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:
Feb. 28, 2017
Filed:
Apr. 03, 2014
Jfe Steel Corporation, Tokyo, JP;
Tatsuya Nakagaito, Tokyo, JP;
Yoshiyasu Kawasaki, Tokyo, JP;
Shinjiro Kaneko, Tokyo, JP;
Saiji Matsuoka, Tokyo, JP;
Yoshitsugu Suzuki, Tokyo, JP;
JFE Steel Corporation, Tokyo, JP;
Abstract
The present invention provides a method for manufacturing a high-strength galvannealed steel sheet. The method includes hot-rolling a slab to produce a hot-rolled sheet having a microstructure in which a total area ratio of bainite and martensite is 80% or more, cold-rolling the hot-rolled sheet to produce a cold-rolled steel sheet, continuously annealing the cold-rolled steel sheet by heating to 750° C. to 900° C. at an average heating rate of 8° C./s or more from 500° C. to an A1 transformation point, holding the steel sheet for 10 seconds or more, and then cooling the steel sheet to a temperature region of 300° C. to 530° C. at an average cooling rate of 3° C./s or more from 750° C. to 530° C., galvanizing the steel sheet, and further coating-alloying the steel sheet in a temperature region of 540° C. to 600° C. for 5 to 60 seconds.