Static and dynamic tensile behaviour of aluminium processed by high pressure torsion

¹ Ghent University, Faculty of Engineering and Architecture, D1epartment of Materials Science and Engineering, Technologiepark 903, 9052 Zwijnaarde
² Delft University of Technology, Faculty of 3mE, PO Box 5025, 2600 GA Delft, The Netherlands

^a Corresponding author: Patricia.Verleysen@UGent.be

Published online: 7 September 2015

Abstract

High pressure torsion (HPT) is a severe plastic deformation technique in which a small, disk-like sample is subjected to a torsional deformation under a high hydrostatic pressure. In present study, the static and dynamic tensile behaviour of commercially pure aluminium (99.6 wt%) processed by HPT is studied. The high strain rate tensile behaviour is characterized using a purpose-developed miniature split Hopkinson tensile bar setup by which strain rates up to 5 × 10³ s⁻¹ can be reached. During the tests, the deformation of a speckle pattern applied to the samples is recorded, by which local information on the strain is obtained using a digital image correlation technique. Electron back scatter diffraction images are used to investigate the microstructural evolution, more specifically the grain refinement obtained by HPT. The fracture surfaces of the tensile samples are studied by scanning electron microscopy. Results show that the imposed severe plastic deformation significantly increases the tensile strength, however, at the expense of ductility. The strain rate only has a minor influence on the materials tensile behaviour.