Comparative study on corrosion behaviors of ferrite-pearlite steel with dual-phase steel in the simulated bottom plate environment of cargo oil tanks

Abstract

The corrosion behaviors of ferrite-pearlite steels before and after intermediate quenching treatment were compared in the simulated bottom plate environment of cargo oil tanks. The results indicate that all tested steels exhibited an enhanced galvanic corrosion caused by the accumulated Fe3C. However, the corrosion resistance of steels could be improved by the change in microstructure from ferrite-pearlite to ferrite-martensite through intermediate quenching treatment, whereas a higher temperature caused an adverse effect. This was mainly due to both the Fe3C morphology and the content of cathodic phase in the steel matrix controlling the area ratio of cathode to anode during the corrosion process. Moreover, the proportion of high-angle grain boundaries and the potential difference in the galvanic couple had a limited effect on the galvanic corrosion.

Keywords

• Galvanic corrosion
• Cementite
• EBSD
• TEM
• EIS