Analysis on the Corrosion Performance of Friction Stir Welding Joint of 7022 Aluminum Alloy

The corrosion performances of base metal (i.e. 7022 aluminum alloy) and the welded joints under different process parameters of 7022 aluminum alloy in the mixed solution of Na2SO4 + dilute H2SO4 (pH = 5) were studied by the weight-loss method and electrochemical method. The weight-loss method results showed that the base metal and the welded joints under different process parameters were occurred corrosion on their surfaces, and the base metal corrosion was far greater than the welded joints under different process parameters, the parameter for 400 /30 welded joint corrosion was minimum. The electrochemical corrosion results were consistent with weight-loss method. Under various parameters of welded joints corrosion rate were not consistent, the parameters for 400 /30 welded joint corrosion rate was lowest. The electrochemical corrosion results showed that the base metal corrosion was mainly for pitting and denser distribution. The welded joints under different process parameters corrosion were appeared only a small amount of spot, their corrosion degree were small.