Effect of Grain Refinement on the Pitting Corrosion Resistance of Fe-12Cr Steel

With industrial advancements, aerospace, energy, and medical fields demand stronger, more durable, and lightweight materials. Ultrafine-grained (UFG) structures, achieved through severe plastic deformation (SPD) techniques like Equal-Channel Angular Pressing (ECAP), enhance mechanical properties and corrosion resistance. However, literature on UFG effects on corrosion resistance remains inconsistent, likely due to microstructural complexity. In this study, Fe-12Cr alloy underwent ECAP (8 passes) for grain refinement. Dislocation density was evaluated using X-ray diffraction and the Williamson-Hall method, and low-temperature heat treatment was applied to selectively reduce dislocations without grain growth. EBSD confirmed grain sizes of 30–50 nm. Despite refined grains, heat-treated samples showed decreased pitting corrosion resistance. The results suggest that dislocation density plays a crucial role in corrosion resistance, indicating that grain refinement alone is insufficient, and residual dislocations are key to improving corrosion resistance.