Superior performance of 18Mn3Cr0.5Mo1V ferrous alloy for strength, ductility, and prolonged corrosion resistance in seawater

High-performance structural materials that combine superior mechanical properties and robust corrosion resistance are vital for sustainable infrastructure and offshore equipment. Here, we report a multi-component (18Mn3Cr0.5Mo1V)-based ferrous alloy with a face-centered cubic structure that demonstrates high strength, hardness, ductility, and extended service life in harsh chloride environments. In contrast to conventional carbon steels for seawater use and Cr/Mo/V-free 18Mn-bearing alloys, this multi-component alloy showed much lower corrosion rates (i.e., lower weight loss and corrosion current density, and higher polarization resistance), which could be comparable even to that of ferritic stainless steel. These surface-inhibiting properties were attributed primarily to the synergistic interactions of the micro-alloying of Cr, V, and Mo, maximizing Cr-enrichment in the oxides composed of inner scale with refined particle size in its structure. Moreover, the cation selectivity characteristics of scale impedes effectively the penetration of Cl ions into the alloy surface.