PNNL

Abstract

Due to the random composite microstructure of DP steels, its failure mode is unstable and the failure mechanism is still unclear. In this paper, the failure mode and mechanism of DP steel are studied by making use of the finite element numerical method, based on real microstructure of DP steel. 2D microstructure of DP steel is recorded by SEM and is used to numerical analysis after numerical image process. The work hardening plasticity of the ferrite phase is determined by synchrotron-based high-energy X-ray diffraction (HEXRD) technique. The work hardening performance of martensite phase is calibrated and determined by the re-analysis of the uniaxial tensile test of the DP steel sample. At different loading cases, the different failure modes due to plastic localization are predicted. It was found that the local failure mode is closely related to the stress state in the material.