To meet the high usability standards, structural components in the aerospace, automotive, and medical technology industries are typically fabricated from metals. Throughout a component’s lifecycle, from its manufacturing to its application, the material behavior is significantly influenced by complex loading conditions, which are typically of both mechanical and thermal character, and which lead for example to irreversible deformations or phase transformations. In general, the overall material behavior is determined by the properties of the underlying microstructure, where metals usually own a polycrystalline microstructure which is characterized by the distribution, size, and orientation of the individual grains. To capture these features in a highly resolved manner, we employ a two-scale FE-FFT-based simulation method [1] considering a fully thermo-mechanically coupled framework [2]. In this context, we take into account quasi-stationary conditions on the microscale and evaluate the microscopic boundary value problem at the associated macroscopic temperature. To ensure the efficiency of the two-scale simulation, we employ a CPU- and memory-efficient solution strategy based on a coarse microstructure discretization. This simulation approach will be used to model the thermo-mechanically coupled material behavior of polycrystalline metals, considering microstructural phenomena such as dissipative processes in crystal plasticity or mechanical and thermal induced phase transformations. To demonstrate the feasibility of the proposed simulation framework, several numerical examples are provided. REFERENCES [1] Spahn J., Andrä H., Kabel M., Müller R., A multiscale approach for modeling progressive damage of composite materials using fast Fourier transforms. Computer Methods in Applied Mechanics and Engineering, Vol. 268, pp. 871-883, 2014. [2] Schmidt A., Gierden C., Fechte-Heinen R., Reese S., Waimann J., Efficient thermo-mechanically coupled and geometrically nonlinear two-scale FE-FFT-based modeling of elasto-viscoplastic polycrystalline materials. Computer Methods in Applied Mechanics and Engineering, Vol. 435, 117648, 2025.