| 摘要 |
PROBLEM TO BE SOLVED: To provide hot tool steel having improved toughness, and to provide its production method. SOLUTION: Regarding the hot tool steel, in hot tool steel comprising, by mass, 0.2 to 0.7% C and 0.5 to 7.0% Cr, the content of Al is regulated to≤0.04%, and also, the degree in the segregation of Cr in the matrix composition lies within±0.2 mass%. Regarding the hot tool steel, preferably, the content of Al is regulated to≤0.015%, or further, the number of aluminum oxides with the maximum diameter of≤5μm observed in the cross-sectional structure is≤2,500 (inclusive of zero) pieces/mm<SP>2</SP>. In the method for producing the hot tool steel, a steel ingot obtained by a remelting method and having a composition comprising, by mass, 0.2 to 0.7% C and 0.5 to 7.0% Cr, and in which the content of Al is regulated to≤0.04% and/or a steel slab obtained by subjecting the steel ingot to hot working are/is subjected to homogenizing heat treatment. COPYRIGHT: (C)2006,JPO&NCIPI
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