直升机关键金属TB6钛合金的划伤、冲击缺陷容限性能
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1.中国直升机设计研究所;2.上海航空材料结构检测股份有限公司

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V215.5

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The influence of impact or scratch flaw on the fatigue performance of TB6 used in helicopter
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Chinese Helicopter Research and Development Institute

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    摘要:

    本文对钛合金TB6材料的划伤和冲击两种典型缺陷容限性能进行了研究。设计了无缺陷、预制划伤和预制冲击缺陷的板状试样并开展了成组法和升降法疲劳试验。试验结果表明两种缺陷均会导致钛合金的疲劳性能下降,且下降程度随着缺陷深度的增加而增大。断口观察表明疲劳源在两种缺陷情况中均倾向于在缺陷底部萌生,但由于冲击缺陷底部在预制时会产生一定塑性区,其疲劳断口形貌与划伤缺陷呈现明显不同的特征。与采用升降法试验测得的疲劳极限相比,采用成组法数据进行S-N曲线拟合推导得到疲劳极限在两种缺陷情况中均偏安全。最后在此基础上运用二次表达式和指数表达式拟合了疲劳缺口系数Kf与理论应力集中系数Kt之间的关系,通过分析发现二次表达式仅对划伤缺陷具有较好的精度,指数关系表达式对两种缺陷均有较好的精度。通过本研究工作,得到了TB6钛合金的划伤、冲击缺陷容限性能,并得到了一种适用于Kf-Kt关系描述的指数表达式。

    Abstract:

    In this paper, the tolerance defect properties of TB6 titanium alloy with scratch and impact defects were studied. Specimens without defects, with scratch defect and with impact defect were designed and fatigue tests were carried out by group method and up-and-down method. The results show that the fatigue properties of titanium alloys decrease with the increase of the depth of defects. Fracture observation shows that the fatigue source of specimens with two kinds of defects tends to germinate at the bottom of the defect. Because plastic zone will generate at the bottom of impact defect, so the fatigue fracture morphology of the Specimens with impact defect and scratch defect show different characteristics. Compared with the fatigue limit measured by the up-and-down method, the fatigue limit obtained by fitting with the data of group method is safe in both of two cases. Finally, the relation between fatigue notch coefficient Kf and stress concentration coefficient Kt is fitted by quadratic expression and exponential expression. Fitting results showed that the quadratic expression is accuracy for only the relationship of Kf-Kt with scratch defects, but the exponential expression is accuracy for both of the relationship of Kf-Kt with scratch and impact defects. Through this research, the tolerance defect properties of TB6 titanium alloy with scratch and impact defects were obtained, and an exponential expression was also obtained to descript the relationship of Kf-Kt

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刘晓丰,田雅馨,邹 静,等. 直升机关键金属TB6钛合金的划伤、冲击缺陷容限性能[J]. 科学技术与工程, 2019, 19(29): 349-355.
刘晓丰,, and. The influence of impact or scratch flaw on the fatigue performance of TB6 used in helicopter[J]. Science Technology and Engineering,2019,19(29):349-355.

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  • 收稿日期:2019-01-20
  • 最后修改日期:2019-05-08
  • 录用日期:2019-05-29
  • 在线发布日期: 2019-10-25
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