Multi-scale evaluation of crevice corrosion behavior in two lean duplex stainless steels: from initiation to propagation

• Precisely identifying the critical crevice corrosion conditions for similar DSSs • Visually and statistically revealing the correlation between CaO and crevice corrosion • Multi-scalely clarifying the mechanism of reversal crevice corrosion behavior This paper evaluates crevice corrosion behavior of lean duplex stainless steels (DSS) 2002 and 2101 using refined methods. DSS 2002 exhibits lower critical conditions, while DSS 2101 exhibits faster propagation. The critical crevice temperatures, 7−8°C for DSS 2002 and 9−10°C for DSS 2101, are established via Z-curves. Crevice corrosion initiation is proved to be induced by CaO through visual and statistical analysis. Corrosion behavior and dynamics in active regions are further studied via FeCl 3 immersion, Comsol numerical simulation and bipolar electrochemical techniques. To comprehensively evaluate crevice corrosion resistance, critical condition and stable propagation should be considered simultaneously.