Development of hard coatings for press hardening processes

The increasing energy prices during the last decade boosted the lightweight design in automotive industry. One result of these developments is to use high strength steels e.g. USIBOR® 1500. Such steel sheets are formed in press hardening processes where especially an enhanced adhesive wear is present. In this thesis, hard coatings within the system Cr-Si-N are investigated with the focus to reduce the adhesive wear during press hardening processes. Therefore, Cr-Si-N coatings with Silicon contents up to 17.5 at% (on the metal sublattice) were deposited by physical vapour deposition using arc evaporation. Detailed investigations of the coatings prepared concentrate on structure, morphology, hardness, residual stress and thermal stability as a function of their Si content. The thermal stability tests include structure, mechanical properties and oxidation characterization after annealing in vacuum and ambient atmosphere at 400 °C and 800 °C. Furthermore the friction and wear behaviour was investigated by ball on disk tests at room temperature and 800 °C. Additional to these investigations special application near measurements on an OPTIMOL® SRV tester and Hardware tests were conducted.