Non-Metallic Inclusions in Steel in Relation with the Formation of Deposited Layers on Rake face of PVD Coated HSS Tools

The existence of non-metallic deposited layers originating from inclusions on workpiece steels on the rake face of high speed steel (HSS) tools coated by physical vapor deposition (PVD) has considerable affects on tool life. However, conditions for the formation of the layers have not been clearly understood. It is evident from this study that the contents of inclusion elements in the steels do not play an important role in the formation of the layers. The existence of silicate inclusions eliminates a built-up edge (BUE) on the cutting edge and may be involved with the formation of the white layer in the crater wear, leading to a reduction of tool wear.