Superficial and structural aspects of the cyclic strain softening in 6063 aluminum alloy bars

The performance of metallic products is profoundly affected by the final mechanical properties of the material. On the other hand, these final properties are directly linked to the employed manufacturing operations. In the case of cold forming processes, the work hardening is the most important phenomenon observed during plastic straining. For cyclic processing, however, unusual flow behaviors are observed, characterized by the development of saturation stresses and by the occurrence of strain softening in prestrained metals. In this paper, the strain softening associated with the cyclic deformation of pre-strained metals is investigated. Annealed and drawn 6063 aluminum alloy bars are subjected to cyclic torsion. The structural and superficial aspects are analyzed. The work softening is caused by the restructuring of the dislocation arrangements due to cyclic torsion. The occurrence of deformation bands is also associated with the subsequent mechanical behavior of the material.