Causes and Improvement Measures of Surface Defects of Hot Rolled Strip in Continuous Casting Rolling Production Line

In view of several typical defects on the surface of hot rolled strip in a new multi-mode continuous casting rolling production line of a factory, the surface and section of defects were analyzed by scanning electron microscope and energy spectrum analysis. The results show that the types of defects are abnormal iron oxide scale, silicate inclusion, aluminate inclusion and slag entrapment. Aiming at the problem of abnormal iron oxide scale, the rotation speed of furnace roller of tunnel furnace can be adjusted to eliminate the speed difference between furnace roller and strip steel, and the high-pressure water nozzle for phosphorus removal can be increased. In view of the inclusion defects of silicate and aluminate, the process improvement should be carried out mainly from the aspects of controlling the oxygen content at the end of steelmaking, controlling the amount of aluminum feeding, optimizing the ladle argon blowing process, reasonably adjusting the argon flow rate, appropriately prolonging the weak stirring time, and adding the casting residue of continuous casting ladle. The problem of slag entrapment can be improved by controlling the stopper action stably, reducing the fluctuation of mold liquid level and casting speed.