| 摘要 |
PROBLEM TO BE SOLVED: To obtain a sintered stainless steel having stable dimensional precision and reduced lowering of strength, in spite of applying a nitriding treatment to the necessary part on the surface, by performing the nitriding treatment for the sintered stainless steel which can not seal the hole with a steam-treatment, by using a method for efficiently and effectively restraining the nitriding in the inner part. SOLUTION: The sintered steel material is subjected to the heat-treatment under high temperature having the nitriding-treatment temperature or higher to generate the nitriding restraining film 3 on the surface 1a of the steel and on the surface layer of the inside hole 2 communicating with the outer part, and successively, the nitriding-restraining film 3 in the necessary part on the surface is removed and thereafter, the nitriding layer is generated at the part with the nitriding-restraining film removed, by applying the nitriding-treatment. COPYRIGHT: (C)2008,JPO&INPIT
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