Identification of the elastic-plastic properties of CrN coating on elastic-plastic substrate by nanoindentation using finite element method-reverse algorithm

This paper proposes an identification methodology based on nanoindentation analysis of coating/substrate system to extract the elastic-plastic properties of coating materials on elastic-plastic substrate when the indenter penetration depth is greater than the film thickness. In order to accurately predict the elastic-plastic properties of the coating materials, a trust-region reflective optimization algorithm is integrated with the finite element analysis, in cooperation with the Jo center dot nsson and Hogmark model. The proposed reverse analysis algorithm modifies a predicted load-displacement (P-h) curve by changing the elastic-plastic properties of the coating and the substrate until it fits the experimental nanoindentation (P-h) curve. Numerical and instrumental indentations tests were carried out on a CrN film/Martensitic stainless steel substrate system to verify the proposed reverse method, by which Young's modulus (E), yield stress (sigma y), and work hardening exponent of the film were obtained. A sensitivity analysis is conducted to study the effect of the elastic-plastic properties of the CrN film/ substrate on the (P-h) curve. The results showed a high impact to the loading and unloading part of the (P-h) curve due to variations in (E) and (sigma y) of the steel substrate compared to those of the CrN coating.

Automated summary

This paper proposes a method for identifying the elastic-plastic properties of coating materials on an elastic-plastic substrate based on nanoindentation analysis of the coating/substrate system. By integrating a trust-region reflective optimization algorithm with finite element analysis and the Jo center dot nsson and Hogmark model, the method accurately predicts the properties of the coating materials and modifies the predicted load-displacement curve to fit the experimental nanoindentation curve. Experimental tests on a CrN film/Martensitic stainless steel substrate system verified the method and obtained Young's modulus, yield stress, and work hardening exponent of the film. Sensitivity analysis demonstrated that variations in the elastic-plastic properties of the steel substrate have a significant impact on the loading and unloading parts of the load-displacement curve compared to those of the CrN coating.