Invention Grant
- Patent Title: High-strength cold-rolled steel sheet having small variations in strength and ductility and manufacturing method for the same
- Patent Title (中): 强度和延展性变化小的高强度冷轧钢板及其制造方法
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Application No.: US14362782Application Date: 2012-12-11
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Publication No.: US09534279B2Publication Date: 2017-01-03
- Inventor: Tomokazu Masuda , Hideo Hata , Katsura Kajihara , Toshio Murakami , Masaaki Miura , Muneaki Ikeda
- Applicant: Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.)
- Applicant Address: JP Kobe-shi
- Assignee: Kobe Steel, Ltd.
- Current Assignee: Kobe Steel, Ltd.
- Current Assignee Address: JP Kobe-shi
- Agency: Oblon, McClelland, Maier & Neustadt, L.L.P.
- Priority: JP2011-274268 20111215; JP2011-274269 20111215
- International Application: PCT/JP2012/082058 WO 20121211
- International Announcement: WO2013/089095 WO 20130620
- Main IPC: C22C38/38
- IPC: C22C38/38 ; C21D8/02 ; C21D9/46 ; C22C38/00 ; C22C38/06 ; C22C38/02 ; C22C38/04 ; C21D8/04 ; C21D1/20 ; C21D1/25 ; C22C38/08 ; C22C38/12 ; C22C38/16

Abstract:
A high-strength cold-rolled steel sheet has a chemical composition including C of 0.05% to 0.30%, Si of greater than 0% to 3.0%, Mn of 0.1% to 5.0%, P of greater than 0% to 0.1%, S of greater than 0% to 0.02%, Al of 0.01% to 1.0%, and N of greater than 0% to 0.01%, in mass percent, with the remainder including iron and inevitable impurities. The steel sheet has a microstructure containing ferrite as a soft primary phase in an area percentage of 20% to 50% with the remainder including tempered martensite and/or tempered bainite as a hard secondary phase. The ferrite grains are adapted to contain cementite particles having an appropriate size in an appropriate number density.
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