Dynamic Recrystallization Simulation for X12 Alloy Steel by CA Method Based on Modified L-J Dislocation Density Model

Abstract

Hot compressive behaviors of X12 alloy steel were investigated using a Gleeble-1500D thermal mechanical simulator in a temperature range from 1050 to 1250 °C and with a range of strain rates from 0.05 to 5 s−1 and a maximum true strain of 0.7. Stress–strain curves were obtained under various deformation conditions. A modified Laasraoui–Jonas (L-J) dislocation density model of X12 alloy steel was established for the given ranges of strain rate and temperature. On the basis of this dislocation density model, a cellular automaton (CA) model was constructed and used to simulate microstructure evolution during the hot compression process. Microstructure and grain size of X12 were predicted for different deformation conditions. The simulated grain size was compared with the actual grain size measured with metallographic photos. An average relative error of grain size was determined to be 6%, indicating that the modified L-J dislocation density model can accurately predict dynamic recrystallization behaviors of X12 alloy steel in hot forging processes.