SLAG MODIFIER AND METHOD FOR PRODUCING HIGH PURITY ULTRA-LOW CARBON STEEL

摘要

PROBLEM TO BE SOLVED: To provide a slag modifier in which a carbon pick-up amount to a molten steel in a slag modification for performing after decarburization can be suppressed to less than 5 ppm in the production of an ultra-low carbon steel using a vacuum degassing apparatus, and also provide a method for producing the ultra-low carbon steel using the same. SOLUTION: After a non-deoxidized molten steel from a steelmaking furnace is decarburized to an ultra-low carbon region by using a vacuum degassing apparatus and successively deoxidized, this slag modifier is used in a slag modification process. The total carbon concentration of the slag modifier is less than 5 mass%.