Simulation of the Electrochemical Corrosion Behavior of 14Cr12Ni3WMoV Stainless in Different Concentrations of Cl^-

Abstract

In order to analyze the effect of Cl- concentration on the electrochemical corrosion of steel commonly used for the final stage blade of steam turbine, the electrochemical corrosion behavior of 14Cr12Ni3WMoV martensitic stainless steel in simulated solutions with different chloride ion concentrations was investigated by various methods including potentiodynamic polarization, electrochemical impedance spectroscopy(EIS), Mott-Schottky(M-S)curves, laser scanning confocal microscope(LSCM)and scanning electron microscope(SEM).Results showed that with the increase of Cl- concentration, the point defect inside the stainless steel passivation film increased, the stability became weaker, the pit corrosion sensitivity increased and its protection ability to material substrate declined.The diameter of corrosion pit on the surface of stainless steel increased significantly with the increase of Cl- concentration, but the depth of the corrosion pit did not increase significantly, indicating that corrosion pits were more likely to develop along the material surface.When pitting corrosion occurred in stainless steel, the elements of Fe, Cr , Ni, W, Mo and V of materials were selectively dissolved.Specifically, Fe and Ni migrated to the solution in the form of ions, while Cr, W, Mo and V deposited in the corrosion pit in the form of oxides.

Keywords

• electrochemistry corrosion|cl-|14cr12ni3wmov stainless steel|blade|steam turbine|passivation film|pitting corrosion