Affiliation:
1. College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and Astronautics Nanjing China
2. College of Astronautics Nanjing University of Aeronautics and Astronautics Nanjing China
3. Wuxi Research Institute Nanjing University of Aeronautics and Astronautics Wuxi China
4. National Center of Supervision and Inspection on Additive Manufacturing Products Quality Wuxi China
Abstract
AbstractThis 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.
Funder
Jiangsu Provincial Key Research and Development Program