PURPOSE: To provide a decarburize-treating method for chromium-containing molten steel in the reduced pressure, by which the oxidation of [Cr] in the molten steel is restrained and the consumption of inert gas for dilution is restrained and the decarburization is efficiency executed at a high speed and the refining cost is reduced.
CONSTITUTION: In the refining method for chromium-containing molten steel executing the decarburizing treatment in vacuum condition after decarburize- treatment in the same refining vessel under the atmospheric pressure, the decarburizing treatment in the vacuum is started at ≤0.7mass% [C] concn. and executed in ≤300Torr degree of vacuum. Further, in the range of ≥0.05mass% [C] concn., gaseous carbon dioxide at ≥0.1Nm3/min/ton of the molten steel is mixed with gaseous oxygen or the mixed gas of the gaseous oxygen and the inert gas or the inert gas and blown. By this method, the unit consumption of the gaseous oxygen and the inert gas are remarkably reduced, and by improving the decarburization oxygen efficiency, as the unit consumption of Si for reduction is reduced, the refining cost is remarkably reduced and the efficient decarburization can be executed.
TANAKA SHIGENORI
OKIMORI MAYUMI
IWASAKI HIROSHI
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