Prediction of the critical load of a metal-rolling system by considering the damage of the coated surface

Under various working conditions, rolling elements may suffer from different types of damage behaviour, including fractures in the coatings and bonding interfaces, and plastic deformation in the substrate materials. The present paper reports research into the prediction of the critical load of a metal-rolling system (metal-rolling system) by considering the damage of the coated surface based on a novel FE simulation-procedure developed by the present authors. The modelling procedure features several modelling approaches including: parameterised FE modelling, Cohesive-Zone modelling and a sub-modelling technique. The typical case examined in this study is linecontact between two cylindrical bodies. The studied surface-modified systems are CrN, TiN and TiN/CrN multilayer PVD coatings applied on 42CrMo4 steel in both the nitrided and quenched-and-tempered states. It was observed through the numerical simulation that for almost all of the configurations, cracking occurs at the edge of the contact when one cylinder is pressing against the other cylinder, due to a bending effect. The critical load of the system was determined by referring to the initiation of the first crack of the coated surface of the ring. Comparison between the numerical-simulation results and the experimental results showed excellent agreement.