- Patent Title: High-strength steel sheet having excellent moldability and impact resistance, and method for manufacturing high-strength steel sheet having excellent moldability and impact resistance
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Application No.: US17312871Application Date: 2018-12-11
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Publication No.: US11885025B2Publication Date: 2024-01-30
- Inventor: Hiroyuki Kawata , Eisaku Sakurada , Kohichi Sano , Takafumi Yokoyama
- Applicant: NIPPON STEEL CORPORATION
- Applicant Address: JP Tokyo
- Assignee: NIPPON STEEL CORPORATION
- Current Assignee: NIPPON STEEL CORPORATION
- Current Assignee Address: JP Tokyo
- Agency: Birch, Stewart, Kolasch & Birch, LLP
- International Application: PCT/JP2018/045552 2018.12.11
- International Announcement: WO2020/121418A 2020.06.18
- Date entered country: 2021-06-10
- Main IPC: C23C2/06
- IPC: C23C2/06 ; C21D8/02 ; C21D9/46 ; C22C38/00 ; C22C38/02 ; C22C38/04 ; C22C38/06 ; C23C2/40 ; C23C2/28 ; C23C2/26

Abstract:
A high-strength steel sheet includes a chemical composition including: by mass %, C: 0.080 to 0.500%, Si: 2.50% or less, Mn: 0.50 to 5.00%, P: 0.100% or less, S: 0.0100% or less, Al: 0.001 to 2.500%, N: 0.0150% or less, O: 0.0050% or less, and the balance: Fe and inevitable impurities. The high-strength steel sheet satisfying a predetermined formula has a microstructure in a region from ⅛t to ⅜t from a steel sheet surface. The microstructure includes: by volume %, 20% or more of acicular ferrite, 20% or more of an island-shaped hard structure including residual austenite, 2% to 25% of residual austenite, and 20% or less of aggregated ferrite.
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