Prediction of flow stress for N08028 alloy under hot working conditions

Based on the dislocation density theory and kinetics of dynamic recrystallization (DRX), a two-stage model was developed to determine the flow stress curves of N08028 corrosion resistant alloy at hot deformation condition. The proposed model is capable of predicting the flow behavior of work-hardening and dynamic recovery (DRV) region as well as the softening caused by DRX. To establish the model, firstly, the flow stress curves of DRV were modeled by adjusting an evolution equation, with a dynamic recovery parameter r describing plastic behavior in work-hardening and dynamic recovery region. Secondly, the flow stress after onset of DRX can be modeled by incorporating the DRX softening behavior into the evolution equation. A modified Avrami equation was employed to represent this softening behavior and a critical strain ε_c for initiation of DRX was determined by a double-differentiation method. The established model was adopted to predict the flow stress in the entire deformation process of N08028 corrosion resistant alloy; the corresponding prediction is in good agreement with the experimental result.