METHOD OF REFINING RAIL STEEL IN FURNACE-LADLE

摘要

FIELD: ferrous metallurgy; off-furnace treatment of steel. ^ SUBSTANCE: refining of steel is performed by arc preheating of metal at rate no less than 40 kW h/t of molten steel, blowing the metal with argon through porous bottom tuyeres at rate of molten steel flow of 15-30 m3/t; blowing procedure is continued for at least 40 minutes. Content of iron oxide is maintained at level not exceeding 0.5% which is achieved by deoxidizing of slag with coke powder and crushed ferro-silicon at flow rate of 0.5-1.5 kg per ton of molten steel; steel is subjected to additional deoxidizing with calcium silicon: 250-300 g of calcium per ton of molten steel. Calcium silicon is added at two stages in equal portions after deoxidizing of slag 5-10 minutes before completion of treatment of steel. Proposed method makes it possible to obtain content of oxygen in rail steel lesser than 35 pmm, average length of line of non-metallic inclusions lesser than 0.4 mm, to increase yield point by 10 N/mm2 and relative elongation and contraction. ^ EFFECT: enhanced efficiency.