Effect of Mo on Corrosion Performance of Inner Bottom Plate of Corrosion-Resistant Storage Tank Steel

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.