Effects of build direction and microstructure on fatigue crack growth behavior of Ti6Al4V fabricated by laser powder bed fusion

作者：Peidong Xie, Deqiao Xie, Kai Zhou, Xuwen Gu, Syed Mesum Raza Naqvi, Lida Shen, Zongjun Tian, Jianfeng Zhao · 发表于：Fatigue & Fracture of Engineering Materials & Structures · 年份：2024 · DOI：10.1111/ffe.14312 · 被引用次数：6 · 研究领域：Additive Manufacturing Materials and Processes、Additive Manufacturing and 3D Printing Technologies、High Entropy Alloys Studies

Abstract This study compares the fatigue crack growth (FCG) behavior of Ti6Al4V parts fabricated by laser powder bed melting (LPBF) with four build directions (0°, 30°, 60°, and 90°) and two heat treatments and analyzed the effect of build direction and microstructure on FCG. The results show that the build direction has a significant effect on the FCG rate. Particularly, specimens with 90° build direction have the best FCG resistance while the 0° specimens have the worst. Furthermore, the fragile deposition layer boundary is the main cause of the crack deflection. The microstructure shows that the columnar β grains have less effect on FCG. The increase in resistance to FCG after heat treatment is attributed to the lath‐like α grains consuming the energy for FCG. As compared to needle‐like α′ grains, the lath‐like α grains are more likely to initiate intergranular fracture and secondary cracking, leading to rugged crack tip paths.