Anisotropy in the impact toughness of selective laser melted Ti-6Al-4V alloy

Apparent anisotropies have been found in the mechanical properties of selective laser melted Ti-6Al-4V alloy. This study investigated the influences of the vertical and horizontal building directions on the impact toughness of selective laser melted Ti-6Al-4V, and a mechanism for the anisotropy in toughness is proposed. Disc-shaped building defects were clearly observed, even though the relative density was as high as 99.5%. The directionality of these defects reduces the load-bearing cross-section of a vertical specimen relative to that of a horizontal specimen; consequently, the impact energy of a horizontal specimen is 96% higher than that of a vertical specimen.