高载荷条件下TC17钛合金低周疲劳和保载疲劳损伤行为研究

Fracture behavior of low cycle fatigue and dwell fatigue ofTC17 titanium alloy under high load

摘要:

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,对于在峰值应力处保载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较等轴组织的疲劳敏感性低。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,常规疲劳试样裂纹源出现在试样表面处,保载疲劳断口较常规疲劳断口附近小平面平坦,保载条件并未从根本上改变断裂模式。

Abstract:

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