Influence of trace silicon addition on microstructure and properties of Ti6Al4V fabricated by wire arc additive manufacturing

To provide a pathway to improve the tensile properties of wire arc additive manufactured Ti6Al4V, the microstructures and properties of Ti6Al4V-0.1Si produced by the wire arc additive manufacturing were investigated in this study. It was demonstrated that the tensile strength of Ti6Al4V-0.1Si improved more than 100 MPa compared with traditional WAAM Ti6Al4V. The microstructures of WAAM Ti6Al4V and Ti6Al4V-0.1Si mainly consists of basket-weave structures but the width of the α-phase lamellae of Ti6Al4V-0.1Si is significantly lower. The added Si is solid-soluble on the α phase matrix of Ti6Al4V, which reduces the β phase transition temperature. Si as well produces the high growth restriction effect, then the α phase size is refined. The fine grain and solid solution strengthening are the main reasons for the increase in the strength of titanium alloy after adding trace Si.