Low temperature anodic nitriding of AISI 304 austenitic stainless steel

In conventional plasma nitriding process, the treated components were submitted to high cathodic potentials. In this present work, AISI 304 austenitic stainless steels were nitrided at anodic potential in plasma atmosphere. Nitriding experiments were carried out at low temperature 430 °C for 3 h, 6 h, and 9 h. The specimen was characterized by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and a microhardness tester. The results showed that the nitrogen expanded austenite layer was formed on the surface during the low temperature anodic nitriding. The surface microhardness and the thickness of the hardened layers increased as the nitriding time increased. It suggested that nitrogen was present as a solid solution in the nitrided layer.