Microstructure and defect sensitivities in the very high-cycle fatigue response of Laser Powder Bed Fused Ti–6Al–4V

This work aims to analyze the sensitivity of the very high-cycle fatigue behavior of LPBF-Ti-6Al-4V to microstructure and porosity variations. To do so ultrasonic fatigue testing is performed on five grades of LPBF-Ti-6Al-4V. These grades were generated using different LPBF process parameters and different thermal post-treatments allowing to separately investigate the sensitivity to microstructure and porosity variations. It was found that both material features highly influenced the VHCF properties of LPBF-Ti-6Al-4V revealing the sensitivity to these features. Furthermore, the largest defect (pore or grain) controls fatigue crack initiation