Hybrid plasma surface alloying of austenitic stainless steels with nitrogen and carbon.

A hybrid plasma surface alloying process has been developed for austenitic stainless steels to improve their surface hardness, wear resistance and corrosion resistance. The process is carried out at temperatures below 450 °C and facilitates the simultaneous introduction of nitrogen and carbon into the surfaces of austenitic stainless steels, forming a dual layer structure with an extremely hard nitrogen-enriched layer on top of a hard carbon-enriched layer. Both nitrogen and carbon reside in the relevant layer forming a precipitation-free and supersaturated solid solution with expanded austenite structure, thus achieving much increased hardness and corrosion resistance. The present paper describes this novel process and the resultant structural and properties characteristics.