Invention Grant
- Patent Title: High-strength steel sheet and method for producing same
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Application No.: US16320864Application Date: 2017-08-10
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Publication No.: US11136643B2Publication Date: 2021-10-05
- Inventor: Katsutoshi Takashima , Koichi Taniguchi , Takashi Kobayashi , Hiroshi Matsuda , Rinsei Ikeda
- Applicant: JFE STEEL CORPORATION
- Applicant Address: JP Tokyo
- Assignee: JFE STEEL CORPORATION
- Current Assignee: JFE STEEL CORPORATION
- Current Assignee Address: JP Tokyo
- Agency: Oliff PLC
- Priority: JPJP2016-157759 20160810
- International Application: PCT/JP2017/029034 WO 20170810
- International Announcement: WO2018/030500 WO 20180215
- Main IPC: C21D9/46
- IPC: C21D9/46 ; C21D8/02 ; C22C38/38 ; C22C38/12 ; C22C38/08 ; C22C38/22 ; C22C38/00 ; C22C38/26 ; C22C38/24 ; C22C38/28 ; C22C38/14 ; C22C38/32 ; C22C38/06 ; C22C38/04 ; C22C38/02 ; C23C2/02 ; C23C2/06 ; C23C2/28 ; C21D6/00 ; C21D1/30 ; C22C38/20 ; C22C38/58

Abstract:
A high-strength steel sheet having a specified chemical composition and a method for producing the same. The steel sheet including a multi-phase structure including, by volume fraction, ferrite of 35% to 65%, residual austenite of 7% or less (including 0%), martensite of 20% to 60%, bainite of 20% or less (including 0%), the ferrite having an average crystal grain size of 8 μm or less and an average aspect ratio of 3.5 or less, the martensite having an average crystal grain size of 3 μm or less, and the bainite having an average crystal grain size of 3 μm or less when contained. A standard deviation of Vickers hardness of the steel sheet being 30 or less when measured at 200 μm intervals from a position of 100 μm from a surface to a central portion in a thickness direction of the sheet.
Public/Granted literature
- US20190161822A1 HIGH-STRENGTH STEEL SHEET AND METHOD FOR PRODUCING SAME Public/Granted day:2019-05-30
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