Enhancing Tensile Properties of Wire-Arc Additively Manufactured Ti-6Al-4 V Deposits Via Cryogenic Vaporised Ar Shielding/Cooling

The cooling time of cryogenic vaporised Ar shielding/cooling of Ti-6Al-4 V deposits was ~ 10 times faster than that of normal Ar gas shielding/cooling. The columnar β grains in rapid cooling condition were observed to be in the longitudinal direction of the deposits same as that in natural cooling condition. Under the rapid cooling, a narrow heat-affected zone band (~ 70 μm) and a wide vanadium-segregation band was observed, along with a reduced aspect ratio of the α plate, which led to improved isotropic-tensile properties along the deposition and building directions. Rapid cooling condition also retained a significant amount of O and N, which enhanced its hardness and tensile strength. Thus, cryogenic vaporised Ar shielding/cooling can produce Ti-6Al-4 V wire-arc additive manufacturing deposits with better tensile properties compared to normal Ar gas shielding.