METHOD OF STEEL MAKING Russian patent published in 2001 - IPC

FIELD: metallurgy. SUBSTANCE: method includes melting of metals in melting unit, deoxidation, nitrogen alloying and teeming followed by rolling. Element whose affinity for nitrogen is higher than that of iron are introduced into molten metal. Molten metal is saturated with nitrogen to concentration exceeding its solubility limit in solid metal, thus ensuring required degree of alloying and separation of nitrogen in gaseous phase at crystallization of metal in the amount sufficient for compensation for shrinkage of metal. Saturation of molten metal with nitrogen is effected by taking nitrogen from atmosphere of melting unit or/and by blowing metal with nitrogen-containing gases. Used as nitrogen-containing gases are: air, gaseous commercial nitrogen, mixture of nitrogen with argon and mixture of nitrogen with combustion gases. Used as nitrogen-containing materials are: nitrogen ferroalloys and/or nitrogen-containing mineral and/or organic materials. Materials containing Cr, Mn, Mo, Al, V, Nb, Ti, Zr and /or their combinations are used as materials whose affinity for nitrogen is higher than that of iron. Elements to be introduced in steel and nitrogen-containing materials to be introduced in steel, their ratio and amount shall be determined individually. EFFECT: possibility of teeming nitrogen-alloyed steel in small end-up molds; increased yield of steel by at least 8 to 10% due to reduction of top discard, avoidance of tops and warmers; reduced labor consumption; extended range of steels at guaranteed level of mechanical properties; increased productivity of complex as a whole; reduction of steel making cost by 10 to 12%. 6 cl