Causes of cracks in continuous casting slab 1. The main cause of longitudinal crack is too high molten steel temperature or too fast drawing speed. Because it

Causes of cracks in continuous casting slab

1. The main cause of longitudinal crack is too high molten steel temperature or too fast drawing speed. Because it is difficult to make the mold cool evenly, the stress is always large or small. When the temperature of molten steel is high, the billet shell is thin and the strength is low. Small stress will tear the billet shell and cause longitudinal crack. High drawing speed is the same as high temperature.

2. The tundish nozzle and crystallizer fitting nozzle are misaligned or the casting nozzle is deformed, and the steel flow is offset. On the side close to the steel flow, the growth of the billet shell slows down, the billet shell thins, resulting in cracks, and even the phenomenon of steel leakage caused by the direct scouring of the billet shell by the steel flow.

3. Insufficient cooling water of crystallizer accessories, low flow rate of water joint, local boiling of cooling water or uneven distribution of water jacket water flow will cause uneven cooling and cause cracks.

4. The use time of crystal accessories is too long, and the copper pipe is seriously damaged, worn and deformed. In particular, the inverted taper becomes smaller, the air gap between shell and wall increases, the heat transfer is blocked, and cracks are easy to occur.

At the same time, it should also be noted that the fluidity of molten steel decreases rapidly with the decrease of temperature. The molten steel has low temperature and high viscosity. It is easy to cause steel condensation at the mold nozzle, resulting in freezing death and blockage of the nozzle. This kind of nozzle blockage mostly occurs in the cold tundish of the first furnace, ladle change and ladle table waiting for too long.