β grain refinement during solidification of Ti-6Al-4V in Wire-Arc Additive Manufacturing (WAAM)

Abstract Constructing titanium aerospace parts by near-net-shape processing has the potential to greatly reduce cost and lead time, one method for this is Wire-Arc Additive Manufacturing (WAAM). Conventional WAAM with most common Ti alloy, Ti-6Al-4V, results in solidification epitaxial growth from previously deposited layers a structure dominated columnar β grains which are heavily <001> fibre textured cm’s scale. In order prevent these large forming, while maintaining deposition parameters, conditions were modified additions of particles melt; either using inoculant, TiN particles, or solutal restrictor, Y, also added as elemental powder that dissolved melt. The adhering them tracks avoid costs manufacturing new wires. With inoculants morphology was completely equiaxed averaging 300 μm diameter. Y narrowed 1-2mm 100-300 μm. induced change grains, late solidification, region remelted subsequent deposition. However, Yttria found have formed interdendritically an interconnected skeletal morphology. High-resolution EBSD analysis showed both yttria exhibit specific orientation relationships solidified confirmed experimentally.