超细晶纯钛的微动疲劳特性

利用自行设计的微动疲劳实验夹具装置研究超细晶纯钛在柱面-平面接触下的微动疲劳特性,分析循环应力对其微动疲劳寿命的影响,通过观察接触区磨损和断口形貌,分析其微动损伤机制。结果表明,当法向载荷不变时,超细晶纯钛的微动疲劳寿命随着循环应力的增加而减小,比常规疲劳寿命更小。微动疲劳裂纹于接触区边缘萌生,磨损区破裂严重且附着有磨粒,在磨粒磨损作用下加速了试样的疲劳失效。断口同时呈现出疲劳形貌和微动形貌,形貌从平滑转向粗糙直至断裂,裂纹由小变大,裂纹扩展速率也逐渐增加,且在裂纹扩展区存在二次裂纹；由于受力不均在裂纹扩展区与断裂区之间存在山脊状形貌。

Fretting fatigue characteristics of ultrafine grained pure titanium

_{: The fretting fatigue characteristics of ultra-fine grain pure titanium under cylindrical-plane contact were studied by using a fretting fatigue experimental fixture designed by ourselves, and the effect of cyclic stress on its fretting fatigue life was analyzed. The fretting damage mechanism was analyzed by observing the wear and fracture morphology of the contact zone.The fretting fatigue life of ultra-fine grain pure titanium decreases with the increase of cyclic stress when the normal load is constant. The fretting fatigue crack originates at the edge of the contact zone, and the wear zone breaks seriously and has abrasive particles attached to it, which accelerates the fatigue failure of the specimen under the action of abrasive wear. The fracture surface shows both fatigue morphology and fretting morphology. The morphology changes from smooth to rough to fracture, the crack increases from small to large, the crack growth rate increases gradually, and there are secondary cracks in the crack propagation zone. Between the crack propagation zone and the fracture zone due to uneven force,there is a ridge-like morphology.}