Topography and Corrosion Resistance Characteristics of Fe40Al5Cr0.2ZrB Alloy and X18CrN28 Steel

This paper presents the results of corrosion resistance tests of materials (Fe40Al5Cr0.2ZrB alloy and X18CrN28 steel) in a 5% NaCl solution at room temperature using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization, complemented by confocal/AFM topography and SEM/EDS analysis. Confocal/AFM mapping showed pronounced roughening and localized features on Fe40Al5Cr0.2ZrB alloy (e.g., Sa rising locally to ~1.63 μm), consistent with heterogeneous chloride-induced attack, whereas X18CrN28 steel exhibited only minor roughness changes (Sa ~ 13–19 nm). SEM/EDS of Fe40Al5Cr0.2ZrB alloy revealed mixed oxides with detectable chlorine at corroded sites, while the steel retained a thin, Cr-rich passive layer with negligible Cl signal. Overall, X18CrN28 steel demonstrates significantly higher resistance to localized corrosion in neutral chloride media than Fe40Al5Cr0.2ZrB alloy, aligning electrochemical metrics with surface and chemical analyses.