高载荷条件下TC17钛合金常规低周疲劳和保载疲劳损伤行为

Damage Behavior of Conventional Low Cycle Fatigue and Dwell Fatigue of TC17 Titanium Alloy Under High Load

研究了高应力水平下不同加载波形对TC17钛合金疲劳损伤的影响。结果表明,对于在峰值应力下保载120s的加载波形,TC17钛合金的保载疲劳寿命低于无保载加载波形试验的寿命;在相同的保载疲劳条件下,片层组织的保载疲劳敏感性低于等轴组织。断口分析表明,保载疲劳试样裂纹源出现在样品表面和亚表面处,常规低周疲劳试样裂纹源出现在试样表面处,保载疲劳断口附近小平面较常规低周疲劳断口平坦,保载条件并未从根本上改变断裂模式。

Effect of different loading waveform on fatigue damage of TC17 titanium alloy under the high stress level was researched. The results show that the dwell fatigue life under the peak stress and dwell loading time of 120 s is lower than low cycle fatigue life for TC17 titanium alloy.Under the condition of the same high load dwell fatigue, the fatigue sensitivity of lamellar structure is lower than that of the equiaxed structure.Fracture analysis shows that the crack source of dwell fatigue appears on the surface and sub-surface of the sample, while that of low cycle fatigue appears on the surface of the sample. The fracture surface of dwell fatigue is flatter than that of the conventional low cycle fatigue, and the fracture mode does not change fundamentally under the dwell loading condition.