Material characterization is a very important tool needed to describe and enhance material mechanical properties and to develop optimum material chemistries and microstructures. The usual approach of achieving the above using extensive experimental methods has been shown to be expensive and time consuming. This led to the development of the micro mechanical modeling, which can be used to predict the material behavior without the need for the extensive experimental investigation and is based on microstructural characteristics of the material. In this work, a micro mechanical model is developed to predict the mechanical properties of dual phase steels consisting of martensite in a matrix of ferrite. This micro model is also used to elucidate the mechanics and mechanisms of deformation, which take place in such materials. DP-steels consisting of several volume fractions of martensite (Vm) representing low, intermediate and high Vm are developed and tested mechanically to obtain their mechanical properties. Metallographical examinations are carried out using image analysis to quantify microstructural material properties of each level of Vm considered. As a validation of the current work, comparison between the model predictions, which include all the significant material behavior investigated in this work and the experimental results, is presented. The comparison demonstrates the ability of the model to capture the behavior of DP-steels up to the instability point. The Gurson-Tvergaard model, which is the most widely known damage model to describe ductile failure, is coupled with the results of the micro mechanical model, presented in this work to form a complete material model of deformation and fracture of DP-steels. A procedure is developed to determine the parameters in the Gurson-Tvergaard model utilizing the micromechanical model. The results are then implemented to simulate the deformation and failure of tensile bars of DP-steels with different Vm, which shows good agreement with the experimental results at failure.

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