logo

For the Inventor, By the Inventor

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 11401569 B1

PDFFull Text
Date of Patent:
Aug. 02, 2022

Filed:

Oct. 29, 2018

High-strength cold-rolled steel sheet and method for manufacturing same

Applicant:

Jfe Steel Corporation, Tokyo, JP;

Inventors:

Seigo Tsuchihashi, Tokyo, JP;

Hidekazu Minami, Tokyo, JP;

Takashi Kobayashi, Tokyo, JP;

Assignee:

JFE STEEL CORPORATION, Tokyo, JP;

Attorney:

Kenja IP Law PC

Primary Examiner:

Seth Dumbris

Int. Cl.
CPC ...
B32B 15/00 (2006.01); C21D 8/02 (2006.01); C21D 9/46 (2006.01); C22C 38/00 (2006.01); C22C 38/02 (2006.01); C22C 38/04 (2006.01); C22C 38/06 (2006.01); C22C 38/10 (2006.01); C22C 38/12 (2006.01); C22C 38/14 (2006.01); C22C 38/20 (2006.01); C22C 38/32 (2006.01); C22C 38/60 (2006.01);
U.S. Cl.
CPC ...
C21D 8/0236 (2013.01); C21D 8/0226 (2013.01); C21D 9/46 (2013.01); C22C 38/001 (2013.01); C22C 38/002 (2013.01); C22C 38/005 (2013.01); C22C 38/02 (2013.01); C22C 38/04 (2013.01); C22C 38/06 (2013.01); C22C 38/105 (2013.01); C22C 38/12 (2013.01); C22C 38/14 (2013.01); C22C 38/20 (2013.01); C22C 38/32 (2013.01); C22C 38/60 (2013.01); C21D 2211/001 (2013.01); C21D 2211/005 (2013.01); C21D 2211/008 (2013.01);
Abstract

Provided is a high-strength steel sheet having a tensile strength (TS) of 750 MPa or more and excellent in ductility and stretch flangeability, in which the steel sheet has a predetermined chemical composition and a microstructure containing, in area ratio, ferrite: 50% to 90%, quenched martensite: 1% to 8%, tempered martensite: 3% to 40%, and retained austenite: 6% to 15%, the quenched martensite has an average grain size of 2.5 μm or less, the quenched martensite has an average circularity index of 0.50 or more, the circularity index being defined as 4 πM/D, where D is a perimeter of the quenched martensite and M is an area of the quenched martensite, and the steel sheet has a ratio of an area ratio of the quenched martensite fto a total area ratio of the quenched martensite and the tempered martensite f, f/f, of 50% or less.

Find Patent Forward Citations

Loading…