Stress corrosion cracking of 316 SS and Incoloy-800 in high temperature aqueous containing sulfate and chloride

The stress corrosion cracking (SCC) susceptibility of 316 stainless steel (SS) which was welded for primary pipe and Incoloy-800 (shotpeening) for steam generator (SG) tube have been investigated by means of a slow strain rate test (SSRT) at a strain rate of 4.2 x 10-6 /s. Tests were conducted at 315 degrees C for 316 SS and 270 degrees C for In-800 in the oxygenated simulated resin intrusion environment (acidic sulfate). Tests of the effect of combination of SO4-2 and Cl- on SCC of Incoloy-800 were also carried out. The results indicate that Incoloy-800 is unsusceptible to SCC either in the environment with SO4-2 (from a few ppm to 1000 ppm, pH 3 ∼ 4) or in the environment of combination of SO4-2 (1000 ppm) and Cl- (from 2 to 1000 ppm). The 316 NG SS is susceptible to transgranular stress corrosion cracking (TGSCC) in the resin intrusion environment with SO4-2 in high temperature water