Wire arc additive manufacturing of Ti6AL4V using active interpass cooling

In this paper, active interpass cooling was implemented in the wire arc additive manufacturing (WAAM) of Ti6Al4V parts. In comparison to standard WAAM processed material, the introduced process contributes to improved microhardness and enhanced mechanical strength due to its ability to produce more fine-grained acicular α and finer α lamellae, offering more grain boundaries and high-density dislocations within the microstructure. As variations in thermal profile occurred along the buildup, different microstructures, grain size, and microhardness developed within the deposited parts. However, by rapid interpass cooling, these thermal variations could be reduced, and more uniform and isotropic material properties could be attained. Different cooling strategies reveal that better production quality is achieved through adjusting cooling time rather than controlling the cooling gas flow rate during deposition. This involves the effective heat transfer at the units of time for thin-walled deposits.