加载波形对Ti-60合金疲劳损伤行为的影响

Effect of loading waveform on fatigue damage behavior of Ti-60 alloy

研究了高应力水平下加载波形对Ti-60高温钛合金疲劳损伤行为的影响。结果发现:对于在峰值应力处保载2 min的加载波形,试样的疲劳寿命明显低于无保载的加载波形的试样的寿命;在保载疲劳条件下,单位循环周次内材料的疲劳变形明显增大。SEM观察表明,在保载波形下,疲劳源出现在样品内部,而无保载的加载波形下疲劳裂纹源于样品次表面。TEM观察表明,在两种疲劳加载条件下,都有(1011)滑移系启动。

The effect of loading waveform on fatigue damage behavior of Ti-60 alloys at high stress level was studied. The results show that, under the loading waveform with 2 min dwell at the peak stress, the fatigue life is shorter than that without dwell. The fatigue strain in a unit cycle under the dwell fatigue condition is obviously larger than that under the no-dwell fatigue condition. It is observed by SEM that, under the dwell fatigue condition, the fatigue crack originates from the interior of specimens, while under the no-dwell fatigue condition, the fatigue crack originates from the subsurface of specimens. TEM observation indicates that, under the two loading waveforms, （^1011） slip system is activated.