Studies of the Corrosion Behaviours of High-strength Alloy Steel in an Environment Containing Cl- Using a Wire Beam Electrode (WBE) and EIS Techniques

The corrosion behaviours of BR1500HS and Aermet100 high-strength alloy steel in an environment containing Cl- were investigated by wire beam electrode (WBE) and electrochemical impedance spectroscopy (EIS) techniques, and the corrosion products were analysed by scanning electron microscopy (SEM) and X-ray photoelectron spectrometry (XPS). The results showed that the microstructure of BR1500HS was coarse ferrite and pearlite, while that of Aermet100 was fine lath martensite. The WBE of BR1500HS showed general corrosion with a large number of total anodes (NTA) and a low localized corrosion intensity index (LCII). While the WBE of Aermet100 displayed severe localized corrosion in the first 24 hours with a small NTA and a high LCII, the localized corrosion was inhibited after the 24th hour. The EIS of BR1500HS revealed a single time constant of reactive corrosion, while the EIS of Aermet100 showed that there was a diffusion phenomenon, and rust layer capacitance and rust layer resistance occurred. The corrosion products of BR1500HS composed of Fe2O3, FeOOH, Fe2+ satellites, Fe and Fe3+ satellites were coarse, loose and porous, and the Fe2+ oxide with high compactness accounted for only 33% of the total oxide. The corrosion products of Aermet100 composed of FeOOH, Fe2+ and Fe2+ satellites were small, uniform and dense, and the Fe2+ oxide with high compactness accounted for 74% of the total oxide. Combining the improvement of Co2+, Ni2+, Cr3+ and Mo6+ in corrosion products, Aermet100 showed a stronger corrosion resistance in the environment containing Cl-.