A novel high-Mn steel with high corrosion resistance

Through corrosion weight gain experiments, x-ray photoelectron spectra, x-ray diffraction, transmission electron microscopy, scanning electron microscopy, and electrochemical tests, the corrosion behavior of a traditional high-Mn steel (Mn13C1.2) and a novel high-Mn steel (Mn18Cr7C0.6N0.3) in a simulated marine atmospheric corrosion environment was investigated. The results revealed that N and Cr acted synergistically to stabilize the amorphous phase in the rust layer, improving its protective performance. Additionally, N drove Cr enrichment in the outer rust layer (OL), resulting in grain refinement within these regions. The rust layer of Mn18Cr7C0.6N0.3 consisted of three diverse regions. First, the steel/rust interface (SRI) was the densest region, where Cr and N promoted the formation of fine β-FeOOH and α-FeOOH grains. Second, the inner rust layer (IL) was relatively dense region, primarily consisting of fibrous β-FeOOH grains. Third, the OL of rust was more porous and had strip-shaped grains of β-FeOOH and γ-FeOOH. The addition of Cr and N improved the rust layer’s structure, thereby enhancing the corrosion resistance of the Mn18Cr7C0.6N0.3 in marine atmospheric environments.