Aqueous corrosion performance of nanostructured bainitic steel

• Aqueous corrosion performance of nanostructured bainitic steel was evaluated.
• Nanostructured bainitic steel performed better than martensitic steel.
• Nanostructured bainitic steel exhibited only general corrosion.
• Martensitic steel revealed high localized corrosion.

In this study, the corrosion performance of nanostructured bainitic steel was compared with martensitic steel in chloride-containing solution using electrochemical techniques. Electrochemical impedance spectroscopy (EIS) results showed that the polarization resistance (Rp) for nanostructured bainitic steel (3400 Ω cm2) was higher than that of martensitic steel (2000 Ω cm2). Potentiodynamic polarization results showed an 85% lower corrosion current density for nanostructured bainitic steel compared to martensitic steel. Galvanostatically polarized martensitic steel revealed high localized corrosion i.e., intergranular corrosion (IGC) as well as localized attack in the grains. However, the nanostructured bainitic steel when polarized galvanostatically exhibited only a marginal selective dissolution of retained austenite. Thus, it can be suggested that nanostructured bainitic steel will perform better than martensitic steel in chloride-containing environments.