EIS Characteristic under Cathodic Protection and Effect of Applied Cathodic Potential on Surface Microhardness of Q235 Steel

Abstract

In order to better understand the electrochemical and mechanical characterizations under different cathodic protection potentials of mild steels, the electrochemical reaction feature in the cathodic potential region was studied by electrochemical methods, surface analysis techniques and microhardness tests. Electrochemical Impedance Spectroscopy (EIS) of Q235 steel was tested at different cathodic potentials to analyze the electrochemical properties. The transfer resistance Rt with different cathodic potentials was obtained by fitting the EIS data with equivalent circuits of fitting software ZSimpwin and Zview. The relationship between Rt and potentials were also investigated. The cathodic protection potential region, best protection potential and hydrogen evolution potential were determined by Rt~E curve. Through the analysis of the cathodic polarization and microhardness relationship after hydrogen permeation, surface mechanics properties were assessed and the results showed that the cathodic protection had a significant impact on the surface mechanical properties of the steel in tidal environment.