| 摘要 |
<p>PROBLEM TO BE SOLVED: To efficiently lower Mn without accompanying extremely lowering Cf in a converter operational process and to secure the quality of an electric steel sheet, etc., without bringing about the rising of N in the steel by specifying the basicity and the total Fe content in converter slag. SOLUTION: The slag basicity (the ratio of SiO2 to the total CaO charged into the converter) is adjusted to 3.0-4.0 to achieve low Mn while restraining such FeO content in the slag as to keep the finish carbon Cf at the time of blowing off. Further, the total Fe content in the converter slag is restrained to in the range of 15-25%. At the time of executing the converter operation so as to satisfy the above condition, the low Mn steel can be produced while keeping the Cf to almost 0.035%, but MgO content in the slag may be adjusted to 8-11% in order to further rise the Mn partition ratio. After completing the check of the steel components and the measurement of the temp. etc., wish a sub-lance at the end stage of the converter operation, the suitable quantity of slag-making material of iron ore, SiO2 , Cab, etc., is added to adjust the slag composition.</p> |
