Nitride layer formation on chromium-nickel steel

The paper presents results of the investigation on the conditions of nitrided layer formation during low temperature nitriding of 316 stainless steel. The treatment was carried out in the nitrogen atmosphere with the following process parameters: voltage - 13 5 0 V, current density 0.7-1.7 mA/cm(2), time - 60 min. The temperatures of the processes were 610 K, 650 K and 705 K. Special attention was paid to the influence of the initial state of the surface on the formation of m phase. The samples used in the experiment were either ground or polished. The structural analysis was performed on the basis of the X-ray diffraction patterns obtained under low incident angle (3degrees). Moreover the surface microhardness of the nitrided layers was evaluated. It was stated that mechanical treatment of the surface has big importance for the composition of the nitrided layer obtained. The formation of m phase was observed only on the polished samples even at very low temperature.