Effects of process configuration and sheet thickness on the deformation behaviour in multi-step electromagnetic forming of aluminium alloy sheet

Multi-step electromagnetic forming is a novel sheet metal forming approach which makes use of electromagnetic force acting on sheet metal incrementally to cause local deformation and further accumulate a final shape. The effects of process configurations including incremental interval and discharge voltage as well as sheet thickness on the radius of curvature and deformation height are investigated by conducting experiments on 2524-T3 aluminium alloy sheet. It is found that the deformation curvature of the workpiece increases with decreasing incremental interval initially, then tends to be saturated. In addition, the enhancement of the discharge voltage proves to be an efficient method for increasing the ultimate curvature and deformation height. However, the pit defect induced by the large discharge voltage has a significantly negative influence on the surface integrity of the fabricated part when discharge voltage exceeds a critical value of 7500 V. Furthermore, the deformation height decreases with increasing sheet thickness under the other same process parameters.