| 摘要 |
PURPOSE:To prevent the un-press welding in the central part of a steel ingot and to prevent surface cracking by subjecting the steel ingot heated in a heating furnace or soaking pit to quick cooling by a refrigerant to decrease the temp. difference between the surface layer and the central part to a prescribed temp. or below, then blooming the ingot. CONSTITUTION:A bloom which is drawn from a cooled casting mold of a continuous casting device and is cut to an adequate length is immediately transferred to the heating furnace or soaking pit. The central part temp. TCO is in the state of the temp. higher than the surface layer temp. TSO at this time. The central temp. TC falls once and rises again during the time when the steel ingot is heated in the heating furnace, etc., until the surface layer temp. TS attains the prescribed temp. The steel ingot is ejected from the heating furnace and is immersed into a cooling water tank at the point of the time t1 when the temp. difference between the surface layer part and the central part is DELTAT1. The surface layer part is shrunk by such quick cooling. The pores, etc., interposed in the central part are press-welded when the blooming is started at the point of the time when the temp. difference DELTAT3 between the surface layer part and the central part decreases to the prescribed temp. difference or below. The density in the central part is thereby increased, by which the un-press welding is prevented and the high-strength slab is obtd. |
