Microstructure-based modelling of formability for advanced high strength dual-phase steels

The macroscopic formability of advanced high strength dual-phase steels (AHSDPSs) relies highly on the microstructure. Therefore, building the relationship between the microstructure and the formability is vital to enhancing the formability by microstructure optimisation. In this study, a formability model based on microstructure for AHSDPSs was proposed. The tensile simulation of representative volume element (RVE) was implemented to acquire the stress-strain curve (SSC). The forming limit curve (FLC) was constructed based on the method developed in our previous research. The simulation of hole-expansion with the pre-damage of the central-hole induced by the blanking process was conducted to obtain the hole-expansion ratio (HER), in which the vital failure model is developed based on the simulated FLC. For a typical advanced high strength dual-phase steel of DP1180 steel, the prediction errors of SSC, FLC and HER are 5.83 %, 6.85 % and 10.71 %, respectively. The results also depicted that the damage of the prefabricated hole has a noticeable influence on the HER, which could not be ignored for the hole-expansion simulation.