Invention Grant
- Patent Title: High-strength cold-rolled steel sheet with high yield ratio having excellent formability and method for producing the same
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Application No.: US13980981Application Date: 2011-11-30
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Publication No.: US09914988B2Publication Date: 2018-03-13
- Inventor: Katsutoshi Takashima , Yuki Toji , Kohei Hasegawa
- Applicant: Katsutoshi Takashima , Yuki Toji , Kohei Hasegawa
- Applicant Address: JP Tokyo
- Assignee: JFE Steel Corporation
- Current Assignee: JFE Steel Corporation
- Current Assignee Address: JP Tokyo
- Agency: RatnerPrestia
- Priority: JP2011-018191 20110131
- International Application: PCT/JP2011/078222 WO 20111130
- International Announcement: WO2012/105126 WO 20120809
- Main IPC: C22C38/04
- IPC: C22C38/04 ; C21D8/02 ; C22C38/00 ; C22C38/02 ; C22C38/06 ; C22C38/12 ; C22C38/08 ; C22C38/14 ; C22C38/16 ; C22C38/26

Abstract:
Provided are a high-strength cold-rolled steel sheet having excellent formability, excellent ductility, excellent hole expansibility, and high yield ratio and a method for producing the same. The high-strength cold-rolled steel sheet contains 0.05% to 0.15% C, 0.10% to 0.90% Si, 1.0% to 2.0% Mn, 0.005% to 0.05% P, 0.0050% or less S, 0.01% to 0.10% Al, 0.0050% or less N, and 0.010% to 0.100% Nb, which are chemical components, on a mass basis, the balance being Fe and unavoidable impurities; has a microstructure which is a multi-phase structure containing 90% or more of a ferrite phase and 0.5% to less than 5.0% of a martensite phase on a volume fraction basis, the remainder being low-temperature transformation phases; and has a yield ratio of 70% or more.
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