微动疲劳影响因素及钛合金微动疲劳行为

综述了影响材料微动疲劳 ( FF)行为的各因素及其相互联系,通过实验探讨了接触压力、位移幅度、接触几何及残余应力状态等重要因素对 Ti6Al4 V合金 FF行为的影响规律及交互作用。结果表明,钛合金 FF寿命随接触压力和位移幅度的变化均是非单调性的,原因是名义接触压力的变化改变了接触区应力分布、应力集中状况和微动位移幅,从而影响裂纹的萌生几率,而位移幅影响了疲劳和磨损因素在 FF过程中的作用主次。接触几何则通过改变接触区应力集中状况而影响裂纹萌生几率的大小。残余压应力主要抑制 FF裂纹扩展,在部分滑动条件下它对提高钛合金 FF抗力的作用更加显著。

REVIEW OF FACTORS THAT INFLUENCE FRETTING FATIGUE (FF) AND INVESTIGATION ON FF BEHAVIOR OF Ti-ALLOY

The factors that influence fretting fatigue process are reviewed and the interactions between these factors are outlined. The effects of major factors, including slip amplitude, contact pressure, contact geometry and surface residual stress, on FF behavior of Ti6Al4V alloy were investigated by experiments. The results show that these major factors affect the action of fatigue and wear in FF process, resulting in the change of crack initiation probability and crack propagating rate. Therefore, the FF life of Ti alloy doesn't change in a monotone way with the slip amplitude and contact pressure increasing. The effect of surface compressive residual stress (SCRS) on FF resistance depends not only on the value and distribution of SCRS, but also on the other major parameters in FF tests. SCRS plays a more important role in improving FF resistance in partial slip situation than in gross slip. This is due to the fact that SCRS restrains crack propagation more remarkably than arrests crack initiation.