Microstructure and microtexture evolution of dynamic recrystallization during hot deformation of a nickel-based superalloy

Abstract

Effect of strain rate route on the microstructure and microtexture evolution during the dynamic recrystallization (DRX) of a nickel-based superalloy subjected to the isothermal compression tests was investigated using electron back-scatter diffraction. The evolutions of microtexture components and fiber textures and the role of Σ3 boundaries in microstructure on the pole density in the partially and fully DRX processes were explored. The α-fiber in Euler space is regarded as the compression microtexture. The locally organized substructures in the matrix grains are formed on certain {111} slip planes with the high Schmid factor. Although the dislocation-free DRX grains show the random orientated distribution, the weak recrystallization 〈001〉 fiber parallel to the compression axis (ND) is developed at the high strain in the fully DRX processes. Whereas the compression 〈101〉 fiber parallel to ND in the partially DRX processes is sharpened. Moreover, the instantaneous decrease of strain rate leads to the highest fraction of Σ3 grain boundaries, indicating the lowest pole density. Cube-Twin component adjacent to Cube component contributes partly to the formation of Σ3 grain boundaries. The findings provide insights into the microtexture characteristics and enhance the understanding of the orientation dependence of the mechanical behavior of nickel-based superalloys.