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.
Patent No.:
Date of Patent:
May. 13, 2008
Filed:
Jan. 31, 2005
Masaaki Miura, Kakogawa, JP;
Yoichi Mukai, Kakogawa, JP;
Yoshinobu Omiya, Kakogawa, JP;
Shinji Kozuma, Kakogawa, JP;
Masaaki Miura, Kakogawa, JP;
Yoichi Mukai, Kakogawa, JP;
Yoshinobu Omiya, Kakogawa, JP;
Shinji Kozuma, Kakogawa, JP;
Kobe Steel, Ltd., Kobe-shi, JP;
Abstract
A high-strength cold-rolled steel sheet is disclosed that comprises a steel including C: 0.05 to 0.13 mass %, Si: 0.5 to 2.5 mass %, and Mn: 0.5 to 3.5 mass %, as well as Mo: 0.05 to 0.6 mass % and/or Cr: 0.05 to 1.0 mass %. The steel sheet is of composite structure of a ferrite+a second phase wherein the second phase has an area rate of 30 to 70% and is combined approximately in a shape of a network; a circle-equivalent average ferrite grain size is not more than 10 μm; and a circle-equivalent diameter of ferrite grain aggregate that exists continuously in an area surrounded by the second phase is not more than 3 times of the average ferrite grain size. The steel sheet has a high-strength and satisfies a balance of elongation and stretch flange formability (ratio of hole expansion) at a higher level.