Comparative study of fatigue properties of Ti-6Al-4V specimens built by electron beam melting (EBM) and selective laser melting (SLM)

Electron Beam Melting (EBM) and Selective Laser Melting (SLM) are two of the most developed powder bed fusion based additive manufacturing processes. In this paper, fatigue properties of Ti-6Al-4V specimens built by EBM and SLM are compared. Several parameters are assessed: processes, manufacturing direction, surface roughness, HIP treatment. Fatigue properties are analyzed in relation with the crack initiation mechanisms identified on each specimen's post-mortem micrographs. Machined specimens show better fatigue properties as surface defects are removed. HIP treatment improves fatigue properties by decreasing the defects size. Small differences in lifetime are observed between horizontal and vertical building directions because of different defect shapes regarding the loading axis. Finally, EBM and SLM parts have approximately the same fatigue properties, which are equivalent to conventional casting processes.