Electrochemical surface nitriding of SUS 430 ferritic stainless steel

Electrochemical surface nitriding of SUS 430 ferritic stainless steel was investigated in a molten LiCl–KCl–Li3N system at 773 K, and surface hardening by this electrochemical surface nitirding process was confirmed. From the results of XPS and XRD analyses, it was found that the surface nitrided layer contained CrN precipitates in α-Fe matrix. The square of the thickness of the surface nitrided layer was proportional to the electrolysis time. The rate constant, KP, increased as the applied potential was more positive. This finding indicated that the chemical potential of adsorbed nitrogen (Nads) on SUS 430 stainless steel electrodes depended on the applied potential and it affected nitrided layer growth.