Revealing Microstructural Evolution and Deformation Mechanism of Pure Titanium through a Quasi In Situ Compression Method at High Strain Rate

In this paper, a quasi in situ method is established to study the microstructural evolution and deformation mechanism transition behavior of pure Ti under a high strain rate of 4000 s⁻¹. The main deformation mechanism is found to be influenced by deformation strain level. In the strain range from 0 to 0.05, {1012} and {1122} twinning is proved to be the main mechanism, while the grains without any deformation twin (about 32% of the whole grains) are deformed by dislocation slip. When the strain increases from 0.05 to 0.10, the growth of twins, secondary twinning, and dislocation movement are proved to be the main deformation mechanism. In the strain range from 0.10 to 0.15, dislocation movement becomes the dominant deformation mechanism. Compared with the traditional observation method, the new quasi in situ method effectively permits observing the microstructure evolution and recording the deformation behavior progressively step by step, which is more suitable to reveal the deformation mechanism of materials at high strain rates.