Recrystallization mechanisms and associated microstructure evolution during billet conversion of a gamma-gamma′ nickel based superalloy

A partially recrystallized sample of the Ni-based superalloy AD730 was taken from an intermediate stage ingot to billet conversion process and isothermally forged in a single stroke compression test at sub-solvus temperature (1080 °C). The as-received material had heterogeneous microstructure, containing mixture coarse much finer grains as well unrecrystallized ones, also γ′ precipitation. recrystallization mechanisms occurring dynamically different grain populations were investigated via electron backscatter diffraction (EBSD). It found that local microstructure could affect operative mechanism, with seen deformed regions, owing their precipitate distributions. Within grain, three apparently distinct dynamic (DRX) identified. interaction precipitates plays central role DRX. In certain cases may stimulate discontinuous DRX by providing nuclei, alternatively they impede limit growth grains, or other still promote continuous recrystallization. • Recrystallisation starting are characterised. Different microstructures lead recrystallisation operating. interactions between processes described. All recrystallised regions result dissolution reprecipitation.