Microstructure based evaluation of real structures in cold formable steels III
The project shall finalises the work performed on the same topic from 2009 to 2013. During the first period of the project, initially an adequate heat treatment was developed by experimental and numerical means in order to generate a TRIP-aided dualphase microstructure from the delivered ferritic-pearlitic steel. To calculate the macroscopic material properties, a micromechanical approach was used by setting up a representative volume element (RVE) in which all phases were represented with precise volume concentration and morphology. Voronoi tessellation was applied in order to achieve a realistic representation of the microstructure. Moreover, a new model based on the work of Olsen and Cohen was modified in two aspects. First, a dislocation mechanism based crystal plasticity approach has been developed. Second, the estimation of shear band intersections and the calculation of the resulting martensite nucleation probability was achieved. Furthermore, failure modeling of DP-TRIP aided steel was performed within the framework of this project. This included the investigation of the competition between failure modes. For this study, the XFEM technique was used to study the damage evolution in martensitic regions without prescribing the crack path. Moreover, the damage curve concept was applied to the ductile ferritic phase.