| 摘要 |
PROBLEM TO BE SOLVED: To provide a high strength steel excellent in delayed fracture resistance, having a tensile strength of≥1,500 MPa and suitable for automotive parts, various industrial machine parts, etc., and a method for manufacturing the same. SOLUTION: The high strength steel consists of, by mass, >0.4 to 0.6% C, <0.2% Si, 0.1-1.0% Mn, >5 to 12% Ni, 0.01-0.1% sol. Al, 0.001-0.1% Ti,≤0.02% N,≤0.01% P,≤0.01% S, one or more selected from 0.1-1% Cu, 0.1-1% Cr, 0.02-1% Mo, 0.0001-0.005% B, 0.0005-0.005% Ca and 0.0005-0.005% Mg, and the balance Fe with inevitable impurities. The steel preferably has an old austenite grain size of≤15μm. COPYRIGHT: (C)2006,JPO&NCIPI
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