Corrosion Behavior of Friction Stir Welded Joints of 2219 Al Alloy in Neutral Chloride Solution

The micro-electrochemical characteristics and corrosion behavior of a friction stir welded AA2219-O joint in 0.5 mol/L NaCl neutral solution were characterized using a microcell method and immersion test, respectively. An optical profilometer was employed to analyze the uniform corrosion depth as well as the pitting corrosion morphology, depth and density of the joint after being immersed for 14 days. The mechanism which affected the corrosion behavior was discussed. The results showed that pitting corrosion occurred without applied potential. Compared to the base metal, the corrosion resistance was similar in the heat affected zone, slightly improved in the thermomechanically affected zone. In the shoulder affected zone (SAZ), the θ phase particles were partly dissolved and broken, which led to an increase in the content of dissolved Cu in the matrix, and decreased the weight-loss corrosion rate as well as the pitting depth, volume and density. As a result, the corrosion resistance significantly increased in the SAZ.