A microstructure-based multiscale approach to predict the formability of multiphase steels

A multiscale approach was proposed to predict the macroscopic forming limit of Q&P980 steel. The microstructure-based simulation was implemented in the microscopic simulation to obtain the macroscopic stress-strain curve. The representative volume element (RVE) was established using the data extracted from the characterised results of electron back-scattered diffraction (EBSD). The microscopic constitutive model of each constituent phase was determined based on a new method. The acquired macroscopic stress-strain curve was extrapolated using the modified Power-Law (MPL) strain hardening model. In the macroscopic simulation, the Nakajima and Marciniak-Kuczynski (M-K) simulations were combined to obtain the macroscopic forming limit only based on the macroscopic stress-strain curve. The microscopic and macroscopic simulations show good agreement with the experiment results, verifying the multiscale approach's accuracy. This study provides a solution for the direct connection between the microstructure and macroscopic forming limit.