FEM-simulation analysis of spherical cavity ECAP design at different channel angles

Abstract

Equal-channel angular pressing (ECAP) is one of the main ways of refinement the structure of metals into a fine-grained and nanostructured state.Regardless the great prevalence and high knowledge of the method, the issues of optimization and improvement of the design and geometry of the working tool still relevant.A number of simulations of the geometry of the channels of the die with a spherical cavity of the junction of the channels were carried out in order to study the regularities of the stress strain state formed in the channel.The study was carried out for different angles of the junction of the die channels using the example of a zirconium alloy Zr-2,5%Nb.Due to the spherical cavity, a back pressure is formed, as a result of which the nature of the accumulation of deformation in the alloy changes.Using die with spherical cavity, it is possible to achieve a more complex of shear deformations scheme in comparison with the conventional method and to increase the treatment of metal in the axial zone of the billet.However, this type of ECAP is characterized by a more heterogeneous distribution of the accumulated strain in the cross section of the billet, as well as an increase in the pressing force in all cases.