Investigation into the role of pin geometry on the corrosion behavior of multi-pass FSWed joints of Al5086 besides applying Al2O3 nanoparticles

Abstract

The current work deals with the role of different pin geometries on the corrosion behavior of the butt friction stir welded (FSWed) joints of Al5086. The joints were produced using multi-pass technique along with the application of Al2O3 nano-powders. In this study, five diverse pin geometries including straight cylindrical, tapered cylindrical, threaded cylindrical, triangular and square were utilized to investigate the effects of pin profile on the corrosion behavior of the joints fabricated using four-pass FSW. Corrosion properties were studied using Tafel polarization and electrochemical impedance spectroscopy tests. Among all the FSWed joints the one fabricated using the square pin-profiled tool offered the highest corrosion resistance. This can be attributed to the higher value of the dynamic to static ratio and pulsating stirring action of this pin geometry. Furthermore, all the FSWed joints offered higher corrosion resistance compared to that of the base material. Pitting and intergranular corrosions, which are typical of welded regions, were spotted and fully investigated using scanning electron microscopy (SEM). These studies verified the results carried out from the Tafel polarization and electrochemical impedance spectroscopy tests.