Influence of sigma-phase formation on the localized corrosion behavior of a duplex stainless steel

摘要: Because of their austenitic-ferritic microstructures, duplex stainless steels offer a good combination mechanical and corrosion resistance properties. However, heat treatments can lower the strength these as well render them susceptible to intergranular (IGC) pitting corrosion. In this study, low-carbon (0.02%) steel is subjected various at 450 950 °C for 30 min 10 h. The heat-treated samples then undergo ASTM IGC tests, results are correlated with microstructures obtained after each treatment. absence Cr23C6 precipitation, σ-phase precipitates Even submicroscopic deleterious resistance. Longer-duration (at 750 850 °C) induce chromium diffusion replenish chromium-depleted regions around improve resistance; resistance, however, not fully restored. Various mechanisms formation discussed show that adjacent depleted molybdenum. effect chemical composition (pitting equivalent) on also noted.