Microstructures and properties of titanium–copper lap welded joints by cold metal transfer technology

• Ti–Cu joints can be successfully performed by cold metal transfer technology.
• Ti–Cu joints can be joined by series of Ti–Cu intermetallic compounds.
• Ti–Cu joint has a tensile strength of 194 N/mm.

Cold metal transfer (CMT) welding has been successfully used to weld dissimilar metals widely. However, a few investigations were carried out on the lap welding of commercially pure titanium TA2 to pure copper T2 with ERCuNiAl copper wire by CMT technique. In this paper, the affected mechanism of lapped location between the two metals on the microstructure and tensile shear strength of joints was revealed. The results indicated that satisfactory lapped joints between commercially pure titanium TA2 and pure copper T2 could be achieved by CMT welding method. A layer of intermetallic compounds (IMCs), i.e. Ti2Cu, TiCu and AlCu2Ti presented in titanium-weld interface, and the weld metal was composed of α-Cu solid solution and Ti–Cu–Al–Ni–Fe multi-phase. The two joints had almost same tensile shear strength, 192.5–197.5 N/mm, and fractured in the heat affected zone (HAZ) of Cu with plastic fracture mode during tensile shear tests.