METHOD FOR MANUFACTURING ULTRA LOW CARBON STEEL BY INGOT TECHNIQUES USING VACUUM-DEGASSING SYSTEM

摘要

The object of the invention is to sufficiently increase the temperature of molten steel by adding heating agent to a degassing chamber and to shorten the vacuum-degassing time by introducing oxygen into the degassing chamber without causing decarburization failure and/or lowering the purity of the molten steel during a decarburization process for manufacturing ultra low carbon steel by melting techniques using a vacuum-degassing system. Specifically, the invention provides a method for manufacturing ultra low carbon steel by using a vacuum-degassing system. The method comprises a molten steel decarburization process of adding desirable amount of oxygen for molten steel decarburization to the vacuum-degassing chamber, and is characterized by also comprising adding oxygen required by combusting heating agent which is to be added for heating the molten steel, adding the heating agent to heat the molten steel during or after a subsequent oxygen adding period, and continuing the molten steel decarburization process.