METHOD FOR PREVENTING SOLID FIN FROM REMELTING IN VACUUM INGOT MANUFACTURING METHOD BY INJECTING MAGNESIUM OXIDE POWDER INTO INGOT MOLD WHEN CASTING LARGE INGOT

摘要

PURPOSE: To develop a method for effectively blocking quality deterioration of cast ingot generated as the remelted solid fin is remained in the ingot mold after solid fin is remelted in molten steel solidified in an ingot mold. CONSTITUTION: In a method for casting a large ingot(3) by a vacuum ingot manufacturing method, the method for preventing solid fin from remelting in the vacuum ingot manufacturing method comprises first step of injecting molten steel into an ingot mold(1) through a molten steel injection port(2) in the state that the ingot mold and the periphery of the ingot mold are maintained under the vacuum conditions; second step of covering the upper surface of molten steel with the heat reserving material by promptly injecting a heat reserving material(4) into the ingot mold in the vacuum state when the first step is completed; third step of covering a refractory material(5) on the circumference of refractory bricks on the mold inner wall around the upper surface of molten steel; and fourth step of releasing vacuum and solidifying molten steel after completing the third step.