| 摘要 |
PURPOSE:To obtain a low P-contg. Cr steel from a P-contg. raw material which is previously unusable by using a dephosphorizing flux for a Cr-contg. molten iron for the molten iron contg. limited amt. of C and Si by blowing added with a C source, and adjusting thereafter the content of C in the molten pig iron to a desired value. CONSTITUTION:A molten iron contg. >=3wt% Cr is put into a refining furnace having double pipe tuyeres through which gaseous O2 and non-O2 gas can be simultaneously or selectively blown, on the bottom. After or while a C source of the enough amt. at which the content of C after the end of blowing attains >=4.5wt% is added to the molten iron, the non-O2 gas is supplied to the molten iron from the bottom of the furnace and is blown to the molten iron under stirring until the Si is decreased to <=0.15wt%, then the slag is discharged. After or while adding a flux to the molten metal for dephosphorization consisting of a prescribed ratio of the fluoride and chloride of an alkali earth metal, the oxide and carbonate of Li, iron oxide, Ni oxide, etc. the molten iron is stirred by the non-O2 gas from the bottom. The slag and molten iron are forcibly brought into contact with each other and thereafter the slag is discharged. The resulting low P molten iron is decarburized and refined to a desired C value by the above- mentioned refining furnace or by a combination of said furnace and the other refining furnace.
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