To explore the improvement of the corrosion resistance of the inner bottom plate of corrosion-resistant storage tank steel and the effects and underlying mechanisms of varying molybdenum (Mo) contents (0Mo, 0.15 wt.%Mo, 0.30 wt.%Mo, and 0.60 wt.%Mo), a systematic study is conducted on the corrosion performance of the steel in a simulated environment (10 wt.% NaCl solution, 30 ± 1 °C). The findings reveal that the steel containing 0.3 wt.% Mo possesses superior corrosion resistance. An optimal dosage of Mo refines corrosion products and fills voids via the formation of nano-scale MoO2/MoO3 particles, mediates the evolution of γ-FeOOH towards α-FeOOH, and improves the protective capability and electrochemical stability of the rust layer. Nevertheless, excessive Mo leads to the residual of elemental Mo arising from incomplete oxidation, which constructs a galvanic cell with Fe, thereby accelerating corrosion. Additionally, an excessively high proportion of MoO3 triggers elevated internal stress and structural degradation of the rust layer.
Hong et al. (Sat,) studied this question.