Experimental Investigation on Plastic Strain and Recrystallization of Single Crystal Nickel Based Superalloys

Recrystallization, which can be ascribed to the plastic deformation, poses one of the major difficulties in post-processing of SX blades castings of Ni-based superalloys. Hot compression and Brinell Indentation were utilized to cause plastic deformation, and thereafter some received solution heat treatment at different temperatures for different time. Profiler observation of indented deformation confirms the anisotropic mechanical properties of single crystal Ni-based superalloys. Deformation at high temperature leads to high dislocation density and stored energy, increasing the propensity of recrystallization, which is revealed by TEM and EBSD analysis. Critical temperature is relatively higher for SX superalloys than DS superalloys, and decreases with increasing plastic strains. Besides, it’s easier for nucleation and grain boundary migration in the dendrite core region, which corresponds to the microsegregation and difference of γ’ morphology between dendrite stern and eutectic regions.