Microstructure and high-cycle fatigue properties of laser melting deposited TC11 titanium alloy repaired by tungsten argon arc welding

Tungsten argon arc welding was used to repair a TC11 plate fabricated by laser melting deposition. Duplex-annealing of the repaired sample was provided. Microstructure and high-cycle fatigue properties of the repaired sample were investigated. The results indicated that the repaired zone shows morphology of columnar grains, both heat affected zone and base metal show alternatel yarranged morphology of columnar grains and equiaxed grains. Before heat treatment, the repaired zone and heat affected zone show finen eedle α(hcp) distributed in the β(bcc) matrix, while base metal shows fine basket-weave microstructure. After heat treatment, all zones show microstructure with primary α and transformed β. The primary α phase laths in repaired zone were longer compared with those in other zones. Fatigue properties of the repaired samples were 7.1% lower than that of the base metal. Fracture analysis of the high cycle fatigue specimens shows that all fatigue sources are porosity in repaired zone. Crack initiation zone is characterized by the crystallographic cleavage facets of α lamellae and tearing of β lamellae.