Harm of too high temperature: when molten steel out of cooper mold, the billet shell is thin and easy to break out; The accelerated erosion of refractory can easily lead to out of control of casting flow and reduce the casting safety; The addition of non-metallic inclusions affects the internal quality of slab; The columnar crystal of billet is developed; The central segregation is aggravated, which is easy to produce centerline cracks.

Harm of too low molten steel temperature: nozzle blockage and casting interruption are easy to occur; Blister, slag inclusion, crack and other defects are easy to occur on the surface of continuous casting; Non metallic inclusions are not easy to float up, which affects the internal quality of slab.

Temperature control of molten steel in ladle: strictly control the tapping temperature according to the smelting steel grade to make it change in a narrow range; Secondly, the temperature drop from tapping, ladle, ladle transportation and the whole process of entering the tundish should be greatly reduced.