Strengthening 5A02 Al alloy via gradient structures processed by severe torsional deformation

Abstract

5A02 Al alloys with gradient structures were designed by controlling the number of torsional revolutions of 1, 2, 4, and 8. The results showed that the yield strength increased and the uniform elongation decreased with the increasing torsional revolution. Preferable comprehensive properties with yield strength of 196.7 ± 3.7 MPa and uniform elongation of 1.9 ± 0.2 % were obtained at the torsional revolution of 4. It is revealed that the increment in yield strength contributed by HDI stress, grain refinement and the introduction of dislocations, in which dislocation strengthening played the major role. The ductility came from HDI hardening and the strain hardening ability of the center region with low dislocation density. The finding provided a promising and cost-effective method to enhance mechanical properties of Al alloys by tailoring gradient structures.