Effect of deformation on corrosion behavior of T92 and Super 304H heat-resistant steels in supercritical CO2 environment

Supercritical CO₂ power generation has been recognized as a promising high-efficiency, low-carbon technology due to its superior thermal performance and operational flexibility. The deformation of heat-resistant steel tubes during the bending process in heat exchanger manufacturing is an inevitable occurrence. In this study, the corrosion behaviors of T92 and Super 304H steels subjected to 5 %, 10 %, and 15 % deformation were evaluated in a supercritical CO₂ environment at 600 ℃ and 15 MPa. T92 steel exhibited a parabolic corrosion kinetics, with the weight gain decreasing as deformation increased. The deformation was found to enhance Cr diffusion via grain refinement, increasing the proportion and stability of the protective FeCr₂O₄ film. In contrast, Super 304H steel showed corrosion-induced weight loss due to the spallation of Nb-rich and Fe-rich oxides. The corrosion resistance of Super 304H was highly sensitive to deformation, with 5 % deformation offering optimal performance. Higher deformation levels resulted in aggravated corrosion, attributed to hindered Cr diffusion caused by high dislocation density and residual stress, which promoted the formation of nodular Fe-rich oxides and reduced the integrity of the Cr₂O₃ protective film.