In this process after making proper chamber to produce plasma in d.c. Glow regime and readiness of samples and doing microhardness and PIXE analyzes, samples nitriding began in different conditions. The hardness changes and the depth of hardened layer of 321, 316 and 304 steels are studied as a function of discharge parameters [8, 9]. The plasma was produced using a mixture of N₂ and H₂ gases at glow discharge regime. The gas composition varied between 0.25< [n (H₂)]/ [n (N₂)] < 0.5, the sample temperature 300°C