Causes of Short-Time Corrosion of 2205 Duplex Stainless Steel Cathode Line

The cathode wire of wet electrostatic precipitator (WESP) of Unit 2 in a domestic thermal power plant was seriously corroded after the installation live test. The causes of corrosion of cathode line were analyzed by macroscopic morphology observation, chemical composition analysis, mechanical property test, metallographic examination, scanning electron microscopy, energy spectrum analysis and simulated flushing test. The results showed that the adsorption and dissolution of passivation film on the surface of 2205 duplex stainless steel cathode line was occurred in a short time under the combined action of low concentration Cl^- and SO₄^2-, which led to the contact between substrate and humid air, resulting in corrosion and rust with Fe₂O₃ as the main component.