Cold Arc MIG Welding of Titanium Ti6Al4V to Aluminum 5A05Al Using Al–Mg5 Filler

Butt welding of titanium Ti6Al4V to aluminum 5A05Al was carried out using cold arc MIG welding with Al–Mg5 filler. Microstructure of the Ti/Al interface was strongly influenced by the welding heat input. Two types of Ti/Al interfaces were observed, i.e. a serrated TiAl₃ layer in the regions with low heat input, a uniform Ti_3.3Al layer and a cellular TiAl₃ layer in the regions with high heat input. The latter interface appeared interesting growth sequence, that is, Ti_3.3Al layer and cellular TiAl₃ layer were formed orderly from titanium side to weld metal side. Tensile test and fractography study were carried out to examine the reliability and fracture mode of the joint, respectively. Crack-free welds were obtained with full-penetration under operational welding process. All the specimens were fractured in aluminum base metal during the tensile test and the average tensile strength reached up to approximately 242 MPa. Interfacial microstructure and properties of the joint indicated that Al–Mg5 filler can be used as effective filler to fabricate sound Ti/Al joints.