The Response of Austenitic Stainless Steels to Low-temperature Plasma Nitriding*

Conventional plasma nitriding of austenitic stainless steels is characterised by the precipitation of chromium nitrides, resulting in hardening of the nitrided case, but at the expense of corrosion resistance due to the depletion of chromium in the matrix. Conversely, low-temperature plasma nitriding of these steels (at temperatures below 450°C) can produce a thin layer of very high hardness and good corrosion resistance. This paper presents recent research results on the structures, compositions and properties of low-temperature plasma-nitrided austenitic stainless steels and discusses the nitriding kinetics and their dependence on temperature and substrate material.