| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing a case hardening steel having excellent cold workability in which, even when being subjected to working at a high reduction of area in wire drawing, coarsening of crystal grains after heat treatment is suppressed, and which is optimum for producing a bolt or the like. SOLUTION: A steel having a composition satisfying, by mass, 0.10 to 0.25% C,≤0.5% (exclusive of 0%) Si, 0.3 to 1.0% Mn,≤0.03% (including 0%) P,≤0.03% (including 0%) S, 0.3 to 1.5% Cr, 0.02 to 0.1% Al, 0.005 to 0.02% N, and the balance iron with inevitable impurities is used and is subjected to hot finish rolling or hot finish forging at 700 to <850°C, is thereafter cooled to 600°C at a cooling rate of≤0.5°C/sec, and is successively made to cool to a room temperature, thus the reduction of area in wire drawing performed after that is suppressed to <20%. COPYRIGHT: (C)2006,JPO&NCIPI
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