冲击坑、划痕对TB6钛合金高周疲劳性能的影响

Effect of Impact Pit and Scratch on High-cycle Fatigue Performance of TB6 Titanium Alloy

通过在TB6钛合金标准试验件上预制冲击坑、划痕缺陷,获得拉伸及疲劳强度,并与无缺陷标准试验件进行对比。研究表明:TB6钛合金冲击坑试验件疲劳强度的平均值为592.0 MPa,其存活率90%,置信度95%的疲劳强度下极限为539.0 MPa,与无缺陷试验件相比疲劳强度下降了18%。划痕试验件疲劳强度的平均值为368.0 MPa,其存活率90%,置信度95%的疲劳强度的下极限为330.0 MPa,疲劳强度仅为无缺陷试验件的一半。通过对试验件断口进行宏微观组织观察,确定了断裂位置及断裂类型。通过本研究工作,得到了TB6钛合金冲击坑、划痕缺陷高周疲劳性能,可以为TB6钛合金零件损伤容限设计和安全寿命评估提供参考价值。

The tensile and fatigue strength of TB6 titanium alloy was tested by processing impact pit and scratch defects on the standard test piece,and compared with that of standard test piece with no defect.The research shows that the average fatigue strength of the TB6 titanium alloy impact pit is 592.0 MPa,and the lower limit of the fatigue strength with 90% survival rate and 95% confidence is 539.0 MPa,which is 18% lower than that of the non-defect sample.The average fatigue strength of the scratch test piece is 368.0 MPa,and the lower limit of the fatigue strength with 90% survival rate and 95% confidence is 330.0 MPa,and the fatigue strength is only half of that without defects.The fracture position and fracture type were determined by the observation of macro and micro structure of the fracture of the test piece.Through this work,the impact and scratch high-cycle fatigue properties of TB6 titanium alloy are obtained,which can provide reference value for the damage tolerance design and safe life assessment of TB6 titanium alloy parts.