Recrystallization Mechanism of Typical Ni-based Superalloys

The dynamic and static recrystallization behavior of GH4760, GH4738, and AD730 typical Ni-based superalloys during hot deformation was investigated. The compressive hot deformation and solution annealing experiments were conducted. Results show that the nucleation mechanism of dynamic and static recrystallizations is dominated by the discontinuous mechanism of grain boundary bulging. Different types of stepped grain boundaries are generated during the dynamic and static recrystallizations due to the transformation from ordinary crystal planes into low-index crystal planes. This transformation results in lower energy of more grain boundaries. The morphology of the stepped boundaries on Sigma 3 grain boundaries mostly decompose into {111}(1)/{111} 2 and 90 degrees{112}(1)/ {112}(2) facets. The stepped grain boundaries promote the migration of grain boundaries, accelerating the recrystallization process. After recrystallization, partial stepped grain boundaries remain, the interfacial energy reduces, and the further grain growth is promoted.