| 摘要 |
PROBLEM TO BE SOLVED: To provide a steel for a high strength bolt having excellent delayed fracture resistance and excellent cold workability. SOLUTION: The steel has a composition comprising, by mass, >0.20 to 0.50% C,≤0.50% Si, <0.90% Mn,≤0.015% P,≤0.015% S, 0.05 to 0.50% Cu, 0.02 to 0.30% Ni,≤0.50% Cr, 0.02 to 0.10% Ti and 0.0003 to 0.0050% B, and the balance Fe with impurities, and in which the content of Ni in the impurities is≤0.01%. COPYRIGHT: (C)2006,JPO&NCIPI
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