High throughput screening of localised and general corrosion in type 2205 duplex stainless steel at ambient temperature

Bipolar electrochemistry is used to produce a linear potential gradient across a bipolar electrode (BPE), providing direct access to the anodic and cathodic reactions under a wide range of applied potentials. The occurrence of pitting corrosion, crevice corrosion, and general corrosion on type 2205 duplex stainless steel (DSS 2205) BPE has been observed at room temperature. The critical pit depth of 10-20 mu m with a 55%-75% probability of pits developing into stable pits at potential from +0.9 to +1.2 V vs. OCP (open circuit potential) are measured. All pit nucleation sites are either within ferritic grains or at the interface between austenite and ferrite. The critical conditions for pitting and crevice corrosion are discussed with Epit (critical pitting potential) and Ecre (critical crevice potential) decreasing from 0.87 and 0.80 V vs. OCP after 150 s of exposure to 0.84 and 0.76 V vs. OCP after 900 s of exposure, respectively. Pit growth kinetics under different applied bipolar potentials and exposure times have been obtained. The ferrite is shown to be more susceptible to general dissolution.