Influence of Salt Solution pH Level on SCC Characteristics of 6082 Aluminum Alloy Joint Made by Friction Stir Welding

The SCC characteristics of 6082 aluminum alloy joints made by friction stir welding (FSW) in air, 3.5% NaCI solution (pH=7, 8, 9 respectively) were studied and comparaed by means of slow strain rate testing (SSRT), SEM, OM and EDS. The causes of the difference of SCC characteristics in different media were discussed. The results show that the SCC sensitivity index I_SSRT of the FSW welds in acid, alkaline and neutral NaCl solutions were 0.13, 0.074 and 0.055 respectively. The weld fracture exhibited mainly ductile fracture without SCC characteristics in neutral and weakly alkaline solutions, and mixed fracture with some SCC characteristics in weakly aid solution.