Formation of expanded phases in low-temperature nitrided stainless steels

Stainless steels have a widespread use due to their resistance to general corrosion in many environments. Among the different types, ferritic and austenitic stainless steels have low hardness and wear resistance, which may limit their use. Modification of the surface characteristics can be performed using low-temperature nitriding, which produces supersaturated N-rich solid solutions, known as expanded phases. The formation of these phases without the precipitation of nitrides is a challenge for ferritic and low-Ni austenitic stainless steels, as it is reported in this study.