Abstract: A workpiece of alloy steel is produced by sintering under a nonoxidizing atmosphere a mass of malleable-iron powder admixed with a comminuted complex ferroalloy. The latter, obtained from a molten mixture of several simple high-carbon ferroalloys saturated with graphite, is a blend of at least three nonferrous metals and iron in carbide form, including a complex carbide of formula M.sub.7 C.sub.3 containing iron and manganese with the possible addition of chromium and another carbide of formula M'.sub.2 C/M'C containing molybdenum with the possible addition of vanadium and/or niobium. The carbidically bound carbon amounts to at least 4%, by weight, of the ferroalloy composition and may constitute between 10% and 60% of the carbon of the sinterable powder mixture to which elemental carbon may be added as graphite. As the mass of iron and ferroalloy particles compacted under high pressure is sintered at temperatures between about 1150.degree. and 1300.degree. C.
Type:
Grant
Filed:
September 26, 1978
Date of Patent:
April 21, 1981
Assignee:
GfE Gesellschaft fur Elektrometallurgie mit beschrankter Haftung
Inventors:
Rudolf Fichte, Hans-Joachim Retelsdorf, Richard Jervis, Gunter Radel
Abstract: The invention relates to a method of rapidly decarburizing a high-carbon ro-alloy with oxygen for avoiding an undesirable oxidation of the principal alloying elements, especially chromium or manganese, comprising blowing an oxidizing gas under the surface of a bath of molten ferro-alloy from one or more gas-jacketed nozzles in an amount ranging between substantially 3 and 15 m.sup.3 S.T.P. per metric ton of ferro-alloy with reduction of the carbon content of the ferro-alloy at a rate of about 0.2% to 1%. Comminuted solids, especially particles of oxides of alkaline-earth metals such as powdered lime, may be admixed with the oxidizing gas to prevent the ejection of molten metal from the bath.
Type:
Grant
Filed:
November 27, 1974
Date of Patent:
August 28, 1979
Assignee:
GfE Gesellschaft fur Elektrometallurgie mit Beschrankter Haftung
Inventors:
Friedrich Breuer, Karl Brotzmann, Gunter Duderstadt, Rudolf Fichte, Fritz Stadler
Abstract: A hign-carbon ferro-alloy, specifically ferrochrome or ferromanganese, is carburized in a converter in which oxygen or air is blown from below into the melt together with a surrounding protective gas. With the bath preheated to a temperature somewhat higher than the melting point of the ferro-alloy, the oxygen is introduced at such a rate that its reaction with the chromium or the manganese locally superheats the bath, in a region well below the surface and spaced from the converter walls, to a temperature high enough to let the resulting oxides react endothermically with the carbon. This reaction takes place in combustion zones believed to be localized in gas bubbles formed above the injection nozzles, the oxidation of the ferrous and nonferrous constitutents occurring at the interface between the gas and the melt with formation of a very thin and highly reactive oxide skin around each bubble.
Type:
Grant
Filed:
November 9, 1977
Date of Patent:
December 19, 1978
Assignee:
GfE Gesellschaft fur Elektrometallurgie mit beschrankter Haftung
Inventors:
Friedrich Breuer, Gunter Duderstadt, Werner Dresler, Rudolf Fichte, Peter Kunert, Gerd Nassauer