Research on high efficiency deposition method of titanium alloy based on double-hot-wire arc additive manufacturing and heat treatment

Wire arc additive manufacturing (WAAM) is a promising additive manufacturing technique with growing acceptance in fabricating large size components. In this paper, titanium alloy Ti-6.5Al-2Zr-1Mo-1V (TA15) for double-hot-wire arc additive manufacturing (DHWAAM) was firstly investigated and analyzed in deposition state and heat treatment, mainly including mechanical properties and microstructure evolution. The heat input modes of the two processes are different, the deposition efficiency is doubled and the material processing efficiency is greatly accelerated but the change of mechanical properties is not obvious. The microstructure and mechanical properties were analyzed. Due to the decrease of heat input, the grains of DHWAAM are mainly equiaxed grains, while the grains of WAAM are coarse columnar grains. In addition, in the perpendicular direction to columnar grains growth, tensile specimens have better mechanical properties. Sample with fine α_P in the microstructure has better elongation. In the heat treatment, it is found that the heat treatment temperature has a great influence on the mechanical properties under air-cooling conditions. The α in the stress-relieved state is finer than the double-annealed state, which shows better yield strength.