The mechanical properties of polycrystals and creation of their models can be obtained in two ways - the direct way, by study of full-scale specimens with the use of phenomenological theory of elasticity, plasticity and deformability and the calculation way, based on simulation, using the properties of single crystals and their interaction with each other under the influence of external loads. The second method is more flexible and cost-effective, despite potential calculation errors. In the pursuit of optimal solutions, it is undoubtedly preferable. Today's software options, such as free software NEPER, FEpX, DAMASK, and commercial software ABAQUS, enable the implementation of the phenomenological approach quite effectively. The main focus has been on examining the capabilities of FEpX and its underlying theoretical models. For polycrystalline materials the most important characteristic for modelling different shaping processes is the stress-strain curves. Verification of the simulation results was done with using known literature data of polycrystalline materials (copper, high-strength titanium alloy Ti-6Al-4V, as well as the experimental data obtained in our earlier studies. A satisfactory matching between the calculated stress-strain curves and the experimental data Radj=0,95 has been obtained. One of the important results of these studies was the study of influence of particular model parameters on plasticity characteristics. The crystal plasticity parameters (in particular, fixed-state strain rate scaling, saturation strength rate scaling coefficient and power) for titanium alloy were found to have a weak influence on stress-strain curve.

Another important issue is the determination of constants of phenomenological models of deformation of a single crystal in the elastic-plastic region. Using machine learning methods, it is rational to analyses flow curves and microstructure together for further estimation of single crystal parameters. The elastic constants may either be taken from experiments or ab-initio simulations. To produce rare-earth-free permanent magnets, such as MnBi or MnAlC, through hot deformation a thorough comprehension of their mechanical properties is crucial.

This project has received funding through the MSCA4Ukraine project, which is funded by the European Union.