Microstructural evolution and dynamic recrystallization of a nickel-based superalloy PM EP962NP during hot deformation at 1150 °C

Abstract

Microstructural evolution and dynamic recrystallization mechanism of a nickel-based superalloy PM EP962NP during isothermal compression at 1150 °C under different strain rates and strains have been investigated. Results show that continuous dynamic recrystallization can be induced to occur when the strain exceeds 0.36. A processing window with high microstructure stability including the evolution of DRX, γ grains and γʹ precipitates is determined to be hot compression at 1150 °C with the strain rate of 0.001 s−1 and strains ranging from 0.69 to 1.20. In addition, due to the interaction between dissolution and precipitation, the γʹ precipitates exhibit inhomogeneous sizes with micron-scale blocky primary γʹ and nano-scale spherical secondary γʹ. Moreover, the abundant microstructural information related to the strain rates and strains can provide a reference for obtaining the gradient microstructures by thermo-mechanical processes.

Keywords

• Nickel-based superalloys
• Grain boundaries
• Dynamic recrystallization
• Microstructure stability
• Gradient microstructures