Fatigue damage recovery and enhanced fatigue limit of austenitic stainless steel using multiple high-density pulsed electric currents

The damage evolution and fatigue life of austenitic stainless steel subjected to high-density pulsed electric currents (HDPECs) were investigated in this study. The change in the fatigue damage evolution owing to the application of HDPECs was evaluated using the cumulative fatigue damage model. Fatigue damage recovery was successfully demonstrated in the low-cycle fatigue and high-cycle fatigue (HCF) regimes. In particular, significant fatigue damage was recovered in the HCF regime when more than six HDPECs were applied. The microstructural features modified by the effect of the HDPEC indicated specific fatigue fracture patterns during fatigue crack initiation, which tended to prefer a transgranular fracture instead of an intergranular fracture. Furthermore, unique fish-eye patterns generated on the subsurface indicated a significant recovery of fatigue damage in the HCF regime owing to the effect of multiple HDPECs. A full fatigue test of R= 0.5 was performed within a fatigue cycle of < 108, resulting in an enhanced fatigue life owing to fatigue damage recovery. Therefore, the application of multiple HDPECs improved the fatigue limit. This study sheds light on the efficiency assessment of the application of HDPECs based on the type of fatigue regime. •Focus on understanding mechanisms of damage recovery and improvement of fatigue limit of 316 austenitic stainless steel.•Effects of the application method of multiple high-density pulsed electric currents.•Retardation of fatigue damage evolution in low- and high cycle fatigue regimes.•Increased tendency of transgranular fracture than intergranular fracture.•Advantageous subsurface crack initiation mechanism for improving fatigue limit.