Influence of process parameters on bead geometry and its effect on mechanical properties of CMT welding of automotive grade steel and aluminium alloy using aluminium based filler wire

This investigation aims to examine the effectiveness of torch position, welding-brazing parameters on the embedded bead profile and load carrying potential of the brazed joint of zinc coated DP600 steel and Al 5052 joined by cold metal transfer (CMT) technique. The base metals were joined at different torch position (-0.6 mm, 0 mm and 0.6 mm) in lap joint position using Al-based filler wire. At different wire feed rate (WFR) 3, 4 and 5 m/min changes in bead shape and its geometry were observed. The various modes of failure were classified based on effective bonding length (LH-LV) and LH/θ ratio. The best combination of welding-brazing parameters at which the maximum load bearing capacity of 4.1 kN and enhanced bead properties was achieved at 0.6 mm torch position and WFR 5 m/min. The intermetallic compound layers formed during the process affects the tensile properties of weld-brazed joint. The possible intermetallics and the presence of major elements in intermetallic layer were analyzed by energy dispersive X-ray spectroscopic analysis. Furthermore, in this investigation it was also observed that the thickness of IMC layer increases with the increasing WFR and heat input up to a critical value of 10 μm.