Tribological behaviour of surface treated and postoxidised tool steels at elevated temperature

The aim of this work is to study the tribological properties of plasma nitrided tool steels which are also post-oxidised to form an oxide layer on top of the nitrided layer. The experimental work has been carried out by using pin on disc machine at room temperature and at 400 ºC. The experimental materials were tool steels of three compositions. All tool steel samples were plasma nitrided and post oxidised at 500 ºC. One of the tool steels was also post oxidised at 480 ºC and 520 ºC. The mating disc specimen was made from hardened high strength boron steel. The specimens have been analysed by using SEM/EDS, XRD and 3D optical surface profiler. The results have shown that both friction and wear of tool steel and high strength boron steel pairs are temperature dependent. Increase in temperature results in increasing of friction and wear. The tool steel wear is higher at elevated temperature when compared to wear at room temperature. The tool steel samples post oxidised at 500 ºC has better friction and wear performance not only at room temperature but also at higher temperature.Validerat; 20101217 (root