Constitutive Equation and Dynamic Recrystallization Behavior of 316L Austenitic Stainless Steel for Nuclear Power Equipment

The hot deformation behavior of 316L austenitic stainless steel used in nuclear power equipment was studied by hot compression tests in the temperature range of 900-1 100℃, and in the strain rate range of 0.01-5 s-1. According to the data of hot compressive experiment, the flow stress curves of 316L under different deformation conditions were plotted. The constitutive model considering the compensation of strain for predicting the flow stress of 316L under all test conditions was developed on the basis of Arrhenius-type equation. The microstructural evolution of 316L during deformation was observed via an optical microscope. The critical strain of dynamic recrystallization of 316L stainless steel is identified based on the work hardening rate versus flow stress curves. The DRX kinetics for 316L can be represented in the form of Avrami equation. The results show that either decreasing deformation temperature or increasing strain rate makes the flow stress level reduce remarkably. The accuracy of the developed model was evaluated using standard statistical parameters such as correlation coefficient and average absolute relative error. It suggested that this developed constitutive equation could accurately predict high temperature flow behaviors of 316L. It is found that the DRX mainly occurred at high strain rates and high temperatures. The DRX volume fraction increased towards 1.0 with an increase in strain in terms of the S-shape and the predicted volume fraction of new grains based on the developed model agrees well with the experimental results. © 2019, Materials Review Magazine. All right reserved.