Cold metal transfer welding of aluminium alloy AA 2219 to austenitic stainless steel AISI 321

The feasibility of joining aluminium alloy (AA 2219) with austenitic stainless steel (AISI 321) in lap configuration was explored using a hybrid manufacturing route consisting of friction surfacing and cold metal transfer (CMT) welding. Prior to CMT welding using Al-Si filler (AA 4047), the stainless steel base metal was friction surfaced with the aluminium alloy in different thicknesses from 0.3 mm to 1.2 mm. The influence of the aluminium coating thickness on the lap-shear strength and failure mode of the joints was investigated. The joints produced using 0.6 mm thick aluminium coating showed the highest strength (260 N/mm), with failure occurring at or close to the coating/stainless steel interface. This interface, which was originally intermetallic-free, was found to develop a thin Fe-Al intermetallic layer after CMT welding. Friction surfacing of aluminium on stainless steel followed by CMT welding appears to be a promising approach for joining aluminum to stainless steel in lap configuration.