- Patent Title: Steel sheet, coated steel sheet, method for producing hot-rolled steel sheet, method for producing full hard cold-rolled steel sheet, method for producing steel sheet, and method for producing coated steel sheet
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Application No.: US16087919Application Date: 2017-03-17
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Publication No.: US11060157B2Publication Date: 2021-07-13
- Inventor: Noriaki Kohsaka , Yoshimasa Funakawa
- Applicant: JFE Steel Corporation
- Applicant Address: JP Tokyo
- Assignee: JFE Steel Corporation
- Current Assignee: JFE Steel Corporation
- Current Assignee Address: JP Tokyo
- Agency: Ratnerprestia
- Priority: JPJP2016-070737 20160331
- International Application: PCT/JP2017/010821 WO 20170317
- International Announcement: WO2017/169871 WO 20171005
- Main IPC: C21D8/02
- IPC: C21D8/02 ; C23C2/06 ; C23C2/40 ; C21D9/46 ; C22C38/60 ; C21D7/02 ; C21D7/13 ; C21D1/26 ; C21D6/00 ; C21D8/04 ; C21D1/76 ; C23C2/02 ; C21D9/48 ; C23C2/28 ; C22C38/00 ; C22C38/02 ; C22C38/04 ; C22C38/06 ; C22C38/10 ; C22C38/12 ; C22C38/42 ; C22C38/44

Abstract:
Provided are coated steel sheets, production methods therefor, and so forth, the coated steel sheets having a tensile strength of 440 MPa or more, good formability, and good aging resistance. A steel sheet of the present invention includes a specific component composition and a steel microstructure having an area fraction of a ferrite phase of 80% or more and 95% or less, an area fraction of pearlite of 5% or more and 20% or less, and an average ferrite grain size of 5 μm or more and 20 μm or less, in which in a ferrite grain size histogram, the average grain size of the largest 20% of ferrite grains in terms of grain size is 10 μm or more, and the pearlite has an average lamellar spacing of 200 nm or less, the area fraction, the average ferrite grain size, and the lamellar spacing being determined by microstructure observation.
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