CORROSION BEHAVIOR OF DISSIMILAR FRICTION STIR WELDED FOR ALUMINUM ALLOYS (5052 H34 AND 7075 T6)

Abstract

Friction stir welding was used widely in joining of dissimilar Aluminum alloys joints which used in aerospace applications due to high specific strength and superior corrosion resistance. Aluminum alloys 5052 H34 and 7075 T6 was successfully welded at tool rotation speed (400) rpm and travel speed (187) mm/min with using adjustable scrolled pin tool. Corrosion behavior of this joint was investigated using potentiostat in two medias “0.5% HCl, 0.5% NaOH” to show the polarization resistance and calculate the corrosion rate from data of “Tafel extrapolation method”. The microstructures of different zones of FSW joint have been investigated. Cyclic polarizations were done to measure the resistance of specimens to pitting corrosion. From the results obtained, it has been shown that best corrosion resistance of welded joint was noticed in 0.5% NaOH comparing with 0.5% HCl. The corrosion rate of FSW welded joint was higher than base alloys in 0.5% NaOH, while it's lower than base alloys in 0.5% HCl. The Base metal alloys susceptible to pitting corrosion while friction stir welded joint exhibit good general and pitting corrosion resistance in NaOH and HCl media.