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The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.

The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.

Patent No.:

US 11208709 B1

PDFFull Text
Date of Patent:
Dec. 28, 2021

Filed:

Feb. 21, 2018

High-strength steel sheet and manufacturing method therefor

Applicant:

Jfe Steel Corporation, Tokyo, JP;

Inventors:

Lingling Yang, Tokyo, JP;

Noriaki Kohsaka, Tokyo, JP;

Tatsuya Nakagaito, Tokyo, JP;

Assignee:

JFE STEEL CORPORATION, Tokyo, JP;

Attorney:

RatnerPrestia

Primary Examiner:

Jenny R Wu

Int. Cl.
CPC ...
C22C 38/04 (2006.01); C22C 38/02 (2006.01); C22C 38/00 (2006.01); C22C 38/06 (2006.01); C22C 38/08 (2006.01); C22C 38/10 (2006.01); C22C 38/12 (2006.01); C22C 38/14 (2006.01); C22C 38/16 (2006.01); C22C 38/32 (2006.01); C22C 38/60 (2006.01); C21D 8/02 (2006.01); C23C 2/00 (2006.01);
U.S. Cl.
CPC ...
C22C 38/04 (2013.01); C21D 8/0205 (2013.01); C21D 8/0226 (2013.01); C21D 8/0236 (2013.01); C21D 8/0273 (2013.01); C22C 38/002 (2013.01); C22C 38/005 (2013.01); C22C 38/008 (2013.01); C22C 38/02 (2013.01); C22C 38/06 (2013.01); C22C 38/08 (2013.01); C22C 38/10 (2013.01); C22C 38/12 (2013.01); C22C 38/14 (2013.01); C22C 38/16 (2013.01); C22C 38/32 (2013.01); C22C 38/60 (2013.01); C23C 2/00 (2013.01); C21D 2211/002 (2013.01); C21D 2211/005 (2013.01); C21D 2211/008 (2013.01);
Abstract

Provided are a high-strength steel sheet having a yield strength of 550 MPa or higher and having a small amount of springback and width-direction uniformity in material properties as well as a manufacturing method therefor. The high-strength steel sheet has a yield strength (YP) of 550 MPa or higher and has a specific component composition and a microstructure containing a ferrite phase, 40 to 70% of a martensite phase in area ratio, and 5 to 30% of a bainite phase in area ratio, where: an average grain size of the martensite phase is 2 to 8 μm and an average grain size of the ferrite phase is 11 μm or less on a cross-section in the thickness direction and in a direction orthogonal to a rolling direction; and the average grain size of the ferrite phase is 3.0 times or less the average grain size of martensite.

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