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公开(公告)号:US06537391B2
公开(公告)日:2003-03-25
申请号:US09878409
申请日:2001-06-12
申请人: Kengo Ishige , Tadashi Shibue , Tsutomu Kakinouchi , Fumimaru Kawabata , Osamu Tanigawa , Kiyoshi Uchida , Junichi Kudou
发明人: Kengo Ishige , Tadashi Shibue , Tsutomu Kakinouchi , Fumimaru Kawabata , Osamu Tanigawa , Kiyoshi Uchida , Junichi Kudou
IPC分类号: C23C3800
摘要: A steel has a tensile strength of 850 to 1700 MPa, a yield ratio of at most 80%, and a penetration border energy ratio of at least 2.0 relative to the penetration border energy of a reference steel JIS SS400 (corresponding to ASTM A36) of the same thickness. The steel can be produced by first effecting a heat treatment 1 on an unstable austenitic steel; then effecting, at least once, one or more or any combination of the heat treatment 1 and a heat treatment 2 on the steel; and then finally effecting the heat treatment 2 on the steel. Heat treatment 1 heats the unstable austenitic steel to at least the Ac3 transformation temperature and then water-cools the steel to a temperature below 350° C. Heat treatment 2 heats the steel to a temperature between Ac3 and Ac1 transformation temperatures and then water-cools the steel to a temperature below 350° C.