| 摘要 |
PURPOSE:To considerably enhance the yield of Cr when a high-Cr alloy steel such as a stainless steel is refined by blowing in a top and bottom blowing converter, by preferentially removing C while inhibiting the oxidation of Cr. CONSTITUTION:A steel bath contg. 0.2-1wt% C and 8-20wt% Cr is refined at 1,550-1,800 deg.C in a top and bottom blowing converter by blowing gas from the bottom by >=0.05Nm<3>/min per 1 ton molten steel and oxygen from the top by <=3.5Nm<3>/min per 1 ton molten steel. At this time, oxygen is blown so as to regulate RI value defined by formula I to 20-40. The refining is finished when the concn. of C in the steel reaches [Cs] value defined by formula II. In the formula I, [Cr] is the concn. (%) of Cr in the steel bath, [C] is the concn. (%) of C in the steel bath and KO2 is the amount (Nm<3>/min/ton) of oxygen blown from the top. In the formula II, alpha is a constant dependent on the desired rate of oxidation of Cr. |
