Joining dissimilar materials is required in many engineering applications and conventional fusion welding of dissimilar materials often results in defective welds. Friction Stir Welding (FSW) has paved way for joining dissimilar alloys and defect-free joints have been obtained for a number of dissimilar material combinations. Numerical modelling of FSW process can provide reasonable insight into the physics of the process and will aid in minimising the number of experimental trials. In this paper, Computational Fluid Dynamics (CFD) based numerical model is developed to predict the temperature distribution and material flow during FSW of dissimilar aluminum alloys AA2024 and AA7075. Volume of fluid approach is used and the FSW process is modelled as a steady-state visco-plastic laminar flow past a rotating cylindrical tool. Results indicate that peak temperature in the welded plates increases with the increase of Tool Rotation Speed (TRS) and Shoulder Diameter (SD), whereas the peak temperature decreases with increase in Welding Speed (WS). Increasing TRS and SD increases material flow, while increasing WS decreases material flow in the stir zone

This article investigates the role of friction stir processing (FSP) process parameters on the evolution of microstructure, hardness, intergranular corrosion resistance and wear resistance of aluminium alloy AA5083. The FSP trials are performed by changing the process parameters as per face-centered central composite design. The friction stir processed (FSPed) specimens subjected to intergranular corrosion test and wear test are characterized using field emission scanning electron microscope, energy dispersive x-ray spectroscopy and X-ray diffraction. Outcomes suggest that grain refinement, dispersion and partial dissolution of secondary phase has simultaneously increased the hardness, intergranular corrosion resistance and wear resistance of the FSPed specimens. The study found that tool rotation speed of 700 rpm, tool traverse speed of 60 mm min⁻¹ and shoulder diameter of 15 mm results in maximum hardness, wear resistance and intergranular corrosion resistance.

In the current study, friction stir processing was applied as a methodology to produce surface composites of AZ91D magnesium alloy with ZrO₂ particles. Microstructural evolution, microhardness profile and corrosion behaviour of the developed surface composite were analysed. The results indicate that the combined effect of friction stir processing and reinforcement of ZrO₂ reduced the grain size, and fragmented and dispersed the secondary phases. The fine dispersion of ZrO₂ particles contributed to the enhancement of cumulative surface potential, and hence the corrosion resistance of the developed surface composite. The analysis of post-corrosion test specimens revealed the formation of corrosion products that had similar composition to that of hydroxyapatite. The formation of such corrosion products is beneficial, as it contributes to corrosion resistance (stable and adherent layer) and biocompatibility.

In the research work, an attempt is made to join nickel-based alloy 825 by employing CO₂ laser beam welding. Successful full penetration weld joint of a 5 mm thick plate is achieved with a very low heat input of 120 J-mm⁻¹. Narrow weld bead width of 0.6 mm at the root and 1.6 mm at the cap is observed fusion zone; the interface and base metal microstructures have been examined using both optical and scanning electron microscopic techniques to understand the microstructural changes which have occurred due to laser welding. A range of tests of Vickers micro hardness, tensile and impact tests had been performed on the weldment to ascertain the mechanical properties of the joint. Tensile failure at the base metal and a 180° root bend test conducted on the weldment ascertain the soundness of the weld joint produced. An attempt is made to correlate the microstructure and mechanical properties of the weldment. Intermetallics TiN and Al₄C₃ observed in the SEM\EDS analysis at the fusion zone are found to have improved the weld metal strength and hardness.