1008. Carbon-oxygen reaction during vacuum degassing of steel melts

Classified abstracts 1001-1016 of compactness has made possible the successful design of a vacuum system for high temperature creep-testing at constant stress. J F Wilson et al, Exp Mech, 6, 1966, 555-558. 37 1001. Deoxidation at low pressures. (USA) The equilibrium bubble pressure in an iron bath at three external pressures was measured and the results are tabulated in a discussion on high vacuum techniques, and suggestions are made for more efficient utilization of existing plant. T R Mcadowcroft, lnd Heating 33, 1966, 1285-1288. 37 1002. Considerations in the use of vacuum in steel making. (USA) Application of vacuum degassing and vacuum deoxidizing of large tonnages of air-melted steel are reviewed. Vacuum consumable electrode remelting is applied to the production of smaller lot sizes of highly alloyed steels, certain tool steels and bearing steels. Application of vacuum techniques results in lower gas levels and cleaner steels. Relative cost and cleanliness of vacuum melted consumable electrode steels are shown for four production methods: air, electric arc, air induction and vacuum induction melting. H E Trout, lnd Heating, 33, 1966, 1617-1624: 1794. 37 1003. High vacuum annealing. (USA) Vacuum bright annealing prevents the formation of an oxidic or scale layer on the material being treated and assures that lubricant layers from drawing and rolling processes are completely removed by gasification. The process is suitable for practically all non-ferrous metals, as well as for mild steel, carbon steels, and alloy steels. A vacuum of 0.1 torr is sufficient for non-ferrous metals; high carbon steels require 0.01 torr to prevent skin decarburization. W Braun-Angott, Wire Worm Intern, 8, 1966, 115-119. 37 1004. Grain refinement of cast steel by vacuum melting. (USA) Vacuum melting cast steel 4330 provided both a shorter column zone length and finer secondary dendrite arm spacing than did air melting. Further refinement was obtained by addition of 0.1 per cent titanium. P F Wiesner and J F Wallace, AFS Cast Metals ResJ, 2, 1966, 1-5. 37 1005. The evaporation of liquid iron alloys under vacuum. (Canada) By the use of levitation melting, an experimental technique has been developed to measure the rate of free evaporation of liquid metal out of contact with any contaminating support material. The evaporation of liquid iron under vacuum in the range 1687-1840°C has been studied. The rate of evaporation of Cu from Fe-Cu droplets between 1700-1760°C was about 50-70% of the value expected if the loss was controlled entirely by the rate of evaporation from the surface. P N Smith and R G Ward, Can Met Quart, 5, 1966, 77-92. 37 1006. Methods of degassing aluminium melts and possibilities of control. (Germany) Principal methods used in the degassing of AI melts are summarized. Standing, stirring and vibration methods are considered impractical. Possible other procedures are vacuum treatments, which are still rare in the AI industry and the use of gaseous rinsing is the most important practical method. K O Hornung, Technica, 15, 1966, 1351-1354 37 1007. Properties of vacuum remelted high speed steels. (Germany) The effects of remelting in vacuum electric-arc or electron beam furnaces on the structure and mechanical properties of S 6-5-2 and S 2-9-1 high speed steels was investigated. Remelting in the arc furnace produced a coarse grain size in the hardened steel while remelting in the beam furnace had no effect on the austenitic grain size. A Randak and J Kurzeja, Stahl Eisen 86, 1966, 1017 1024 (in German). 37 1008. Carbon-oxygen reaction during vacuum degassing of steel melts. (Germany) Methods of vacuum degassing steels melts are reviewed and the oxygen-carbon reaction is studied by a method developed by Harders. Samples were taken from the ladle and the vacuum vessel and the final oxygen content determined. H Knueppel et al, Arch Eisenhuettenw, 3, 1966, 621-632 (in German). 302

37 1009. Recent developments in crystal pulling from the crucible. (France) Crystal pulling from the melt is a particularly suitable method for the production of homogeneous, strongly doped silicon crystals, of great interest to the semiconductor industry. The design of equipment for crystal pulling under vacuum or in gas atmosphere is described and recommendations made for optimum crystal properties. Economic considerations are discussed and some results obtained on silicon and germanium crystals are briefly summarized. C Korn and J Moll, Le Vide, 21 (126), Nov-Dec 1966. 442-447 (in

French and German). 37 : 33 1010. Development of an apparatus for the doping of silicon by activated phosphorous ions. (France) The development and construction of an ion gun for the acceleration of heavy ions up to a maximum energy of 30 kV, is described. The ion source uses phosphorous pentachloride containing radioactive phosphorous and may be recharged without demounting or breakage of the vacuum. Quadrupole focusing and magnetic separation of the singly ionized ions, together with suitably positioned diaphragms, gives accurate control of beam composition and area of the target irradiated. An oil diffusion pump with an annular liquid nitrogen trap provides contamination-free pumping of the target chamber. Properties of semiconductor diodes obtained with this equipment are presented as well as evaluations of the concentration profiles recorded during thermal annealing. P GIotin and J Grapa, Le Vide, 21 (126), Nov-Dec 1966, 459~166

(in French). 37 1011. Degassing installation by the D H H U process. (France) Steel from an electric furnace passes directly into the casting ladle and is alternatively raised and lowered under complete vacuum. F Cousin, Met Constr Mech, 98, 1966, 79-87 (in French). 37 1012. Production of 3 5 N C D 1 6 steel by remelting under vacuum. (France) It is shown that by very accurate control of the fabrication stages this steel can be used in very exacting applications such as the landing gear of the Concorde aircraft. A Gervais, Met Constr Mech, 98, 1966, 171-177 (in French). 37 1013. Applications of vacuum techniques in metallurgical extraction. (Belgium) A summary of the development of vacuum techniques in extraction metallurgy is given. Thermodynamics and equipment applied to phase separation, compound reduction, fractional distillation and degassing are discussed with their industrial application. J Kruger et al, Compt Rend Coil Intern Met Sous Vide, Brussels, June 1966, 13-19 (in French). 37 1014. Study of beryllium fusion under vacuum. (Belgium) Advantages and disadvantages of melting beryllium by using hf current melting at 10-4 torr and electron bombardment at 4 × I0 : torr are discussed. Mass spectrometric analysis of residual gases shows a water reaction with Be above 600°C to give 83 per cent H2 at 800°C and 50 per cent at 1350°C. A correlation was found between hydrogen partial pressure and the residual hydrogen in Be. B Schaub, Compt Rend Coil Intern Met Sous Vide, Brussels, June 1966, 103-107 (in French). 37 1015. Calculation of the course of degassing of metal melts. (Belgium) The relationships between degassing rates and pumping speed on melt phase gas transport is reviewed. Comparison of modern degassing plant efficiency and theoretical calculations are made. T Klaus and O Winkler, Compt Rend Coil Intern Met Sous Vide, Brussels, 1966, 115-120 (in French) 37 1016. Studies of the influence of vacuum treatment on the quality of some Cr-Ni-Mo type alloy steels. (Rumania) The technology is described as well as the results obtained in the treatment of some low-alloy carbon steels, under pressure of 0.2-0.8 torr in a vacuum plant with steam injection, having a capacity of 500 kg of steel. I Tripsa et al, Cercetan Metalurgie 7, 1966, 57 79 (in Rumanian).