Compared Corrosion Resistance of 430 Ferritic Stainless Steels Produced via Unidirectional and Reversible Rolling

This study investigates the comparative effects of unidirectional (R1) and reversible (R2) rolling processes on the corrosion resistance of 430 stainless steel, specifically evaluating the roles of residual stress versus microstructural stability. The experimental approach involved microstructural characterization of processed samples followed by corrosion performance evaluations, including salt spray testing and post-corrosion morphological analysis. The results indicate that R1 processing produces a dense, aligned microstructure with high residual stress, whereas R2 rolling leads to cyclic stress dissipation but results in extensive carbide delamination and surface porosity. Despite its higher residual stress, the R1 sample demonstrated significantly higher corrosion resilience. In contrast, the R2 sample exhibited pronounced localized degradation, characterized by deep intergranular cavities and intragranular attack. The findings reveal that microstructural voids and interfacial stability, rather than residual stress levels, are the primary factors governing passive film rupture and pit nucleation in these rolling conditions. The study demonstrates that unidirectional rolling preserves microstructural coherence, thereby enhancing the overall corrosion resistance of 430 stainless steels.