Invention Grant
- Patent Title: High-strength hot-rolled steel sheet having excellent baking hardenability and low temperature toughness with maximum tensile strength of 980 MPa or more
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Application No.: US14653787Application Date: 2014-02-25
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Publication No.: US10196726B2Publication Date: 2019-02-05
- Inventor: Masafumi Azuma , Hiroshi Shuto , Tatsuo Yokoi , Yuuki Kanzawa , Akihiro Uenishi
- Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATION
- Applicant Address: JP Tokyo
- Assignee: NIPPON STEEL & SUMITOMO METAL CORPORATION
- Current Assignee: NIPPON STEEL & SUMITOMO METAL CORPORATION
- Current Assignee Address: JP Tokyo
- Agency: Birch, Stewart, Kolasch & Birch, LLP
- Priority: JP2013-035597 20130226
- International Application: PCT/JP2014/054570 WO 20140225
- International Announcement: WO2014/132968 WO 20140904
- Main IPC: C22C38/00
- IPC: C22C38/00 ; C23C2/02 ; C21D8/02 ; C23C2/06 ; C22C38/38 ; C22C38/28 ; C22C38/26 ; C21D9/46 ; C22C38/14 ; C22C38/02 ; C22C38/04 ; C22C38/06 ; C22C38/08 ; C22C38/12 ; C22C38/16 ; C22C38/18

Abstract:
Provided is a high-strength hot-rolled steel sheet consisting of, in mass %, C: 0.01% to 0.2%, Si: 0% to 2.5%, Mn: 0% to 4.0%, Al: 0% to 2.0%, N: 0% to 0.01%, Cu: 0% to 2.0%, Ni: 0% to 2.0%, Mo: 0% to 1.0%, V: 0% to 0.3%, Cr: 0% to 2.0%, Mg: 0% to 0.01%, Ca: 0% to 0.01%, REM: 0% to 0.1%, B: 0% to 0.01%, P: less than or equal to 0.10%, S: less than or equal to 0.03%, O: less than or equal to 0.01%, one or both of Ti and Nb: 0.01% to 0.30% in total, and the balance being Fe and inevitable impurities. The steel sheet has a structure in which a total volume fraction of tempered martensite or lower bainite is 90% or more, a dislocation density thereof is greater than or equal to 5×1013 (1/m2) and less than or equal to 1×1016 (1/m2) and 1×106 (numbers/mm2) or more iron-based carbides are included therein.
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