A Novel Unified Dislocation-Density Based Model for Hot Deformation Behavior of a Nickel-Based Superalloy

Abstract

In hot forming processes, metallic materials often undergo a series of plastic deformation and heat treatments. Hot working parameters, including deformation temperature, strain rate, and strain, exert great impacts on hot deformation behavior of alloys. Work hardening (WH), dynamic recovery (DRV), dynamic recrystallization (DRX), phase transformation, and metadynamic recrystallization (MDRX) often take place, and affect hot deformation behavior of metallic materials. Therefore, a comprehensive investigation on the intrinsic interactions between microstructural evolution and hot deformation behavior is necessary. In this study, a novel unified dislocation-density based model is presented to characterize the hot deformation behavior of a nickel-based superalloy In the Kocks-Mecking model, a new softening item is proposed to represent the impacts of dynamic recrystallization behavior on dislocation density evolution. The grain size evolution and dynamic recrystallization kinetics are incorporated into the developed model. Material parameters of the developed model are calibrated by a derivative-free method in MATLAB toolbox. Comparisons for the experimental and predicted results confirm that the developed unified model can accurately reproduce the hot deformation behavior, DRX kinetics, and grain size evolution in wide scope of initial grain size, deformation temperature, and strain rate.