Clay A Gross

US Patent:

20020174746, Nov 28, 2002

Filed:

Apr 2, 2002

Appl. No.:

10/114627

Inventors:

Clay Gross - Ladoga IN, US
Rama Mahapatra - Indianapolis IN, US
Walter Blejde - Brownsburg IN, US
Steve Wigman - Brownsburg IN, US

International Classification:

C21C005/34

US Classification:

075/546000

Abstract:

A steel charge and slag forming material is heated in a ladle to form molten steel covered by a slag containing silicon, manganese and calcium oxides. The steel is stirred by injection of an inert gas such as argon or nitrogen to cause silicon/manganese deoxidation and desulphurization to produce a silicon/manganese killed molten steel. Stirring of the molten steel by the inert gas injection while in contact with slag high in calcium oxide generates low free oxygen levels in the steel and desulphurization to sulphur levels below 0.009%. The slag may subsequently be thickened by lime addition to prevent reversion of sulphur back into the steel and oxygen may be injected into the steel to increase its free oxygen content to produce a steel that is readily castable in a twin roll caster.