Friction & wear propertices of ion-nitrided HSS (High Speed Steel) SKH 55 (KS Designation) were examined.
Wear tests of the ion-nitrided steel were carried out at various temperatures ranging from 15℃-400℃ using an Ogoshi high speed wear tester under dry condition with sliding distance of 400m. The result showed that as the nitriding time increased, the wear volume increased until the wear depth reached a critical value depending on the compound layer thickness of the specimens considered. In case the wear depth greatly exceeded the thickness of the compound layer but not exceeding the thickness of the diffusion layer, the wear volume was almost the same as the nitriding time increased. The wear volume became larger as the test temperature rose. It, therefore, appears that the compound layer of the ion-nitrided steel is easily worn out while the diffusion layer resists the wear, and the degree of improvement of wear resistance in the ion-nitrided steel decreases as the test temperature rises.
In addition, friction coefficient of the ion-nitrided steel with some other metals, mean flank wear land, and maximum crater wear depth of ion-nitrided insert tool in outfeed facing operation were measured and compared to the corresponding quantity of the steel without nitriding.
The friction coefficient was reduced with the amount of reduction depending on sliding material, and the mean flank wear land was reduced to half to two thirds, compared to the steels without nitriding.