Passive Behaviour of New Alloy Corrosion Resistant Steel Cr10Mo1 in Simulating Concrete Pore Solutions with Different Chloride Contents

This work aims at studying the passive behaviour of new alloy corrosion resistant steel Cr10Mo1 and plain carbon steel (as a reference), in simulating concrete pore solutions contaminated with different concentrations of chloride (0 M, 0.2 M, 0.6 M and 1.0 M, as NaCl). The electrochemical behaviour was evaluated by linear polarization resistance, d.c. potentiodynamic polarization and electrochemical impedance spectroscopy. The surface films composition was investigated by X-ray photoelectron spectroscopy (XPS). The results show that the passivity of the corrosion-resistant steel has no significant decline with chloride contents increasing, while carbon steel hardly passivates with chloride above 0.6 M. The primary constituents of the passive films formed on the corrosion-resistant steel and carbon steel are very different; the former contains both Cr and Fe oxides while the letter consists of only Fe species. Cr oxides, as the key components for the passive film on the corrosion-resistant steel, can still remain stable and protective under high concentration of chloride, which supports the excellent passive performances of the corrosion-resistant steel in severe conditions.