| 摘要 |
PROBLEM TO BE SOLVED: To obtain a hardening-treatment method, in which an ultra-hardened layer which is hardened to the maximum H880 in Shore hardness can be formed for a high carbon steel material. SOLUTION: A fine pearlitic metallic structure generated with the hardening heat-treatment, is further made ultra-fine by including: a hardening heat-treatment process in which the surface of the high carbon steel material containing 0.5-1.0 wt.% carbon is subjected to heat treatment, thereby the pearlitic structure is made fine and hardened to such an extent that the surface hardness is Hs 45-60 in Shore hardness; a pressing process in which the surface is recessed by pressing; a cutting process for cutting the projected part formed when the material surface is plastically deformed in the pressing process; a hardened layer forming process in which the ultra-hardened layer to be further hardened plus Hs 10-20 in the Shore hardness is formed on the surface by allowing plastical deformation by striking the surface hardened in the hardening heat-treatment process with a mechanical means, so that the fine pearlitic metallic structure in the range of 1 mm or more depth from the surface is further made fine; and a cutting process for cutting the projected part formed when the plastic deformation is performed in the hardened layer forming process. COPYRIGHT: (C)2008,JPO&INPIT
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