Tribological performance of plasma nitrided 42CrMo4 steel at elevated temperature

This paper is focused on the tribological behaviour of the plasma nitrided 42CrMo4 steel at elevated temperature to 300 °C. The hardened steel was treated in plasma in two variants of nitriding atmosphere: 24H2:8N2 and reverse ratio 8H2:24N2, which is greater nitrogen concentration. This leads to forming the nitriding layers with different phases, therefore, to distinct mechanical and tribological properties of nitride layers. The "ball on disc" wear test was performed at the variation of temperatures. A profilometer was used to investigate the wear track on the disk surface. Experimental results indicated that the coefficient of friction changed over the test time and temperature, and plasma nitriding in the atmosphere of 8 H2 : 24 N2 improved wear resistance better than nitriding in the atmosphere of 24 H2 : 8 N2. The results of wear test were further supplemented by measurement of surface roughness, metallografical documentation, layer thickness measurements, surface hardness and microhardness test. © 2017 TANGER Ltd., Ostrava.