X-ray residual stress analysis on CrN/Cr/CrN multilayer PVD coatings deposited on different steel substrates

Hard physical vapour deposition (PVD) coatings as CrN, TiN and NbN have been successfully exploited for wear and corrosion protection. One limit to their performances under service is caused by the presence of large residual stresses, which adversely affect their properties as fatigue, fracture, corrosion, friction and wear resistance.X-ray diffraction (XRD) has been used for measuring residual stress on CrN/Cr/CrN multilayer coatings, produced by cathodic arc evaporation on substrates of three different steels (AISI H 13, AISI 1040 and K340). The thickness of the external and internal CrN layer was 1.6 μm in all the samples, while three thicknesses of the intermediate Cr layer, respectively, 0.5, 1.0 and 1.6 μm were used.The stress along two perpendicular directions (ϕ = 0°, 90°) on the coating surface have been measured by recording the peak positions of CrN {111} reflection for each ϕ at different tilt angles ψ. Regardless of the type of steel employed as substrate, residual compressive stresses are present in the external CrN layers. Furthermore, the results reveal stress anisotropy (σϕ=0° ≠ σϕ=90°) in the coating plane. In the coatings deposited on AISI 1040 steel stress is more isotropic independently on the Cr interlayer thickness.