Abstract: The lap-shear joint configuration that the titanium alloy Ti6Al4V sheet is placed on the top of the pure copper T2 sheet is carried out. 1 mm thick titanium alloy Ti6Al4V is joined to 1 mm thick pure copper T2 using ERCuNiAl filler wire by cold metal transfer(CMT) welding technology. Microstructure and intermetallic compounds of the welded joints are examined by scanning electron microscopy (SEM) with energy dispersive spectrometer (EDS). The mechanical properties are characterized by tensile-shear tests. Results indicate that the welding process is stable and the continuous and uniform welded joint is formed. Satisfied lapped joint between titanium alloy Ti6Al4V and pure copper T2 can be achieved by CMT welding method. Copper sheet and welding wire are melted, and then copper-weld interface is formed. Titanium sheet is partially melted, copper sheet and welding wire melting is surrounded around titanium sheet, so three titanium-weld interfaces are formed. Ti-Cu welded interface is composed of an intermetallic compounds layer of TiCu, TiAl, Ti2Cu, AlCu2Ti and copper base solid solution. The joint has tensile shear strength of 200 MPa, and fractures with plastic fracture mode in the copper heat affected zone (HAZ).

Key words: titanium alloy;pure copper;dissimilar metals welding;cold metal transfer;lap welded joint