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:
Nov. 24, 2015

Filed:

Jun. 03, 2009
Applicants:

Shushi Ikeda, Kobe, JP;

Koichi Makii, Kobe, JP;

Hiroshi Akamizu, Kobe, JP;

Inventors:

Shushi Ikeda, Kobe, JP;

Koichi Makii, Kobe, JP;

Hiroshi Akamizu, Kobe, JP;

Assignee:

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

Attorney:
Primary Examiner:
Int. Cl.
CPC ...
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); C21D 1/20 (2006.01); C21D 8/04 (2006.01); C22C 38/12 (2006.01);
U.S. Cl.
CPC ...
C21D 1/20 (2013.01); C21D 8/0426 (2013.01); C21D 8/0436 (2013.01); C21D 8/0473 (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 38/12 (2013.01); C21D 8/02 (2013.01); C21D 2211/001 (2013.01); C21D 2211/002 (2013.01); C21D 2211/005 (2013.01);
Abstract

A dual phase steel sheet with good bake-hardening properties is provided. The steel sheet is characterized in containing (in terms of percent by mass) C: no less than 0.06% and less than 0.25%; Si+Al: 0.5 to 3%; Mn: 0.5 to 3%; P: no more than 0.15%; and S: no more than 0.02%; and also meeting the following condition (in terms of space factor) that retained austenite is at least 3%, bainite is at least 30%, and ferrite is no more than 50%, and further characterized in differing in stress larger than 50 MPa before and after application of 2% pre-strain and ensuing heat treatment for paint baking at 170° C. for 20 minutes. The steel sheet has well-balanced strength and workability, exhibits good bake-hardening properties at the time of paint baking, and offers good resistance to natural aging.


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