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Ladle degassing: a report on in-plant tests with the Finkl-Mohr units
Classified abstracts 496---504 E C Nelson and R Houston, Trans 6 Vac Metall Conf, American
H S Philbrick, Jr, Trans 6 Vac Metall Conf, American Vacuum
Vacuum Society, 1964, 345-353.
Society, 1964, 297-327.
37 496. De-oxidation of molten steel by Dortmund Horder vacuum degassing process. (USA) This paper describes theoretical considerations with some assumptions for de-oxidation in the D H vacuum degassing process; they are compared with the results of experiments carried out with 30 ton and 70 ton degassing equipment. The authors found that it is possible to calculate and estimate the progress of de-oxidation in the vacuum vessel from the carbon and oxygen content, the amount of melt per cycle, diameter of vessel, number of cycles per minute and pressure in vessel. The calculations involve many assumptions and the figures can only be regarded as approximate. In order to follow the process of degassing more exactly, the surface area and motion of the melt should be known at any instant. T Kato and K Matsuda, Trans 6 Vac Metall Conf, American
37 : 41 500. The stability of molten uranium and refractory carbides in high vacuum. (USA) Conclusions based upon results of this study are: (1) An electron beam furnace technique which was devised can be used satisfactorily for the semi-quantitative study of materials at high temperatures. (2) Carbides of uranium, tungsten, tantalum, vanadium, zirconium, and niobium can be melted in the electron beam furnace. Allowances, however, must be made for vaporization losses. (3) Molten carbides of tungsten, zirconium, vanadium, titanium, tantalum, uranium (with 6.9 and 9.0 wt per cent carbon), and niobium all lose carbon atoms preferentially to metal atoms. Uranium atoms are lost preferentially to carbonatoms in uranium monocarbide (5.02 wt per cent carbon). (4) Carbides at temperatures of approximately their melting points ranked in order of increasing rates of evaporation are: W2C, WC, NbC, UC, ZrC, TaC, UC2, VC, and TiC. (5) Larger carbon partial vapour pressures than metal vapour pressures were noted for W2C, WC, and ZrC. For all other carbides, metal partial vapour pressures were larger than carbon vapour pressures. (USA) S G Nelson et al, Trans 6 Vac Metall Conf, American Vacuum
Vacuum Society, 1964, 328--344. 37 497. Vacuum sampler. (USSR) A metallic vacuum sampler for collecting samples of liquid metal from a mould is described. The sampler is connected to a vacuum installation comprising of a pump of VN-461 type, vacuum flask with gauge and a three-way tap, serving to connect sampler with the pump or acting as air inlet when the pump is disconnected. Prior to operation, the sampler is heated to about 100°C. The negative pressure during sampling should not exceed 3 torr. V I Dorokhov et al, Machines and Instruments for testing of metals
and plastics, Collection of Papers Moscow, 1965, (in Russian). 37 498. Vacuum mould degassing. (USA) The Gero vacuum mould degassing process is described in some detail and some preliminary results noted. The process is essentially a vacuum degassing process in which ingot moulds are equipped with a hood through which the vacuum is applied. Vacuum casting is carried out at pressures of 300 to 500 microns. The preliminary evaluation of the process indicates that it is at least as effective as other more elaborate systems in removing hydrogen and in lowering oxygen. Thus it is capable of the same quality improvements as those attainable with other processes.
( USA ) A E Nehrenberg, Trans 6 Vac Metall Conf, American
Vacuum
Society, 1964, 258-272. 37 499. Ladle degassing: a report on in-plant tests with the Finkl-Mohr units. (USA) Beginning in March, 1961 a portable vacuum degassing unit (Steel, June 12, 1961) was offered to steelmakers for in-plant tests and evaluation of the Finkl vacuum degassing process. A second, 10,000 lb unit was placed in service in 1962. To date these units have operated in a total of nine melt shops, 3 making sand mold castings, the balance ingots, degassing a variety of steel from these tests makes up the bulk of the material presented by the author and contributes to our knowledge of vacuum degassing. Two years of operation have shown that floor mounted shell and tube intercondensers in place of full leg barometrics are practical for vacuum degassing service provided a regular schedule of water flushing is followed. The units were ready for steel frequently within 30 rain following start up of boiler from cold water. Low micron pressures were not required for hydrogen removal. Fifty per cent reduction was obtained at 1 to 2 m m Hg absolute. Oxygen on the other hand was dependent on steel analysis and its removal was improved by lower pressures, some tests being conducted near 100 microns. Low carbon steels showed the greatest oxygen changes, high carbon and high alloy steels the least. Lowest oxygen levels were reached with ball bearing steels. Oxygen levels on all carbon and low alloyed steels seemed to have a limit shown by the 100 mm pressure equilibrium line for carbon with oxygen in an iron solution. The drop in oxygen for several selected heats was accompanied by a loss in carbon greater than could be accounted for by a carbon monoxide reaction. Two proposals for improved degassing of steels under vacuum are made. One unit is for large tonnage open hearth and basic oxygen furnace steels. The second unit is intended for high alloy electric furnace steels. (USA)
Society, 1964, 148-166. 37 501. Kinetics of vacuum degassing of steel. (USA) The author considers the kinetics of vacuum stream degassing in some detail, paying special attention to the effect of pour rate, nozzle size, length of fall and vacuum level. In vacuum stream degassing, practically all the degassing occurs during the fall. Curves are given showing the removal of hydrogen, oxygen and nitrogen as a function of exposure time and the difference in the response of "killed" and "unkilled" steels is pointed out. Vacuum degassing significantly improves the quality of the steel and reduces many internal operating costs. In addition it will make new casting techniques a practical reality. A E Hokanson, Trans 6 Vac Metall Conf, American Vacuum
Society, 1964, 238-257.
38. Distillation, organic chemistry, isotopic gas analysis 38 502. Superpurification of metals by vacuum distillation: a theoretical study. (USA) The effect of process variables in the production of very-highpurity metals (i.e. impurity levels for metallics and gases at low ppm levels) has been explored. The most important variables for high purity are: (1) High evaporation rate, i.e. a high evaporation temperature. (2) Minimum contamination from vacuum environment, i.e. a good clean vacuum chamber and accessories. (3) Control over the condensation temperature. (4) A high-quality starting material, if necessary prepurified by vacuum melting. (5) Elimination of melt-crucibles reactions. (USA) R F Bnnshah, Trans 6 Vac Metall Conf, American Vacuum Society,
1964, 121-139. 38 : 41 503. Production of hydrocarbons on barium films. (USA) Typical features of the cracking patterns of simplest hydrocarbons obtained with an omegatron mass spectrometer are preliminarily illustrated. The well known production of hydrocarbons by the action of water vapour over barium films previously treated with carbon monoxide is re-examined, with special attention to the time evolution of the gaseous phase in an isolated system. Other possible ways for the formation of hydrocarbons are considered; in particular the direct low pressure hydrogenation of the "carbide" complexes present at the surface of barium films is studied. P della Porta and T A Giorgi, Trans 10 A VS Nat Vac Symp,
MacMillan & Co, 1963, p 491.
39. Miscellaneous applications 39
504. Automatic column for the chemical purifcation of mercury. (ussR) The purification is carried out by the simultaneous application of air scavenging and successive exposure to the chemical action of
283
H S Philbrick, Jr, Trans 6 Vac Metall Conf, American Vacuum
Vacuum Society, 1964, 345-353.
Society, 1964, 297-327.
37 496. De-oxidation of molten steel by Dortmund Horder vacuum degassing process. (USA) This paper describes theoretical considerations with some assumptions for de-oxidation in the D H vacuum degassing process; they are compared with the results of experiments carried out with 30 ton and 70 ton degassing equipment. The authors found that it is possible to calculate and estimate the progress of de-oxidation in the vacuum vessel from the carbon and oxygen content, the amount of melt per cycle, diameter of vessel, number of cycles per minute and pressure in vessel. The calculations involve many assumptions and the figures can only be regarded as approximate. In order to follow the process of degassing more exactly, the surface area and motion of the melt should be known at any instant. T Kato and K Matsuda, Trans 6 Vac Metall Conf, American
37 : 41 500. The stability of molten uranium and refractory carbides in high vacuum. (USA) Conclusions based upon results of this study are: (1) An electron beam furnace technique which was devised can be used satisfactorily for the semi-quantitative study of materials at high temperatures. (2) Carbides of uranium, tungsten, tantalum, vanadium, zirconium, and niobium can be melted in the electron beam furnace. Allowances, however, must be made for vaporization losses. (3) Molten carbides of tungsten, zirconium, vanadium, titanium, tantalum, uranium (with 6.9 and 9.0 wt per cent carbon), and niobium all lose carbon atoms preferentially to metal atoms. Uranium atoms are lost preferentially to carbonatoms in uranium monocarbide (5.02 wt per cent carbon). (4) Carbides at temperatures of approximately their melting points ranked in order of increasing rates of evaporation are: W2C, WC, NbC, UC, ZrC, TaC, UC2, VC, and TiC. (5) Larger carbon partial vapour pressures than metal vapour pressures were noted for W2C, WC, and ZrC. For all other carbides, metal partial vapour pressures were larger than carbon vapour pressures. (USA) S G Nelson et al, Trans 6 Vac Metall Conf, American Vacuum
Vacuum Society, 1964, 328--344. 37 497. Vacuum sampler. (USSR) A metallic vacuum sampler for collecting samples of liquid metal from a mould is described. The sampler is connected to a vacuum installation comprising of a pump of VN-461 type, vacuum flask with gauge and a three-way tap, serving to connect sampler with the pump or acting as air inlet when the pump is disconnected. Prior to operation, the sampler is heated to about 100°C. The negative pressure during sampling should not exceed 3 torr. V I Dorokhov et al, Machines and Instruments for testing of metals
and plastics, Collection of Papers Moscow, 1965, (in Russian). 37 498. Vacuum mould degassing. (USA) The Gero vacuum mould degassing process is described in some detail and some preliminary results noted. The process is essentially a vacuum degassing process in which ingot moulds are equipped with a hood through which the vacuum is applied. Vacuum casting is carried out at pressures of 300 to 500 microns. The preliminary evaluation of the process indicates that it is at least as effective as other more elaborate systems in removing hydrogen and in lowering oxygen. Thus it is capable of the same quality improvements as those attainable with other processes.
( USA ) A E Nehrenberg, Trans 6 Vac Metall Conf, American
Vacuum
Society, 1964, 258-272. 37 499. Ladle degassing: a report on in-plant tests with the Finkl-Mohr units. (USA) Beginning in March, 1961 a portable vacuum degassing unit (Steel, June 12, 1961) was offered to steelmakers for in-plant tests and evaluation of the Finkl vacuum degassing process. A second, 10,000 lb unit was placed in service in 1962. To date these units have operated in a total of nine melt shops, 3 making sand mold castings, the balance ingots, degassing a variety of steel from these tests makes up the bulk of the material presented by the author and contributes to our knowledge of vacuum degassing. Two years of operation have shown that floor mounted shell and tube intercondensers in place of full leg barometrics are practical for vacuum degassing service provided a regular schedule of water flushing is followed. The units were ready for steel frequently within 30 rain following start up of boiler from cold water. Low micron pressures were not required for hydrogen removal. Fifty per cent reduction was obtained at 1 to 2 m m Hg absolute. Oxygen on the other hand was dependent on steel analysis and its removal was improved by lower pressures, some tests being conducted near 100 microns. Low carbon steels showed the greatest oxygen changes, high carbon and high alloy steels the least. Lowest oxygen levels were reached with ball bearing steels. Oxygen levels on all carbon and low alloyed steels seemed to have a limit shown by the 100 mm pressure equilibrium line for carbon with oxygen in an iron solution. The drop in oxygen for several selected heats was accompanied by a loss in carbon greater than could be accounted for by a carbon monoxide reaction. Two proposals for improved degassing of steels under vacuum are made. One unit is for large tonnage open hearth and basic oxygen furnace steels. The second unit is intended for high alloy electric furnace steels. (USA)
Society, 1964, 148-166. 37 501. Kinetics of vacuum degassing of steel. (USA) The author considers the kinetics of vacuum stream degassing in some detail, paying special attention to the effect of pour rate, nozzle size, length of fall and vacuum level. In vacuum stream degassing, practically all the degassing occurs during the fall. Curves are given showing the removal of hydrogen, oxygen and nitrogen as a function of exposure time and the difference in the response of "killed" and "unkilled" steels is pointed out. Vacuum degassing significantly improves the quality of the steel and reduces many internal operating costs. In addition it will make new casting techniques a practical reality. A E Hokanson, Trans 6 Vac Metall Conf, American Vacuum
Society, 1964, 238-257.
38. Distillation, organic chemistry, isotopic gas analysis 38 502. Superpurification of metals by vacuum distillation: a theoretical study. (USA) The effect of process variables in the production of very-highpurity metals (i.e. impurity levels for metallics and gases at low ppm levels) has been explored. The most important variables for high purity are: (1) High evaporation rate, i.e. a high evaporation temperature. (2) Minimum contamination from vacuum environment, i.e. a good clean vacuum chamber and accessories. (3) Control over the condensation temperature. (4) A high-quality starting material, if necessary prepurified by vacuum melting. (5) Elimination of melt-crucibles reactions. (USA) R F Bnnshah, Trans 6 Vac Metall Conf, American Vacuum Society,
1964, 121-139. 38 : 41 503. Production of hydrocarbons on barium films. (USA) Typical features of the cracking patterns of simplest hydrocarbons obtained with an omegatron mass spectrometer are preliminarily illustrated. The well known production of hydrocarbons by the action of water vapour over barium films previously treated with carbon monoxide is re-examined, with special attention to the time evolution of the gaseous phase in an isolated system. Other possible ways for the formation of hydrocarbons are considered; in particular the direct low pressure hydrogenation of the "carbide" complexes present at the surface of barium films is studied. P della Porta and T A Giorgi, Trans 10 A VS Nat Vac Symp,
MacMillan & Co, 1963, p 491.
39. Miscellaneous applications 39
504. Automatic column for the chemical purifcation of mercury. (ussR) The purification is carried out by the simultaneous application of air scavenging and successive exposure to the chemical action of
283