Investigation of the influence of heat treatment of cold work steel on coating adhesion under mechanical load between substrate and thin titanium coatings deposited by PVD

Abstract Metastable phases can be shifted to a different state by thermal loads on components. This leads to structural changes and precipitation. Within the scope of this investigation, a coating is applied to a solution annealed and a quenched and tempered substrate of the same chemical composition by means of a cold PVD process. The investigation is based on the process of polymer extrusion without additives. The substrate examined is 1.2379 tool steel. The substrate is used as a screw extruder material and is exposed to operating temperatures of up to 400 °C. A titanium layer is applied which is used in practice as an adhesion promoter and is in direct contact with the substrate. An annealing temperature above 500 °C results in special carbide hardening. These should show a worse layer adhesion than the metal bonds of the solution annealed sample. The aim is to investigate whether a difference is measurable or negligible. The loads during polymer extrusion are simulated by means of bending and pin-on-disk tests. The 3-point bending test simulates the mechanical load during extrusion. The pin-on-disk test simulates the friction between the extrusion screw flank and the extrusion cylinder. The substrate is characterized before and after sample preparation. Wear measurements are carried out using CLSM and SEM. The surface topography is recorded and then evaluated for comparison.