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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 10550446 B1

PDFFull Text
Date of Patent:
Feb. 04, 2020

Filed:

Oct. 29, 2015

High-strength steel sheet, high-strength hot-dip galvanized steel sheet, high-strength hot-dip aluminum-coated steel sheet, and high-strength electrogalvanized steel sheet, and methods for manufacturing same

Applicant:

Jfe Steel Corporation, Chiyoda-ku, Tokyo, JP;

Inventors:

Yoshiyasu Kawasaki, Tokyo, JP;

Hiroshi Matsuda, Tokyo, JP;

Takeshi Yokota, Tokyo, JP;

Takako Yamashita, Tokyo, JP;

Kazuhiro Seto, Tokyo, JP;

Assignee:

JFE STEEL CORPORATION, Chiyoda-ku, Tokyo, JP;

Attorney:

Kenja IP Law PC

Primary Examiner:

Vanessa T Luk

Int. Cl.
CPC ...
C22C 38/04 (2006.01); C22C 38/58 (2006.01); C21D 8/02 (2006.01); C22C 38/38 (2006.01); C21D 6/00 (2006.01); C21D 9/46 (2006.01); C23C 2/02 (2006.01); C23C 2/06 (2006.01); C23C 2/12 (2006.01); C23C 2/28 (2006.01); C22C 38/00 (2006.01); C22C 38/14 (2006.01); C22C 38/60 (2006.01); B32B 15/01 (2006.01); C22C 38/02 (2006.01); C22C 38/06 (2006.01); C22C 38/08 (2006.01); C22C 38/12 (2006.01); C22C 38/16 (2006.01); C22C 38/28 (2006.01); C23C 2/40 (2006.01); C23G 1/00 (2006.01); C25D 3/22 (2006.01);
U.S. Cl.
CPC ...
C21D 9/46 (2013.01); B32B 15/012 (2013.01); B32B 15/013 (2013.01); C21D 6/001 (2013.01); C21D 6/002 (2013.01); C21D 6/005 (2013.01); C21D 6/008 (2013.01); C21D 8/0205 (2013.01); C21D 8/0226 (2013.01); C21D 8/0236 (2013.01); C21D 8/0263 (2013.01); C21D 8/0273 (2013.01); C22C 38/00 (2013.01); C22C 38/001 (2013.01); C22C 38/002 (2013.01); C22C 38/005 (2013.01); C22C 38/008 (2013.01); C22C 38/02 (2013.01); C22C 38/04 (2013.01); C22C 38/06 (2013.01); C22C 38/08 (2013.01); C22C 38/12 (2013.01); C22C 38/14 (2013.01); C22C 38/16 (2013.01); C22C 38/28 (2013.01); C22C 38/38 (2013.01); C22C 38/58 (2013.01); C22C 38/60 (2013.01); C23C 2/02 (2013.01); C23C 2/06 (2013.01); C23C 2/12 (2013.01); C23C 2/28 (2013.01); C23C 2/40 (2013.01); C23G 1/00 (2013.01); C25D 3/22 (2013.01); C21D 2211/001 (2013.01); C21D 2211/005 (2013.01); C21D 2211/008 (2013.01);
Abstract

A high-strength steel sheet with excellent formability and high yield ratio that has TS of 980 MPa or more and YR of 68% or more is obtained by providing a predetermined chemical composition and a steel microstructure that contains, in area ratio, 15 to 55% of polygonal ferrite, 8% or more of non-recrystallized ferrite, and 15 to 30% of martensite, and that contains, in volume fraction, 12% or more of retained austenite, in which the polygonal ferrite has a mean grain size of 4 μm or less, the martensite has a mean grain size of 2 μm or less, the retained austenite has a mean grain size of 2 μm or less, and a value obtained by dividing an Mn content in the retained austenite (in mass %) by an Mn content in the polygonal ferrite (in mass %) equals 2.0 or more.

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