Experimental investigations and constitutive modeling of the dynamic recrystallization behavior of Inconel 740 superalloy

Abstract

The dynamic recrystallization (DRX) behavior of Inconel 740 superalloy was investigated via the isothermal compression tests and constitutive modeling. The unified constitutive model involving the flow behavior and the microstructural evolution was developed for modeling the DRX behavior via considering the critical strain of DRX initiation, DRX grain nucleation rate and DRX grain size. The results show that the variations of flow stress, grain size and DRX fraction during hot deformation are well described at the constant strain rate. The strain hardening behavior is also well predicted under the deformation conditions outside the calibration range of this model. Moreover, the complex hot deformation characteristics are also well predicted and estimated in the transient deformation process caused by the strain rate jump. The developed model is validated by the experimental results. Furthermore, the DRX diagram in the optimum hot-workability temperature range of Inconel 740 superalloy is established to visualize the DRX kinetics. This work provides a basis for understanding of the flow behavior and microstructural evolution of Inconel 740 superalloy and helps process determination and quality assurance in hot working of this superalloy.