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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 10253389 B1

PDFFull Text
Date of Patent:
Apr. 09, 2019

Filed:

Mar. 17, 2015

High-yield-ratio, high-strength cold-rolled steel sheet and production method therefor

Applicant:

Jfe Steel Corporation, Tokyo, JP;

Inventors:

Katsutoshi Takashima, Chiba, JP;

Kohei Hasegawa, Tokyo, JP;

Assignee:

JFE Steel Corporation, , JP;

Attorney:

DLA Piper LLP (US)

Primary Examiner:

Helene Klemanski

Int. Cl.
CPC ...
C21D 9/46 (2006.01); C21D 1/25 (2006.01); C21D 8/02 (2006.01); C21D 8/04 (2006.01); C22C 38/02 (2006.01); C22C 38/04 (2006.01); C22C 38/06 (2006.01); C22C 38/08 (2006.01); C22C 38/12 (2006.01); C22C 38/14 (2006.01); C22C 38/16 (2006.01); C22C 38/28 (2006.01); C22C 38/38 (2006.01); C22C 38/58 (2006.01); C22C 38/00 (2006.01); C23G 1/00 (2006.01);
U.S. Cl.
CPC ...
C21D 9/46 (2013.01); C21D 8/0226 (2013.01); C21D 8/0236 (2013.01); C21D 8/0263 (2013.01); C21D 8/0273 (2013.01); C21D 8/0278 (2013.01); C21D 8/0473 (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 38/08 (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); C23G 1/00 (2013.01); C21D 1/25 (2013.01); C21D 2211/001 (2013.01); C21D 2211/002 (2013.01); C21D 2211/005 (2013.01); C21D 2211/008 (2013.01);
Abstract

A high-yield-ratio, high-strength cold-rolled steel sheet has a composition containing, in terms of % by mass, C: 0.13% to 0.25%, Si: 1.2% to 2.2%, Mn: 2.0% to 3.2%, P: 0.08% or less, S: 0.005% or less, Al: 0.01% to 0.08%, N: 0.008% or less, Ti: 0.055% to 0.130%, and the balance being Fe and unavoidable impurities. The steel sheet has a microstructure that contains 2% to 15% of ferrite having an average crystal grain diameter of 2 μm or less in terms of volume fraction, 5 to 20% of retained austenite having an average crystal grain diameter of 0.3 to 2.0 μm in terms of volume fraction, 10% or less (including 0%) of martensite having an average grain diameter of 2 μm or less in terms of volume fraction, and the balance being bainite and tempered martensite, and the bainite and the tempered martensite having an average crystal grain diameter of 5 μm or less.

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