The incidence of chromium-rich corrosion products on the efficiency of an imidazoline-based inhibitor used for CO2 corrosion prevention

A study has been conducted to analyze the influence of 1% Cr additions, microstructure, and pre-corrosion on the performance of CO2 corrosion inhibitors for C–Mn steels. Two carbon steels with two different microstructures were tested in a deoxygenated 5 wt.% NaCl solution, saturated with CO2 at 40 °C, pH 6. An imidazoline-based inhibitor was added after different pre-corrosion periods. Its performance was studied by means of d.c. electrochemical measurements, SEM and EDS. The results demonstrated a detrimental effect of 1% Cr and pre-corrosion on the inhibitor efficiency. It was also proven that the impact of pre-corrosion depends on microstructure and chemical composition.