PURPOSE: To stably form a defectless unidirectionally solidified steel ingot by preventing the solidification from the side walls of a casting mold in the stage of forming the steel ingot by pouring a molten steel into the casting mold consisting of an ingot mold stool and a molding flask body coated with a heat insulating material on the inside wall and solidifying the molten metal.
CONSTITUTION: The casting mold is constituted of the ingot mold stool 1 and the casting wall 2 coated with the heat insulating material on the inside wall. An exothermic casting mold 14 is set to the upper part of the side wall and top part of the casting mold. The mold 14 is then energized to hold or heat the shoulder part of the casting mold and at the same time the molten steel 4 is introduced from a pouring pipe 11 through a runner 13 into the casting mold, by which the molten steel is solidified and the steel ingot is formed. The defectless unidirectionally solidified steel ingot which has the nearly complete unidirectionally solidified structureand is substantially free from defects such as segregation ghosts is thereby produced and therefore the steel material having excellent characteristics even at a relatively low forging ratio of about 2 forging ratio is obtd.
KODAMA HIDEYO
UCHIDA TOSHIO
KAJIWARA HIDEFUMI
SHIMIZU MASAMI
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