Processing And Characterisation Of PM T42 HSS For Its Application As Valve Seat Inserts In Diesel Engines

摘要

Water atomised T42 High Speed Steel (HSS) powders have been processed for obtaining a material suitable for valve seat inserts in diesel engines. Processing variables concerning powder preparation, pressing, sintering and heat treatment have been analysed in order to obtain a near-net-shape component with a microstructure satisfying service conditions (hardness, thermal stability and wear resistance). The microstructural evolution of the material during all the processing stages has been characterised as well as the wear behaviour in the heat treated material. Pin-on-disc tests at service temperatures (360℃) have demonstrated an excellent wear resistance of the seat without a considerable wear of the valve material. Addition of solid lubricant particles to the original powders for improving the machinability and reducing the friction coefficient without affecting the sintering and heat treatment processing parameters has also been carried out. At present, service tests at the engine manufacturer are in progress.