| 摘要 |
PROBLEM TO BE SOLVED: To provide a steel for structural use combining excellent cold forgeability and chip-breakability. SOLUTION: The steel for structural use having excellent cold forgeability and chip-breakability has a composition comprising, by mass, 0.1 to 1% C, 0.5 to 0.2% Si, 0.1 to 1% Mn, 0.03 to 0.1% S,≤0.0005% Al, 0.001 to 0.01% Ti, 0.001 to 0.005% O and 0.01 to 0.05% N, and the balance Fe with inevitable impurities. Also, in the steel structure after cold forging, the number of sulfide-based inclusions 1 parted to≥3 pieces to the cogging direction, and in which the respective length in the cogging direction is≤20μm covers≥40% to the whole number of the sulfide-based inclusions in the polished face. COPYRIGHT: (C)2006,JPO&NCIPI
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