Low pressure plasma arc source ion nitriding of austenitic stainless steel

A series of low pressure plasma are source ion nitriding experiments has be en conducted on AISI 304 stainless steel at temperatures ranging from 350 t o 460 degrees C in an N-2-H-2 gas mixture. The structure and composition of the plasma nitrided layers were studied by optical metallography, X-ray di ffraction (XRD) and Auger electron spectroscopy (AES). The thickness of the nitrided layer depends on the plasma nitriding temperature. After 2h of ni triding at 420 degrees C, a 12 mu m nitrogen supersaturated austenite nitri ded layer with nitrogen content up to 45 at% on the surface was formed. The hardness values of the nitrided layer measured are in the range of 4.6 GPa for the sample nitrided at 350 degrees C to 12.0 GPa for the sample nitrid ed at about 420 degrees C. (C) 2000 Elsevier Science S.A. All rights reserv ed.