Patent ID: 6830606
Filing Date: 2004-12-14
Classification: C21B,C21C,Y02P,Y10S

Abstract:
A method for decarburization-refining chromium-contained molten steel under one of an atmospheric pressure and a reduced pressure by blowing oxygen gas and inert gas into the molten steel, comprising the steps of:a) refining the molten steel; b) determining, in sequence: i. a temperature of the molten steel during step (a) using at least one of an actual measurement and a computation of the temperature of the molten steel before step (a) and refining conditions, ii. [C] and [Cr] concentrations during step (a) using the at least one of the actual measurement and the computation from components of the molten steel before step (a) and the refining conditions, iii. a CO partial pressure PCO in an atmosphere during the refining from the total pressure P of the atmosphere, an oxygen gas supply rate and an inert gas supply rate, iv. a Hilty's equilibrium temperature TH from concentrations of [C] and [Cr] and PCO, v. a difference &Dgr;T between the molten steel temperature during step (a) and the Hilty's equilibrium temperature TH; and c) controlling the refining conditions so that the &Dgr;T may be at least a predetermined value.