Strength ranking for interfaces between a TiN hard coating and microstructural constituents of high speed steel determined by micromechanical testing

[Display omitted] •New test method for strength of metal-ceramic and ceramic-ceramic interfaces.•Micromechanical test using a novel micro shear compression (MSC) specimen geometry.•Strength ranking of interfaces between HSS microstructural constituents and TiN hard coating.•Plastification before fracture in metal-ceramic interface specimen.•Basis to study failure behaviour of substrate-coating composites. Knowledge about the adhesion of protective hard coatings on tool materials is of great importance to understand their failure mechanisms in metalworking. Until now, common techniques such as scratch and indentation tests are used to establish a qualitative ranking of a coating’s adhesion on various substrate materials. Nevertheless, there is a lack of quantitative measures to describe the strength of the interfaces between individual microstructural constituents of substrate-coating composites. The current work investigates the interfacial strength and thus the adhesion of TiN deposited as a hard coating on an MC-type carbide, an M6C-type carbide and on martensite being constituents of high speed steels. Tensile stresses were introduced at the interface between TiN and the individual microstructural constituents of a high speed steel via micromechanical testing of a novel MSC specimen within a scanning electron microscope. The tested MSC specimens were subsequently investigated in detail by scanning electron microscopy. Evaluation of the interface stress at fracture via finite element analysis yielded a ranking in interface strength and therefore coating adhesion in a sequence from high to low strength values from MC/TiN over M6C/TiN to martensite/TiN.