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Influence of PVD-coating manufacturing steps on the subsurface integrity of hardened and soft AISI M3:2 high speed steel

Influence of PVD-coating manufacturing steps on the subsurface integrity of hardened and soft AISI M3:2 high speed steel

Kategorien Konferenz (reviewed)
Jahr 2016
Autoren Denkena, B., Grove, T., Lucas, H., Tillmann, W., Stangier, D.:
Veröffentlicht in 12th International Conference THE A Coatings 2016, 31.03. - 01.04.2016, Garbsen, S. 23 - 30.
Beschreibung

Modern forming tools must fulfil high requirements concerning their wear resistance and friction behaviour. This is particularly important for high forces forming operations such as sheet-bulk metal forming, where contact pressures of several GPa might occur. These requirements can be achieved by means of thin film Cr-based PVD-coatings. At the same time, the subsurface residual stress state significantly influences the wear resistance of the substrate, as well as the adhesion of the coating. Thus, the pre-treatment as well as the magnetron-sputtering process have to be optimized in order to ensure a favourable residual stress state and to optimize the coating performance.
To examine the influence of each individual process step of the coating’s manufacturing chain on the substrate material, soft annealed as well as hardened AISI M3:2 high-speed steel samples are exposed to two different pre-treatments prior to the deposition of a CrAlN coating. One of the treatments includes a plasma nitriding process. Mechanical properties of the heat-treated steel and the coating system were analysed by means of nanoindentation. The adhesion between the coating and substrate was determined via scratch tests and analysing the specimen using a scanning electron microscope. Residual stresses in the substrate were measured via sin2ψ-method after each individual process step. The results show that the nitriding process step is necessary to achieve a better coating adhesion due to the induced compressive residual stresses. The hardened substrate is qualified to withstand high contact forces, which are characteristic for the sheet-bulk metal forming process.