The fitness and corrosion mechanisms of high-strength steel in corrosive oil-water environment at high temperature

This work investigated the mechanical decay mechanism and high-temperature corrosion mechanism of high-strength steel via high-temperature mechanical experiments, and corrosion and stress corrosion cracking tests were performed in simulated working conditions where water, oil, H2S, and CO2 coexist. The results show that the tensile strength and yield strength of high-strength steel decrease with increasing temperature; the tensile strength and yield strength at 350 & DEG;C reduce 11.91% and 19.08%, respectively, compared with 25 & DEG;C. Moreover, the corrosion rate of high-strength steel gradually increased from 0.0914 mm/a at 150 & DEG;C to 1.2288 mm/a at 350 & DEG;C. In addition, the influence of high temperature on the corrosion mechanism was inferred through thermodynamic calculations, and the reason for the presence of Fe3O4 in the corrosion products at 350 & DEG;C was analyzed. At 350 & DEG;C, stress corrosion cracking was observed in high-strength steels when the applied stress reached 90% of the yield strength. Based on the aforementioned studies, the relevant mechanisms related to the decay of mechanical properties, corrosion, and stress corrosion cracking are also proposed. We verified the inevitability of the presence of Fe3O4 in the corrosion products at 350 & DEG;C. This was done through a combination of thermodynamic calculations and experiments, which helped us enhance our understanding of the high-temperature corrosion mechanism.image