Numerical and experimental studies of the plastic strains distribution using subsequent direct extrusion after three twist extrusion passes

In this investigation, simulation of three consecutive clockwise twist extrusion for commercially pure aluminum samples at ambient temperature with and without subsequent direct extrusion is presented. The influences of 50% reduction on strains distribution are analyzed on the specimen middle transverse cross-section. The results show that performing subsequent direct extrusion after twist extrusion increases the shear strain magnitude in the center of the specimen. High shear strain results in more grain refinement in the center regions in contrast to the corner ones. Few experiments were also carried out to validate the numerical findings. Furthermore, examination of microstructure evolutions and mechanical properties for the commercially pure aluminum samples were conducted using SEM, microhardness and tensile tests. The study shows that adding direct extrusion to the twist extrusion process alleviates the mechanical heterogeneity due to producing more intensified strains in the center regions than in the corner ones. (C) 2010 Elsevier B.V. All rights reserved.