微激光冲击提高TC17钛合金高周疲劳性能研究

Study on high cycle fatigue performance of TC17 titanium alloy improved by micro-scale laser shock processing

针对钛合金薄构件激光冲击强化过程中由于在叶背部分冲击波反射与耦合降低残余压应力的问题,提出采用微激光冲击强化(μLSP)的方法对TC17钛合金进行强化,利用高周疲劳实验验证其改善效果,从残余应力和疲劳断口形貌观察两个方面讨论分析疲劳性能改善的原因。实验结果表明:与未处理试件相比,微激光冲击强化试件疲劳强度提高了32%。微激光冲击在钛合金试件表层诱导产生一定数值,深度为100μm厚的残余压应力层;在残余压应力的作用下,疲劳裂纹源内移,同时在其疲劳断口扩展区中有疲劳条带和二次裂纹,这是微激光冲击后TC17钛合金试件疲劳性能改善的主要原因。

As the reflection and coupling of shock wave at the back of specimens reduces residual compressive stresson the surface of titanium alloy thin components, the TC17 Titanium Alloy was processed by the micro-scale lasershock processing（ jjlLSP） ,and the improvement effect was verified through the high cycle fatigue tests. The improvementreasons of high cycle fatigue performance were analyzed from residual stress distribution and fatigue fracture morphology.The results show that, compared with untreated specimens, the fatigue strength of the specimens treated byjjlLSP is improved by 32%. Residual compressive stress layer with 100 jjim thick and certain values was induced onthe surface of the TCI7 titanium alloy specimens by jjlLSP. Under the influence of the residual compressive stress,thecrack sources move inward. Simultaneously,there are some fatigue strips and quadric cracks in the propagation zone ofthe fatigue fractures,and these are the main reasons of the high cycle fatigue performance improvement.