Finite element analysis of plastic deformation in twist extrusion

Twist extrusion (TE), a promising severe plastic deformation (SPD) technique for grain refinement down to ultrafine/nanocrystalline microstructures, was introduced as an attempt to provide large plastic deformation conditions similar to those in high pressure torsion while allowing large workpiece dimensions for industrial applications. As a relatively new SPD technique, TE requires in-depth investigation of its plastic deformation characteristics. The present study investigates the influence of process parameters such as backward pressure and friction on the loading history, the stress/strain states, and the final shape of processed workpieces using the finite element method. The results provide a basis for reasonable decision of processing conditions and also identify prerequisites for studies in formability and fracture of metals subjected to TE.