DEPHOSPHORIZING METHOD FOR CRUDE MOLTEN STAINLESS STEEL BY ADDITION OF FLUX

摘要

PURPOSE:To perform dephosphorizing treatment with high efficiency without chromium loss by determining the end temp. of the dephosphorization from the components of an added fux and the optimum oxygen partial pressure at the end of refining, starting the refining from the temp. higher than said temp. and decreasing the temp. by oxygen blowing. CONSTITUTION:The value of LAMBDA is first calculated in accordance with the equation II from the components except the compds. of Fe, Cr, Mn, Co, Mo and Ni in the flux at the time of subjecting the crude molten stainless steel contg. >=3% chromium to the dephosphorization refining by using the flux. The temp. T is then calculated by the equation I from the oxygen partial pressure of the molten steel in the refining stage and the value of LAMBDA. The dephosphorization refining is started from the temp. higher than the temp. T( deg.K) and the temp. is decreased by stirring or addition of the flux. The dephosphorization refining is ended in the range of the temp. T( deg.K). The dephosphorizing treatment with a high dephosphorization rate is executed with low dephosphorizing agent consumption by the above-mentioned method. In the equa tion II, LAMBDAi is 1/{1.36(xi-0.26)}, xi is the Pauling's electronegativity of the respective metallic elements, and alphai is the constant to be determined by the combination state of the respective component molecules.