Definition and appearance
Along the casting direction, continuous or intermittent groove-shaped mechanical damage appears on the surface of the billet, especially on the outer arc and side arc of the billet.
Causes and hazards
(1) The high-temperature strength of the billet is low.
(2) Cold steel (especially cold steel caused by steel leakage) is adhered to the foot roller, the second cooling section roller, and the support, causing the billet to be scratched by the cold steel.
(3) The second cooling section roller, the front cutting roller, and the rear cutting roller cannot operate normally, causing the billet to be scratched by the roller.
(4) The billet deviates and is scratched by the guide groove.
(5) There are foreign objects or unevenness on the surface of the straightening roller.
(6) The coating of the crystallizer falls off or is adhered to hard cold steel, slag iron and other foreign objects.
Prevention and elimination methods
(1) Clean the cold steel on the foot roller, the second cooling section roller, and the support before casting to control steel leakage.
(2) Before casting, check the foot roller, the second cooling section roller, the pre-cut roller, and the post-cut roller to ensure their normal operation.
(3) Before casting, check the inner wall of the crystallizer, the nozzle, and the spray pipe to prevent the billet from running off.
(4) Before casting, check the surface condition of the straightening roller to ensure that it is smooth and free of foreign matter.
