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.

Date of Patent:
Jan. 26, 2021

Filed:

Mar. 21, 2017
Applicant:

Jfe Steel Corporation, Tokyo, JP;

Inventors:

Katsutoshi Takashima, Tokyo, JP;

Chikaumi Sawanishi, Tokyo, JP;

Yoshimasa Funakawa, Tokyo, JP;

Assignee:
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
C22C 38/02 (2006.01); C21D 8/02 (2006.01); C21D 9/46 (2006.01); C22C 38/14 (2006.01); C22C 38/38 (2006.01); C22C 38/16 (2006.01); C22C 38/00 (2006.01); C22C 38/08 (2006.01); C22C 38/50 (2006.01); C22C 38/48 (2006.01); C21D 1/74 (2006.01); C22C 38/04 (2006.01); C22C 38/06 (2006.01); C22C 38/12 (2006.01); C23C 2/02 (2006.01); C23C 2/06 (2006.01); C23C 2/40 (2006.01);
U.S. Cl.
CPC ...
C21D 8/0226 (2013.01); C21D 1/74 (2013.01); C21D 8/0236 (2013.01); C21D 8/0263 (2013.01); C21D 8/0273 (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 38/08 (2013.01); C22C 38/12 (2013.01); C22C 38/14 (2013.01); C22C 38/16 (2013.01); C22C 38/38 (2013.01); C22C 38/48 (2013.01); C22C 38/50 (2013.01); C23C 2/02 (2013.01); C23C 2/06 (2013.01); C23C 2/40 (2013.01); C21D 2211/004 (2013.01); C21D 2211/005 (2013.01); C21D 2211/008 (2013.01); C21D 2211/009 (2013.01);
Abstract

Provided herein is a steel sheet of a specific composition that has a micro structure containing, by volume, 75 to 95% of ferrite, 3 to 15% of martensite, 0.5 to 10% of perlite, 10% or less of unrecrystallized ferrite, and 21.5% or less of a low-temperature occurring phase representing the remainder, and in which the ferrite has an average crystal grain diameter of 6 μm or less, and the martensite has an average crystal grain diameter of 3 μm or less, and an average aspect ratio of 4.0 or less, and in which a Nb base precipitate having an average grain diameter of 0.10 μm or less is contained. The steel sheet has a tensile strength of 590 MPa or more.


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