The processing map and microstructure evolution of Ni-Cr-Mo-based C276 superalloy during hot compression

Isothermal hot compression tests have been performed to study the hot working characteristics of Ni-Cr-Mo-based C276 superalloy in the temperature range 1000-1200 degrees C and strain rate range 0.001-5.0s(-1). The critical strain and stress for the initiation of dynamic recrystallization (DRX) were determined from the strain rate hardening curves. The processing map based on dynamic materials model was developed at the true strain of 1.0. Coupled analysis with the microstructure observation illustrates that the processing map give good representations of microstructure evolution. And in-grain shear bands were found to be formed when deformed in flow instability area. The grain boundary character and misorientation were analyzed using electron backscatter diffraction (EBSD). It is found DRX fraction increases with the increasing deformation temperature and deformation degree, associated with the increasing fraction of high angle grain boundary (HAGB) and Sigma 3 twin boundary. And the misorientation distribution approaches the microstructure with random distributed orientation with the increasing DRX, implying no obvious texture was formed after DRX. (C) 2017 Elsevier B.V. All rights reserved.