| 摘要 |
PROBLEM TO BE SOLVED: To provide a steel for cold working which has excellent cold workability (where cracks are not generated in a cold-worked steel component, also, deformation resistance upon working to component hardness is suppressed, and the prolongation of the service life of a die can be attained in particular), and further can secure prescribed hardness and strength after working. SOLUTION: The steel for cold working has a composition satisfying 0.20 to 0.40% C (mass%, the same hereinafter), 0.01 to 0.30% Si, 0.2 to 1.0% Mn,≤0.05% (not including 0%) P,≤0.05% (not including 0%) S, 0.010 to 0.1% Al, and≤0.0070% (not including 0%) N, and the balance iron with inevitable impurities; wherein, when the steel structure is observed at a magnification of 150,000 using a transmission electron microscope, the density of cementite with a grain size of≤50 nm is 5 to 25 pieces/0.25μm<SP>2</SP>, and also, the density of cementite with a grain diameter of >50 nm is≤1 piece/0.25μm<SP>2</SP>. COPYRIGHT: (C)2009,JPO&INPIT
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