Effect of annealing heat treatment on microstructure and corrosion behavior of Ti6Al4V alloy fabricated by multi-laser beam wire-feed additive manufacturing in vacuum environment

Ti6Al4V alloy thin wall was successfully fabricated by multi-laser beam wire-feed additive manufacturing in vacuum environment. The effect of annealing heat treatment (AHT) on microstructure and corrosion behavior of specimens in 3.5 wt% NaCl and 1 mol/L H2SO4 electrolytes was investigated. Results showed that AHT led to the reduction of the non-equilibrium phase α′ and texture weakening. AHT700 was beneficial to achieve crystal refinement while AHT850 had obvious coarsening phenomenon. In addition, AHT could improve the corrosion behavior of the specimens due to the reduction of α′ phase and relief of residual stress. Compared with the specimen of AHT850, the specimen of AHT700 with finer crystal size and obvious texture weakening improved the corrosion resistance more obviously.