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Enhancing strength-ductility synergy of materials has been for decades an objective of research on structural metallic materials. It has been shown by many researchers that significant improvement of this synergy can be obtained by tailoring heterogeneous multiphase microstructures. Since large gradients of properties in these microstructures cause a decrease of the local fracture resistance, the objective of research is to obtain smoother gradients of properties by control of the manufacturing process. Advanced material models are needed to design such microstructures with smooth gradients. These models should supply information about distributions of various microstructural features, instead of their average values. Models based on stochastic internal variables meet this requirement. Our objective was to account for the random character of the recrystallization and to transfer this randomness into equations describing the evolution of dislocations and grain size during hot deformation and during interpass times. The idea of this stochastic model is described in the paper. Experiments composed of uniaxial compression tests were performed to supply data for the identification and verification of the model in the hot deformation and static recrystallization parts. Histograms of the grain size were measured after hot deformation and at different times after the end of deformation. Identification and validation of the model were performed. The validated model, which predicts evolution of heterogeneous multiphase microstructure, is the main output of our work. The model was implemented in the finite element program for hot rolling of plates and sheets and simulations of these processes were performed. The model’s capability to compare and evaluate various rolling strategies are demonstrated in the paper.

The general objective of the present work was to perform numerical tests for the inverse analysis of various plastometric tests. Uniaxial compression, plane strain compression and ring compression were investigated for different materials. The experimental results, in the form of load vs. displacement measurements carried out in two laboratories for various sample dimensions, were used as input for inverse calculations. As a result, a large number of data was obtained and the comparison of flow stress values determined in various tests and in various laboratories was possible. The capabilities of the inverse analysis as well as the influence of the method of testing on the material properties were examined. It is shown, in general, that when the inverse analysis is applied to the interpretation of the plastometric tests, the properties of the material are insensitive to the method of testing and to the sample dimensions.