MICROSTRUCTURAL OBSERVATION OF M50 AND T1 HIGH SPEED STEELS DURING SLIDING WEAR

The sliding wear behaviour of M50 and Tl high speed steels was investigated using a pin on disc machine. The wear mechanism is one of severe oxidation wear and wear damage was more severe in M50 steel; this was attributed to its lower primary carbides content. The following factors improve the wear resistance of the steels: a higher percentage of primary carbide, a less dispersed carbide distribution, a simple carbide morphology, and smaller carbide paticles. Sliding wear tests were carried out on Tl steel at elevated temperaturesand more pronounced wear was observed: at 600°C it was catastrophic. At this temperature the debris became detached from the counterfaces with considerable ease.