Effect of crystal integrity on the fretting wear of Ni-based single crystal superalloys

The fretting wear performance of the precision-machined surface of single crystal superalloy blades is an important guarantee to ensure its service stability in extreme environments. In this work, scanning electron microscope (SEM), electron back scatter diffraction (EBSD), and transmission Kikuchi diffraction (TKD) techniques used to characterize the change of crystal integrity, such as microstructure evolution and dislocation density distribution on machined surface, of single crystal parts after grinding and thermal exposure, and the variation of friction coefficient, the characteristics of worn profiles and the wear rate were obtained after fretting wear test, so as to elaborate the influence mechanism of recrystallization structure of the machined surface on the fretting wear performance. The results show that the grinding-induced high density dislocation structure can improve the wear resistance, while the recrystallized grains continue to grow and consume a lot of dislocations after thermal exposure with high temperature of 1050-1250 degrees C, and the wear resistance shows a decreasing trend. This work improves the theory of the relationship between crystal integrity and fretting wear of single crystal parts, and provides new ideas for the actual processing and design of single crystal blades.