Effect of Cu/V multi-interlayer on the microstructure and mechanical properties of TC4/IN718 joint by laser welding

In order to realize the effective connection between TC4 and GH4169 alloy, the Cu/V multi-interlayer was applied to join TC4 and IN718 alloy by continuous laser welding. The regulating mechanism of the Cu/V multi-interlayer on the cracks, microstructure and mechanical properties of TC4/IN718 joint was analyzed. The results show that a large number of Ti-Ni brittle intermetallic compounds are generated in the weld area of TC4/IN718 joint with the conventional laser welding, resulting in the formation of a large number of longitudinal cracks in the joint. The microstructure structure of weld zone in the TC4/IN718 joint is comprised of Ti(s,s) + Ti₂Ni + Ti-Cr + NiTi + Ni₃Ti + Cr(s,s). When adopting the Cu/V multi-interlayer, the effective joining between TC4 and IN718 alloy is realized, the tensile strength of the joint reaches 271MP. The microstructure structure of weld zone in the TC4/ Cu/V/IN718 joint is transformed into Ti(s,s) + V(s,s) + NiV₃ + Cr(s,s) + Cu(s,s) + unmelted copper.