Post-forming, electro-plastic effect internal stress reduction in AA5754 aluminium alloy

Abstract

Aluminium alloys are one of the most efficient materials for weight reduction in the car industry. However, the favourable performance of alloys conflicts with the difficulties of transforming these materials through plastic deformation processes such as stamping. Among the different issues, they are characterised by a high springback effect. Numerous authors have explored the use of the electro-plastic effect (EPE) to mitigate internal stresses and the resultant springback. However, up-scaling existing laboratory solutions to an industrial framework is a critical challenge. Therefore, in this work, the post-forming electro-plastic effect (PFEPE) is explored in AA5754 material. Stress-relaxation + PFEPE experiments were conducted using different electric pulse charge passing though the sample, and, apart from the impact on residual stresses, the potential occurrence of recrystallisation was evaluated. The results indicate that a range of pulses exists (>2000 A·ms/mm2 and <4500 A ms/mm2) in which a 10–30% reduction in stresses can be achieved without critically impacting the material's mechanical performance.