There are transverse fold marks on the surface of the billet, which are accompanied by transverse cracks in severe cases.
(1) The solidification shell is torn by hanging in the mold. Due to the strong cooling of the mold, the molten steel leaking from the tearing place immediately solidifies and forms fold marks on the surface;
(2) Improper adjustment of crystallizer vibration parameters;
(3) Poor arc alignment between the outlet of the mold and the secondary cooling section;
(4) The mold is poorly lubricated, and the billet shell is bonded to the copper wall.