Identification of stress state dependent fracture micromechanisms in DP600 through representative volume element modeling

The stress state dependent fracture behavior of DP600 was investigated using a representative volume element (RVE) based finite element model. To simulate fracture at the microscale, fracture models for ferrite and martensite were incorporated into the RVE, which was loaded under seven stress states. To compare the simulated damage accumulation and eventual failure in the RVE with experimentally measured continuum-based strain to failure, five RVE-level failure criteria are presented, and their ability to predict the continuum-level stress state dependent fracture strain of the material is discussed. The microstructural heterogeneity resulted in heterogeneous strain fields, and played a dominant role in the stress state dependent fracture behavior of materials. The simulations showed that in DP600, microcracks initiate from martensite regardless of the global stress state, whereas the propagation of cracks or initiation of new cracks depends on stress state.