Numerical and experimental investigation of thermal history, material flow and mechanical properties of friction stir welded aluminium alloy to DHP copper dissimilar joint

Dissimilar Al-Cu joining is an emerging area of interest for both academic and industrial research. Friction stir welding being a novel solid-state joining process can overcome a number of issues raised by fusion welding of such dissimilar joint and thus good joint strength is expected. However, understanding the material flow and simultaneously the formation and control of intermetallics in friction stir welding (FSW) can only attribute good joint performance. In the present study, thermal cycle has been experimentally measured and simulated as well as simulation of thermal profile and detailed material flow behaviour have been analysed and correlated with the process response on mechanical property evaluation for different combination of parameters. Material flow behaviour and identification of intermetallics have been exclusively characterized by energy-dispersive X-ray spectroscopy (EDS) mapping and X-ray diffraction (XRD). Experimentally measured thermal cycles are found to be in a good agreement with those numerically calculated. The maximum joint strength achieved for 1000 rpm and travel speed 20 mm min−1 (86.5 % of aluminium base metal) is the optimized parameter with intermetallic (IMC) thickness of 3.6 μm for the present study.