PROBLEM TO BE SOLVED: To prevent heat cracks and splits which may occur during cast molding at any sections of a nest or an inner mold between die faces of the nest and a cooling hole formed in the nest.;SOLUTION: A material having metal property is preliminarily provided in the nest 1 before casting molten metal, wherein the material provides a yield strain which becomes larger than a heat strain at the section between the die faces 1s (L=0) of the nest 1 and a position (L+ΔL) and becomes smaller than a heat strain at the section below the position (L+ΔL) by a heat treatment using a salt bath 4, provided that the position (L+ΔL) separated by ΔL from the shortest distance L between the die faces of the nest 1 and the cooling hole 1H is defined to be a boundary. Consequently, the heat shock caused by molten metal at the casted molten-metal side and the stress generated in the nest 1 are alleviated to prevent the nest 1 from heat cracks and splits.;COPYRIGHT: (C)2012,JPO&INPIT
展开▼
