Understanding activation energy of dynamic recrystallization in Inconel 718

Abstract

Hot compression tests were performed on Inconel 718 to study high temperature flow stress-strain response and activation mechanism in the hot deformation. To model the flow stress response, we employed two physically based models namely Schӧcks-Seeger-Wolf and Kocks model in addition to extensively used Sellers model. Flow curves from all three models were compared and it was found that predictions of Sellers model closely resemble the experimental results. However, activation energy calculated using Sellers model differs significantly from the activation energy of micro mechanism as reported in the literature. Schӧcks-Seeger-Wolf model predictions are in close agreement with experiments at low strain rate and the activation energy corresponds to diffusion activation energy. Though Kocks model shows much deviation from the experimental results, qualitative comments on the activation energy profile can be made using this model. We utilized hardening models to derive a constitutive model for DRX and simultaneously establish an understanding of rate controlling deformation mechanism in Inconel 718.