Microstructure and Mechanical Properties of TB6 Titanium Alloy Fabricated by Arc Additive Manufacturing

The TB6 titanium alloy deposition parts are prepared by arc additive manufacturing technology. The macro and micro structure characteristics and mechanical properties anisotropy of the deposition parts at different deposition heights are analyzed, and the influence of deposition current parameters on macro and micro structure and mechanical properties is studied. The results show that the macrostructure of the deposited parts is mainly composed of columnar and equiaxed β grains, and the volume fraction of equiaxed β grains decreases with the increase of deposition current. The microstructure is mainly composed of α basketweave structure uniformly distributed on the β matrix. The size of α lamellae increases first and then decreases with the increase of deposition height, which is mainly due to the difference of heat accumulation and heat dissipation capacity between the sedimentary layers at different deposition heights. In addition, the size of columnar β grains and α lamellae increases with the increase of deposition current. For the mechanical properties of the deposited parts, the transverse and longitudinal mechanical properties show that with the decrease of current, the tensile strength and yield strength of the deposited parts increase, while the plasticity decreases. This is because under the condition of low current, the heat input of the deposited parts is small, the size of α is relatively small, and the corresponding number of grain boundaries is large. While the grain boundaries hinder the movement of dislocations, they easily lead to the dislocation accumulation at the interface, which leads to the increase of the strength of the deposited parts and the decrease of plasticity. Further calculation of the anisotropy of the transverse and longitudinal mechanical properties of the deposited parts shows that the anisotropy of elongation is the most significant.