METHOD FOR PREVENTING LONGITUDINAL CRACK ON CAST SLAB IN CONTINUOUS CASTING

摘要

PURPOSE:To prevent the development of longitudinal crack in a cast slab by supervising temp. informations at mutually different positions to longitudinal direction and traverse direction of a mold wall and reducing casting velocity until positional distribution of the detected temp. at plural positions to the traverse direction comes to substantially uniform. CONSTITUTION:The temp. at each position in the mold is measured and by discriminating whether abnormal temp. lowering with the lapse of time is developed or not, whether abnormal temp. pattern in positional distribution to the traverse direction of temp. is developed or not, and whether these phenomena at plural positions almost in the same time are detected or not, detection or prediction of the longitudinal crack is executed. The longitudinal crack is developed by uneven flowing of powder into between the mold and molten steel, etc., and by lowering casting velocity, this can be prevented in some degree. Therefore, normally casting is executed at comparatively high velocity, but only at the time of detecting the longitudinal crack, by lowering the casting velocity, the longitudinal crack can be restrained to the min. without excessively lowering to the necessary casting velocity.