Effect of SO^2-₄ on SCC Susceptibility of Nickel-Based Alloy 690TT in Simulated PWR Primary Water at High Temperature

The effect of SO₄^2- concentration on stress corrosion cracking (SCC) susceptibility of nickel-based alloy 690TT in simulated pressurized water reactor (PWR) primary water was investigated by slow strain rate testing (SSRT) at 310 ℃. The results show that necking occurred near the fracture of the nickel-based alloy 690TT samples. In the PWR primary water containing low concentration of SO₄^2-, most fractures of the nickel-based alloy 690TT samples were shear-like, and the stress corrosion susceptibility of the alloy was low. When the mass fraction of SO₄^2- reached 1 500 μg/kg, transgranular cracks occurred at the localized zones of fracture edge, which means high concentration of SO₄^2- increased the SCC susceptibility of nickel-based alloy 690TT.