METHOD OF MAKING STEEL Russian patent published in 2004 - IPC

FIELD: ferrous metallurgy; steel making processes; micro-alloying of steel and alloys with nitrogen.

SUBSTANCE: proposed method includes blowing of metal with gaseous nitrogen in furnace-ladle unit at flow rate of 150-1000 l/min. Simultaneously with blowing, melt is heated by electric arc and nitride-forming additives are introduced for bonding the dissolved nitrogen in nitrides. Then, steel-teeming ladle is transferred to circulating evacuation plant where melt is subjected to evacuation continued for 5-30 minutes and flow rate of carrier gas (nitrogen) of 900-1600 l/min. At the end of evacuation, aluminum and calcium silicon wire is introduced into metal in the amount of 0.05-0.30 and 0.5-3.5, respectively and metal is blown with nitrogen through porous plug fitted in bottom of ladle. Vanadium and aluminum may be used as nitride-forming elements. Content of nitrogen, nitride-forming elements and oxygen in metal corresponds to the following relationship: (N)/(A)=0.3-10.0; (N)/(V)=0.04-0.50; (N)/((O)= 2.0-20.0. It is good practice to discontinue evacuation of metal upon completion of introduction of aluminum and calcium-silicon wire. Proposed method ensures high purity of metal excluding toxic gases and non-metallic inclusions.

EFFECT: improved quality of steel; reduced melting losses; smooth distribution of materials in metal.

1 dwg, 2 tbl, 1 ex