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:
Jul. 05, 2022

Filed:

Mar. 30, 2018
Applicant:

Nippon Steel Corporation, Tokyo, JP;

Inventors:

Takafumi Yokoyama, Tokyo, JP;

Kohichi Sano, Tokyo, JP;

Riki Okamoto, Tokyo, JP;

Hiroyuki Kawata, Tokyo, JP;

Eisaku Sakurada, Tokyo, JP;

Yuji Yamaguchi, Tokyo, JP;

Kazuki Shiokawa, Tokyo, JP;

Yuichi Nakahira, Tokyo, JP;

Kohei Ueda, Tokyo, JP;

Masahiro Nakata, Tokyo, JP;

Satoshi Uchida, Tokyo, JP;

Assignee:
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
C22C 38/18 (2006.01); C22C 38/16 (2006.01); C22C 38/14 (2006.01); C22C 38/12 (2006.01); C22C 38/10 (2006.01); C22C 38/08 (2006.01); C22C 38/04 (2006.01); C22C 38/02 (2006.01); C22C 38/00 (2006.01); C23C 2/40 (2006.01); C23C 2/28 (2006.01); B32B 15/01 (2006.01); C21D 6/00 (2006.01); C21D 8/02 (2006.01); C21D 9/46 (2006.01); C22C 38/06 (2006.01); C22C 38/60 (2006.01); C23C 2/06 (2006.01); C22C 38/42 (2006.01); C22C 38/44 (2006.01); C22C 38/46 (2006.01); C22C 38/48 (2006.01); C22C 38/50 (2006.01); C22C 38/52 (2006.01); C22C 38/58 (2006.01); C25D 3/56 (2006.01); C23C 2/26 (2006.01); C23C 30/00 (2006.01); B32B 15/04 (2006.01); B32B 15/18 (2006.01); C21D 8/00 (2006.01); C22C 38/20 (2006.01); C22C 38/34 (2006.01); C22C 38/30 (2006.01); C22C 38/32 (2006.01); C22C 38/40 (2006.01); C22C 38/26 (2006.01); C22C 38/28 (2006.01); C22C 38/38 (2006.01); C22C 38/22 (2006.01); C22C 38/24 (2006.01); C22C 38/54 (2006.01);
U.S. Cl.
CPC ...
C21D 9/46 (2013.01); B32B 15/01 (2013.01); B32B 15/013 (2013.01); B32B 15/04 (2013.01); B32B 15/043 (2013.01); B32B 15/18 (2013.01); C21D 6/001 (2013.01); C21D 6/002 (2013.01); C21D 6/004 (2013.01); C21D 6/005 (2013.01); C21D 6/007 (2013.01); C21D 6/008 (2013.01); C21D 8/005 (2013.01); C21D 8/02 (2013.01); C21D 8/0205 (2013.01); C21D 8/0226 (2013.01); C21D 8/0236 (2013.01); C21D 8/0247 (2013.01); C21D 8/0263 (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 38/10 (2013.01); C22C 38/105 (2013.01); C22C 38/12 (2013.01); C22C 38/14 (2013.01); C22C 38/16 (2013.01); C22C 38/18 (2013.01); C22C 38/20 (2013.01); C22C 38/22 (2013.01); C22C 38/24 (2013.01); C22C 38/26 (2013.01); C22C 38/28 (2013.01); C22C 38/30 (2013.01); C22C 38/32 (2013.01); C22C 38/34 (2013.01); C22C 38/38 (2013.01); C22C 38/40 (2013.01); C22C 38/42 (2013.01); C22C 38/44 (2013.01); C22C 38/46 (2013.01); C22C 38/48 (2013.01); C22C 38/50 (2013.01); C22C 38/52 (2013.01); C22C 38/54 (2013.01); C22C 38/58 (2013.01); C22C 38/60 (2013.01); C23C 2/06 (2013.01); C23C 2/26 (2013.01); C23C 2/28 (2013.01); C23C 2/40 (2013.01); C23C 30/00 (2013.01); C23C 30/005 (2013.01); C25D 3/565 (2013.01); C21D 2211/001 (2013.01); C21D 2211/003 (2013.01); C21D 2211/005 (2013.01); C21D 2211/008 (2013.01); C21D 2211/009 (2013.01); Y10T 428/12674 (2015.01); Y10T 428/12757 (2015.01); Y10T 428/12799 (2015.01); Y10T 428/12951 (2015.01); Y10T 428/12958 (2015.01); Y10T 428/12965 (2015.01); Y10T 428/12972 (2015.01); Y10T 428/12993 (2015.01); Y10T 428/2495 (2015.01); Y10T 428/24983 (2015.01); Y10T 428/26 (2015.01);
Abstract

A steel sheet has a chemical composition with a steel structure containing, by volume fraction, soft ferrite: 0-30%, retained austenite: 3-40%, fresh martensite: 0-30%, pearlite and cementite: 0-10%, and a remainder including hard ferrite. In the steel sheet, a number proportion of retained austenite having an aspect ratio of 2.0 or more in the total retained austenite is 50% or more, and a soft layer having a thickness of 1-100 μm is present. In the soft layer, a volume fraction of ferrite grains having an aspect ratio of less than 3.0 is 50% or more, and a volume fraction of retained austenite is 50% or more of the volume fraction of the retained austenite of the inside of the steel sheet. A peak of an emission intensity at a wavelength indicating Si appears in a range of more than 0.2 μm to 5 μm or less from the surface.


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