Tribological behaviour and mechanical properties of low temperature gas nitrided austenitic steel in relation to layer morphology

The authors present the results of investigations on the influence of the morphology of the nitrided layers produced on austenitic steel on their mechanical properties and tribological behaviour. The layers were obtained during low temperature (475 °C) gas nitriding preceded by cathode sputtering in nitrogen as an activation technique. The layers containing various stages of “expanded austenite” were obtained as a result of different cathode sputtering parameters applied during the treatment. It was found by MFM, TEM and XRD investigations that the coatings produced have complex multilayer structures. The hardness and Young's modulus were measured using nanoindentation and wear and friction testing were used to characterise the tribological behaviour.