Abstract: The growth process of low-temperature plasma-nitriding layer was investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The layer is composed of expanded fcc phase (γN), whose lattice parameter of the layer increases with process time resulting from increasing the nitrogen content. The layer hardness increases gradually with nitrogen content. The high slip band density on the layer surface observed in situ by SEM shows that the surface yield occurs when supersaturated nitrogen content in the layer attains to some value, which is also responsible for the increase in layer hardness.

Key words: austenitic stainless steel, plasma nitriding, slip band