Deformation behavior of 5052 aluminum alloy sheets during electromagnetic hydraulic forming

Abstract

Hydraulic forming (HF) has good forming accuracy, but causes the material to break easily. Electromagnetic forming (EMF) can greatly improve the forming limit of materials, but its shape control ability is poor. In this paper, the two techniques were combined, i.e., electromagnetic hydraulic forming (EMHF), to obtain a new high-strain-rate forming method, which was investigated through experimental and simulation studies. Three kinds of specimens were designed, and the forming limits of 5052 aluminum alloy were determined. The results show that EMHF specimens have higher forming height and limit strain compared with HF specimens. The increase in forming limit is due to the uniform dislocation distribution at microscopic level and inertia effect at macroscopic level. The simulation results show that the deformation velocity exceeds 55.6 m/s and strain rate exceeds 689.7 s−1. The experimental results are consistent with the simulated deformation contours, which proves the reliability of simulation. Flat bottom die and wave shape die were used to investigate the shape control ability of EMF and EMHF. The sheet and die can be closely fitted in EMHF. However, EMF has significant rebound effect and poor forming accuracy. Thus, better forming accuracy can be obtained if liquid is added in high-speed forming. The difference between EMHF and EMF formation mechanisms is essentially the difference of force action. EMHF not only retains the strong shape control ability of HF, but also greatly improves the forming limit of materials. It is a potential forming process that can be widely used in industrial manufacturing field in the future.