SCC behavior and anodic dissolution of Inconel 600 in low concentration thiosulfate

The anodic dissolution behavior and the resistance to stress corrosion cracking of Inconel 600 in low concentration thiosulfate were studied utilizing the potentiodynamic polarization and constant load test methods under potential control. It was found that sensitized Inconel 600 was susceptible to IGSCC in thiosulfate solution only when pH was lower than 3. There existed an optimum combination of dissolution/repassivation rates that shortest failure time occured, which corresponded well with the maximum potentiostatic current at onset of abrupt current increase. The constant load test results for samples of different heat treatment also showed that the grain boundary chromium concentration and the crack tip electrochemical potential control the anodic dissolution behavior and thereby determine the stress corrosion resistance of Inconel 600.