Determination of bulk flow properties of a material from the flow properties of its constituent phases

The aim of the present work is to determine the bulk flow properties of a material from the flow properties of its constituent phases using simple empirical relationships. The materials chosen for this investigation are DP 780 and DP 590 steels. It is well known that the linear rule of mixtures is not generally able to predict the flow behaviour of DP steels using conditions of iso-stress, iso-strain and iso-energy. Therefore, a weighted energy condition has been proposed which is found to predict the flow properties reasonably well except in the elasto-plastic transition zone (initial 2-4% strain). Using FE simulation based micromechanics modelling, it has been shown that the iso-stress, iso-strain and iso-energy conditions are not valid for DP steels. In order to be able to use the linear rule of mixtures, it has been shown that the different steps of the deformation process needs to be considered. It has also been shown that the variation in degree of strain partitioning with deformation has to be accounted for, to be able to predict the flow behaviour. The flow curves calculated with the proposed methodology has been found to have very good agreement with the FE simulation results as well as the experimental data.