camera giving a magnification of X2. Surface-tension values were determined from the resultant drop using the method described by Baes and Kellogg.l4 The high vapor pressure of molten iron made it necessary to conduct all the experiments under a 1/4 atm of argon (greater than 99.995 pct purity). The analysis of the base iron used in the investigation is given in Table I. Each sample was approximately 3 g in weight and had a hemispherical base to ensure a uniform advancing contact angle on melting. The iron alloys were prepared individually in the sessile-drop apparatus by drilling a hole in the top of each sample and adding the required amount of solute, the drops being analyzed after the experiment. This method of preparation had the advantage of ensuring a consistent minimal contamination by oxygen due to refractory attack and also allowed surface tension to be measured at the same time. Every precaution was taken to ensure that the specimen was not contaminated by grease when it was introduced into the apparatus, the samples being cleaned in acid, dried in alcohol, and rinsed in petroleum ether. All handling was done with tweezers. Once the specimen had been placed inside the susceptor, the furnace was evacuated and the Sample leveled. The furnace was then degassed at approximately 1000"C before the argon was introduced. In every case the surface tension was determined at 1550" C.

Jan 1, 1963

By G. K. Manning, A. R. Elsea, A. B. Westerman

A considerable number of high-tem-perature alloys, that is, alloys which have load-carrying ability at elevated temperatures, have been developed on an empirical basis. In order to determine why these alloys possess this particular ability, a project was started at Battelle Memorial Institute on the fundamental factors promoting high-temperature strength of alloys. .4t the time of inception of this study, the cobalt-base alloy, Vitallium, was widely used because of its good high-temperature properties. One phase of this study was to include an investigation of the structures observed in vitalliurn after various heat treatments. Howcver, before investigating the structural features of Vitallium, it appeared logical to examine the phase diagrams of the related binary systems in order to develop information as to which phases might be present in Vitallium. A preliminary survey of the pertinent alloy systems was made, with particular emphasis on the cobalt-chro-mium system, which is the base for the Vitallium series of alloys. The early work of Lewkonja and Guertler2 indicated that cobalt and chro-mium are completely miscible in the liquid state, and, within a narrow temperature range, in the solid state; that the liquidus shows a minimum; and that the alloys containing 45 to 85 pct chromium undergo a transformation at [zoo to 12 50 c More recently, Wever and Haschimoto,3 Wever andLange,4and Matsunaga5 carried Out experimental work which led to the diagrams shown in Fig I and 2. Both diagrams are based on thermal analysis, metallogra~hic, magnetic, and dilatation data; in addition, X ray diffraction results were used by Wever and Haschimoto, and electrical resistance measurements by Mat-SUnaRa. It is apparent from a comparison of the two diagrams that there was a difference of opinion as to the locations of the boundaries of the various phases, and as to the existence of a phase containing approximately 47 pct chromium. With these excep-tions noted, it might be pointed out that the two diagrams are similar, and that, in general, any particular reaction which is shown on both diagrams occurs at a lower temperature on the Matsunaga diagram than on that of Wever-Haschimoto-Lange. Thus, in view of the gaps in the data arid the questionable features in the published diagrams, it appeared desirable to start the fundamental study of Vitalhum by deter-mining the diagram for the cobalt-chro-mi~m system- Experimental Work For the convenience Of the reader, the diagram as determined by the present investigation is presented in Fig 3. The liquidus and solidus data for the low-chromium alloys were taken from the work of Wever and Haschimoto,3 while the melting point for pure chromium is the

Jan 1, 1949

By W. C. Coffin

The refractory linings of open-hearth steel furnaces above the bath line are subject to severe wear not only from the heat caused by the combustion of the fuel and the reactions of the bath, but also from the melting action of the gases when not controlled and directed, and from the scouring of the oxides, etc. with which the products of combustion are charged. The framework that encases or binds the furnace is made up primarily of an iron or steel pan in which the furnace proper is built, side and end buckstays, and tie-rods. The expansion and contraction are so great and variable that the bindings may be subjected to severe stresses unless the tie-rods are carefully adjusted in heating up the furnace, but they are most affected by direct heat and usually become deformed from that cause when the lining is worn thin and, sometimes, when sections of the lining fall in and expose some of the framework. A deformed framework displaces the skewback of the roof arch and tends to distort or crush the roof. Bent buckstays deform the front wall, causing the door frames to stand away from the lining so that the gases burn between the lining and the frames, destroying both of them. Frequently the frames are attached to the buckstays; then when the latter bend the frames usually break. Preventing the distortion of the framework and maintaining the economy of the refractories are real factors in the cost of steel making. Nat only does the cost of general repairs and reconstruction add directly to the cost of steel produced, but the time lost in making repairs cuts down the steel production and increases the overhead expense of both the furnace shop and its allied foundry or mills. Many years ago water-cooled equipment applied to iron blast furnaces made it possible to increase greatly not only the size and production of the furnaces but also the life of the lining. It also cut down the loss from frequent repairs. The open-hearth furnace is a much later invention, especially as a commercial factor; for though it dates from the Fred Siemens patent of 1856, much more progress was made in the Bessemer process until the latter eighties and most of the development

Jan 1, 1920

ZAY JEFFRIES (written discussion*).-I have read with much interest Mr. Ruder's discussion of Professor Howe's paper, "The Supposed Reversal of Inheritance of Ferrite Grain Size from that of Austenite." I am yet of the opinion that my first explanation' of Mr. Ruder's samples is substantially correct. In that explanation I did not intend, however, to convey the impression that "reversed inheritance" was the general rule nor even of common occurrence but rather that." Non-inheritance" was the general rule. Mr. Ruder suggests that a " perfectly formed" grain is an indication of inheritance. The grains in my Fig. 52 are perfectly formed and in fact more nearly equiaxed than those in Mr. Ruder's Fig: C,3 yet the grains in the former are known not to be inherited but to have been formed by the partitioning of larger austenite grains. On close examination of Mr. Ruder's Fig. C the very shapes of the grain suggest partitioning. Again, the grain size (25 to 30 grains per square millimeter) is at least 10 or- more likely 20 times smaller than might be expected of the austenite from which these grains were .formed under the given time and temperature conditions. Mr. Ruder's newer results on electrolytic and Armco iron are most interesting and instructive. His results fit in. nicely with my conclusions 5, 6 and 10.4 His photographs, however, indicate that the thickness of the pieces of sheet metal are such that abnormal grain growth is promoted. He indicates that equilibrium grain size after heating to 950° C., with furnace cooling, is about the same as his Fig. 1, above. I estimate this to be approximately one-half -grain per square millimeter, or 40 times as large as I have obtained with the same material (Armco iron) after heating Y4-in. bars to 1300° C. for 2 hr. and cooling in the furnace. The effect of thickness of sample on grain size is one which needs more attention.

Jan 3, 1918

By E. O. Wagner, V. F. Parry, W. S. Landers

Development work has shown that the yield of primary tar from coal is proportional to the heat in the volatile matter of the coal and that the yield of tar from noncoking coals may vary from 10 to 45 gal per ton on the ash-free and moisture-free basis. Pilot plant operations have proved that 100 to 135 pct of the bench-scale carbonization-assay yield of tar can be obtained. FOLLOWING investigations by the Denver Bureau of Mines on drying fine coal in the entrained state,'. ' Texas Power & Light Co. employed the fluidized technique to upgrade Texas lignite for use in power plants. Because of the rapidly rising cost of natural gas in Texas the company agreed to cooperate with the Bureau of Mines in studying further the upgrading of lignite by low-temperature carbonization, since potential value of the tar would help offset the cost of fuel. Considerable interest was aroused, therefore, when Aluminum Co. of America decided to use dried lignite in its 240,000-kw power plant at Rockdale, Texas, operated by Texas Power & Light. Carbonization of coal before burning in a power plant is not new. Plants in Germany have been operated for many years on carbonized brown coal and lignite briquets produced in large integrated plants. Large-scale experiments in carbonizing pulverized coal with hot flue gases were made 30 years ago at Milwaukee," and many inventors have proposed other processes. In the U. S., technical and economic problems have prevented successful operation of large plants on carbonized coal. but new techniques of handling solids in fluidized beds may overcome these difficulties, particularly if the higher volatile noncoking coals are used. Any bituminous material will decompose when heated to about 900°F to yield primary tar, gas, and char. The quantity of tar obtained from various coals depends on their rank and volatile content and to some extent on rate and method of heating. The liquid products derived from thermal decomposition of peat, brown coal. lignites, oil shale, and noncoking bituminous coals can be easily liberated by rapidly heating these materials in a fluidized bed at about 500°C (932°F). Since it takes only a few minutes to heat small particles of fuel to carbonizing temperature in a fluidized bed, processing plants can be built to handle up to 50 tph at relatively low cost. The pioneering development work being conducted at Rockdale, Texas, by Alcoa and Texas Power & Light will solve many engineering problems of such operations. The Bureau of Mines at Denver has studied the carbonizing properties of several hundred coals by small scale assay at 500°C, deriving a simple correlation between the potential yield of tar and the proximate analysis. This correlation, shown in Fig. 1, compares the heat in the volatile matter of the coal with the potential yield of primary tar. The yield of primary tar varies from 12 to 50 gal per ton of pure coal." About the same amount of heat is needed to * MAF equals moisture-and-ash-free basis. distil any dry coal at 500°C, and the time required to carbonize a given particle size is about the same for any coal. It is therefore obvious that coals rich in volatile matter will show the greatest profits when processed. Texas lignites are rich in volatile matter, which contributes some 5700 Btu per lb of MAF coal, and the potential primary tar and oil yield from this lignite averages 12 pct by weight or 27 gal per ton from the pure lignite. Texas lignites are considerably richer in potential tar than lignites of North Dakota and Montana. During 1950 the Bureau of Mines conducted many experiments on carbonizing fine dry coal in the entrained state, publishing a report4 n major features of pilot and commercial-size units required to carry out the process. Additional experimental work has been done at Denver and the pilot plant has been improved, particularly the facilities for studying removal of fine dusts from tar vapors and gases at high temperatures by electrostatic precipitation. A number of materials have been carbonized, including sawdust, peat, brown coal, Brazilian oil shale, lignites, and the lower rank bituminous coals having noncoking properties. Straight coking coals cannot

Jan 1, 1957

By G. L. Corrigan, J. R. Coleman

Four factors that largely determine the end product obtained when cement and water are mixed are the chemical compo ition of the cement, the fineness to which the cement is ground, the amount of mixing water used, and the procedure used in mixing the slurry. In order to study the effect of two of these factors, the other two, the chemical composition and method of mixing, are kept constant, leaving as variables fineness and water-cement ratio. Through years of experimentation and usage it has been well established that the reduction of cement clinker to a very fine state by grinding improves its cementing value, principally because the reaction between cement and water takes place only at the surface of the cement particle, further action being hindered by the accumulation of reaction products that tend to coat the unreacted material. Therefore, the more finely ground a cement, and the greater the surface exposed in proportion to its mass, the more rapid is the hydration rate. Similarly, the greater the surface exposed, the greater the proportion of the cement that reacts, and the lower the amount of residue that is unreacted and so remains inert and unable to make any contribution to cementing properties.1 Although it is more expensive to manufacture a finely ground cement than a coarser cement, the advantages of fine grinding of construction cements were so marked that the fineness of cement has increased considerably in past years. When the manufacture of special oil-well cements was begun, it was necessary to consider properties of cement that previously were considered of minor importance, foremost of these being pumpability. Since, with the water-cement ratio constant, a finely ground cement will produce a neat slurry of higher consistency and shorter time of pumpability than will a coarser cement, there is a tendency to grind oil-well cements to a lower degree of fineness. Therefore, in order to produce oil-well cements that will make a slurry having a long time of pumpability, cements are manufactured that because of their coarseness generally are poorer cementing materials than some of the more finely ground construction cements. On the other hand, often it is necessary to pump oil-well cements for long periods of time to place them properly behind a string of casing in a deep well, and since high strength is not of foremost importance for such cement, there is room for considerable controversy concerning the proper fineness range.

Jan 1, 1941

By R. F. Favreau, G. E. Larocque

The objective of the study is development of an analytic process based on rock and explosive properties which allows the prediction of the stress distributions and fracture zone around explosive charges. A computer program has been written for this purpose, using a finite difference approximation to the momentum equation, to describe the motion of the surrounding rock by step-wise integration. Its application provides ground motion data such as stress components, displacement and particle velocity as a function of position and time with respect to a spherical charge. The effect of tensile and shear failure on these ground motion parameters can be included. The analytic procedure contained within this program has been used to predict peak stress as a function of distance in rock for rock-explosive combinations for which field data exists to determine peak stress levels directly. Two methods have been used for the spherical charge which in the analysis replaces the actual cylindrical charges: instantaneous application of peak pressure to a charge having a radius equivalent in contained volume to a charge having a length to diameter ratio of 1, and gradual pressure build up to peak pressure with a charge radius equivalent in contained volume to the total charge used in the field test. The agreement with field data would appear best with the latter treatment. The peak stresses obtained are in closer agreement with field measured peak-stress and a better approximation to field stress wave duration exists in the case of gradual pressure build up. One of the assumptions made in the analysis is that, in the case of cylindrical charges, the explosion pressure rather than the detonation pressure of an explosive establishes the peak stresses in the

Jan 1, 1971