Study on dynamic recrystallization kinetics and microstructural refinement of high-strength 36CrNi3MoV steel during hot deformation

The flow characteristics and grain morphology evolution of 36CrNi3MoV steel were systematically investigated through isothermal hot compression experiments under temperatures of 900-1200 degrees C and strain rates of 0.001-1 s-1. The true stress-strain curves revealed that the flow stress increases with rising strain rates and decreasing deformation temperatures. A strain-coupled constitutive equation for flow stress was constructed based on a phenomenological model. Using single-pass compression experimental data, dynamic recrystallization (DRX) volume fraction and DRX grain size models were established, both demonstrating high accuracy in predicting and characterizing the DRX behavior of the studied alloy. Furthermore, hot processing maps at different true strains were developed based on the dynamic materials model (DMM). By partitioning these maps according to power dissipation efficiency and the Prasad instability criterion, the deformation mechanisms in different regions were analyzed through corresponding microstructures. The results revealed that the optimal deformation parameters are a temperature range of 1050-1100 degrees C and a strain rate range of 0.1-1s-1. These findings provide theoretical guidance for optimizing hot working processes of high-strength steels.