The effects of Al content on the corrosion behaviors of aluminum-bearing steels were studied in NaCl solutions. Electrochemical measurements and Raman and scanning electron microscopy (SEM) surface analyses revealed that the aluminum-bearing steel formed two passivation films: the outer layer film contained Al2O3 and Cr2O3, and the inner layer film contained lepidocrocite (gamma-FeOOH), regardless of whether the NaCl solution was faintly acidic/alkali or neutral. Lepidocrocite is unstable and can transform to alpha-Fe2O3 and gamma-Fe2O3 when exposed to air. The electrochemical impedance spectroscopy (EIS) results showed that the dominant anticorrosion effect comes from the inner layer film, but a larger Al content causes a larger charge transform resistance and larger outer and inner passive resistances, which result in better anticorrosion properties. Furthermore, corrosion weight gain tests revealed that the Al content (Al%) and corrosion rate (V) exhibit a negative linear relationship V = -1.3667A1 % (wt.%) +1.9691 in the investigated conditions.

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