Damping Behavior of Typical Titanium Alloys by Varied Frequency Micro Harmonic Vibration at Cryogenic Temperatures

In this paper, micro harmonic vibration was applied to the typical titanium alloys at different frequencies to clarify their damping performance at cryogenic temperatures. The effects of vibration modulus at different frequencies were elaborately analyzed, and the crack propagation mechanism was discussed. In the process of low temperature, harmonic vibration causes the internal stress concentration of titanium alloys at cryogenic temperature, resulting in dislocation accumulation phenomenon. The increase of internal dislocations improves the damping performance and eventually leads to interface cracking, which is positively correlated with frequency. More importantly, dislocations of β phase aggregated at the interface, leading to interface cracks and transgranular fractures by stress concentration. Whereas, dislocations in the α phase are first activated and then glide toward the boundary to cause cracking, resulting in intergranular fracture. During harmonic vibration at 0~-60℃ with 200 Hz, the crack propagation of α phase always has a hysteresis behavior compared with that of β phase. When △K=0.137 MPa∙m 1/2 (-60℃, 200 Hz), the second crack tip of β phase is deflected in different directions, leading to higher harmonic vibration energy is consumption. As a result, the crack growth rate slows down and the damping performance reaches its peak. This contribution is expected to provide experimental data and theoretical support for the vibration damping behavior of typical titanium alloys at cryogenic temperature