Sensitivity of Friction Condition in Finite Element Investigations of Equal Channel Angular Extrusion

Abstract

Equal channel angular extrusion (ECAE) is an effective forming technique that increases the material strength by accumulating plastic strain into the workpiece without changing its cross-sectional shape in the multi-pass processing. This study concentrates on the investigation of interface contact phenomenon between the workpiece and channel in terms of forming load and material flow predictions. The change of contact conditions during remeshing was also investigated in terms of variation of load requirements and volume losses. In order to validate the numerical algorithm proposed, simulation results were compared with the experimentally measured data of the ECAE with the CP-Ti Gr-1 cylindrical specimen. Numerical simulations were obtained by applying the mixed finite element formulation with tetrahedral elements under the non-isothermal condition. For determination of the material data, compression test was carried out and the tested data was interpolated as a function of strain, strain rate and temperature. The current investigation clearly showed the importance of proper handling of the friction boundary condition during numerical simulations to guarantee the solution accuracy of the ECAE.