Invention Grant
- Patent Title: Hot-pressed member and method for manufacturing same, and cold-rolled steel sheet for hot pressing and method for manufacturing same
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Application No.: US16619814Application Date: 2018-03-30
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Publication No.: US11111558B2Publication Date: 2021-09-07
- Inventor: Katsutoshi Takashima , Takashi Kobayashi , Yoshimasa Funakawa , Seiji Nakajima
- Applicant: JFE STEEL CORPORATION
- Applicant Address: JP Chiyoda-ku Tokyo
- Assignee: JFE STEEL CORPORATION
- Current Assignee: JFE STEEL CORPORATION
- Current Assignee Address: JP Chiyoda-ku Tokyo
- Agency: Kenja IP Law PC
- Priority: WOPCT/JP2017/024259 20170630
- International Application: PCT/JP2018/013720 WO 20180330
- International Announcement: WO2019/003541 WO 20190103
- Main IPC: B32B15/01
- IPC: B32B15/01 ; C21D9/48 ; C21D6/00 ; C21D8/04 ; C22C38/00 ; C22C38/02 ; C22C38/06 ; C22C38/08 ; C22C38/22 ; C22C38/24 ; C22C38/26 ; C22C38/28 ; C22C38/32 ; C22C38/38 ; C22C38/60 ; C23C2/06 ; C23C2/12 ; C23C2/40

Abstract:
Disclosed is a hot-pressed member that can exhibit very high tensile strength after hot pressing as high as TS: 1780 MPa or more, and excellent resistance to resistance welding cracking by properly adjusting its chemical composition and its microstructure such that a prior austenite average grain size is 7.5 μm or less, a volume fraction of martensite is 95% or more, and at least 10 Nb-based and Ti-based precipitates having a grain size of less than 0.10 μm are present on average per 100 μm2 of a cross section parallel to a thickness direction of the member within a range of 100 μm or less in the thickness direction from the surface of the member, and such that a B concentration in prior austenite grain boundaries is at least 3.0 times a B concentration at a position 5 nm away from the grain boundaries.
Information query