The surface characteristics and corrosion behavior of plasma nitrided austenitic stainless steel containing Mo

The surface characteristics and corrosion behavior of plasma nitrided auste nitic stainless steel containing Mo has been investigated using a wear test er, a micro-hardness tester and potentiostat equipment. It was found that p lasma nitriding at 823 K, compared with at 653 K, resulted in a thick nitri ded layer, and consequently good wear resistance and hardness, as the nitri ding time increased. Whereas for the Mo addition, wear resistance and hardn ess decreased. Intergranular corrosion(IGC) resistance improved significant ly in the case of plasma nitrided SS containing 4.05 mass%Mo at 653 K becau se the nitrogen and Mo act synergistically to form a protective surface lay er which is responsible for the aggressive SCN- ion. Plasma nitriding at 82 3 K decreased IGC resistance as the Mo content increased owing to retardati on of the nucleation and growth of chromium carbide (Cr23C6) or nitride(CrN ) in grain boundary.