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:
Mar. 03, 2015
Filed:
Jun. 07, 2010
Tatsuya Nakagaito, Nagoya, JP;
Yoshiyasu Kawasaki, Fukuyama, JP;
Shinjiro Kaneko, Fukuyama, JP;
Saiji Matsuoka, Kurashiki, JP;
Yoshitsugu Suzuki, Fukuyama, JP;
Tatsuya Nakagaito, Nagoya, JP;
Yoshiyasu Kawasaki, Fukuyama, JP;
Shinjiro Kaneko, Fukuyama, JP;
Saiji Matsuoka, Kurashiki, JP;
Yoshitsugu Suzuki, Fukuyama, JP;
JFE Steel Corporation, Tokyo, JP;
Abstract
The present invention provides a high-strength galvanized steel sheet having excellent ductility, stretch flangeability, and fatigue resistance, and a method for manufacturing the same. A high-strength galvannealed steel sheet having excellent formability and fatigue resistance is characterized in that the steel sheet is composed of steel having a composition containing, by % by mass, C: 0.05% to 0.3%, Si: 0.5% to 2.5%, Mn: 1.0% to 3.5%, P: 0.003% to 0.100%, S: 0.02% or less, Al: 0.010% to 0.1%, and the balance including iron and unavoidable impurities, and the steel sheet has a microstructure containing 50% or more of ferrite, 5% to 35% of martensite, and 2% to 15% of pearlite in terms of an area ratio, the martensite having an average gain size of 3 μm or less and an average distance of 5 μm or less between adjacent martensite grains.