LOWER POURING CASTING METHOD

PROBLEM TO BE SOLVED: To prevent the generation of a surface defect due to hydrogen upon casting using a mold with temperature close to ambient temperature even in the case weather conditions upon the casting are inferior. SOLUTION: In the lower pouring casting method for a steel kind in which a primary crystal is solidified at a γ phase, the changes of ambient temperature, dew point temperature and mold temperature are measured, and the preheating of the mold is performed so as to eliminate moisture trapped in a solidified shell and blow-holed in such a manner that the hydrogen saturation solubility of the solid phase is exceeded. In the case the casting is performed using a mold having temperature close to ambient temperature, even in the case weather conditions upon the casting are inferior, the surface defect of an ingot due to hydrogen can be prevented, and, a linear flaw in the outer face of a product and a gap defect directly below the surface thereof caused by the defect can be reduced. COPYRIGHT: (C)2011,JPO&INPIT