Role of microstructural factor in wear resistance and cutting performance of high-speed steel end mills

The present paper describes the wear of high-speed steel (HSS) end mills with special emphasis on the influence of microstructural features, primarily the spatial distribution of eutectic carbides, on wear resistance. Hence, the wear resistance and performance of three HSSs of the same chemical composition but manufactured in three different ways, i.e. gravity casting, vacuum casting and a conventional metallurgical route, were compared. It was shown that the character of eutectic carbide spatial distribution in the HSS plays a major role in its wear performance, and, at the same hardness, it is independent of bending strength and impact toughness. For the studied range of eutectic carbide spatial distributions, tool life could differ up to 65 %. At both cutting speeds, 26 m/min and 40 m/min, the lowest wear resistance was determined for the end mills manufactured from the wrought HSS with uniformly distributed single particles of the dispersed eutectic carbides, and hence significantly higher values of bending strength and impact toughness. In contrast, the end mills manufactured from the as-cast material with coarser eutectic carbide networks along the primary matrix grain boundaries, and therefore worse mechanical properties exhibited the best wear resistance to abrasive and oxidational wear.