Strain distribution during tensile deformation of nanostructured aluminum samples

To optimize the mechanical properties, especially formability, post-process deformation by cold rolling in the range 5–50 % reduction was applied to aluminum sheets produced by accumulative roll bonding to an equivalent strain of 4.8. During tensile testing high resolution maps of the strain distribution over the tensile sample gage length were obtained in situ using a commercial ARAMIS system. Significant improvements in total elongation from 6 to 13.3 % and in post-UTS uniform elongation from zero to 4.4 % were observed when introducing
a post-process deformation step and the observations were underpinned by the in situ observations of the evolution of strain distribution in the sample during tensile straining. The mechanisms responsible for the enhancement were discussed based on strain rate sensitivity measurements and microstructural observations.