Rapid crack healing and fatigue life extension in single-edge notched pure titanium via electropulsing treatment

This study investigates the efficacy of electropulsing treatment (EPT) in healing a fatigue-induced crack and improving the fatigue resistance of a single-edge notched pure titanium specimen. Targeted fatigue cycles are applied to induce a pre-crack at the notch root. Then, an electric pulse with a density of 88 A/mm² and a duration of 0.4 s is applied to the fatigued specimen. The experiment demonstrates that EPT completely heals the fatigue-induced crack and extends the fatigue life of the specimen to the conditional fatigue limit greater than one million cycles from the original fatigue life around 55,000 cycles. Electric-thermal simulation and microstructure analysis show that the significant enhancement in fatigue life is predominantly driven by the formation of large compressive residual stress, generating due to the inhomogeneous thermal expansion and phase transformation-induced volume change at the notch region. Also, microstructure change during EPT weakens the texture strength and ultimately enhances the ductility of the notch root, further increasing fatigue life. The induced compressive residual stress and enhanced ductility at the notch root effectively inhibit crack initiation and propagation. This study confirms that EPT technique is effective to heal fatigue damage or to prolong the fatigue life of notched pure Ti component.