Fatigue performance of additively manufactured Ti6Al4V: effects of printing parameters and FEM-based residual stress analysis

This study addresses the limited understanding of fatigue behavior in 3D-printed Ti6Al4V under non-proportional multiaxial loading—a scenario common in real-world applications but underexplored in literature. By integrating experimental fatigue tests with thermo-mechanically coupled FEM simulations, the research quantifies how build orientation, residual stresses, and phase-shifted loading influence fatigue life. The investigation evaluated the impact of print orientation (X, Y, Z) and the phase shift of applied loads (BT00, BT45, BT90) on the fatigue life of the material, with the optimal fatigue life obtained for specimens printed in the Z orientation under a 90° phase shift. Microstructural analysis revealed the occurrence of porosity and surface defects that reduced fatigue life by approximately 30 %, underscoring the necessity to optimize parameters such as laser power and scanning speed. The results unequivocally indicate that, when assessing the durability of additively manufactured components, it is essential to account for the effects of residual stresses as well as to maintain precise control over the production process conditions.