| 摘要 |
PROBLEM TO BE SOLVED: To obtain a long service life of a die for forging, regarding the die for forging and a producing method therefor with which the toughness is improved from the inner part to the surface layer part. SOLUTION: On the surface of a small diameter part 32 in a preform body 52 composed of SKH51 (Fe-based alloy), powder of a material containing an element which contains in the SKH51 and does not contribute to the raising of hardness, is applied. W etc., contained in the SKH51 is diffused onto the surface side by performing a heat-treatment to the preform body 52 after applying. As a result, on the surface of the small diameter part 32, a diffusion layer and a concentration-changing part 35 are formed. In the concentration-changing part 35, the content of W etc., is lowest on the uppermost side approached to the diffusion layer and therefore, the toughness at the uppermost side becomes large in comparison with the inner part side. Thereafter, an upper punch 26a for forging, having a prescribed shape can be produced by performing a finish-working. COPYRIGHT: (C)2007,JPO&INPIT
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