Optimisation of friction stir welding parameters to improve corrosion resistance and mechanical properties of AA2219 aluminium alloy welds

摘要

AA2219 Al-Cu alloy is mainly used for aerospace and defence applications. Welding is used in the fabrication of components made of AA2219 aluminium alloy and causes microstructural changes in various zones that form during fusion welding of AA2219 alloy, which strongly influence the corrosion behaviour. Friction stir welding (FSW) could be the remedy to avoid the above problems and mainly joint strength of AA2219 FS welds gets affected by tool pin profile parameter. Mathematical models are developed using response surface method (RSM). A central composite design with four parameters and five levels has been used to limit the experimental conditions. Response optimisation shows the optimum combination of tensile strength, hardness and corrosion resistance were achieved with hexagon tool pin profile and welding parameters of rotational speed 1,214 rpm, welding speed 63 mm/min and axial force 11 KN. From the microstructural studies it was found that properties of the welds made with hexagonal tool pin profile are superior when compared to conical tool pin profile, and is attributed to relatively more fine grain structure in hexagonal tool pin profile when compared to conical tool pin profile.