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:
Feb. 13, 2018

Filed:

Feb. 06, 2013
Applicant:

Kobe Steel, Ltd., Kobe-shi, JP;

Inventors:

Elijah Kakiuchi, Kobe, JP;

Toshio Murakami, Kobe, JP;

Katsura Kajihara, Kobe, JP;

Tatsuya Asai, Kakogawa, JP;

Naoki Mizuta, Kakogawa, JP;

Hideo Hata, Kobe, JP;

Assignee:

Kobe Steel, Ltd., Kobe-shi, JP;

Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
C22C 38/06 (2006.01); C21D 8/00 (2006.01); C21D 8/02 (2006.01); C21D 9/46 (2006.01); C22C 38/58 (2006.01); C22C 38/00 (2006.01); C22C 38/02 (2006.01); C22C 38/04 (2006.01); C22C 38/08 (2006.01); C22C 38/12 (2006.01); C22C 38/16 (2006.01); C22C 38/18 (2006.01);
U.S. Cl.
CPC ...
C21D 8/005 (2013.01); C21D 8/02 (2013.01); C21D 8/0236 (2013.01); C21D 8/0247 (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 38/16 (2013.01); C22C 38/18 (2013.01); C22C 38/58 (2013.01); C21D 2211/001 (2013.01); C21D 2211/002 (2013.01); C21D 2211/005 (2013.01); C21D 2211/008 (2013.01);
Abstract

This high-strength steel sheet contains, in mass %, 0.05 to 0.3% of C, 1 to 3% of Si, 0.5 to 3% of Mn, up to 0.1% (inclusive of 0%) of P, up to 0.01% (inclusive of 0%) of S, 0.001 to 0.1% of Al and 0.002 to 0.03% of N with the balance consisting of iron and unavoidable impurities, and has a microstructure which comprises, in area fraction relative to the microstructure, 40 to 85% of bainitic ferrite, 5 to 20% of retained austenite (γ), 10 to 50% (in total) of martensite and γ, and 5 to 40% of ferrite. The retained austenite (γ) has a C concentration of 0.5 to 1.0 mass %, while the quantity of γpresent in the ferrite grains is 1% or more (in area fraction) relative to the microstructure.


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