Modeling the Stress-Strain Curves and Dynamic Recrystallization of Nickel-Based A230 Alloy During Hot Deformation

The stress-strain curves and recrystallization behavior of materials during high-temperature deformation can generally be modeled using the Zener-Hollomon parameters expressed as a function of strain, temperature, and activation energy. However, reports of the effects of the activation energy with respect to the variation in the strain rate during hot deformation on the modeled stress-strain curves are limited. Therefore, in this study, the effect of the activation energy on the stress-strain curves was analyzed. For this purpose, uniaxial compression tests at temperatures of 900-1200 degrees C and strain rates of 0.001-1 s(-1) were performed using a nickel-based A230 alloy. Using the measured stress-strain curves, constitutive modeling based on the Zener-Hollomon parameters was performed. To analyze the effect of the activation energy at different strain rates on the modeling accuracy, two types of models derived using the strain-rate-dependent and strain-rate-independent activation energies were established. Then, two types of flow stresses were calculated using the models, and their accuracies were compared using the average absolute relative error. In addition, the dynamic recrystallization (DRX) behavior was modeled by applying the derived Zener-Hollomon parameters. Finally, the established DRX kinetic model was applied to finite element simulations to predict the microstructure of the deformed specimen. As a result, it was found that the volume fraction of DRX grains and the grain size, which greatly affect the mechanical properties of the material, can be predicted.