  The manufacturing of refractory-metals components presents some limitations
induced by the materials characteristic low-temperature brittleness and high
susceptibility to oxidation. Powder metallurgy is typically the manufacturing
process of choice. Recently, Wire + Arc Additive Manufacturing has proven
capable to produce fully-dense large-scale metal parts at relatively low cost,
by using high-quality wire as feedstock. In this study, this technique has been
used for the production of large-scale tungsten linear structures. The
orientation of the wire feeding has been studied and optimised to obtain
defect-free tungsten deposits. In particular, front wire feeding eliminated the
occurrence of pores and micro-cracks, when compared to side wire feeding. The
microstructure, the occurrence of defects and their relationship with the
deposition process have also been discussed. Despite the repetitive thermal
cycles and the inherent brittleness of the material, the as-deposited
structures were free from internal cracks and the layer dimensions were stable
during the entire deposition process. This enabled the production of a
relatively large-scale component, with the dimension of 210 x 75 x 12 mm. This
study has demonstrated that Wire + Arc Additive Manufacture can be used to
produce large-scale parts in unalloyed tungsten by complete fusion, presenting
a potential alternative to the powder metallurgy manufacturing route.
