Investigation of Hot Working Performance and Microstructure Evolution of GH1059 Superalloy Based on Processing Map

The hot working performance and microstructure evolution of an innovative GH1059 superalloy are investigated via Gleeble-3500 simulator under the deformation parameters of 950-1100 celcius and 0.01-5 s(-1). Through the true stress-true strain curves, the Arrhenius high temperature constitutive model is established, which is able to describe the influence of deformation parameters on deformation resistance. The processing map based on the dynamic materials model is constructed for the GH1059 superalloy. Along with the optical microscopy and electron backscattered diffraction microstructure analyses, the processing map is classified into three typical domains: unstable domain, safety transition domain and optimal domain. The optimal processing domain covers the deformation parameters of 1030-1100 celcius and 0.01-0.1 s(-1), where DRX occurs, leading to the best hot working performance for GH1059, while the absence of DRX is responsible for the unstable behavior. Furthermore, from the comprehensive analyses of crystallographic orientation and dislocation density, the major dynamic recrystallization (DRX) mechanism for this GH1059 superalloy is determined as the discontinuous dynamic recrystallization while the continuous dynamic recrystallization plays the minor role.