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

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 Sigma 3 boundaries in microstructure on the pole density in the partially and fully DRX processes were explored. The alpha-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 Sigma 3 grain boundaries, indicating the lowest pole density. Cube-Twin component adjacent to Cube component contributes partly to the formation of Sigma 3 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. (C) 2019 The Authors. Published by Elsevier Ltd.