- 专利标题: HIGH-STRENGTH HOT-ROLLED STEEL SHEET HAVING SUPERIOR PUNCHABILITY AND METHOD FOR PRODUCING SAME
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申请号: EP11825306.1申请日: 2011-09-15
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公开(公告)号: EP2617851B1公开(公告)日: 2018-07-11
- 发明人: NAKAJIMA, Katsumi , SAITO, Hayato , FUNAKAWA, Yoshimasa , MORIYASU, Noriaki , MURATA, Takayuki
- 申请人: JFE Steel Corporation
- 申请人地址: 2-3, Uchisaiwaicho 2-chome Chiyoda-ku Tokyo 100-0011 JP
- 专利权人: JFE Steel Corporation
- 当前专利权人: JFE Steel Corporation
- 当前专利权人地址: 2-3, Uchisaiwaicho 2-chome Chiyoda-ku Tokyo 100-0011 JP
- 代理机构: Hoffmann Eitle
- 优先权: JP2010210190 20100917
- 国际公布: WO2012036308 20120322
- 主分类号: C22C38/00
- IPC分类号: C22C38/00 ; B21B3/00 ; C21D9/46 ; C22C38/14 ; C22C38/58
摘要:
A high strength hot rolled steel sheet having excellent blanking workability is provided. The composition contains C: 0.050 to 0.15%, Si: 0.1 to 1.5%, Mn: 1.0 to 2.0%, P: 0.03% or less, S: 0.0030% or less, Al: 0.01 to 0.08%, Ti: 0.05 to 0.15%, N: 0.005% or less, and the balance being Fe and unavoidable impurities. More than 95% of the microstructure is formed of a bainite phase in terms of area fraction. Average grain diameters of the bainite phase in a region having a thickness equal to 1/4 of the sheet thickness from the surface in the sheet thickness direction is 5 µm or less in an L-direction cross section and 4 µm or less in a C-direction cross section. The number of crystal grains extended in the rolling direction and having an aspect ratio of 5 or more is 7 or less in a sheet thickness center portion. As a result, the strength is increased to a tensile strength TS of 780 MPa or more, the blanked edge forms a fine and uniform ductile fracture surface, and a hot rolled steel sheet having excellent properties at blanked edges and excellent blanking workability is obtained.
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