Influence of scaleboard on the dispersion deformation behavior of DP600 steel sheets during electrohydraulic forming

Abstract

The action mechanism of scaleboard on the dispersion deformation behavior of DP600 steel sheets during electrohydraulic forming (EHF) was explored by means of experiments and numerical simulation. The results showed that a maximum major strain of 60% was achieved during the pure EHF process, which was improved by 70% compared with that during the quasi-static condition, but the scaleboard played a negative role and decreased the hyperplasticity effect of EHF by 20%. Under the action of the energy absorption of the scaleboard and its interaction with the tested specimen, the utilization rate of critical discharge energy for crack bifurcation and dispersion deformation was decreased by 55.3% and 26.8%, respectively. Under the instantaneous impact of scaleboard, an additional tensile stress was generated on the central element of the tested specimen, which destroyed the effect of inertial coordination deformation on the elements near failure and decreased the proportion of inertial dispersion deformation by 48.6%. Due to the mechanical impact action of scaleboard in the biaxial tensile stress state and the accompanying bidirectional friction effect, the failed elements changed from the uniaxial tensile stress state to the biaxial tensile stress state gradually, while the central element underwent a fluctuating transition of uniaxial-biaxial-uniaxial tensile stress state. Besides, the curling effect of scaleboard induced the edge elements along the width direction of the tested specimens to change from the uniaxial tensile stress state to the biaxial tensile stress state, which aggravated the uneven deformation along the width direction obviously. In summary, the pure EHF with profiled blank holder is more suitable for industrial application and production than that with scaleboard.