Confirmation of Rapid-Heating β Recrystallization in Wire-Arc Additively Manufactured Ti-6Al-4V

The coarse columnar β grains in Ti-6Al-4V WAAM can be refined by relatively low strain inter-pass deformation. Simulation, with rapid heating, has shown this may partly occur by a novel recrystallization mechanism that involves twinning during β regrowth through the α-β transus, as a result of the prior deformation promoting faults in the α-β interface, which produces a unique micro-texture in each parent β grain. Here, this potential mechanism has been investigated further, using a different deformation mode – uniaxial tensile deformation rather than plane-strain compression – to enable the texture contribution from conventional recrystallization to be more unambiguously discriminated. The tensile-deformed samples are shown to produce the same unusual unique micro-texture seen previously, at low strains, despite the different deformation mode, but this disappeared at higher strains, which provides more evidence in support of this new rapid heating β recrystallization mechanism.