Introduction of multiple slip systems for anisotropic microstructure modelling in FEM-framework

The history of a metal’s handling is imprinted on the material, due to the microstructure evolution happening inside, which is known to influence its macroscopic mechanical properties. Predicting the microstructure using forming simulations can help to adjust industrial process parameters to obtain application favourable material properties. However, due to the development of the microstructure being temperature, strain and strain-rate dependent, its evolution might vary at points of different strain rates during large deformations, even within an isotropic alloy composition. This is partly the case because the deformation leads to an increase in thermal energy in the crystal system, which in turn can lower the energy threshold for slip system activation. The presented work explains the physical effects of plastic deformation in polycrystalline metals of isotropic chemical composition and applies a multiscale simulation approach, that couples the evolution of the microstructure via the Visco-Plastic Self-Consistent (VPSC) mean-field model for texture simulations to a commercial Finite Element Method (FEM) software. This method is computationally less expensive than typical crystal plasticity (CP)FEM-models and allows simulating industrial scale metal forming processes together with the developing microstructure. An optimization model is used to determine the 4 parameters per slip mode of the extended Voce hardening law, which is done for an industrial EN AW-5754 (AlMg3) alloy at several constant temperatures by simulating tensile tests and comparing them with measured force-displacement curves. Furthermore, a method for estimating the slip system activation with temperature change is presented. The macroscopic material behaviour of the investigated alloy was brought into good agreement with the measurements of forces at constant temperatures by adjusting the hardening parameters of the microstructure model. The aim of developing a model for simulating temperature dependent industrial metal forming processes that depends on only a few, easily determined material parameters was achieved and evaluated against experimental results.