Effect of Various Welding Parameters on Corrosion Behavior of Friction-Stir-Welded AA 7075-T651 Alloys

The 7000 series aluminum alloys provide the highest strength of all aluminum alloys and are widely used in the aerospace industries. They are practically unweldable by conventional fusion welding techniques. Friction stir welding is a widely accepted process to join this material. The paper intends to evaluate the electrochemical behavior of friction-stir-welded AA 7075-T651 alloy under varying welding conditions. An attempt has been made to evaluate the effect of tool rotation speed, welding speed, and shoulder diameter on its corrosion characteristics. The temperature histories during welding were continuously recorded with the help of thermocouples. The corrosion characteristics have been examined as per ASTM G-34 standards. The analysis is done by immersing the plates in EXCO solution and analyzing through optical imaging, SEM and TEM. The analysis revealed that the heat-affected zone was found to be most susceptible to corrosion. The corrosion resistance is found in the order—weld nugget > unwelded base metal > HAZ. The experiments revealed that the corrosion resistance of the welded plates is directly proportional to the heat input during the welding process. The plates welded with lower tool rotation speed, higher welding speed, and lower shoulder diameter exhibited higher corrosion resistance.