| 摘要 |
PROBLEM TO BE SOLVED: To improve the strength at an optional portion and the toughness at the other portion in a die for forging composed of Fe-based alloy. SOLUTION: On the surface of a punching-formed part 34 and the end part of a small diameter part 32 of a preform body 52 composed of SKH51 (Fe-based alloy), powder of a material containing an element which improves the hardness of the SKH51, is applied, and on the other hand, on the surface of the barrel part of the small diameter part 32, the powder of the material containing an element which contains in the SKH51 and does not contribute to the raising of hardness, is applied. After applying, a heat treatment is performed to the preform body 52 and thus, in the punching formed part 34 and the end part of the small diameter part 32, a diffusion layer 36a for raising the hardness as coming to the surface layer part, is formed, and in the barrel part of the small diameter part 32, a concentration varied part 37 improving the toughness as coming to the surface layer part, is formed. COPYRIGHT: (C)2007,JPO&INPIT
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