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Failure modeling of multiphase steels using representative volume elements based on real microstructures
The current work aims at predicting of damage and failure in multiphase steels (Dual phase and transformation-induced plasticity (TRIP) steels) during production processes. These kinds of steel consist of a ferritic matrix with dispersed second phases like bainite, martensite and retained austenite. A microstructure-based approach by means of representative volume elements (RVE) is used taking into account carbon partitioning for the flow curve description of each individual phases. With the help of the RVE it is possible to establish a link between the microstructure and the macroscopic failure behavior. In the case of DP-steels, the real microstructures were investigated in a two-dimensional approach. A cohesive zone model (CZM) has been used to study the debonding analysis of the martensitic islands from the ferrite parent phase. To describe the ductile damage of the ferritic matrix, the Gurson–Tvergaard–Needleman model (GTN) was applied. The parameter identification for the CZM and GTN models is based on metallographic investigations and fracture surface analysis. The calculated stress-strain distribution in the heterogeneous microstructure was studied. The investigations provide a physically-based correlation between the multiphase microstructures, mechanical properties, and failure behavior of multiphase steels for automotive applications.