Determining the elasto-plastic behaviour of AlCrTiN coatings through combined nano-indentation experiments and finite element modelling

Physical vapour deposition (PVD) coatings are widely used to improve the wear resistance and service life of tool contact surfaces in advanced manufacturing. However, the elasto-plastic behaviour of multi-element nitride coatings remains insufficiently quantified, limiting the reliable prediction of coating deformation and failure under complex thermo-mechanical loading conditions. To address this issue, an integrated nano-indentation and inverse finite element (FE) optimisation framework was developed to identify the elasto-plastic parameters of AlCrTiN coatings. Nano-indentation experiments were first conducted to obtain representative force-displacement responses, and FE-simulations were then calibrated against the experimental curves by iteratively minimising the discrepancy between the numerical and measured indentation responses. A hierarchical layered FE model was further established to account for the through-thickness variation in mechanical properties caused by the heterogeneous coating architecture. Compared with the homogeneous model, the layered model reproduced the experimental force-displacement curve with improved accuracy and captured the graded mechanical response of the coating. The identified Young’s modulus, yield stress and plastic tangent modulus should be interpreted as an effective elasto-plastic parameter set within the present indentation-based inverse modelling framework. These parameters provide essential input estimates for subsequent thermomechanical simulations of coated tools under cutting-related contact conditions, thereby enabling more reliable life prediction and performance optimisation.