Surface modification of austenitic steel by low-temperature plasma

The paper presents a part of the investigations on the influence of cathode sputtering on the surface characteristics in 316 austenitic steel and its influence on nitrided layer formation during gas nitriding. Moreover, the importance of the initial state of the surface is analysed. The samples were cathode sputtered with various parameters of current density and time. The changes in the upper surface were evaluated using grazing angle X-ray diffraction (GXRD) for various angles of incidence, by atomic and magnetic force microscopy and by SIMS. It was found that both the initial state of the samples (polished and ground) and the parameters of cathode sputtering (current density) have an important influence on the further growth of nitrided layers during gas nitriding and particularly on their phase composition. It was also observed that the kinetics of nitride layer formation depends on its composition.