喷丸强化因素对Ti合金微动疲劳抗力的作用

探讨了喷丸强化（SP）三因素（残余压应力引入，表面粗糙度增大和表面加工硬化）在改善Ti合金微动疲劳（FF）性能中的作用规律和机制。结果表明，SP引入表层残余应力和导致粗糙度增大对提高Ti合金FF抗力起重要作用。前者的作用大于后者，且二者之间存在协同作用效应，即SP表面因粗糙度增大而减缓了表层残余应力的SP引入的表面残余应力主要通过增加裂纹闭合力，抑制FF裂纹早期扩展来提高FF抗力。在表面应力集中严重的接触几何条件下，裂纹扩展控制FF过程，此时SP层残余应力的作用更加显著。

EFFECTOF SHOT PEENING FACTORS ON FRETTING FATIGUE RESISTANCE TITANIUM ALLOY

The effects of the three factors, i.e., compressive residual stress (CRS), surface roughness (SR) and micro-structure hardening in shot peened (SP) surface on fretting fatigue (FF) resistance were evaluated. The mechanisms of SP on FF were investigated. The experimental results show that the compressive residual stress and surface roughness are predominant factors in improving FF resistance of Ti alloy, and CRS plays more important role than SR which decreases decaying of CRS. Compressive residual stress induced by SP arrests the crack into closure and slow growth. When the contact stress plays a dominant role in FF, the crack propagation controls FF process and the effect. of CRS is more remarkable than other factors of SP.