Effect of solution annealing and Al addition on the corrosion behavior of austenitic stainless steel in supercritical carbon dioxide at high temperature

The corrosion behavior of three austenitic stainless steels with basial composition of 20Cr25Ni (R1, SR1 and R1Al) was investigated in supercritical CO2 at 650℃. R1 was cold-rolled, SR1 was solution-annealed and R1Al was R1 with aluminum addition. The results indicate that solution annealing enhanced the corrosion resistance, reducing weight gain by 37.9% and mitigating preferential corrosion. Adding aluminum to R1 further improved its corrosion resistance, decreasing weight gain by 75.5% and eliminating preferential corrosion. The oxide film structure of R1 is SiO2, Mn2O3, Cr2O3 from the inside out, while that of R1Al is Al2O3, Cr2O3, and spinel oxides.