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:
Mar. 25, 2025

Filed:

Dec. 19, 2019
Applicant:

Jfe Steel Corporation, Tokyo, JP;

Inventors:

Takuya Hirashima, Tokyo, JP;

Yuma Honda, Tokyo, JP;

Akinori Nakamura, Tokyo, JP;

Shinjiro Kaneko, Tokyo, JP;

Assignee:
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
C21D 9/46 (2006.01); C21D 8/02 (2006.01); C22C 38/00 (2006.01); C22C 38/02 (2006.01); C22C 38/04 (2006.01); C22C 38/06 (2006.01); C22C 38/22 (2006.01); C22C 38/24 (2006.01); C22C 38/26 (2006.01); C22C 38/28 (2006.01); C22C 38/32 (2006.01); C22C 38/42 (2006.01); C23C 2/02 (2006.01); C23C 2/06 (2006.01); C23C 2/28 (2006.01); C23C 2/40 (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 8/0284 (2013.01); C22C 38/001 (2013.01); C22C 38/002 (2013.01); C22C 38/02 (2013.01); C22C 38/04 (2013.01); C22C 38/06 (2013.01); C22C 38/22 (2013.01); C22C 38/24 (2013.01); C22C 38/26 (2013.01); C22C 38/28 (2013.01); C22C 38/32 (2013.01); C22C 38/42 (2013.01); C23C 2/02 (2013.01); C23C 2/022 (2022.08); C23C 2/06 (2013.01); C23C 2/28 (2013.01); C23C 2/29 (2022.08); C23C 2/40 (2013.01); C21D 2211/005 (2013.01); C21D 2211/008 (2013.01);
Abstract

A high-strength steel sheet having a low yield ratio and a method for producing the same. The high-strength steel sheet has a specified chemical composition and a microstructure in which ferrite is present as a major phase, and martensite is present in an area fraction of 10% or greater and less than 50% relative to an entire area of the microstructure. The martensite has an average grain diameter of 3.0 μm or less, in an entirety of the martensite, a proportion of martensite having an aspect ratio of 3 or less is 60% or greater, and the martensite having an aspect ratio of 3 or less has a carbon concentration of 0.30% or greater and 0.90% or less in mass %.


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