Effect of grain boundary engineering on electrochemical and intergranular corrosion of 316L stainless steel

The grain boundary engineering of 316 L SS was carried out by cold rolling and annealing. The microstructure was analyzed by EBSD, and the corrosion behavior was studied by electrochemical test, immersion and acid electrolytic corrosions. The results showed that the proportion of the low-Sigma coincidence site lattice (CSL) boundaries in the sample via 60 % cold rolling deformation and annealing at 1050 degrees C for 50 min increases to 58.04 %, with the Sigma 3 accounting for 91.49 % of the total low-Sigma CSL boundary. In terms of corrosion properties, this sample has larger total polarization resistance (97,247 Omega/cm2). The improved corrosion resistance is attributed to its higher proportion of Sigma 3 grain boundaries (especially coherent Sigma 3 boundaries), and larger proportion of (J2 +J3) in the triple junction distribution. The combined effect obtained from the increase of lowenergy Sigma 3 boundaries and the interruption of the random high-angle grain boundary network is more effective in suppressing intergranular attacks. The corrosion morphology showed that the specimens with the degree of sensitization values more than 0.5 % exhibit significant intergranular corrosion, and their corrosion morphology transitioned from boundary-controlled (ditch) to surface-controlled (step) corrosion.