Austenitic stainless steels are attractive materials for various industrial sectors to combat environmental and corrosive attack. However, the inherent poor tribological behaviour (in terms of high friction and low wear resistance) has been the main barrier to their wider applications under corrosion-wear conditions. Therefore, it has long been a dream for surface engineering researchers to develop novel surface engineering technologies to effectively enhance the wear resistance of stainless steel surfaces without loss of their attractive "stainless" characteristics. This has been highlighted by the discovery of low temperature plasma nitriding phenomenon in the mid 1980's, where a new phase with a high hardness and good corrosion resistance could be produced on austenitic stainless steel surfaces. Since then great research and development have been made towards combined improvements in wear, corrosion and fatigue properties. This has been demonstrated by various low temperature surface alloying processes (including plasma, ion beam, gaseous and salt bath methods) and increasing numbers of academic publications, reflecting rapidly expanding niche markets in the food, chemical, nuclear and medical sectors. In this paper, the historical evolution and development of low temperature thermochemical surface alloying processes are overviewed; the research and development of low temperature surface alloying of austenitic stainless steels towards combined improvements in wear, corrosion and fatigue properties are assessed; finally new directions and key areas for future development are identified and discussed.
