Abstract: A mathematical model of solidification and heat transfer process was established for the Φ600mm round billet of Q345E steel. The result generated by ProCAST was in agreement with the nail test. The simulation results showed: casting temperature had little impact on the surface, central temperature of the round billet and the distribution of solid-liquid phase; as the casting speed increased by 0.02m/min, the surface temperature almost remained unchanged and the mushy zone moved ahead, the distance from the mould to the solidification end increased by around 1.75m; as the specific water flow of secondary cooling zone raised by 0.01L/kg, the surface temperature of secondary cooling zone decreased by about 30℃ and mushy zone moved back slightly, the distance from the mould to the solidification end raised by around 0.3m. Therefore, the proper condition was at T=1539℃, v=0.22m/min and R=0.08L/kg. The practical product of Φ600mm round billet of Q345E steel can reach the national standard, with central shrinkage of 0.5, central porosity of 1.0 and central carbon segregation of ≤1.09.

Key words: Q345E steel, bloom, numerical simulation, solidification rule