Pitting and crevice corrosion evolution characteristics of 2205 duplex stainless steel in hot concentrated seawater

The pitting and crevice corrosion behaviors of 2205 stainless steel were studied in the concentrated seawater at 72 degrees C, i.e., the simulated low-temperature multi-effect distillation environments, during 11,550 h of immersion by using electrochemical measurement techniques and surface analysis methods. The corrosion evolution successively shows passive, transient, and active corrosion stages. In comparison with the non-creviced specimens, the creviced specimens show insignificant difference in the corrosion potential, but the much lower polarization resistance values in the whole immersion process and shorter induction time for the transition of passive to active state. Crevice corrosion is easier to occur than pitting corrosion in hot concentrated seawater. The corrosion depth is deeper for the crevice than the pits, but is still very shallow. The pitting and crevice corrosion changes from charge transfer control to mixed control of charge transfer and diffusion process in the long-term immersion conditions. The diffusion process dominates the crevice corrosion since about 10,200 h. The ferrite phase dissolves preferentially in the crevice.