CASTING METHOD OF UNIDIRECTIONALLY SOLIDIFIED STEEL INGOT

摘要

PURPOSE:To decrease the concn. of hydrogen in a molten steel and to obtain a unidirectionally solidified steel ingot having no blowholes by decreasing the parital pressure of hydrogen in the atmosphere in a casting mold during operation. CONSTITUTION:A casting mold 3 provided with a heat insulating sleeve 4 is covered by a heat insulating cover 11 provided with a blowing port 9 for dehydrated air and a discharging part 10 for the atmosphere in the casting mold. The dehydrated air of a high temp. is blown into the mold 3 to substitute the atmosphere in the casting mold with said air. As a result, the partial pressure of hydrogen in the atmosphere in the casting mold is decreased with an increase in the volume of the air to be blown from the same state as in the conventional casting mold wherein the substitution with the air is hardly performed. The concn. of the hydrogen in the molten steel is thereby decreased. As a result, a unidirectionally solidified steel ingot obviating the generation of the blowholes which are not press-stuck in a rolling stage is obtd. The air to be blown is preferably of >=0.1Nm<3>/m<3>.sec flow rate and >=400 deg.C.