Experiments and FE-simulations of stretch flanging of DP-steels with different shear cut edge quality
Dual-Phase (DP) steels are today used in the automotive industry due to its large strength to weight ratio. However, the high strength of DP-steel does have a negative impact on the general formability in sheet metal forming. Unfavourable process conditions in the press shop will, on top of this, reduce the formability of DP-steels even more. This paper addresses the problem of edge fracture in stretch flanges in sheet metal parts made of DP-steel. The experimental part involves tests of ten different DP590 and DP780 steel grades with three different shear cut qualities. The influence on the fracture strain of the sample orientation of the shear cut are also studied by facing the burr away or towards the punch and testing samples with the cut edge parallel with the rolling direction and the transverse direction. The strains are measured with an ARAMIS system in each test, together with punch displacement and punch force. All tests are then simulated with AutoFormplus R7 and the results from these simulations are compared with the experimental results in order to find the appropriate failure strain for each combination of supplier, coating, thickness and shear cut quality. © Published under licence by IOP Publishing Ltd.
Sigvant, M., J. Falk, J. Pilthammar (2017)Experiments and FE-simulations of stretch flanging of DP-steels with different shear cut edge quality, Journal of Physics: Conference Series / [ed] Volk W., Institute of Physics Publishing , 2017, Vol. 896, no 1, article id 012101