Studies of plasma nitriding of stainless-steels

The paper deals with the surface hardening of stainless steels trough the application of suitable plasma nitriding cycle to different austenitic and martensitic grades. The cylindrical shaped samples, 18 to 30 mm in diameter and 50 mm long, have been plasma nitrided in an industrial plant, performing the heating in hydrogen based plasma up to 420 °C for 2 h, then the temperature has been elevated at 530 °C in plasma obtained by H2 - N2 (80% and 20% respectively), the cooling has been done in nitrogen based atmosphere. After treatments the samples were used to study the microstructure features, as well as the undergone hardening effect. The surface hardening effect, as well as the penetration of the treatment strongly depends upon the alloy composition and microstructure. The martensitic grade showing the thickest nitrided layer accompanied by the highest hardening effects.