| Abstract |
| A bimodal microstructure containing very fine α_2 particles was obtained by over-aging of a Ti-6Al-4V alloy, and its quasi-static and dynamic deformation behaviors were investigated in comparison with those of an unaged bimodal microstructure. Quasi-static and dynamic torsional tests were conducted on them by using a torsional Kolsky bar. The quasi-static torsional test data indicated that the over-aged specimen showed higher fracture shear strain than the unaged one, while their maximum shear stress was similar. Under dynamic torsional loading, both maximum shear stress and maximum shear strain showed higher than those of the unaged microstructures. The possibility of the adiabatic shear band formation under dynamic loading was quantitatively analyzed by critical shear strain and absorbed plastic deformation energy concepts. Fine α_2 precipitation in αphase by over-aging was effective in both the improvement of quasi-static and dynamic torsional properties and the reduction in the adiabatic shear banding, which provided a new idea to improve ballistic performance of Ti alloy armor plates. |
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| Key Words |
| Ti-6Al-4V alloy, Bimodal, Dynamic torsional test, α2-Ti3Al precipitate, Adiabatic shear band, Void initiation, Critical shear strain |
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