| 摘要 |
PURPOSE:To prevent surface crack and edge crack in direct feed rolling or direct rolling by once subjecting a steel ingot or billet to force cooling only at the transverse ends thereof then reheating the transverse ends and rolling the ingot or billet under the conditions under which the shape ratio thereof attains a specific value. CONSTITUTION:Only the transverse ends of the steel ingot or billet in the direct feed rolling or direct rolling are once forcibly cooled down to the Agamma1 transformation point or below and thereafter the transverse ends are reheated. The ingot or billet is then rolled under the conditions under which the shape ratio (m) defined by the equation attains >=1. In the equation, R: the radium of a rolling roll, h1, the material thickness on the inlet side of the roll, h2: the material thickness on the outlet wide of the roll. Since only the transverse ends are first cooled down to the Agamma1 transformation point or below, the edge crack is prevented. The quantity of the eat required for the reheating is small as only the transverse ends are forcibly cooled with water, etc. The surface crack is prevented as well by the rolling with the controlled shape ratio (m). |
