Microstructure and mechanical properties of cold metal transfer welded aluminium/dual phase steel

In this work, an attempt was made to join A6061-T6 aluminium alloy to Dual Phase 800 steel using AlSiMn filler by cold metal transfer (CMT) processes. The effect of process parameters on the microstructures and tensile strength of the joints are analysed. Microstructural analysis revealed the formation of the Fe-Al intermetallic (IM) layer. The IM layer thickness was found to be very small. Electron microscopy analysis revealed the presence of long plate shape (Al5FeSi) and fragmented particles in the IM layer. At the interface, Theta-FeAl3 and eta-Fe2Al5 phases were formed. Pulsed process resulted in better joint strength when compared to conventional CMT method. X-ray diffraction study revealed the formation of the Fe3Al and eta-Fe2Al5 phases in the weld. The welding currents and arc length correction factor had significant effects on the joint strength. Tensile failure occurred at the heat affected zone.