Molecular dynamics, thermodynamics and experimental studies on the corrosion mechanism of T92 and TP347H steels in high-pressure CO2 and H2O at 600 °C

In the initial atom-scale corrosion stage, the formation of chemical bonds and the distribution of atoms were obtained by the molecular dynamics. The thermodynamic and experimental results indicated the distribution of oxides and carbides formed on T92 and TP347H steels. [Display omitted] •The corrosion mechanisms of steels in HTHP CO2 and H2O were investigated by molecular dynamics, thermodynamics and experiments.•The combination between Cr and O was earlier than Cr and C.•The carbonization rate of T92 steel was lower than that of oxidation rate.•The Fe3O4 oxides on T92 steel were coarsened and pulverized.•The volatile CrO2(OH)2 were formed on the surface of TP347H steel. The corrosion mechanisms of T92 and TP347H heat-resistance steels in high-temperature and high-pressure (HTHP) CO2 and H2O environments were investigated by molecular dynamics, thermodynamics and experiments. In the initial corrosion stage, the combination ability of Cr with O and C was stronger than that of Fe with O and C, which caused oxygen and carbon absorption capacity of TP347H steel was higher than that of T92 steel. In HTHP H2O environment, the Fe3O4 oxides on T92 steel were coarsened and pulverized, which made the Fe3O4 oxides become loose. The volatile CrO2(OH)2 were formed on the surface of TP347H steel, which caused the coarsening of Cr2O3 oxides.