Study On Hi-B Steel Recrystallization During The Hot Deformation Process By Thermal Simulation

In this paper, the effects of processing parameters on the evolution ofmicrostructures and the mechanical properties of HiB steel during being deformed areinvestigated by thermal simulation.The stress-strain curves of single compression andthe double compression and the evolution of microstructures are analyzed.The stress-strain curves at different deforming temperature or strain rate and thequenched microstructures of HiB steel are analyzed. The results show that bothdynamic recovery and dynamic recrystallization take place during different deformingtemperatures or strain rates, but dynamic recovery is more prominent. At thesame deforming temperature, the subgrain size of dynamic recovery becomes largerwith the strain-rate decreasing, and the dynamic recovery becomes more thorough. Onthe contrary, the dynamic recrystallization softening mechanism comes to dominate thematerial softening behavior when strain rate increases. When the strain rate is contant,it becomes more difficult for dynamic recovery to take place at the lower deformingtemperature, which is very different with the ordinary austenitic steel. Keeping strainrate constant, it’s easy for microstructures dynamic recovery to take place whileincreasing the deforming temperature, which has consumed most of dislocation energy,and the dynamic recrystallization nucleation became difficult to occur.According to stress-strain curves of double compression by thermal simulation,the softening ratios are calculated and then softening ratio curves are drawn. Therecrystallization behavior and microstructure feature of Hi-B steel have been analyzedwith the quenched microstructure after deformation for different interval times. Theresult shows that the static softening ratio increases when the interval time becomeslonger at the same deforming temperature. And the static softening ratio also increaseswith the deforming temperature increasing. During the interval time, static recoverystatic crystallization and the meta-dymatic crystallization all can take place.