Frishauf, Holtz, Goodman & Chick, P.C.
Method for manufacturing a steel sheet
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 Ar3 transformation point to the Ar3 transformation point +60&deg; 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&deg; C./sec down to a temperature of Ar3 &#8722;30&deg; C. to the Ar1 transformation point; slow cooling or air-cooling the primary-cooled steel sheet at a temperature of the Ar3 transformation point to the Ar1 transformation point at 10&deg; C./sec or less for 2 seconds or more; secondary-cooling the steel sheet after the slow cooling or the air-cooling at 30&deg; C./sec or more; and coiling the secondary-cooled steel sheet at 300&deg; C. or less.
NKK Corporation
C C
C21D C21D
additional inventional
Sadanori Yoshimasa Hiroshi Hiroyasu Toru Yoichi Tadashi
Imada Funakawa Nakata Kikuchi Inazumi Motoyashiki Inoue