Asymmetric cryorolling of AA6061 Al alloy: Strain distribution, texture and age hardening behavior

Asymmetric rolling combines direct compression and shear strain imposed by working rolls with different diameters or different rotations speeds. Processing at cryogenic temperatures may partially suppress dynamic recovery mechanisms, modifying the work-hardening rate and increasing the amount of accumulated strain. In this work, samples of AA6061 Al alloy were processed by asymmetric and conventional rolling, at room and cryogenic temperatures. The effects of asymmetric cryorolling were analyzed in terms of strain distribution, grain refinement, hardness, tensile strength and crystallographic texture after post-deformation heat treatments. Artificial aging after conventional rolling at room temperature proved to be more effective in increasing hardness and tensile strength, while the same heat treatment after asymmetric rolling at cryogenic temperature increased uniform elongation and reduced texture intensity. This behavior was associated with recovery and recrystallization phenomena after aging, which cause small dislocation-free grains to be generated inside deformation bands. This was observed directly by TEM and indirectly by texture analysis.