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:
Nov. 16, 2004
Filed:
May. 27, 2003
Tadashi Inoue, Fukuyama, JP;
Yoichi Motoyashiki, Fukuyama, JP;
Hiroyasu Kikuchi, Fukuyama, JP;
Yoshimasa Funakawa, Yokohama, JP;
Hiroshi Nakata, Fukuyama, JP;
Sadanori Imada, Fukuyama, JP;
Toru Inazumi, Ann Arbor, MI (US);
NKK Corporation, Tokyo, JP;
Abstract
A method for manufacturing a steel sheet comprising continuously casting a steel containing 0.04 to 0.2 wt. % C, 0.25 to 2 wt. % Si, 0.5 to 2.5 wt. % Mn, and 0.1 wt. % or less Al to form a slab; hot-rolling by rough-rolling the slab to form a sheet bar and finish-rolling the sheet bar with a reduction in thickness at the final stand of less than 30%, the finish-rolling being completed at a temperature from the Ar transformation point to the Ar transformation point +60° C.; primary-cooling the hot-rolled steel sheet, the primary cooling being started within 1 second after the completion of hot-rolling and conducting the cooling at a cooling speed of higher than 200° C./sec down to a temperature of Ar −30° C. to the Ar transformation point; slow cooling or air-cooling the primary-cooled steel sheet at a temperature of the Ar transformation point to the Ar transformation point at 10° C./sec or less for 2 seconds or more; secondary-cooling the steel sheet after the slow cooling or the air-cooling at 30° C./sec or more; and coiling the secondary-cooled steel sheet at 300° C. or less.