Microstructural characterization and mechanical properties of SLM-printed Ti–6Al–4V alloy: Effect of build orientation

Manufacturing parameters play a significant role on the final quality and mechanical integrity of the structural components manufactured by selective laser melting (SLM) method. Among these parameters, the build orientation is quite crucial since it determines not only the manufacturing time and total cost of a 3D-printed part but also the mechanical strength with respect to loading axis. For this reason, this study is aimed at investigating the effect of build orientation (vertical vs. horizontal) on the microstructure, tensile strength, and wear properties of Ti–6Al–4V alloy manufactured by selective laser melting (SLM) method. The acicular(alpha^prime)martensite was the dominant phase in SLMed samples; however, the size of needles was finer in the vertically printed samples as compared to the horizontally printed ones. Grain boundary map revealed that the fraction of high-angle grain boundary (HAGBs) was dominant in the as-printed state whereas low-angle grain boundary (LAGBs) was dominant in the wrought alloy. The ultimate tensile strength (UTS) of the horizontally and vertically printed samples was ≈ 27% and 15% higher than that of wrought alloy while the ductility is almost one-third of the commercial alloy and quite close to the minimum requirement of ASTM F1108 for surgical implants. The dry sliding pin-on-disc showed that the wear resistance of the as-printed alloy irrespective of build orientation was inferior when compared to the wrought alloy.Graphical abstract