Computational microstructural model of ordinary state-based Peridynamic theory for damage mechanisms, void nucleation, and propagation in DP600 steel

In this study, the evolution of microscopic damage mechanisms in DP600 was investigated by developing an ordinary state-based two-dimensional Peridynamic model. The real microstructure was extracted from scanning electron microscope (SEM) images and employed to predict the deformation and damage behavior of dual-phase (DP) steels under tension static loading. Isotropic hardening plasticity and nonlinear failure criterion were considered for both ferrite and martensite phases. The Peridynamic (PD) modeling procedure is improved to reduce simulation time and increase applied displacement steps. For improving the prediction of damage initiation, a new method was proposed for the properties of the martensite/ferrite interface. At four applied strains (no-damage, damage initiation, partly damage propagation, and coalescence of damages), deformation and damage patterns were investigated. The cumulative plastic stretch of interactions and the number of damaged interactions were obtained for every applied strain. These parameters were evaluated by the energy rate of acoustic emission signals. Void formation due to fracture of martensite particles and decohesion of the interface were predicted and validated by available experimental results and previous studies. Damage initiation was predicted in thin martensite grains, interfaces of martensite/ferrite, and sandwiched ferrite regions between martensite particles. In thin martensite phases, the crack was initiated at boundaries, and then it crossed through martensite phases. PD model successfully predicted crack propagation and branching that matched with the experimental data.