Effect of cold rolling on the pitting corrosion of 316L and 304 austenitic stainless steels

In this study, microstructural analyses, electrochemical measurements, and chemical immersion tests were used to investigate the effect of cold rolling on the pitting corrosion resistance of 316L and 304 austenitic stainless steels (ASSs). The results indicated that the yield and tensile strength of both ASSs were much higher after severe cold rolling at 150 °C. In addition, the microstructural analyses revealed that deformation bands were the main feature for the deformed ASSs. The pitting corrosion potentials Ep of the ASSs monotonously decreased with an increase in the degree of rolling deformation and were similar under heavy deformation. The diameter of the semicircle in the Nyquist plot decreased, and the donor density in the passive film increased with an increase in the degree of cold rolling. Moreover, several pits were observed at the deformation bands in the cold-rolled ASSs. The average diameter and depth of the pits increased with an increase in the degree of cold rolling. After the cold rolling process, the deformation bands were high-stress regions and would provide more potential sites for pitting nucleation. Finally, with an increase in the deformation degree, more deformation bands were generated, and the pits nucleated more easily, indicating that the pitting corrosion resistance of the two ASSs was poorer after the deformation. Pitting corrosion resistance decreases with an increase in the degree of cold rolling deformation, and deformation bands would be the potential sites for pitting initiation in the ASSs which is rolled at 150 °C.