Flow behavior and processing map of FGH96 superalloy during two-pass hot deformation

Isothermal interrupted hot compression tests of FGH96 superalloy at the two-pass strains of 0.6 + 0.6 and 0.3 + 0.9 were performed on a Gleeble-1500 thermo-mechanical simulator. The hot deformation behavior and microstructural evolution of the superalloy were investigated in the deformation temperature range of 1050 to 1125℃ and the strain rate range of 0.001 to 0.1 s^-1. It is found that recrystallization happens during the two-pass hot deformation, and less deformation in the first pass results in less cracks in samples. As the first-pass hot deformation is less, the recrystallization degree increases during the deformation gap with increasing deformation temperature and strain rate. An obviously change is found in the processing map with different strains or different two-pass strains. Under the same deformation condition, when the energy dissipation rate changes with strain, different microstructural evolution rules happen. When the energy dissipation rate decreases with increasing strain, the recrystallization grains coarsen; otherwise, the recrystallization grains refine. But when the energy dissipation rate does not change with strain, coarse grains appear with the energy dissipation rate lower than 20% or a fine grain microstructure appears with the energy dissipation rate higher than 35%.