Electrochemical and Surface Insights Into X12CrMoWVNbN10‐1‐1 Steel Corrosion in Chloride Solutions at Variable pH

ABSTRACT The corrosion behavior of X12CrMoWVNbN10‐1‐1 steel was investigated in 0.1 M NaCl solutions of different pH values (2.9, 6.5, and 10.3) using electrochemical impedance spectroscopy (EIS), linear sweep voltammetry (LSV), and potentiodynamic polarization (PDP). A pronounced pH dependence was observed, with the highest corrosion rate and lowest polarization resistance in acidic medium. Neutral and alkaline environments promoted passive film formation, with the alkaline solution providing superior protection against general and pitting corrosion. The enhanced passivation is attributed to the stabilizing role of hydroxide ions. Surface morphology by optical microscopy and SEM confirmed these trends, revealing severe degradation in acid and compact surfaces in neutral and alkaline media. Quantitative comparison with reference steels (P91 and 316 L) confirms an order‐of‐magnitude improvement in corrosion resistance, emphasizing the practical relevance of X12CrMoWVNbN10‐1‐1 for chloride‐containing environments. The results highlight its strong corrosion stability under variable‐pH exposure.