Wear performance of PVD coated tool steels

Abstract

The paper describes the performance of high alloy tool steels coated by PVD techniques. Performance evaluation was based on the wear resistance in the conditions of prevalence of adhesion and on tool wear (durability) in the conditions of blanking of electrotechnical sheet steel. Hardmetal (WC-15% Co) was used as a primary standard material. It is shown that adhesive wear resistance depends both on the composition of the PVD coating and on that of the tool material to be coated - steels with higher adhesive wear resistance ensure also a higher strengthening effect of the surface. Sharpening of specimens (cutting tools) - removal of coating at the face zone of the tool by grinding - revealed the difference in the efficiency of the coating in different zones of the tool. In terms of durability, thin PVD coatings do not enable improvement of the performance of sheet metal blanking tools (dies, punches). No correlation between durability in blanking and adhesive wear resistance was revealed. In terms of durability prognostication, alloys' (tool steels, hardmetals, cermets) adhesive wear resistance enables tool life assessment only when materials of similar nature (steels, carbide composites) are compared.