Mechanism of porosity formation and influence on mechanical properties in selective laser melting of Ti-6Al-4V parts

An original approach based on 2D fracture surface and 3D X-ray tomography analysis is proposed in this paper. Its application in selective laser melting of Ti-6Al-4V provides substantive clarifications regarding both mechanisms of porosity formation and their influence on mechanical properties. Unambiguously, a one-to-one relationship between the scanning strategy pattern and the 3D spatial distribution of porosities is highlighted. In an original manner, the 3D location of porosities, their morphology and their orientation are analyzed with respect to the laser spot path. The results show that pores are mainly localized on the overlay zones and support the lack of energy induced by the lower energy at the periphery of the laser spot as the main mechanism of porosity formation. Finally, both tensile properties and crack path are shown to be influenced by the presence and 3D distribution of porosities. [Display omitted] •An original approach based on 2D fracture surface and 3D X-ray tomography is applied in selective laser melting of Ti-6Al-4V.•3D spatial distribution, morphology and orientation of porosities are shown to be linked to the scanning strategy pattern.•Pores are mainly localized on the overlay zones.•The lack of energy induced is identified as the main mechanism of porosity formation.•Both tensile properties and crack path are shown to be influenced by the presence and 3D distribution of pores.