Direct simulation of dislocation slip and twinning in hcp single crystals with the [0001] load axis

This study develops a crystal plasticity-based model incorporating prismatic, basal, and first-order <c + a> pyramidal slip systems, as well as tensile twinning. A set of finite-element calculations is performed for the α‑titanium single crystal with tension applied along the [0001] axis. The results reveal that twinning is initiated in regions of high pyramidal slip and is accompanied by local lattice reorientation, enabling the activation of prismatic slip. The latter subsequently becomes the dominant deformation mechanism in the twin regions. The variation in the critical value of accumulated pyramidal slip is shown to affect twin propagation, emphasizing the need for careful calibration of the model parameters using experimental data.