Strain effects on corrosion inhibition in stress corrosion of tubing steel

In this investigation, we explored the corrosion inhibition mechanism of an imidazoline quaternary ammonium salt (IQA) on J55 steel in simulated annulus environment through a series of experiments, including electrochemical testing, stress corrosion immersion experiments, and hydrogen permeation testing. Our findings reveal that IQA functions as a mixed-type inhibitor, exerting its inhibitory action through chemical adsorption. Notably, it exhibits a stronger inhibitory effect on the anodic dissolution reaction compared to the cathodic hydrogen evolution reaction. Despite the minor influence of tensile plastic strain on the average inhibition efficiency, it notably exacerbates pitting and initiates stress corrosion cracking. This underscores the limitation of average inhibition efficiency in accurately assessing IQA's efficacy against stress corrosion. Additionally, hydrogen permeation experiments and electrochemical testing demonstrate that plastic strain diminishes IQA's inhibitory effect on the cathodic hydrogen evolution reaction, facilitating hydrogen diffusion into the steel substrate and thereby exacerbating stress corrosion in J55 steel. Consequently, at low IQA inhibitor concentrations (as in this study, 12.5 mg L), despite high average inhibition efficiency, it proves ineffective in mitigating stress corrosion.