© 2019 The deformation behaviour of coarse-grained α-uranium is studied using crystal plasticity finite element simulations. The constitutive model includes 8 slip and 2 twin systems, based on dislocation densities as state variables. Polycrystal simulations are carried out to reproduce the manufacturing procedure: a quenching stage is followed by cutting out a sub volume to allow relaxation of the internal stresses. Room temperature tension and compression experiments are simulated for the textured samples that are generated by this process. Calibration of the model parameters is obtained by comparing simulated experiments against measured stress-strain curves and lattice strains from published in situ neutron diffraction studies. The comparison of the internal elastic strains allows the activity of slip and twin modes to be quantified, and to estimate their critical resolved shear stresses. The comparison between the present simulation results and previous models for fine-grained α-uranium provides information about the grain size dependence of the strength of slip and twin systems. The critical resolved shear stress of the most prominent twinning mode {1 3 0} is found to be similar to single crystal samples and much smaller than for fine-grained samples, showing the strong grain size dependence of this deformation mode.
