GB1462247A - Production of steel - Google Patents

Abstract

1462247 Producing vacuum-treated steel for forging ingots FRIED KRUPP HUTTENWERKE AG 22 March 1974 [24 March 1973] 12965/74 Heading C7D Vacuum-treated steel suitable for forging ingots is produced by refining pig iron by oxygen topblowing at a temperature not above 1650‹C under slag(s) to form metal having a carbon content of 0.1 - 1wt per cent, a phosporus content of < 0.01 wt per cent and optionally one or more alloying agents which do not oxidize under these conditions, e.g.Ni or Mo; tranferring the metal produced into a converter-like vessel into which oxygen and inert gas, e.g. argon and/or nitrogen, are bottom blown whilst optionally oxygen is top blown; adding substances which oxidize to heat the melt, e.g. carbon and/or ferrosilicon, and oxygen top blowing to raise the temperature to above 1700‹C whilst bottom-blowing only at a rate sufficient to prevent accumulation of metal in the nozzles; adding any further alloying elements required, e.g. Cr, Mn, V, Ti, Ta or Nb, with intensified bottom-blowing with oxygen and inert gas; injecting inert gas only whilst adding reducing agent(s), e.g. Al or FeSi, and sulphur combining substance(s) e.g. lime, until the melt has a sulphur content of < 0.010 wt per cent; and subjecting the resultant metal to vacuum refining treatment.