Abstract: Based on the heat transfer and phase transformation principles, the ANSYS thermal simulation software was used to establish the finite element mathematical model of the rolled 70Si2MnV steel ball during quenching and heat transfer process, and to obtain the change of temperature field in the steel ball with time. Meanwhile, the phase transformation during quenching process was predicted combiring uith CCT curves, and the microstructure and hardness characterizations were conducted to verify the simulation results. The results show that the surface and the position 20 mm from surface exhibit the highest cooling rate, which are mainly composed of fully martensitic microstructure; the cooling rate of the position 40 mm from surface gradually decreases, and a small amount of bainitic structure is obtained during quenching; the cooling rate of central position is less than the critical cooling rate, so the pearlite and bainite transformations occur during quenching process. However, the martensite content in the steel ball center is still maintained at about 80%, indicating that the experimental steel has good hardenability, which can ensure that the steel ball with a diameter of ø120 mm can be completely hardened.

Key words: 70Si2MnV steel, quenching, finite element simulation, CCT curves