METHOD FOR PRODUCING BEARING STEEL Russian patent published in 2003 - IPC

FIELD: metallurgy. SUBSTANCE: method involves discharging metal from steel melting unit into ladle while introducing 70-80% of required amount of ferroalloys under metal flow; cutting off steel slag; moving ladle with metal to "furnace-ladle" unit, where melt is heated by means of graphite electrodes to temperature of 1,550-1,560 C and metal is deoxidized by aluminum wire or lump aluminum introduced in an amount of 0.15-0.25 kg/t of steel; adding slag-forming mixture comprising 75% of lime and 25% of fluorspar or aluminous-lime slag at mixture consumption of 4.0-7.5 kg/t of steel. During treatment in "furnace-ladle" unit, metal is subjected to argon blasting, with argon being supplied at flow rate of 150-350 l/min. If necessary, metal is heated by means of electrodes to temperature of up to 1,550-1,560 C and fed to vacuumizer, where it is subjected to vacuumizing. When oxygen activity reaches 0.0010-0.0017%, aluminum wire is introduced in an amount of 0.3-0.4 kg/t of steel and calcium-silicon wire is added in an amount of 1.3-2.5 kg/t of steel, with following final argon blasting of melt for 3-6 min and delivery of blasted melt to continuous casting machine. Chemical composition of metal is finally corrected at "furnace-ladle" unit by partial adding of lacking amount of ferroalloys. Vacuumizing process is stopped after required amount of aluminum and calcium-silicon wire is introduced. EFFECT: increased efficiency in producing bearing steel in converters, improved quality of bearing steel and reduced amount of non-metal inclusions. 3 cl, 2 tbl, 1 ex