An Investigation into the Stress Corrosion Cracking Characteristics of Duplex Stainless Steel under the Oxygen–Chloride Synergism

To address the issue that 2205 duplex stainless steel (DSS) of reboiler tube bundle is prone to stress corrosion cracking (SCC) under high temperature, high chloride, and dissolved oxygen (DO), the SCC mechanism of 2205 DSS was investigated in this paper in an oxygen–chloride synergistic corrosion environment. To characterize the fracture morphology of SCC under different oxygen–chloride conditions, the slow strain rate tensile (SSRT) test was used. SSRT tests were performed on 2205 DSS in high temperature (100°C–200°C), high salt ($0–\mathrm{150,000}\mathrm{mg}/\mathrm{L}$), and different DO ($0–20\mathrm{mg}/\mathrm{L}$) corrosive environments. As the DO ($0–20\mathrm{mg}/\mathrm{L}$), chloride ion concentration ($0–\mathrm{150,000}\mathrm{mg}/\mathrm{L}$), and temperature (100°C–200°C) increased, so did the elongation, internal product work, and stress corrosion cracking tendency of 2205 DSS. A stress corrosion sensitivity index $F(A)$ calculation model was established, incorporating the interaction of temperature, chloride ions, and dissolved oxygen. The rupture of the passivation film and the superposition of anodic dissolution are the failure mechanisms of 2205 DSS. Transgranular stress corrosion cracking is caused by the rupture of the passivation film, which accelerates the failure process and eventually causes 2205 DSS to rupture.