Influence of nickel alloying on microstructure evolution and corrosion resistance of low-density steel Fe-Mn-Al-C in chloride-rich environment

Low-density Fe-Mn-Al-C-Ni steel shows promise for automotive and marine applications due to its excellent mechanical properties. However, research has mainly focused on strength and ductility, with limited attention given to corrosion. This paper investigates the effect of Ni on the corrosion resistance of Fe-28Mn-9Al-1C low-density steel in 3.5 wt% NaCl solution. This study employs microstructure characterization, electrochemical testing, immersion experiments, and surface corrosion product film analysis. The results show that Ni alloying promotes the formation of the B2 phase, inhibits kappa-carbides precipitation, and alters the phase composition of the material. It also promotes the growth of Al2O3 while suppressing the formation of FeO, leading to the formation of a denser corrosion product film. This film acts as an effective physical barrier, hindering the penetration of corrosive ion, reducing the dissolution of preferential inclusions, and enhancing the corrosion resistance of the material.