The effect of wire size on high deposition rate wire and plasma arc additive manufacture of Ti-6Al-4V

Wire + arc additive manufacture (WAAM) is suitable for building large-scale components with high deposition rate. However, in order to further increase the deposition rate of Ti-6Al-4V to improve productivity and reduce manufacture costs without significantly compromising the quality, some fundamental process characteristics need to be investigated. In this paper, the effect of wire size on the limitation of deposition rate and bead shape in plasma arc additive manufacture was studied along with the process tolerance and melting characteristics, such as the effect of current and nozzle size on keyhole behaviour and the effect of wire feeding position on deposition process. The results show that with the same heat input the deposition rate increases linearly with the wire size due to the increasing melting efficiency. The bead geometry obtained with a thinner wire has a higher aspect ratio, which can be attributed to the difference in the distribution of the energy between wire and workpiece. The likelihood of keyhole increases with increasing current and decreasing nozzle size, and it can be mitigated by using thicker wires. The wire feeding position plays a significant role in determining the metal transfer mode, which has a great impact on the bead shape and process stability. Also, as the deposition rate changes thin wire is more sensitive to wire feeding position than thick wire in terms of metal transfer behaviour.