Characterization of Ti64 forging friction factor using ceramic coatings and different contact conditions

Abstract

Hot forging processes are highly influenced by the contact conditions between the billet and the dies. A wrong definition of the contact conditions may lead to wrong predictions of the final component geometry, the quantity of material necessary to fill in the cavity, the wear of the tools and the force necessary to manufacture the component. Furthermore, when dealing with titanium alloys, the alpha case formation due to oxidation is critical. For that reason, ceramic coatings are used to prevent billet oxidation during the heating stage and to improve the material flow lowering the friction coefficient between the billet material and tooling. In the present study, Ring Compression tests and T-Shape tests are carried out using ceramic-coated samples and friction behavior of Ti64 in contact with heated tool steel is studied. The final aim of the study has been to analyze the same tribo-system but having different contact pressures, sliding velocities and surface enlargement factors, which could affect the coating behavior. As a result, the friction coefficients are calculated for the above-mentioned tribo-tests by the comparison of the experimental data and numerical simulation results.