Electrochemical corrosion characteristics of type 316L stainless steel in hot concentrated seawater

• Impedance features for 316L stainless steel in hot concentrated seawater.
• Pitting is under mixed control of charge transfer and diffusion processes.
• Thin salt layer forms on the electrode surface and retards the oxygen diffusion.
• Pits propagate slowly in the simulated distillation environments.

The corrosion behaviour of 316L stainless steel was studied in the concentrated artificial seawater at 72 °C, i.e., the simulated low temperature-multi effect distillation environments, by using electrochemical measurement techniques. The corrosion state changes from spontaneous passivation to pitting after about 1150 h of immersion. Pitting corrosion is under mixed control of charge transfer and diffusion processes in the long-term immersion. The salt deposits retard the diffusion of oxygen to the metal surface. The pit depth only reaches about 38 μm after one year of immersion due to the alloying effect of Mo, low dissolved oxygen levels and weak occlusion states.