The formability and application of hot-rolled dual-phase steel under nonlinear strain paths

The hot-rolled dual-phase steel 700DP was developed to reduce weight and improve safety in automobile industry. However, strain path changes inevitably occur for most of components during sheet forming process. Therefore, it's valuable to predict the cracking accurately under nonlinear strain paths for the application of 700DP steel with finite element method (FEM). In this paper, the mechanical properties of hot-rolled dual-phase steel 580DP and 700DP were studied with tensile test. Nakazima test and two-step nonlinear loading test were used to establish the modelling with the method of equivalent plastic strain-based FLC (ep-FLC). Furthermore, the ep-FLC was applied to predict the disc forming result of three-stage process, which agreed well with the experimental results for both 580DP and 700DP compared with conventional FLC.