Shear localization behavior in hat-shaped specimen of near-α Ti-6Al-2Zr-1Mo-1V titanium alloy loaded at high strain rate

The microstructure characteristics in early stage shear localization of near-alpha Ti-6Al-2Zr-1Mo-1V titanium alloy were investigated by split Hopkinson pressure bar (SHPB) tests using hat-shaped specimens. The microstructural evolution and deformation mechanisms of hat-shaped specimens were revealed by electron backscattered diffraction (EBSD) method. It is found that the nucleation and expansion of adiabatic shear band (ASB) are affected by both geometric and structural factors. The increase of dislocation density, structure fragment and temperature rise in the deformation-affected regions provide basic microstructural conditions. In addition to the dislocation slips, the extension twins detected in shear region also play a critical role in microstructural fragmentation due to twin-boundaries effect. Interestingly, the sandwich structure imposes a crucial influence on ASB, which finally becomes a mature wide ASB in the dynamic deformation. However, due to much larger width, the sandwich structure in the middle of shear region is also possible to serve as favorable nucleation sites for crack initiation.

Automated summary

The microstructure characteristics and deformation mechanisms of near-alpha Ti-6Al-2Zr-1Mo-1V titanium alloy during early stage shear localization were investigated using SHPB tests and EBSD method. It was found that the nucleation and expansion of ASB are influenced by geometric and structural factors, with dislocation slips and extension twins playing critical roles in microstructural fragmentation. Additionally, the sandwich structure imposes a crucial influence on ASB formation, potentially serving as nucleation sites for crack initiation.