Forming limit diagram of DP600 steel sheets during electrohydraulic forming

Electrohydraulic forming is a typical high-speed forming which can significantly improve the formability of sheet metal. The objectives of this paper are to explore the influence of preset wire length and lifting height on the equi-biaxial stretching forming limit of DP600 steel sheets during electrohydraulic forming. The results showed that the maximum equi-biaxial stretching forming limit was obtained at the optimal wire length of 45 mm and lifting height of 37 mm, then the entire FLC was generated to evaluate the formability of DP600 steel sheets with these optimal parameters: a relative increase of 17.5–70% in major strain obtained by EHF was observed in all three regions of the FLC (tension-tension, plane strain, and tension-compression) relative to that obtained by quasi-static forming. Numerical simulation using ANSYS/LS-DYNA was conducted to reproduce the dynamic deforming behavior of a DP600 blank bulged by EHF, with an error of about 8%. A narrower radiation zone, a wider shear lip zone, and a mass of deeper and larger dimples on the fracture morphologies during EHF were observed compared with quasi-static conditions.