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. 11, 2014
Filed:
Jul. 27, 2010
Junichiro Hirasawa, Chiba, JP;
Naoto Yoshimi, Hiroshima, JP;
Hiroki Nakamaru, Chiba, JP;
Kohei Hasegawa, Hiroshima, JP;
Hideyuki Tsurumaru, Hiroshima, JP;
Keita Yonetsu, Okayama, JP;
Hideyuki Takahashi, Hiroshima, JP;
Masato Sasaki, Hiroshima, JP;
Junichiro Hirasawa, Chiba, JP;
Naoto Yoshimi, Hiroshima, JP;
Hiroki Nakamaru, Chiba, JP;
Kohei Hasegawa, Hiroshima, JP;
Hideyuki Tsurumaru, Hiroshima, JP;
Keita Yonetsu, Okayama, JP;
Hideyuki Takahashi, Hiroshima, JP;
Masato Sasaki, Hiroshima, JP;
JFE Steel Corporation, Tokyo, JP;
Abstract
A method for the manufacturing of high strength cold rolled steel sheets includes continuously annealing a cold rolled steel sheet that has a composition containing C: 0.05-0.3% mass, Si: 0.6-3.0% mass, Mn: 1.0-3.0% mass, P: ≦0.1% mass, S: ≦0.02% mass, Al: 0.01-1% mass, N: ≦0.01% mass, and Fe and inevitable impurities: balance, in a manner such that the cold rolled steel sheet is heated in a furnace using an oxidizing burner to a steel sheet temperature of ≧700° C., then soak-annealed in a reducing atmosphere furnace at 750-900° C., then cooled so the average cooling rate between 500° C. and 100° C. is ≧50° C./s. High-Si cold rolled steel sheets with high strength and good phosphatability while containing Si≧0.6% are obtained without controlling conditions so as to increase the dew point in the reducing atmosphere in the soaking furnace or to increase the vapor hydrogen partial pressure ratio.