Formation of non-metallic protective layers on high-speed steel tools

AbstractThe phenomenon of the formation of a protective layer on conventional or coatedcarbide tools when machining specially deoxidized high-machinability steels has been known to exist for many years. The layer is a result of the smearing of silicate inclusions from the workpiece over the surface of the tool. Tests using TiN-coated M2 high-speed steel tools to turn conventional and high-machinability variants of the structural steel C45, combined with optical metallography and electron-microprobe studies, have shown that this phenomenon can also be observed on these tools and that the formation of a protective layer significantly increases the service life of the tip edge.