Fatigue life evaluation of TC4 titanium alloy with impact flaw

This study investigates the fatigue behavior of TC4 titanium alloy with impact flaws under axial loading conditions. Surface flaws were introduced via dropweight impact, and their geometries were characterized using 3D scanning. Fatigue tests were conducted at multiple stress levels following national testing standards, and the fatigue life data were analyzed using Stromeyer equations and damage evolution models. Fractographic analysis revealed that fatigue cracks consistently initiated near the impact pit edge due to localized stress concentration and residual stress fields. Finite element simulations were employed to predict stress distribution and residual fields around the flaws, providing insights into failure mechanisms. The flaw influence coefficient Kflaw was used to quantify the impact of surface defects on fatigue performance, showing a notable reduction in fatigue limit, with impact-induced flaws yielding the highest degradation. This work contributes to the understanding of flaw tolerance in titanium alloys and supports fatigue life prediction in safety-critical components.