Investigation in the corrosion behaviour of bulk nanocrystalline 316L austenitic stainless steel in NaCl solution

Corrosion resistance of nanocrystalline 316L stainless steel was compared with a coarse-grained (CG) one using potentiodynamic polarisation and electrochemical impedance spectroscopy methods and electron microscopy. The results showed that the corrosion resistance of nanocrystalline 316L stainless steel was higher than CG stainless steel. It was attributed to unstable passive layer on CG 316L stainless steel, which could be removed in a corrosive medium. The lower grain size facilitated fast diffusion of Cr and formation of passive layer. Nanocrystalline 316L stainless steel showed a relatively stable current density in anodic potentials, which was related to the higher corrosion resistance of nanocrystalline 316L stainless steel.