Modeling of the processing force for performing ECAP of circular cross-section materials by the UBM

Equal channel angular extrusion or pressing (ECAP) is a process used to impart severe plastic deformations (SPD) (ε << 1) to materials with the aim of improving their mechanical properties by reducing the grain size. In this study, an analytical modeling of the ECAP processing force required, taking circular cross-section for ECAP dies into consideration, is developed where non-strain hardening materials are processed. To obtain the equation that relates the geometry and required force, the upper bound method was used after taking an appropriate and admissible field into consideration. In addition, a comparison between analytical methods and experimental results was made. In order to perform the experimental tests, an F-1050-AA (F means as fabricated) was selected and processed at room temperature. This alloy has a yield stress of 70 MPa and an insignificant strain hardening. The experimental results obtained agree closely with those provided by the analytical formulation. With this study, it is possible to have an analytical approach to the required force for performing the ECAP process. This could help scientists and practical engineers involved in SPD processes such as ECAP, to optimize ECAP dies and the process itself thanks to the knowledge of the analytical expressions of the required force.

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