40Cr and 0.20C steel in 25 t ladle and 16 t tundish has been studied. The controlling of molten steel superheat was mainly depended on temperature decreasing speed of molten steel as the heat storage process of ladle line came to equilibrium state - temperature decreasing speed of molten steel in ladle ≤l ℃/min and that in tundish ≤0.5 ℃/min; as superheat of molten steel was between 15 T and 35 T
the equiaxial crystal ratio in 200 mm x 200 mm billet was up to 20%-30%
the ratio of casting breaking out ≤0.23%
and it was available to get better quality of billet.