Electric current-driven microstructural recovery and crack resistance enhancement in Ni-based superalloy Inconel 718

Fatigue failure poses a serious threat to the safety and durability of engineering structures, making it crucial to enhance and restore the fatigue performance of critical components. In this study, we employed high-density pulsed electric current (HDPEC) treatment to improve the crack initiation life of Ni-based superalloy Inconel 718. Experimental results revealed that multiple HDPEC treatments can increase the crack initiation life by up to 108.3 %. This improvement is attributed to the recovery of the localized plastic zone, which effectively suppresses crack initiation. Quasi-in-situ electron backscatter diffraction observations confirmed a significant reduction in dislocations, slip bands, and sub-grain boundaries, likely driven by the coupled effects of electron wind force and Joule heating that promote dislocation motion and elimination. This work demonstrates that HDPEC is a simple and effective method for enhancing fatigue resistance and offers promising prospects for application in high-performance structural materials. • HDPEC enhanced the crack initiation life of IN718 by 108.3 %. • HDPEC significantly reduced dislocations, slip bands, and sub-grain boundaries. • Grain boundary migration and new grain formation were observed after HDPEC. • Electron wind force facilitated dislocation motion and annihilation. • Stress gradients induced by electron wind contributed to grain boundary migration.