Relaxation of the Residual Stress in an Aluminum Alloy Ring by Electromagnetic Bulging Methods

Aluminum alloy rings are a key component in realizing lightweight designs and improving the mechanical properties of aerospace vehicles and devices. However, residual stress is inevitably introduced by uneven heating and mechanical loading, which has a negative effect on the dimensional accuracy and performance of aluminum alloy rings. The common methods of eliminating residual stress have some shortcomings, as their machining ranges are limited, contact stress is too concentrated, and the temperature increase may soften the strength of components. A novel method of using the electromagnetic driving force to bulge alloy rings into the plastic phase and eliminate the residual stress is proposed in this work. First, a 2D multiphysics coupling model was built, and a high-performance magnet was designed and produced. Furthermore, electromagnetic bulging experiments were carried out to relieve the residual stress of 5 series aluminum alloy rings with an external diameter of 720 mm, thickness of 60 mm and height of 60 mm, and it was found that 2%-3% plastic deformation occurred after discharge. Finally, X-ray diffraction was used to measure the changes of the residual stress field to verify the effect of the proposed method. The results show that the average residual stresses on each surface of the alloy ring were reduced by more than 60% after electromagnetic bulging treatment.