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By E. F. Reed

CONSIDERABLE deep hole prospect drilling has been done in the last few years in the Globe-Miami mining district about 70 miles east of Phoenix, Arizona, and in the San Manuel-Tiger area about 50 miles south of the Globe-Miami region. More than 205,000 ft of churn drilling have been completed by the San Manuel Copper Corp. at their property in the Old Hat Mining District in southern Pinal County. The deepest hole on this property is 2850 ft; there are 49 holes deeper than 2000 ft. At the adjoining Houghton property of the Anaconda Copper Mining Co., where only one hole reached 2000-ft depth, there were 27,472 ft of churn drilling and 3436 ft of diamond drilling. Three churn drill holes were deepened by diamond drilling methods. Near Miami in the Globe-Miami district the Amico Mining Corp. drilled four holes by combined churn and rotary drilling methods, the total amounting to 13,879 ft, of which 2256 ft were drilled with a portable rotary rig. In the same district, besides doing a large amount of shallow prospect drilling, the Miami Copper Co. drilled two holes of 2560 and 3787 ft, respectively, which were completed by churn drilling methods. The rocks encountered in drilling at San Manuel and Tiger are described by Steele and Rubly in their paper on the San Manuel Prospect' and by Chapman in a report on the San Manuel Copper Deposit.' The rocks are well-consolidated Gila conglomerate, quartz monzonite, and monzonite porphyry. In some places these formations stand very well while being drilled, and three holes were drilled without casing, the deepest of which was 2200 ft. In other holes faulted and fractured ground made drilling difficult. In the Globe-Miami district the deep drilling was done in the down-faulted block of Gila conglomerate east of the Miami fault and in the underlying Pinal schist. The geology of this area is described by Rannome. In the Amico holes the conglomerate varied from material consisting entirely of granite boulders and fragments to a rock made up of schist fragments in a sandy matrix; in the Miami Copper Co. holes there were more granite boulders and the material was poorly consolidated. Drilling was much more difficult and expensive in the Miami area than in the San Manuel district, mainly because of the depth of the holes and the formations drilled. All the deep hole prospecting described in this paper was done with portable rigs. The churn drill rigs were of several types, of which the Bucyrus-Erie were the most popular. Bucyrus-Erie 28L, 29W, and 36L rigs were used on some of the deeper holes on the San Manuel property. A few Fort Worth spudder types were tried, and the deepest hole at San Manuel was drilled with a Fort Worth Jumbo H. The spudder type is considerably larger than most other rigs used on this work and required a larger location site. The spudders were belt-driven machines with separate power units, and time required for setting up and moving was much longer than with the more portable drills. All the churn drilling was done by contractors or with machinery leased from them. A few of the contractors had complete equipment, including most of the necessary fishing tools. Unusual and special fishing tools were obtainable from the supply companies in the oil fields of New Mexico or in the Los Angeles area. Most of the contractors used equipment with standard API tool joints, so that much of it was interchangeable. Failure of tool joints is one of the principal causes of fishing jobs. It can be minimized if the joints are kept to the API specifications and the proper sized joints are used in the various holes. The minimum sizes that should be used with various bits are as follows: 12-in. and larger bits, 4x5-in. tool joints; 10-in. bits, 31/4x41/4-in. tool joints; 8-in. bits, 23/4x 33/4-in. tool joints; 6-in. bits, 2Y4x3Y4-in. tool joints; 4-in. bits, 15/ix25/8-in. tool joints. Two rotary drill rigs were tried at San Manuel on the same hole, and a portable rotary drill rig was used on the Amico drilling for test coring the formation and for drilling in holes 3 and 4. Rotary drilling differs from churn drilling or cable tool drilling in that the bit is revolved by a string of drill pipe and the cuttings are removed from the hole by a thin solution of mud pumped through the drill pipe. The principal parts of a rotary rig are the power unit, a rotating table to revolve the drill pipe, hoists to raise and lower the pipe and to handle casing, and a pumping system to circulate the drilling liquid. The rig used on the Amico property at Miami was mounted on a truck. The larger rig used on the San Manuel property was hauled by several trucks and had separate turntable and pumping units. Diamond drill coring equipment was used successfully with the rotary rig in the holes on the Amico property. To allow for 23/8-in. drill pipe with tool joints, 31h-in. core barrels and bits were used. With the standard 31h-in. core barrel there was considerable difficulty in maintaining circulation with mud, so a barrel was designed with a smaller inner tube and a broad-faced bit. This allowed coarser material to circulate between the barrels. Rock bits of 55/8 to 3 in. were used with the rotary rig for drilling between core runs. Diamond drill equipment is much lighter than churn drill tools, so that fishing tools can usually be obtained from supply houses by air express when needed. Three churn drill holes on the Houghton property at Tiger were deepened by diamond drilling with Longyear UG Straitline gasoline-driven machines. The open churn drill hole was cased with 21h-in. black pipe. In deep hole churn drilling, casing is one of the most important items, especially in drilling in un-consolidated material like the formations drilled by

Jan 1, 1953

By E. F. Reed

CONSIDERABLE deep hole prospect drilling has been done in the last few years in the Globe-Miami mining district about 70 miles east of Phoenix, Arizona, and in the San Manuel-Tiger area about 50 miles south of the Globe-Miami region. More than 205,000 ft of churn drilling have been completed by the San Manuel Copper Corp. at their property in the Old Hat Mining District in southern Pinal County. The deepest hole on this property is 2850 ft; there are 49 holes deeper than 2000 ft. At the adjoining Houghton property of the Anaconda Copper Mining Co., where only one hole reached 2000-ft depth, there were 27,472 ft of churn drilling and 3436 ft of diamond drilling. Three churn drill holes were deepened by diamond drilling methods. Near Miami in the Globe-Miami district the Amico Mining Corp. drilled four holes by combined churn and rotary drilling methods, the total amounting to 13,879 ft, of which 2256 ft were drilled with a portable rotary rig. In the same district, besides doing a large amount of shallow prospect drilling, the Miami Copper Co. drilled two holes of 2560 and 3787 ft, respectively, which were completed by churn drilling methods. The rocks encountered in drilling at San Manuel and Tiger are described by Steele and Rubly in their paper on the San Manuel Prospect' and by Chapman in a report on the San Manuel Copper Deposit.' The rocks are well-consolidated Gila conglomerate, quartz monzonite, and monzonite porphyry. In some places these formations stand very well while being drilled, and three holes were drilled without casing, the deepest of which was 2200 ft. In other holes faulted and fractured ground made drilling difficult. In the Globe-Miami district the deep drilling was done in the down-faulted block of Gila conglomerate east of the Miami fault and in the underlying Pinal schist. The geology of this area is described by Ranaome. In the Amico holes the conglomerate varied from material consisting entirely of granite boulders and fragments to a rock made up of schist fragments in a sandy matrix; in the Miami Copper Co. holes there were more granite boulders and the material was poorly consolidated. Drilling was much more difficult and expensive in the Miami area than in the San Manuel district, mainly because of the depth of the holes and the formations drilled. All the deep hole prospecting described in this paper was done with portable rigs. The churn drill rigs were of several types, of which the Bucyrus-Erie were the most popular. Bucyrus-Erie 28L, 29W, and 36L rigs were used on some of the deeper holes on the San Manuel property. A few Fort Worth spudder types were tried, and the deepest hole at San Manuel was drilled with a Fort Worth Jumbo H. The spudder type is considerably larger than most other rigs used on this work and required a larger location site. The spudders were belt-driven machines with separate power units, and time required for setting up and moving was much longer than with the more portable drills. All the churn drilling was done by contractors or with machinery leased from them. A few of the contractors had complete equipment, including most of the necessary fishing tools. Unusual and special fishing tools were obtainable from the supply companies in the oil fields of New Mexico or in the Los Angeles area. Most of the contractors used equipment with standard API tool joints, so that much of it was interchangeable. Failure of tool joints is one of the principal causes of fishing jobs. It can be minimized if the joints are kept to the API specifications and the proper sized joints are used in the various holes. The minimum sizes that should be used with various bits are as follows: 12-in. and larger bits, 4x5-in. tool joints; 10-in. bits, 3Y4x41/4-in. tool joints; 8-in. bits, 23/4x 3 3/4-in. tool joints; 6-in. bits, 21/4x31/4-in. tool joints; 4-in. bits, 15/ix25/s-in. tool joints. Two rotary drill rigs were tried at San Manuel on the same hole, and a portable rotary drill rig was used on the Amico drilling for test coring the formation and for drilling in holes 3 and 4. Rotary drilling differs from churn drilling or cable tool drilling in that the bit is revolved by a string of drill pipe and the cuttings are removed from the hole by a thin solution of mud pumped through the drill pipe. The principal parts of a rotary rig are the power unit, a rotating table to revolve the drill pipe, hoists to raise and lower the pipe and to handle casing, and a pumping system to circulate the drilling liquid. The rig used on the Amico property at Miami was mounted on a truck. The larger rig used on the San Manuel property was hauled by several trucks and had separate turntable and pumping units. Diamond drill coring equipment was used successfully with the rotary rig in the holes on the Amico property. To allow for 2-in. drill pipe with tool joints, 31/2-in. core barrels and bits were used. With the standard 31h-in. core barrel there was considerable difficulty in maintaining circulation with mud, so a barrel was designed with a smaller inner tube and a broad-faced bit. This allowed coarser material to circulate between the barrels. Rock bits of 5 to 37/8 in. were used with the rotary rig for drilling between core runs. Diamond drill equipment is much lighter than churn drill tools, so that fishing tools can usually be obtained from supply houses by air express when needed. Three churn drill holes on the Houghton property at Tiger were deepened by diamond drilling with Longyear UG Straitline gasoline-driven machines. The open churn drill hole was cased with 21h-in. black pipe. In deep hole churn drilling, casing is one of the most important items, especially in drilling in un-consolidated material like the formations drilled by

Jan 1, 1953

By E. F. Reed

CONSIDERABLE deep hole prospect drilling has been done in the last few years in the Globe-Miami mining district about 70 miles east of Phoenix, Arizona, and in the San Manuel-Tiger area about 50 miles south of the Globe-Miami region. More than 205,000 ft of churn drilling have been completed by the San Manuel Copper Corp. at their property in the Old Hat Mining District in southern Pinal County. The deepest hole on this property is 2850 ft; there are 49 holes deeper than 2000 ft. At the adjoining Houghton property of the Anaconda Copper Mining Co., where only one hole reached 2000-ft depth, there were 27,472 ft of churn drilling and 3436 ft of diamond drilling. Three churn drill holes were deepened by diamond drilling methods. Near Miami in the Globe-Miami district the Amico Mining Corp. drilled four holes by combined churn and rotary drilling methods, the total amounting to 13,879 ft, of which 2256 ft were drilled with a portable rotary rig. In the same district, besides doing a large amount of shallow prospect drilling, the Miami Copper Co. drilled two holes of 2560 and 3787 ft, respectively, which were completed by churn drilling methods. The rocks encountered in drilling at San Manuel and Tiger are described by Steele and Rubly in their paper on the San Manuel Prospect' and by Chapman in a report on the San Manuel Copper Deposit.' The rocks are well-consolidated Gila conglomerate, quartz monzonite, and monzonite porphyry. In some places these formations stand very well while being drilled, and three holes were drilled without casing, the deepest of which was 2200 ft. In other holes faulted and fractured ground made drilling difficult. In the Globe-Miami district the deep drilling was done in the down-faulted block of Gila conglomerate east of the Miami fault and in the underlying Pinal schist. The geology of this area is described by Rannome. In the Amico holes the conglomerate varied from material consisting entirely of granite boulders and fragments to a rock made up of schist fragments in a sandy matrix; in the Miami Copper Co. holes there were more granite boulders and the material was poorly consolidated. Drilling was much more difficult and expensive in the Miami area than in the San Manuel district, mainly because of the depth of the holes and the formations drilled. All the deep hole prospecting described in this paper was done with portable rigs. The churn drill rigs were of several types, of which the Bucyrus-Erie were the most popular. Bucyrus-Erie 28L, 29W, and 36L rigs were used on some of the deeper holes on the San Manuel property. A few Fort Worth spudder types were tried, and the deepest hole at San Manuel was drilled with a Fort Worth Jumbo H. The spudder type is considerably larger than most other rigs used on this work and required a larger location site. The spudders were belt-driven machines with separate power units, and time required for setting up and moving was much longer than with the more portable drills. All the churn drilling was done by contractors or with machinery leased from them. A few of the contractors had complete equipment, including most of the necessary fishing tools. Unusual and special fishing tools were obtainable from the supply companies in the oil fields of New Mexico or in the Los Angeles area. Most of the contractors used equipment with standard API tool joints, so that much of it was interchangeable. Failure of tool joints is one of the principal causes of fishing jobs. It can be minimized if the joints are kept to the API specifications and the proper sized joints are used in the various holes. The minimum sizes that should be used with various bits are as follows: 12-in. and larger bits, 4x5-in. tool joints; 10-in. bits, 31/4x41/4-in. tool joints; 8-in. bits, 23/4x 33/4-in. tool joints; 6-in. bits, 2Y4x3Y4-in. tool joints; 4-in. bits, 15/ix25/8-in. tool joints. Two rotary drill rigs were tried at San Manuel on the same hole, and a portable rotary drill rig was used on the Amico drilling for test coring the formation and for drilling in holes 3 and 4. Rotary drilling differs from churn drilling or cable tool drilling in that the bit is revolved by a string of drill pipe and the cuttings are removed from the hole by a thin solution of mud pumped through the drill pipe. The principal parts of a rotary rig are the power unit, a rotating table to revolve the drill pipe, hoists to raise and lower the pipe and to handle casing, and a pumping system to circulate the drilling liquid. The rig used on the Amico property at Miami was mounted on a truck. The larger rig used on the San Manuel property was hauled by several trucks and had separate turntable and pumping units. Diamond drill coring equipment was used successfully with the rotary rig in the holes on the Amico property. To allow for 23/8-in. drill pipe with tool joints, 31h-in. core barrels and bits were used. With the standard 31h-in. core barrel there was considerable difficulty in maintaining circulation with mud, so a barrel was designed with a smaller inner tube and a broad-faced bit. This allowed coarser material to circulate between the barrels. Rock bits of 55/8 to 3 in. were used with the rotary rig for drilling between core runs. Diamond drill equipment is much lighter than churn drill tools, so that fishing tools can usually be obtained from supply houses by air express when needed. Three churn drill holes on the Houghton property at Tiger were deepened by diamond drilling with Longyear UG Straitline gasoline-driven machines. The open churn drill hole was cased with 21h-in. black pipe. In deep hole churn drilling, casing is one of the most important items, especially in drilling in un-consolidated material like the formations drilled by

Jan 1, 1953

By R. W. Bartlett

The rates of oxidation of tungsten have been determined at temperatures between 1320" and 3170°C and oxygen pressures to 1 amn using a surface -recession measurement technique. Above approximately 2000°C and 10-6 atm the rate is independent of temperature and can be calculated from gas collision theory assuming a constant reaction probability, e, of 0.06. Oxygen molecules react at surface sites where oxygen atoms have previously chemisorbed. This provides a direct pressure dependence at low pressures but at high pressures tungsten oxide molecule s form an adjacent gas boundary layer which lowers the PO2 at the tungsten surface. A correction for this effect using free-convection theory fits the rate data over the entire oxygen-pressure range from 10-8 to 1 atrn as well as data using O2-A mixtures. Below 10-6 atrn and above 2000°C, e decreases with increasing temperature because of desorption of oxygen atoms. Below 2000°C the rate decreases with decreasing temperature at all oxygen pressures following an apparent activation energy of 42 kcal per mole and depending on (Po2)n with n varying between 0.55 and 0.80. MOST of the previous tungsten oxidation studies have employed gravimetric methods and have been limited to temperatures below 1000°C where the weight loss associated with evaporation of tungsten oxides is negligible compared with the weight gain from oxidation.' At higher temperatures, oxygen-consumption rates have been determined from pressure measurements, usually at constant flow rates, by Langmuir,2 Eisinger,3 Becker, Becker, and Brandes,4 and Anderson.5 The sensitivity of this method decreases with increasing pressure and, with the exception of Langmuir's work, these investigations were confined to pressures below 10-6 atm. Above approximately 1300°C, depending on the oxygen pressure, the rate of oxide evaporation is greater than the oxide-formation rate and the recession of the tungsten surface can be measured optically without interference from an oxide layer. This was first done by Perkins and crooks6 who heated tungsten rods in air pressures from 1 to 40 torr at temperatures between 1300" and 3000°C. The present investigation of the oxidation kinetics of tungsten at high temperatures emphasizes oxygen pressures from 10-6 to 1 atm. This is the range of interest for earth atmosphere re-entry applications of tungsten for which little data were previously available. APPARATUS The apparatus is a modification of the type used by Perkins and crooks.' Ground tungsten seal rods, 6 in. long by 0.125 in. diam, were mounted vertically between two water-cooled electrodes, one fixed and the other having free vertical travel. The movable counter-weighted electrode is prevented from undergoing horizontal displacement by three sets of runners mounted at 120-deg intervals. Electrical contact is made by means of a water-cooled mercury pool. A 24-in. vacuum bell jar having a volume of approximately 267 liters was used as the reaction chamber with the sample holder mounted in the middle of the chamber. Power was supplied from an 800-amp dc variable power supply. Temperature readings were made by means of a Latronics automatic two-color recording pyrometer. With this instrument, corrections for emissivity are not necessary provided the spectral emissivi-ties at two closely spaced wavelengths are equal. Supporting measurements were made with a micro-optical pyrometer corrected for emissivity of bare tungsten and window absorptivity. The micro-optical pyrometer was calibrated against a National Bureau of Standards calibrated tungsten lamp and both pyrometers were periodically checked against the melting points of tungsten and molybdenum using the oxidation apparatus. Above 10-6 atm, pressures were measured with an Alphatron gage calibrated against a McCleod gage. At 10-6 atm, a hot-filament ionization gage was employed. A magnified image of the self-illuminated tungsten rod was formed using a 360-mm objective lens mounted outside the bell jar. When the experiment exceeded 1 hr, the image was focused on a ground-glass plate about 10 ft from the tungsten rod at about X8 and the recession of the thickness of this image was monitored with a Gaertner cathe-tometer. When faster rates were encountered, a 35-mm time-lapse cinecamera with a telephoto lens and bellows extension was substituted for the ground-glass plate and cathetometer. Diameter recession rates were determined from the photograph image projected on the screen of an analytical film reader. EXPERIMENTAL PROCEDURE After installing the rod in the apparatus and cleaning it with acetone, the system was evacuated to 5 1 x 10-5 torr. Before oxygen was introduced,

Jan 1, 1964

By E. F. Reed

CONSIDERABLE deep hole prospect drilling has been done in the last few years in the Globe-Miami mining district about 70 miles east of Phoenix, Arizona, and in the San Manuel-Tiger area about 50 miles south of the Globe-Miami region. More than 205,000 ft of churn drilling have been completed by the San Manuel Copper Corp. at their property in the Old Hat Mining District in southern Pinal County. The deepest hole on this property is 2850 ft; there are 49 holes deeper than 2000 ft. At the adjoining Houghton property of the Anaconda Copper Mining Co., where only one hole reached 2000-ft depth, there were 27,472 ft of churn drilling and 3436 ft of diamond drilling. Three churn drill holes were deepened by diamond drilling methods. Near Miami in the Globe-Miami district the Amico Mining Corp. drilled four holes by combined churn and rotary drilling methods, the total amounting to 13,879 ft, of which 2256 ft were drilled with a portable rotary rig. In the same district, besides doing a large amount of shallow prospect drilling, the Miami Copper Co. drilled two holes of 2560 and 3787 ft, respectively, which were completed by churn drilling methods. The rocks encountered in drilling at San Manuel and Tiger are described by Steele and Rubly in their paper on the San Manuel Prospect' and by Chapman in a report on the San Manuel Copper Deposit? The rocks are well-consolidated Gila conglomerate, quartz , monzonite, and monzonite porphyry. In some places these formations stand very well while being drilled, and three holes were drilled without casing, the deepest of which was 2200 ft. In other holes faulted and fractured ground made drilling difficult. In the Globe-Miami district the deep drilling was done in the down-faulted block of Gila conglomerate east of the Miami fault and in the underlying Pinal schist. The geology of this area is described by Ransome.3 In the Amico holes the conglomerate varied from material consisting entirely of granite boulders and fragments to a rock made up of schist fragments in a sandy matrix; in the Miami Copper Co. holes there were more granite boulders and the material was poorly consolidated. Drilling was much more difficult and expensive in the Miami area than in the San Manuel district, mainly because of the depth of the holes and the formations drilled. All the deep hole prospecting described in this paper was done with portable rigs. The churn drill rigs were of several types, of which the Bucyrus-Erie were the most popular. Bucyrus-Erie 28L, 29W, and 36L rigs were used on some of the deeper holes on the San Manuel property. A few Fort Worth spudder types were tried, and the deepest hole at San Manuel was drilled with a Fort Worth Jumbo H. The spudder type is considerably larger than most other rigs used on this work and required a larger location site. The spudders were belt-driven machines with separate power units, and time required for setting up and moving was much longer than with the more portable drills. All the churn drilling was done by contractors or with machinery leased from them. A few of the contractors had complete equipment, including most of the necessary fishing tools. Unusual and special, fishing tools were obtainable from the supply companies in the oil fields of New Mexico or in the Los Angeles area. Most of the contractors used equipment with standard API tool joints, so that much of it was interchangeable. Failure of tool joints is one of the principal causes of fishing jobs. It can be minimized if the joints are kept to the API specifications and the proper sized joints are used in the various holes. The minimum sizes that should be used with various bits are as follows: 12-in. and larger bits, 4x5-in. tool joints; 10-in. bits, 3 1/4x4 1/4-in. tool joints; 8-in. bits, 2 3/4x 3 3/4-in. tool joints; 6-in. bits, 2 1/4 x3 l/4 -in. tool joints; 4-in. bits, 1 5/8 x2 5/8-in. tool joints. Two rotary drill rigs were tried at San Manuel on the same hole, and a portable rotary drill rig was used on the Amico drilling for test coring the formation and for drilling in holes 3 and 4. Rotary drilling differs from churn drilling or cable tool drilling in that the bit is revolved by a string of drill pipe and the cuttings are removed from the hole by a thin solution of mud pumped through the drill pipe. The principal parts of a rotary rig are the power unit, a rotating table to revolve the drill pipe, hoists to raise and lower the pipe and to handle casing, and a pumping system to circulate the drilling liquid. The rig used on the Amico property at Miami was mounted on a truck. The larger rig used on the San Manuel property was hauled by several trucks and had separate turntable and pumping units. Diamond drill coring equipment was used successfully with the rotary rig in the holes on the Amico property, To allow for 2 3/8-in. drill pipe with tool joints, 3 1/2-in. core barrels and bits were used. With the standard 3 1/2-in. core barrel there was considerable difficulty in maintaining circulation with mud, so a barrel was designed with a smaller inner tube and a broad-faced bit. This allowed coarser material to circulate between the barrels. Rock bits of 5 5/8 to 3 7/8 in. were used with the rotary rig for drilling between core runs. Diamond drill equipment is much lighter than churn drill tools, so that fishing tools can usually be obtained from supply houses by air express when needed. Three churn drill holes on the Houghton property at Tiger were deepened by diamond drilling with Longyear UG Straitline gasoline-driven-machines. The open churn drill hole was cased with 2 1/2-in. black pipe. In deep hole churn drilling, casing is one of the most important items, especially in drilling in unconsolidated material like the formations drilled by

Jan 1, 1952

By G. E. Pellissier, P. H. Salmon Cox, B. G. Reisdorf

Banding that occurred in plates rolled from the early production heats of 18Ni(250) maraging steel is described and related to the segvegation of certain alloying elements (nickel, molybdenum, titanium), the extent of which was quantitatively evaluated by means of electron-microprobe analysis. The effect of banding on mechanical properties is discussed, with particular reference to observed directional differences in plane-strain fracture toughness of plates. It is shown that banding originates as interdendritic segvegation during ingot solidification and persists in some degree through normal soaking and hot reduction to plate. The results of the study showed that heating sections of small laboratory-cast ingots at 2200°F for 4 hr was sufficient to markedly reduce microsegregation and to considerably improve mechanical properties. Hot rolling of 7-in.-thick ingot sections to 1/2-in.-thick plate effected a similar reduction of microsegregation, but resulted in even greater increases in ductility and toughness than that obtained by homogenization treatment alone. DURING the past few years, considerable attention has been directed towards the low-carbon, high-alloy maraging steels and in particular towards the 18Ni-8Co-5Mo-0.4Ti alloy. The steels of this group, having an excellent combination of high strength and toughness, have a number of advantages over their more conventional medium-carbon low-alloy, quenched-and-tempered counterparts. In the annealed condition, the maraging steels are in the form of a ductile marten-site; aging at a relatively low temperature, typically 900°F for 3 hr, increases greatly the strength through the precipitation of intermetallic compounds. One problem in the early production heats of maraging steel was that the finished plate frequently displayed a banded structure. Previous work on other steels1-' had established that banding in wrought products is either a direct or an indirect consequence of chemical segregation, which occurs during solidification and persists to some extent through normal thermal and mechanical treatments. For example, Smith and others: in a study of low-alloy steel, were able to correlate the severity of banding in the wrought product with the degree of interdendritic segregation of nickel and chromium in the as-cast ingot. The effect of banding on the mechanical properties of steels is usually considered to be detrimental, although there is only limited evidence to suggest that a marked improvement in properties can be obtained with less heterogeneous structures. Comparison of the longitudinal and transverse tensile properties of banded and of homogenized 4340 steel showed that only the transverse ductility was improved by homogenization, but even then the improvement was not commercially significant.' Conversely, homogenization of through-the-thickness tension specimens of quenched-and-tempered steel plate, containing 1.47 pct Mn, increased the strength by as much as 10 pct and the tensile ductility by at least a factor of twos5 This improvement was related to the elimination of manganese-rich bands, which also are one of the factors responsible for cold cracking in the heat-affected zone of metal-arc welds.7 In the present study the nature and severity of banding in early commercial 18Ni(250) maraging steel plate and in laboratory-melted 18Ni(250) maraging steel plate was determined. The effects of banding on plane-strain fracture toughness and the effects of thermal homogenization treatments on the strength, tensile ductility, and toughness of 18Ni(250) maraging-steel as-cast ingots and rolled plate were evaluated. In addition, the effects of hot deformation by rolling on the mechanical properties of ingots were determined. 1) STUDIES OF BANDING IN EARLY PRODUCTION PLATE The chemical composition of the steel (A) used in this part of the investigation is shown in Table I. Banding was not clearly evident in either as-rolled or annealed* plate, but annealed and agedc** plate had a banded structure. The typical banded condition, Fig. 1, consists of layers of unetched austenite (white) and dark-etching martensite in a light-etching martensitic matrix. X-ray diffraction measurements showed that this steel contained more than 6 pct austenite. An electron-probe X-ray microanalyzer (using a focused beam of electrons) was used to determine the composition of the bands and of the material between the bands with respect to the main alloying elements— nickel, molybdenum, titanium, and cobalt. The recorded X-ray intensities were converted to concentration values with the use of a standard of similar composition. To facilitate probe positioning, all analyses were conducted on specimens that had been given a light etch. The influence of this etching on the analytical results was negligible; analyses made on the identical area before and after etching yielded essentially the same concentration values. The results of the electron-microprobe analyses at selected points revealed that the layers of austenite and adjacent dark-etching martensite contained greater amounts of nickel, molybdenum, and titanium than did the surrounding matrix, Table 11. The austenite layers

Jan 1, 1968

By K. Brack, G. H. Schwuttke

Annealing properties of subszerface amorphous lavers produced through high-energy ion implantation in silicon are studied. The buried layers are produced through the implantation of ions (nitrogen), ranging in energy from 1.5 to 2 mev. X-ray interference patterns, transmission electron microscopy, and resistivity profiling are used to study the annealing characteristics of the ion damage. The annealing experiments indicate a low temperature (below 700°C) and a high temperature (above 700°C) region. Significant changes occur in the amorphous layer during the high-temperature anneal. Such changes are corre-lated with the re crystallization of the amorphous silicon and the formation of subsurface (buried) silicon-nitride films. TODAY'S main problems in the field of ion implantation are related to the accurate determination and prediction of 1) the distribution profiles of implanted ions, 2) the lattice sites occupied by the implanted ions, 3) the lattice damage produced through ion implantation, and 4) the annealing characteristics of damage centers in the lattice. This paper reports investigations concerned with the problems listed under 3) and 4). EXPERIMENTAL Our investigations cover the energy range of incident ions from 100 to 300 mev and from 1 to 2.5 mev. The emphasis of this study is on the energy range from 1.5 to 2 mev. The experiments are conducted with single charged nitrogen ions. To implant the ions a van de Graaff generator is used as described by Roosild et al.1 Accordingly, a gas containing the desired ion specie is passed through a thermome-chanical leak into a radio frequency activated source. The positive ions are driven into the van de Graaff with the help of a variable voltage probe. Emerging from the accelerator the ions drift into a magnetic analyzing system and here the desired ion specie is bent 90 deg into the exit port. The ion beam leaving the analyzer is defocused and drifts down a 4-ft long tube to hit the silicon target. At this position the 20 pamp ion beam has a circular cross-section of 2.1 cm. N2 is used as a source gas for nitrogen ions. The implantation target is silicon with zero dislocation density, 2 ohm-cm resistivity, (111) orientation, mechanically-chemically polished, and 1 mm thick. The target is mounted on a water-cooled heat sink and kept at room temperature. A fluence of 1015 to 1016 ions per sq cm is used. RESULTS 1) Silicon Perfection after Bombardment. High-energy ion bombardment of silicon has some striking effects on lattice perfection. Some results were reported in detail previously at the Santa Fe conference2 and are here briefly summarized for the benefit of the experiments described in the following. 1.1) Identification of Surface Films on Silicon. After bombardment all samples are found to be coated with surface films. The films on the silicon surface vary in thickness and color; they can be transparent, slightly brown, or opaque. The films are thicker and darker in the high-intensity area of the beam and they delineate the bombarded surface area of the crystal. The films produce electron diffraction patterns characteristic of carbon and of SiO2. Carbon is predominant. The presence of carbon in these films was confirmed by use of the electron microprobe. Formation of the films occurs independently of the ions used and is attributed to a contaminated vacuum of the high-voltage machine. The carbon is most likely the product of the pump oil which is cracked and polymerized under ion impact. The films stick tenaciously to the silicon surface and burn off in a low-temperature Bunsen flame. 1.2) Mechanical Perfection of the Silicon Surface. The mechanical perfection of the bombarded silicon surface was investigated through optical microscopy, electron microscopy in which the replica technique is used, and optical interferometry. No mechanical damage of the surface was visible after bombardment. However, if a bombarded sample is soaked for several minutes in hydrofluoric acid (HF), gas bubbles may develop in certain spots of the silicon surface. It is also noted that in these areas the surface film starts to peel off. Relatively large patches of film come off if the sample is soaked in HF during ultrasonic agitation. After HF treatment, pits may be present on the silicon surface. The pit dimensions are estimated to be as large as 50 µ. The pits appear in the region of most intense irradiation. 1.3) Lattice Perfection After Bombardment. No lattice damage is found on the silicon surface. Electron transmission micrographs and selected area diffraction patterns of the surface show no difference before and after bombardment. Measured approximately 2 µm down from the surface, the silicon lattice throughout this depth is of good perfection. Well-defined Laue spots and Kikuchi lines are obtained from the surface as well as from the indicated area below the surface. However, some radiation damage is dispersed in this top layer. A sharp boundary line separates this surface layer from a highly damaged layer which extends further downward into the silicon. Typical of this

Jan 1, 1970

By R. D. Schoone, J. T. Michalak

Recovery, recrystallization, and texture development of a cold-rolled aluminum-killed steel have been studied during simulated box annealing. Two different initial conditions existed prior to cold rolling: 1) essentially all of the nitrogen in solid solution and 2) most of the nitrogen precipitated as AlN. The combined effect of nitrogen and aluminum in solid solution before annealing was to inhibit recovery and sub-grain growth at temperatures above about 1000°F and to raise the recrystallization temperature range on continuous heating at 40°F per hr from 1000"-1050°F to 1065"-1085°F. For the material with nitrogen and aluminum initially in solution there was an inhibition in the nucleation of the (001) [110] texture component and an enhancement of the (111) [110] texture component. The differences in annealing behavior mzd texture development are attributed to preprecipitation clustering of aluminum and nitrogen at subboundary sites developed by prior cold working. THE annealing of cold-worked aluminum-killed steels has been the subject of numerous investigations.'-'2 These studies have been concerned with kinetics of recrystallization, with microstructure and texture development, and with the individual and combined effects of composition, thermal history prior to cold rolling, and heating rates during subsequent annealing. It has been shown that the inhibition of recrystallization, and the development of the pancake-shaped grain and recrystallization texture characteristic of aluminum-killed steels, can be associated with the precipitation of A1N particles during a recrystallization anneal involving heating rates in the range 20" to 80°F per hr. If the AIN is precipitated before cold rolling or if more rapid heating rates are employed, the cold-rolled steels recrystallize more rapidly to an equiaxed grain structure and texture comparable to that of rimmed low-carbon steel. The retardation of recrystallization, the development of the elongated grain structure, and the pronounced (111) texture have been attributed to: 1) precipitation of A1N at prior cold-worked grain boundaries to form a mechanical barrier to grain boundary migration;' 2) precipitation on the boundaries of the growing recrystal-lizing grains as well as on cold-worked grain boundaries;'" and 3) preprecipitation clustering or precipitation on subboundaries to retard recovery, nucleation, and growth. The present study was undertaken to study in more detail recrystallization and texture development during commercial box annealing of cold-rolled aluminum-killed steels. Comparison of the annealing be- havior after cold rolling, for two different conditions prior to cold rolling, was made in an attempt to define more clearly the role of aluminum and nitrogen in forming the recrystallization texture. A) MATERIAL AND PROCEDURE The material used in this investigation was a commercial low-carbon aluminum-killed steel which was hot-rolled with a finishing temperature of about 1565"F, then coiled at about 1020°F. The composition, in wt pct, was: 0.050 C, 0.30 Mn, 0.007 P, 0.019 Si, 0.03 Cu, 0.02 Ni, 0.02 Cr, 0.045 Al, and 0.004 N. Two 4.5 by 13 by 0.078 in. sections were cut from the center section of a hot-rolled panel and one of these was reheated to provide two different conditions prior to cold rolling: low AlN: as commercially hot-rolled, with aluminum and nitrogen in solid solution; and high AlN: as commercially hot-rolled, then reheated at 1300°F for 3.5 hr to precipitate most of the nitrogen as AlN. ~etallc&a~hic examination indicated that the reheating did not change grain size nor carbide distribution (some spheroidization of pearlite was noted). Texture analysis at half-thickness level showed that both sections had the same substantially random as-hot-rolled texture. The results of check chemical analysis of each sample are given in Table I. Both sections were cold-reduced 65 pct on a laboratory rolling mill to a final thickness of 0.027 in. Cold rolling, in one direction only, was in the direction of the prior hot rolling. Specimens 1.0 by 1.25 in. were cut from the cold-rolled sheets and given a simulated box anneal in an atmosphere of 2 pct HZ-98 pct He. Specimens were heated at a constant rate of 40°F per hr from room temperature to various temperatures in the range 750" to 1300°F and cooled immediately by withdrawal to the water-cooled end of a tube furnace. The temperature in the 6-in. uniform hot zone of the furnace was controlled within 3"F. Selection of the individual specimens was made to give a random distribution of annealing temperatures with respect to location in the cold-rolled sheet. At least two specimens of each condition were annealed to the same temperature and smaller specimens for light microscopy, transmission electron microscopy, and X-ray studies were prepared from each of these. Rolling-plane sections for each of these studies were taken at half thickness. Light microscopy and transmission electron micro-

Jan 1, 1969

By M. H. Merriss

IN THE last few years, there have been developed at the plant of the Nichols Copper Co., Laurel Hill, Borough of Queens, New York City, improvements in electrolytic copper refining by the series system that have materially increased the flexibility and economy of that system. The purpose of this paper is to discuss, as of interest to refiners and to those who have copper to refine, as well as to the engineering profession in general, the changes that have taken place resulting in wider application and increased efficiency of the series system. Copper is electrolytically refined in two ways, which are spoken of as the "multiple system" and the "series system." In both systems, the electrolytic tanks are in series electrically. In the multiple system the electrodes in a single tank are in multiple or in parallel, thus: In the series system, the electrodes in a single tank are in series, thus: There are two important adaptations of the series process, one represented by the series electrolytic tank room at the Baltimore Copper, Smelting & Rolling Co., Baltimore, Md., and the other by that of the Nichols Copper Co.'s plant. At Baltimore, the anode is rolled to perfect

Jan 6, 1925

By J. T. Eash, E. M. Wise

In a previous communication1 the improvement in slrength, harden-ability and color, occasioned by replacing gold in a typical gold-silver-copper alloy by various amounts of platinum, or palladium, was discussed. In the present paper the results of further studies upon the constitution and the nature of the hardening transformation in these alloys are presented. This research may be summarized as follows: 1. The liquidus and solidus have been determined for the alloys of the palladium and platinum series. Cooling curves were utilized for determining the liquidus of the palladium alloys but this method proved unsuitable for the platinum alloys so that a novel quenching method was utilized for the latter. Both the liquidus and solidus of the palladium alloys increase steadily with the palladium content. The liquidus of the platinum alloys increases rapidly with the platinum content, while the solidus temperature increases with the platinum content up to about 14 atomic per cent platinum, but suffers no further increase with additional increments of platinum up to 20 atomic per cent at least, owing to a peritectic reaction. 2. Palladium, and even more effectively platinum, reduces the rate of grain growth. Owing to this fact and to the increase in the solidus temperature, "overheating" does little or no damage to alloys containing reasonable quantities of these elements. This is confirmed both by tensile tests and metallographic examination. 3. The excess phase present in one of the high-platinum-content alloys has been isolated and chemically analyzed and was found to consist almost wholly of platinum, gold, and copper, evidently derived from the compound AuCu, by the partial replacement of gold by platinum. 4. The variation in the solubility of this platinum-content phase in the alpha solid solution with the temperature has been determined. This

Jan 1, 1933

By W. R. Crane

MINING of the red iron ores of the Birmingham district has been carried on energetically during the past 50, years, and their development has created a large iron and steel manufacturing, center, the only important one in the South. The district produces approximately 10 per cent. of all the iron ore of the United States (80 per cent. of the Alabama ore mined is red ore) ; also, 43 of the 419 blast furnaces of the country are in the district tributary to Birmingham. The rapid growth of the district has been made possible through investigations that resulted in radical changes in furnace practice, and a still greater impetus will come from the study of the low-grade, high-silica ores, as a result of which they will be made amenable to treatment by concentration. Mining practice in this district has been comparatively simple because of the occurrence of the ore; but with the-rapid extension of the work-ings and the disturbed condition of the ore bed at some distance from the outcrop, more difficult conditions are encountered and the tendency is toward worse rather than better conditions. Should the high-silica ores of the lower bench of the Big Seam become available through beneficiation, mining practice will have to be modified to meet the new conditions, which will be rendered more difficult by the increased weight of cover that will exist at considerable distances from the outcrop. Support of workings will require greater attention and the efficient and economical operation of the mines will depend largely on the successful solution of the problems of working-and handling the ore.

Jan 9, 1924

ECONOMICS In the preceding pages you will find an attempt to judge the direction of one phase of the mining industry in Drift, and following that a quick round up of what happened to production in 1958 in Trends. Next, Charles Merrill presents a comprehensive price history for the mineral products of greatest importance, complete with figures for the past 50 years. On the following pages Nathaniel Arbiter and Charles Will Wright take a look at price trend prospects and the cold war in mining, respectively. MINERALS BENEFICIATION Fifty years progress is reviewed as a springboard for a look ahead. In the past decade the art has moved forward, but the author fears that the science is not progressing as promisingly.

Jan 2, 1959

By Cyril Smith

SOMEWHAT over ten years ago the author described studies1,2 on the constitution of the copper-silicon system. The copper-rich portion of this diagram is shown in Fig. 1. The experimental points freely dotted about the diagram seemed to justify an otherwise unconvincing diagram and for several years the curious reverse bend in the alpha-phase bound-ary was accepted as substantially correct, even by later investigators3,4 of the system who introduced changes in the high-silicon phases. The binary diagram has been used as a base for several ternary systems" without any suggested changes. Voce10 suspected the existence of another phase from his study of the cast alloys in the copper-manganese¬silicon system, but evidently hesitated to extrapolate this to the binary diagram, particularly in view of the too ingenious explanation that was advanced" to account for the pools of constituent clearly visible in castings; namely, that they were secondary alpha of twinned orientation deposited from beta. Von Schwarz,12 in 1932, called attention to the fact that this micro-constituent in copper-silicon alloy castings was anisotropic under polar-ized light and asserted that a new phase, not cubic, should be placed in the diagram adjacent to alpha. Sautner,13 on the basis of investigations with the polarizing microscope and with X-rays, introduced this phase into the diagram at about 6 per cent Si. The relevant part of his dia-gram is shown in Fig. 2. Sautner called the new phase beta, renaming the old beta phase zeta. To avoid confusion, in redrawing Fig. 2 the phases have been renamed in accordance with the terminology adopted in the present paper, in which the new phase is called kappa and the other phases retain the designation given them by Arrhenius and Westgren.4

Jan 1, 1939

By E. H. Jr. Dix

IN selecting the subject, "Acceleration of the Rate of Corrosion by High Constant Stresses," for the 1940 Institute of Metals Division Lec-ture, I have been influenced by its highly theoretical and speculative nature as well as by the great practical importance of the correct inter-pretation and appraisal of the engineering significance of the phenomenon. I lay no claim to originality in talking on this topic, since it has been the subject of discussion for over a quarter of a century. However, as our technical thinking advances, old phenomena take on new and more significant aspects. In our studies at the Aluminum Research Labora-tories, we have encountered many perplexing and seemingly contradictory results and have been fascinated by the problem of dovetailing all of the many pieces of information to make a complete picture. I hope that in the brief period of this lecture I may share with you some of the enjoy-ment we have had in attempting to meet this challenge to metallur-gical science. The emphasis generally has been placed on the spontaneous failure by cracking of a metal under the combined action of high stress and corrosion, hence the present-day use of the terms "stress corrosion" or "stress corrosion cracking." The older term "season cracking," applied more specifically to copper-base alloys, includes, by inference, the element of time. For the purpose of the discussion today I will use "stress corro-sion" to cover broadly the effect of stress in accelerating the rate of corrosion of metals. To stay within the limits of allotted time the dis-cussion will cover the effect of high static stresses rather than repeated or dynamic stresses, which would take us into the related field of corro-sion-fatigue. The subject is particularly appropriate for an Institute of Metals Division Lecture because much the same phenomenon has been observed in almost all metal systems. Thus, in addition to the season cracking of brass may also be mentioned the "caustic embrittlement" of steel boiler

Jan 1, 1940

By G. A. Stamboltzis, N. Arbiter, C. C. Harris

Fracture under low-velocity free-fall and double impact and under slow compression have been investigated. The pattern of breakage and the size distribution of resulting fragments of sand-cement and glass spheres have been determined. Photoelasticity methods were used to simulate the stress distributions in free-fall impact in order to explain the observed patterns of breakage. Oblique fracture planes, occurring only in free-fall impact, develop along lines which coincide with the trajectories of maximum compression as determined by mathematical analysis. Breakage efficiencies for different modes of fracture were compared for both types of spheres. For the same specimen and loading system, static loading and low-velocity dynamic loading induce geometrically similar stress fields resulting in reasonably similar fracture patterns and shapes of fragments. This work had its origin in a desire to understand three fundamental processes involved in autogenous comminution: namely; free-fall impact, double impact, and slow compression. To simplify the investigation, it is preferable to reduce the entire multi-stage fracture process to its most elementary form; that is, to study products resulting from a single-stage operation, such as the breakage of a specimen under single fracture conditions. The goal of this research is to study the energy utilization in the single fracture of brittle specimens and to relate the pattern of breakage and the resultant fragment size distribution with the nature of the material, the specimen size, the manner of load application, and the rate of loading. Published works on single fracture have mainly been concerned with tests on large (> 1-in.) irregular mineral pieces, especially coal and coke. These were mainly friability tests employing a single blow on closely sized pieces. More recently, small mineral specimens in the sieve range and glass spheres have been investigated.5-7 Kick8 has reported free-fall and double impact tests with large large cast-iron, cement, and clay spheres. The establishment of a minimum breaking height independent of size in the free-fall impact tests, and the direct proportionality between the minimum work required for fracture and the volume of the specimen in double impact tests were used by Kick as an experimental proof of his classical law of "Proportional Resistances." In the present work, spherical shapes were chosen because of their simple body geometry and consequent impact and stress field symmetry. Because the study involves several physical principles in connection with brittle-fracture, it may be of interest in fields where the strength of materials is of importance. APPARATUS The equipment for the free-fall impact testing is illustrated in Figs. 1 and 2. This consisted of a massive (17 x 17 x 3-in.) hard steel plate onto which specimens were dropped and a specimen release mechanism which could be set at any desired height up to 10 ft above the plate so that the impact velocity could be varied up to about 25 ft per sec. Double impact breakage is characterized by two points of loading situated at opposite poles. For this mode of breakage the apparatus was modified (Figs. 3, 4 and 5) so that a falling mass provided an impact of predetermined magnitude on a specimen resting on the plate. A spring-loaded device operated immediately after fracture to arrest the falling mass and to record its residual kinetic energy. Precautions were taken to avoid secondary breakage. Slow compression tests were performed on a conventional hydraulic testing machine, the specimen being held between two hardened parallel bearing blocks. In the case of glass spheres, carbide bits were used. Photoelasticity studies were performed on two-dimensional models held in a loading frame equipped with a force gauge (Fig. 6). The models were viewed in a polariscope and isochromatic fringe patterns were recorded photographically. SPECIMENS Sand-Cement Spheres: A series of sand-cement spheres were prepared by molding in spherical glass flasks.

Jan 1, 1970

By B. A. Wilcox, A. H. Clauer

The steady-state creep of TD Nickel NL + 2 001 pct TltOz) has been studied orer the telirperatve range 325&apos; to 1100O and the stress range 15,000 to 36,000 psi. At high temperatures (aboue 0.5 T& gran-boundary slzding is the )nost znportant )node of creep deformation, and the steady-state creep rate, is, can be related to stress and temperature by: where Q = 190 kcal pev mole and n has an unusually high value of 40. A creep mechanism based on cross slip of dislocations around The O2 particles can satisfactovily explain the low-temperature (T < 0.5 T,) cveep behavior, and the follo wing relation is applicable: Q, (a) is found to decrease from 57 to 46 kcal per mole as the stress is increased from 32,000 to 36,000 psi. THERE have been a variety of theories proposed to explain the influence of dispersed second-phase particles on the yield strength and flow stress of metals, and these have been reviewed recently by Kelly and icholson.&apos; However, only several attempts2"4 have been made to develop mechanistic treatments which characterize the creep behavior of dispersion-strengthened metals, and to date these have not been fully evaluated experimentally. weertman2 and Ansell and weertman3 proposed a quantitative creep theory for coarse-grairzed dispersion-strengthened metals, based on the concept that the rate-controlling process for steady-state creep was the climb of dislocations over second-phase particles, as suggested by choeck. The theory predicted that the steady-state creep rate, <,, was proportional to the applied stress, a, for low stresses and that is a4 o for high stresses. The activation energy for creep, Q,, was equivalent to that for self-diffusion, Qs.d., in the matrix. Some limited experimental evidence in support of this theory was obtained on a recrystallized Al-Alz03 S.A.P.-type alloy by Ansell and Lenel.6 Ansell and weertman3 also developed a semiquanti-tative theory for high-temperature creep of lineg-rained dispersion-strengthened metals in order to explain their results on an extruded S:A.P.-type alloy, which had a fine-grained fibrous structure. They suggested that the rate of dislocation generation from grain boundaries was the rate-controlling process, and fitted their results to the equation: where Q, was found to be 150 kcal per mole, i.e., QC- 4Q,.d. in aluminum. Similar high activation energies for creep7-&apos;&apos; and tensile deformation" of dispersion-strengthened alloys have been observed by other investigators for S.A.P.,&apos;" indium-glass bead omosites, and Ni + A1203 alls.&apos; There is no general agreement regarding the mechanisms involved in the creep of dispersion-strengthened metals, and this is due in part to the lack of detailed studies relating the structures of crept specimens to the mechanical behavior. The present investigation on thoriated nickel was undertaken with the aim of studying the structural changes which occur during creep of a dispersion-strengthened alloy and rationalizing the observed mechanical behavior in terms of the creep structures. EXPERIMENTAL METHODS The material used in this investigation was 1/2-in.-diam TD Nickel bar, which contained 2.3 vol pct Tho,. Obtained from E. I. duPont de Nemours & Co., Inc. The final fabrication treatment by DuPont consisted of -95 pct reduction by swaging followed by a 1-hr anneal at 1000°C. Transmission and replica electron microscopy revealed that the material had a fine-grained fibered structure with an average transverse grain size of -1 p and a longitudinal grain size of 10 to 15 p. Selected-area diffraction indicated that the fiber axis was parallel to (OOl), in agreement with the results of Inman eta1." All creep specimens were vacuum-annealed at 1300°C for 3 hr prior to testing. Transmission electron microscopy showed that the only structural change due to annealing was a slight decrease in dislocation density, confirming the reported high degree of structural stability.13 Furthermore, recrys-tallization or grain growth during creep was never observed. The structure typical of uncrept material (after the 1300 C, 3-hr anneal) is shown in Fig. 1. The grain boundaries are predominantly high angle and. although some areas show a tangled cell structure, the grain interiors are relatively dislocation-free. Individual dislocations are strongly pinned by the Tho2 particles; i.e., very rarely did dislocations move within a thin foil. The grey "halos" around some of the larger particles which protrude out of the foil surface arise from contamination in the electron microscoge. The Tho, particle size ranged from -100 to IOOOA, and the distribution is shown in Fig. 2. The technique used to obtain the data in Fig. 2 consisted of dissolving the nickel matrix in acid, collecting the Tho2 particles on cellulose acetate, and measuring about 1000 particle diameters in the electron microscope. Similar results were obtained by measuring about 600 particles in thin foils, an; the average particle size was found to be 2r, = 370A. Using the data in Fig. 2 (annealed structure), the mean planar center-to-center particle

Jan 1, 1967

By E. I. Gordon

The electronic pickup tube is the image-to-video signal-converter or transducer in tele vision-like systems. Images may relate to visible light or IR excitation as in conventional TV systems, X-ray excitation as in some medical and production control applications, or electron excitation as in electron microscopy. The latter process is also important in some forms of light or X-ray sensitive pickup tubes as an intermediate step. In virtually all of these devices the image ends up as a stored charge pattern on a suitable target electrode and the video signal is created by periodically scanning the target with a low energy electron beam and removing the stored charge. In a major group of tubes radiation induced conductivity creates the charge pattern. In others, photoemission is used. In this paper an attempt is made to illuminate some of the device requirements placed on materials exhibiting radiation induced conductivity, some of the materials and techniques that are used, and the problems. The emphasis will be on visible light and IR sensitive targets although some attention will be given to X-ray and electron imaging. Photoconducting films as well as diode arrays will be discussed. ELECTRONIC pickup tubes find their greatest use in commercial, entertainment television, and in industrial and educational closed-circuit television. Video telephone systems, such as AT&T&apos;s PICTURE-PHONE System will become eventually the greatest user. Military use is also very important. Nevertheless the use of electronic pickup tubes in technology, science, and medicine is assuming ever greater relevance and demands the greatest diversity and perfection in the pickup tube art. Commercial television and closed-circuit television use requires visible light response, high resolution, low lag, and uniform response. Video telephone use requires the same plus extreme reliability, stability, and low cost. Military use emphasizes, in addition, sensitivity, IR response, and ruggedness. (Devices for far IR response will not be considered here.) The use of pickup tubes in medicine and biology emphasizes UV response for microscopy, X-ray response for radiology, and energetic electron response for electron microscopy. Astronomy and nuclear physics demands low light level response, storage ability, and resolution (here the tube is a successful replacement for film). The interested reader might profitably read Advances in Electronics and Electron Physics, vol. 12,&apos; 16,2 and 22A3 and 22B4 for detailed discussion of the use, properties, and technology of electronic pickup tubes. In general, because of the importance of these uses, none of the above properties will be ignored. Nevertheless attention will be restricted to only those imaging devices, called pickup tubes, using a scanning electron beam to dissect the image with a resulting video signal for conventional CRT display. However pickup tubes have become so complex that many of them include components such as image in-tensifiers which would be normally excluded by this restriction. Thus some of the other imaging devices will not be ignored entirely. We will first review the fundamental elements and physical phenomena involved in modern electronic pickup tubes, then the relevant materials and some of the material problems and then an interesting goal yet to be achieved. REVIEW OF PICKUP TUBE PRINCIPLES In all modern television systems using pickup tubes there is an interval called the frame interval, during which the incoming radiation flux is allowed to produce a cumulative effect in the form of a stored charge pattern which is a replica of the radiation image, and a scan interval during which the stored charge pattern is converted into a video signal. The frame interval bears no fixed relation to the scan interval and may be shorter or longer. In conventional, real time television the scan interval including retrace is identical to the frame interval. Integration and storage is the key to the sensitivity of modern pickup tubes, in contrast to earlier tubes such as the image dissector. At equivalent light levels and without integration, the number of photons contributing to the video signal in the image dissector is lower by a factor approximating the number of picture elements in the displayed image, a number of order 10. Statistical fluctuations in the number of contributing photons represent a serious limitation to the attainable signal to noise ratio, resolution and contrast. As a result considerably greater light levels have to be used then in targets which integrate over the full frame period. Thus the crucial elements, common to all modern pickup tubes, are the charge storage surface and the scanning electron beam which is incident on the charge storage surface at very low energy. These are shown in Fig. 1(a). The charge storage insulator is generally very thin with a thickness of several microns or less. The surface of the insulator is held near cathode potential. The backplate potential is held at cathode potential or at a small positive voltage relative to cathode. The combination of storage insulator and backplate electrode is commonly called the "target". In the absence of incident radiation flux the electron beam scans over the storage surface depositing negative charge uniformly over the scanned part of the surface by virtue of the fact that the effective secondary

Jan 1, 1970

By E. W. Johnson, M. L. Hill

Cold working of iron-carbon alloys was found to increase greatly the hydrogen solubility and to decrease the diffusivity at temperatures up to 400° C. These effects are increasing functions of both the carbon content and the degree of deformation. The hydrogen behavior is consistent with the idea that cotd working creates "traps", which are concluded to be microcracks in which the hydrogen is chemisorbed. Hydrogen embrittlement is explained by the Petch theory of metal crack surface energy loss due to hydrogen adsorption. HYDROGEN embrittlement of steel has been studied for many years and has been the subject of an extensive literature, but the mechanism of the effect has not been completely understood. The embrittlement is unusual in that the ductility loss is not accompanied by an increase of the yield strength, being primarily a decrease of the fracture strength alone. The loss of fracture strength is usually most severe in the temperature range between 0°and 100°C. Here the solubility of hydrogen in the iron lattice at ordinary H2 pressures is extremely low while the diffusivity is still quite high. From the relationships between the ductility and the hydrogen content, test temperature and strain rate, it is apparent that the hydrogen atoms causing the ductility loss difbse to and concentrate in small regions of the metal which are especially susceptible to the initiation and propagation of fracture. This hydrogen segregation apparently occurs after plastic straining has begun. Below 0°C the ductility loss persists only at low strain rates in confirmation of the view that the embrittlement is diffusion .controlled. The tendency of the embrittlement to disappear above 100°C can be explained by the increasing lattice solubility of hydrogen with rising temperature. A common view of hydrogen embrittlement of steel is that the hydrogen initially dissolved in the metal lattice diffuses to structural discontinuities and there precipitates as H2 gas at very high pressures which assist the external stress in causing premature failure.1,2 The idea of a high H2 pressure in equilibrium with ordinary amounts of hydrogen in steel at room temperature is due to observations of hydrogen behavior in fully annealed material, for which the Sieverts&apos; law constant relating solute concentration to H2 pressure is extremely small. Hydrogen-embrittled steel, however, is always plastically deformed to some extent, and therefore it is important that hydrogen embrittlement be explained primarily in terms of hydrogen behavior in plastically deformed material. Such an explanation is attempted in this paper. Previous studies of hydrogen in cold-worked steel have shown that both the solubility and the diffusion rate are significantly chaned when the steel is cold worked. Darken and Smith discovered that the amount of hydrogen absorbed from acid by cold-rolled steel at 35°C is many times greater than that absorbed by hot-rolled steel. They found also that the hydrogen permeability of the steel is unaffected by cold working. Keeler and Davis4 confirmed the high apparent solubility of hydrogen in cold-worked iron-carbon alloys at temperatures up to and even beyond the recrystallization temperature. They also found that this solubility increase accompanying cold work is a sensitive function of the carbon content, being absent when no carbon is present. The present experimental study was undertaken primarily to obtain an improved understanding of the behavior of hydrogen in cold-worked steel. Data were obtained on the effects of temperature, H, pressure, carbon content, and degree of cold work on the hydrogen solubility and diffusivity in iron-carbon alloys. These data have been helpful in elucidating the nature of the cold-worked steel structure as well as in providing information on the mechanism of hydrogen embrittlement of steel. EXPERIMENTAL Cylindrical specimens for hydrogen absorption and diffusion rate measurements were prepared from three iron-carbon binary alloys and a commercial SAE 1010 steel. The iron-carbon alloys were prepared by vacuum melting electrolytic iron with graphite in a magnesia crucible. The alloys were cast in vacuum as 2 1/2-in. sq ingots weighing about 20 lb each. The ingots were hot rolled (above 1900°F) to 5/8-in.-diam round bars and then cooled in air to room temperature. The resulting metallographic structure consisted of islands of fine pearlite surrounded by free ferrite. Chemical analyses of the materials are given in Table I. The 5/8-in. diam bars were turned to diameters such that cold reduction to the desired final specimen diameters would result in either 30 or 60 pct reduction in area (RA). The machined bars were then cold worked by swaging at room temperature

Jan 1, 1960

By H. L. Lovell, L. H. E. Weyher

Cyclones have been used successfully in the mineral industries to solve solid-liquid as well as solid-solid separation problems in the processing of fine particles. Substantial information is available about the operation of cyclones as thickeners, classifiers, and concentrators using a dense medium. However, very little is known about the operation of the cyclone as a fine coal concentrator not using dense medium. This application of the cyclone, namely to wash fine coal in water, requires that classification phenomena be minimized in order to arrive at an effective separation of the high density ash and sulfur-bearing mineral particles from the low density coal particles over a wide particle size range. The authors have investigated the role of feed pressure, orifice diameters, and vortex-finder length in the cyclone washing of fine coal (--1/4 in.) in water. The results of this investigation show that cyclone washing of fine coal in water is an effective unit operation particularly capable of reducing the inorganic pyritic sulfur content. The combination of hydrocyclones with complimentary equipment such as Sieve bends, shaking tables, and flotation units appears to be especially promising and may ultimately yield fine coal processing systems that could approximate the high recovery efficiencies of today&apos;s coarse coal cleaning circuits. In the future, fine coal beneficiation can be expected to receive even greater research emphasis as a result of increasing sulfur restrictions on all major coal markets. In a previous paper, work, conducted at the Pennsylvania State University, on the hydrocyclone washing of fine coal was discussed.&apos; The initial evaluation based on that wo-rk demonstrated the feasibility of hydrocyclones as fine-coal cleaning devices, and in that previous paper selected test data were presented that showed in principle how product yield and assay respond to variations of the major cyclone operating variables. The present paper reports in greater detail on the findings and presents a comprehensive evaluation of the data as follows: (1) Hydrocyclone throughput rates were related to feed pressure and other variables by regression equations. These equations are compared with other capacity-vs.-pressure drop expressions taken from the literature on classification cyclones. (2) The flow ratio was found to be the most important variable for the separation of the solids. Control of this ratio through various cyclone operating parameters is discussed. (3) The data on the product yield as well as the ash and sulfur assays from the tests were evaluated by means of correlation and multiple regression analyses. Because size-classification phenomena cannot be suppressed completely in hydrocyclone washers, product yield and assay data are regressed against cyclone operating variables separately for different size classes. These equations then reveal how the interactions of the cyclone operating variables vary in terms of the separation for different size classes. (4) Density partitions from additional tests were analyzed by supplementing product-size analyses with sink-float analyses of the separated product size classes. The evaluation of these data show how classification phenomena affect separation by density. The results demonstrate in particular the feasibility of the hydrocyclone washer for removing pyritic sulfur from fine coal. In addition to these specific findings, the investigation points up the value, in general, of using hydrocyclone washers in combination with unit operations such as screening, table concentration, and flotation. In order to make optimum use of the hydrocyclone washers and work out the most effective combination of unit operations, it is important to have careful flowsheet analyses corresponding to the given feed and product requirements. Analyses of this kind are now possible by means of computer simulation of flowsheets and other operation research tools. INTRODUCTION Before proceeding with the detailed treatment and evaluation of our results, it will be useful to review the fundamental aspects of cyclone separators and also restate the experimental procedures and data handling employed in these studies. Review of Cyclone Fundamentals: AS shown in Fig. 1, the basic components of cyclones commonly used

Jan 1, 1970

By C. G. Bieber, J. R. Mihalisin, R. T. Grant

A growing demand for longer service life of gas turbines has placed increasingly rigorous requiret~rents upon superalloys employed for that application. Long-titne testing at high temperature has revealed that phase transformations occur in all superalloys. A common one of particular interest is o formation. Presented here are studies made to identify a and to characterize its formation and effect on properties in three cast nickel-base superalloys—IN 100 alloy, alloy 713C, and alloy 713LC. Methods are discussed by which o can be eliminated or inhibited in IN 100 alloy and alloy 713C. Evidence was obtained to indicate that some types of o may be more detrimental than others. Limitations in the electron vacancy approach to o prevention are pointed out, and it is shown how alternative approaches, such as reducing a complex superalloy matrix to the form of a pseudo-ternary system permitting equilibrium diagram treatment, lead to additional insights into the formation of in these alloys. AROUND 1960. Beiber1 developed IN 100 alloy, which still remains one of the strongest commercially available nickel-base superalloys. The principle used in the design of this alloy was to produce large quantities of y&apos; phase in a y matrix through the use of copious amounts of aluminum and titanium. In 1963, ROSS&apos; showed that when certain heats of this alloy were held for a long time at 1650°F they formed an acicular phase, subsequently identified as a.3 a is a hard and brittle phase first discovered in the Fe-Cr system by Bain and Griffiths.4 They termed it the "B" constituent. Subsequently this same phase was found in other systems, primarily those of the transition elements, and acquired the name "a" by which it is now known. The crystal structure of the a phase was first determined in the Fe-Cr system in 1950.5 It was shown to be tetragonal with a c/a ratio of about 0.52. as is the case with a found in other systems. This characteristic crystal structure is now the means by which a is identified. In superalloys, such as IN 100 alloy. large amounts of o impair the high-temperature creep strength and drastically reduce room-temperature tensile ductility. Discovery of o phase in some heats of IN 100 alloy quickly led to investigations of other superalloys for similar transformations. It was found that many of the stronger, more highly alloyed. super-alloys were indeed susceptible to o formation. This investigation has been concentrated on three commercial alloys: IN 100 alloy, alloy 713C, and alloy 713LC. J.R.MIHALISIN,MemberAIME, and C.G.BIEBER are with The International Nickel Co., Inc., Paul D. Merica Research Laboratory, Sterling Forest, Suffern, N. Y. R. T. GRANT, Member AIME, is with The International Nickel Co., Inc., Pittsburgh, Pa. Manuscript submitted May 22. 1968. IMD A detailed study has been made of the phase transformations and their relation to a formation along with a consideration of electron vacancy approaches for predicting a-forming propensity in these alloys. EXPERIMENTAL PROCEDURE Phase transformations were studied by light and electron microscopy, electron diffraction, microprobe investigations, and X-ray diffraction. Specimens for light micrographic examination were prepared by conventional grinding and polishing followed by etching with glyceregia (2:l HC1/HNO3 + 3 glycerine by volume). Photomicrographs of stress-rupture specimens were taken adjacent to the fracture unless otherwise noted in the text. Negative replicas for electron microscopy were taken from surfaces electropolished with a solution of 15 pct H2SO4 in methanol. For carbon extraction replication, a solution of 10 pct HC1 in methanol was used. A Siemens Elmiskop I was used for all electron microscopy. Selected-area diffraction studies were made at 80 kv using evaporated aluminum for standardizing the patterns. A nondispersive electron microprobe attachment was used to analyze the extracted precipitates chemically. The fluorescent X-rays were recorded using a flow counter containing P10 gas (90 pct Ar-10 pct methane) with a beryllium window and a single-channel pulse-height analyzer. The pulses from the analyzer were passed to a scaler-ratemeter and differential curves of counting rate vs pulse amplitude were obtained. The base line of the analyzer was driven with a synchronous motor at 0.5 v per min and a channel width of 0.5 v. The time for 105 counts was printed out for each 0.5-v increment. The microscope was operated at 80 kv with beam currents of 1 to 20 pa. This equipment detects elements from atomic number 13 to 40. X-ray diffraction studies were usually made on residues electrolytically extracted in 10 pct HC1 in H2O, although in one case a pattern was obtained from an etched surface of a metallographic specimen. A Siemens Crystalloflex IV was used with iron-filtered CoKa radiation. X-ray patterns were recorded using a goniometer speed of : deg per min. The scintillation counter and pulse-height analyzer operated at a channel height of 10 v and a channel width of 12 v. The equipment was calibrated with a powdered gold standard. The residues usually contained a number of phases. several of which could not be found in the ASTM card file. In addition, as is shown for the case of a phase in IN 100 alloy, other phases had a somewhat different lattice parameter from that reported in the ASTM card file, making it difficult to separate and identify constituents by comparison with ASTM d spacings. For these reasons, phases were identified on the basis of the lattice parameter obtained by indexing the ob-

Jan 1, 1969