PURPOSE: To reduce the development of porous defect in an ingot by immediately adding electric conductive flux on upper surface of molten steel after casting the molten Cr-Mo steel having high Cr content into a horizontal rotating mold and electric-conducting and heating the top part of the ingot.
CONSTITUTION: The mold 3 is set on a rotating base plate 4 and the molten high Cr-Mo steel containing 5W13wt.% Cr is cast into the mold 3 and just after that, the flux 2 is charged on the molten steel pool 5 and the electricity is conducted and heated with a graphite electrode 1. Then, at the initial stage of electric-conducting for heating, in order to prevent surface solidified skin of the molten steel, the charging power is regulated to the prescribed quantity, and after the initial stage, the charging power is increased by a little. Further, dipping depth of the electrode 1 into slag is increased to the suitable quantity, to increase molten steel supply into developing part of porous defect. By this method, dendritic structure in the molten steel is made to fine and also the development of the porous defect in the high Cr-Mo steel ingot is reduced.
SAITO KENJI
NOZAKI TSUTOMU
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