The occurred surface crack of products rolled from 0380 mm high carbon steel ball steel continuous casting round bloom has been statistcally analyzed. The results show that there is a longitudinal crack on the surface of the continuous casting round bloom after shot peening

which is mainly caused by the uneven cooling of the molten steel in the mold. By adjusting the taper of the crystallizer copper tube from 0.45%/m to 0.63%/m

the 1 300 °C viscosity of mold slag is reduced from 0. 60 Pa • s to 0. 50 Pa ・s

and the flux rate of the mold shield slag at 1300 °C is adjusted from 36s to 49s

secondary cooling water ratio decreasing from 0. 30 L/kg to 0.25 L/kg

the four-sided cooling of the second cooling section is changed to eight-sided cooling

the surface longitudinal cracks of the large-size steel ball steel billets and rolled materials are effectively reduced

and the surface inspection qualified rate of the rolled material increases to more than 95%.