Contributions of intra-build design parameters to mechanical properties in electron beam additive manufacturing of Ti6Al4V

Abstract

Defects and microstructure are key concerns in Additive Manufacturing (AM) of metal components. Further understanding of contributions from build design to metal quality is needed. For this investigation, multiple builds were designed and printed to determine the relative influence of part thickness, spacing, and location on the tensile properties of Grade 5 Ti6Al4V produced by electron beam melting (EBM). Including both vertically and horizontally oriented specimens, a suite of mechanical properties were evaluated. Both the elongation at failure and tensile toughness were found to be highly correlated with part thickness. For the vertical orientation, these properties were further influenced by part location, with non-linear dependence on height and a linear dependence on radial distance from the center of the build plate. The metal with horizontal orientation did not exhibit the same relationships, with only mild correlations with height and radial position. For the vertical orientation, the elongation at failure and toughness were primarily dependent on characteristics of the lack of fusion defects, whereas microstructure was the dominant contributor to properties for the horizontal orientation. Visual maps representing property distributions over the build space were constructed. These tools can contribute to design decisions and lead to more consistent part performance for AM metals.