Nitriding of Austenitic Stainless Steel

Abstract

Stainless steel is a difficult material to nitride because a passive oxide film is present on its surface. Hence it is essential to remove this film by chemical or mechanical means before any surface treatment can be carried out. This increases the cost of the treatment substantially. The commonly used processes for the surface treatment of stainless steel have been gas nitriding, salt bath nitrocarburising and lately plasma nitriding. Plasma nitriding due to its operating conditions, does not require any prior treatments for removal of the passive oxide film. Plasma nitriding also provides the possibility of treatment at low temperature, which is important to retain corrosion resistance of stainless steel. The fact that nitriding of stainless steel improves the wear characteristics but impairs the corrosion resistance has been reported by many researchers. However, very little work has been carried out to study and analyse this problem. This research work has studied the corrosion and wear properties of austenitic stainless steels using the three different nitriding techniques mentioned above. It was also the objective to study the optimum plasma nitriding conditions required to achieve optimum wear and corrosion properties...