Improving tribological properties of tool steels through combination of deep-cryogenic treatment and plasma nitriding

Abstract In metal forming industry tools can be exposed to very complex and surface demanding conditions, which are the result of different effects (mechanical, thermal, chemical or tribological loading) and require well defined mechanical and especially tribological properties. The aim of the present work was to investigate the effect of deep-cryogenic treatment parameters (treatment time and temperature) in combination with plasma nitriding on the tribological performance of powder–metallurgy (P/M) high-speed steel. Special emphasis was put on abrasive wear resistance and resistance to galling under dry sliding conditions. Test results show that deep-cryogenic treatment contributes to improved abrasive wear resistance and better galling properties of P/M high-speed steel. Selection of the proper austenizing temperature is also an important factor, with higher austenizing temperature resulting in higher friction and wear. Plasma nitriding gives excellent tribological properties of P/M high-speed steel and reduces the effect of austenizing temperature. However, if combined with deep-cryogenic treatment it eliminates beneficial effect of deep-cryogenic treatment.