Microstructure formation mechanism and mechanical properties of super-thickness TC11 titanium alloy joint by electron beam welding and laser additive manufacturing hybrid connection technology

Abstract

Advanced connection technology for extra-large/super-thickness titanium wrought components is urgent demand in aerospace manufacturing industries. For achieving high-performance titanium alloy super-thickness joint with a high connecting efficiency, a novelty concept of hybrid connection technology with electron-beam welding and subsequent laser additive connection is proposed. A super-thickness (200 mm) TC11 titanium alloy joint has been successfully prepared, and microstructure, tensile properties and fracture behavior of different regions in which are investigated. The results suggest that in stress-relieve heat treatment (SRT) condition, deformation and fracture of the joint are prone to occur in its low-strength wrought base material zone; after double annealing heat treatment (DAT), lamellar α phases in different zones of the joint become similar, associating with a higher fraction of fine secondary α phases in wrought base material zone. Therefore, the tensile properties of the joint are comparable to wrought properties. Although strength in different zones of hybrid connection joint is similar, ductility is not uniform and apparently lower in middle fusion zone due to grain heterogeneity. Overall, these findings indicate that hybrid connection can be one potential technology for fabricating high performance super-thickness titanium alloy joint with a high connection efficiency in engineering application fields. • A super-thickness (200 mm) TC11 titanium alloy joint was high-efficiency fabricated. • A higher strength value is observed in fusion zone of stress-relieved joint. • Grain heterogeneity contributes to a lower ductility of middle fusion zone in joint. • Heat treatment promotes strength and ductility increase of weak zones in joint. • Heat-treated joint is plastic deformation in a strain-dominant mode with slip bands.