MANUFACTURE OF CONTINUOUS CASTING SLAB WITH FEW BLOWHOLES AND LITTLE NONMETALLIC INCLUSION

摘要

PURPOSE:To manufacture continuous casting slab with few blowholes and little nonmetallic inclusion as well, by conducting the vacuum degassing operation as well as deoxidating operation using Al in a cradle and conducting again the vacuum degassing operation in a tundish. CONSTITUTION:The molten steel, after being treated by converter steel making process, is tapped into a cradle 3 which being set in a vacuum chamber, where the molten steel is subjected to the vacuum degassing operation as well as deoxidizing operation using Al and thus, contents such as carbon and residual oxygen are reduced. The molten steel havng been degassed in the cradle is then poured into a tundish 2, where the contineous vacuum degassing operation as well as decarbonizing and deoxidizing operations are again conducted before pouring to a mold. The deoxidized molten steel is poured into a mold 1 sealed from the atmosphere by means of an immerged nozzle 9 and an artificial slag 12. Therefore, the generation of gaseous CO is minimized in the process of solidification of molten steel in the mold 1 and a sound and continuous casting slab with no blowholes is manufactured.