Strong relation between corrosion resistance and nanostructure of compound layer of treated 316 austenitic stainless steel

Nanometric-sized carbide-based crystallites have been synthesized successfully through the pulsed nanocrystalline plasma electrolytic carburizing method on the surface of 316 austenitic stainless steel. It was found that the corrosion resistances of coated samples has a direct relation ship with the average size of complex carbide-based nanocrystallites. The synthesized carbide-based crystallites exhibit average sizes at around 37–80 nm. Furthermore, the surface response method (including Box–Behnken design) was applied to deal with the effective conditions of the coating process. This method reveals that the optimal conditions were obtained at 700 V for the peak applied cathodic voltage, 15 kHz for the frequency of pulsed current, 40 °C for the temperature of the electrolyte and 10 min for the treatment time. These results indicate that the corrosion resistances of the resulting layers are a direct function of the average size of the nanocrystallites.