Invention Grant
- Patent Title: High-strength cold rolled steel sheet and method for producing the same
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Application No.: US16325299Application Date: 2017-08-29
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Publication No.: US11136644B2Publication Date: 2021-10-05
- Inventor: Yoshie Obata , Katsutoshi Takashima , Takashi Kobayashi , Hiroshi Matsuda
- 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: JPJP2016-168905 20160831
- International Application: PCT/JP2017/030849 WO 20170829
- International Announcement: WO2018/043456 WO 20180308
- Main IPC: C21D9/46
- IPC: C21D9/46 ; C21D8/02 ; C21D6/00 ; C22C38/38 ; C22C38/32 ; C22C38/28 ; C22C38/26 ; C22C38/16 ; C22C38/14 ; C22C38/12 ; C22C38/08 ; C22C38/06 ; C22C38/04 ; C22C38/02 ; C22C38/00 ; C23F17/00 ; B32B15/01 ; C23C2/06 ; C22C38/60 ; C21D8/04 ; C22C38/18 ; C23C2/28 ; C23C2/40 ; C21D1/18 ; C21D1/25 ; C22C18/04 ; C25D3/22

Abstract:
A high-strength cold rolled steel sheet having a specified chemical composition and a method for producing the same. The steel sheet having a microstructure including, in terms of volume fraction, 35% or less of ferrite, 1% or more and 10% or less of retained austenite, 2% or more and 12% or less of as-quenched martensite, and a total of 25% to 70% of bainite and tempered martensite. The microstructure has an average crystal grain diameter of the ferrite: 5.0 μm or less, an average crystal grain diameter of the retained austenite: 2.0 μm or less, an average crystal grain diameter of the as-quenched martensite: 3.0 μm or less, an average crystal grain diameter of the bainite and the tempered martensite phase: 4.0 μm or less, and an average intergrain distance of the as-quenched martensite of 1.0 μm or more.
Public/Granted literature
- US20190203315A1 HIGH-STRENGTH COLD ROLLED STEEL SHEET AND METHOD FOR PRODUCING THE SAME Public/Granted day:2019-07-04
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