Tensile properties and microstructural characterization of additive manufactured, investment cast and wrought Ti6Al4V alloy

This paper presents an evaluation of the tensile properties and microstructural characterization of Ti6Al4V alloy manufactured with three different processing routes; traditional wrought processing, investment cast and Laser Engineered Net Shaping (LENS). Tensile specimens were machined from each process and tensile tested at room temperature. Fractured specimens were characterized using light optical microscopy, stereo microscopy, microhardness and Scanning Electron Microscopy (SEM) to investigate the microstructural morphology and the structural hardness variation. The investment cast Ti6Al4V alloy microstructure revealed large equiaxed grains containing various orientated lamellar colonies. The additive manufactured microstructure revealed long columnar grains with Widmanstatten α' martensite laths and retained β grain boundaries. While the wrought Ti6Al4V microstructure was observed as smaller equiaxed grains with large colonies of fine lamellar and transformed β. Additive manufactured specimens had higher yield strength, ultimate tensile strength and hardness compared to the investment cast and wrought manufactured specimens. (paper)