Stress-strain distribution and failure mechanisms in dual-phase steels investigated with microstructure-based modeling

Abstract

In this study, the microstructural-based finite element modeling of dual-phase steels was investigated to visualize the crack initiation and its propagation through the phases that exist in the material. The parameters of various failure models, including Gurson, Gurson-Johnson-Cook, and Johnson-Cook (JC), were calibrated for different microstructure levels of DP600, DP800, and DP1000 steels. The onset of cracking, nucleation, void growth, and coalescence was determined using the models. As a result of the optimization studies, there is not much difference between the flow curves of the materials and the tensile values calculated from the tensile tests for DP600 and DP800, while it is slightly higher for DP1000. However, considering the fracture, martensite phases were found to be the main determinant of this situation. Cracks that start in the martensite phases then propagate through the ferrite phase and eventually cause the material to break. According to the results of the simulations, the difference between the experiments and the simulation results of the Gurson is 3.33%, the Gurson-JC is 1.82%, and the JC model is 2.39%.

A study on micro‐mechanical deformation behaviour of heat‐treated 20MnMoNi55 steel

“…There are also some instances of studying the formability and damage behaviour of multi-phase steel as an application of representative volume elementbased micromechanical modelling in predicting the macro-mechanical behaviour of materials [20,21]. Whereas, the distribution of stress-strain behaviour along with the failure mechanism of dual-phase steels can also be predicted with 2-dimensional representative volume element model [22]. Moreover, with the help of representative volume element based micro-mechanical model it can be shown that the phase composition, grain size, intergranular boundary and its orientation with respect to tensile axis determines the strain partitioning and damage initiation [23].…”