JPS5674304A - Hot rolling method for steel material - Google Patents

Abstract

PURPOSE:To prevent the generation of the surface crack in the rolled steel material, in the direct-feed rolling line, by carrying out the rolling work while applying the pushing force to the rolled material at the brittle temperature region in order to forcibly feed the rolled material into the rolling line, at hot rolling the steel material. CONSTITUTION:The internal unsolidified part 12a of the continuously cast steel billet 12 disappears before arriving at the outelt of the casting machine and the billet 12 completely solidifies. Next, the billet 12 is cut into the slabs 16. The side edges of this slab 16 are heated by the induction heating device 18, and the slab 16 is fed into the reversing mill 20. Hereupon, the rear end of the slab 16 at the hot brittle temperature region is forcibly pushed by the pusher 22 comprising the hydraulic cylinder, etc., for example, and is fed into the rolling mill; hereby, the slab 16 is prevented from the tension acting in the rolling direction. As a result, the generation of the surface carck in the slab 16 to be rolled can be prevented. Besides, it is desirable for the rolled steel material to enter the rolling line directly following to the casting work still being in the state of the high brittle temperature region, and to finish the rolling work still keeping the state of the brittle temperature region, or in the state of the hot deformability recovering region after passing the brittleness recoverying curve as the lower limit of the brittle temperature region.