Abstract: In this paper, the formation mechanism of the starting slab surface longitudinal cracks were discussed from a mechanical point of view. Combined with Shougang Jingtang United Iron & Steel Co., Ltd. slab production practices, the  apply effects of  mold  thermal images   in predicting and controlling cracks in the slab  were  analyzed. Through the analysis of the field data,  the breakout crack propagation mechanism   was  illustrated. When cracks in the mold, the heat can be seen on the map as a slight temperature drop phenomenon,  and  the emergence of  vertical cracks always with longitudinal depression  was  briefly described.

Key words: continuous casting, mould, shell rupture, longitudinal crack