Effect of porosity distribution on the strength and strain-to-failure of Laser-Powder Bed Fusion printed Ti-6Al-4V

The mechanical reliability of alloys produced by Laser-Powder Bed Fusion (LPBF) is a key concern limiting their practical insertion into structural applications. While it is generally accepted that the presence of process induced defects such as lack-of-fusion porosity influences strain to failure, it is unclear what aspects of the defect distribution affect mechanical properties. To this end, we measured the mechanical properties and defect structure of LPBF fabricated Ti-6Al-4V coupons at 4 different porosities. We found that both the strength and strain to failure decreased with increasing porosity. To understand this trend, an experimentally validated computational model was utilized that describes the porosity distribution at two scales: processing induced defects are explicitly represented as voids, while plasticity induced defects are implicitly represented as damage. Analysis of this model allowed the identification of key statistical metrics able to qualify the effects of porosity on mechanical properties.