Springback Prediction in Bending of AHSS-DP 780

Forming of AHSS creates several challenges because these materials have higher strength and lower formability compared to low carbon steels. One of these challenges is springback that leads to dimensional inaccuracy in the formed part. In the present study, the effect of unloading apparent modulus (E- modulus) variation with strain on the accuracy of springback prediction in V-die bending and U-bending of DP 780 is investigated. A reliable methodology to measure springback which is very important is developed. Load-unload tensile tests were performed to obtain unloading apparent modulus variation. Springback in V-die bending and U bending was estimated by using FEA and a variable E-modulus. Compared with experimental data, the predictions gave reasonably accurate results.