Characterization and Modeling of Titanium Single Crystals Following Dynamic Compression by Split‐Hopkinson Pressure Bar

Abstract

Split-Hopkinson pressure bar (SHPB) was used to dynamically load single crystal titanium samples in two different orientations. Characterization of the resulting microstructure, especially twin activity, was performed to understand the observed mechanical behavior. Twinning was quantified using microtextures measured using electron backscatter diffraction (EBSD). Compressive twinning followed by secondary, tensile twinning was observed for both [0001] and [1011]-oriented crystals. Dislocations, though prevalent in the microstructure, contributed to final texture far less than twinning. The microstructures of the strained samples were heavily twinned after loading, and twin variants and corresponding textures were different as a function of initial orientation. Large amounts of dislocations were present, indicating that plasticity was achieved through slip and twinning together. Due to the severe deformation imparted to the samples, the pathway from initial to final states was difficult to discern using post-mortem characterization alone. Viscoplastic Self-Consistent (VPSC) modeling was used to determine the complex order of operations as a function of strain. Crystal orientation was found to play a large role in the activation of different mechanisms in each sample, even under these high strain rate conditions.