DEPHOSPHORIZING METHOD FOR CRUDE MOLTEN STAINLESS STEEL AT HIGH TEMPERATURE

摘要

PURPOSE:To efficiently dephosphorize a crude molten steel at a high temp. and to make effective use of the sensible heat held by said steel by subjecting the molten steel to a refining treatment in the specified range of flux components and the oxygen partial pressure of the crude molten steel in the refining stage. CONSTITUTION:The flux having LAMBDA satisfying the equation I is used at the time of subjecting the crude molten stainless steel contg. >=3% chromium to a dephosphorizing treatment using the flux at the high temp. of >=1,500 deg.C. The LAMBDA is defined by the equa tion III by the component compsn. except the compds. of Fe, Cr, Mn, Co, Mo, and Ni contained in the flux. The oxygen partial pressure of the crude molten steel in the refining stage is specified within the range determined by the equation II. The dephosphorizing treatment of the high-Cr molten metal at a high temp. with high efficiency is executed by the above-mentioned method. In the equation III, Mi is the molar fraction of the respective component molecules, ni is the number of the metallic elements to form one molecule, Zi is the formal charge per piece of the respective metalic elements, Ai 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 combina tion state of the respective component molecules.