The hot deformation behaviors of coarse, fine and mixed grain for Udimet 720Li superalloy

In this work, the hot deformation behaviors of Udimet 720Li superalloy with the microstructures of coarse grain, fine grain and mixed grain were studied contrastively by means of various microstructural analysis approaches. Based on the experimental results, in single-phase region, dynamic recrystallization (DRX) mainly occurs along the boundaries, while a decrease in the grain size accelerates the DRX kinetics. In two-phase region, the DRX on grain boundaries of coarse grain is limited, but intragranular continuous sub-grain rotation and accumulation takes effect remarkably; no DRX occurs in fine grain, but local migration of grain boundaries and deformation of γ′ independently occur. The coarse-grain and fine-grain portions of mixed grain perform in a similar way of the coarse grain and fine grain respectively.