Low temperature plasma nitriding and carburising are it-all known as methods for improving tribological properties without deterioration of corrosion properties of austenitic stainless steels. 'S phase' is a key alloyed layer; achieved front these two plasma thermochemical processes, referred as nitrogen and carbon S phase, respectively. The present work has been focused on full characterisation of the mechanical and chemical properties of carbon and nitrogen S phase on austenitic stainless steel AISI 316 produced during loth temperature plasma processes with different process parameters. A series of theoretical, experimental, and analytical studies hate been conducted in order to lay the necessary foundations for fully realising the application potential of these processes in carious stress and environmental conditions. (C) 2002 MAI Communications Ltd.