PURPOSE: To prevent sticking of slag to the crazing on the inside surface of a casting mold for making ingot and deterioration of the quality of the steel ingot cast in the succeeding batch by the effect of the slag by coating and packing a repair meterial consisting principally of expandable graphite into the crazing.
CONSTITUTION: The molten steel 16 in a ladle 14 is cast by bottom pouring into plural pieces of radially erected casting molds via a pouring pipe 20 and a runner 22. A crazing 28 arises on the outside surface of the molds 10 owing to thermal fatigue upon repetitive use. Molten slag intrudes into the crazing 28 and remains there. Such slag contacts the molten steel to be cast in the next casting and there is the possibility of changing the compsn. of the molten steel and making the steel ingot rejective. Expandable graphite 30 consisting of laminar carbon in which oxygen is trapped is coated and packed into the crazing 28 in this case. The graphite 30 expands to prohibit intrusion and sticking of the molten slag in the stage of the next casting and therefore the contamination of the steel ingot by the slag is obviated in the succeeding casting and the steel ingot having always the target quality is obtd.
OOTSUKA DENJIROU
INABA HIDEAKI
