Tensile Behavior of a Titanium Alloy Additively Manufactured via Selective Electron Beam Melting

Additive manufacturing or 3D-printing of titanium alloys with a high strength-to-weight ratio holds significant interest in the aerospace and biomedical industries. The purpose of this investigation was to determine microstructure and tensile deformation behavior of a 3D-printed Ti-6Al-4V alloy via selective electron beam melting (SEBM). Plentiful multi-oriented α-lamellae were present in the prior columnar β grains, which were oriented in the building direction because of the presence of temperature gradients during 3D-printing. The processing parameters selected in this study ensured superior strength and high ductility by controlling the thickness of α-lamellae, with both surpassing the values specified in the ASTM standard. The horizontally orientated 3D-printed alloy demonstrated a certain extent of strain rate sensitivity which decreased with increasing strain, suggesting that dislocation slip was a predominant deformation mode, since the fine and abundant multi-oriented α-lamellae could impede the formation of extension twinning. Fracture surface was observed to be characterized by typical dimples and some entrapped gas pores.