PRODUCTION OF STEEL INGOT

PURPOSE:To produce a steel ingot having no internal defects such as segregation and loose structure by positioning an internally sound billet which is beforehand cleaned of the surface in a casting mold, and charging molten steel into the mold while bubbling the surface of the billet with gas thereby casting the ingot. CONSTITUTION:An internally sound billet or steel plate 5 which is beforehand cleaned of the surface is fixed in the central part of a casting mold by a weight 6 for supporting. The inside of the mold 1 is under neutral atmosphere formed of the inert gas blown through an inert gas blow pipe 12 prior to the commencement of casting, then the casting through a casting port 4 is started. When the melt level arrives at the intermediate position between a molding board 8 and the bottom of the billet 5 to be embedded by casting, the bubbling of an inert gas 9 is started from a gas blowing hole 10 and the casting through the port 4 is continued. The part of the billet 5 in contact with the molten steel 7 at the bottom and over entire side surface thereof is washed by the gas bubbling whereby the solidification is progressed. The gas bubbling is executed right after the end of the casting. The internally sound steel ingot is thus obtd.