In this paper, the inclined cold expansion (ICE) method of superalloy open hole structures was proposed, which provided valuable insights for the life improvement of aero-engine inclined hole structures. The improvements in the static and fatigue properties of GH4169 specimens with inclined holes were characterized. In addition, tensile and fatigue tests were carried out, and the surface strains were assessed by digital image correlation (DIC). The stiffness degradation and fatigue fracture behavior of GH4169 specimens with inclined holes were also discussed. The results showed that ICE could cause the expansion of inclined hole structures and the enlargement of bulges, resulting in tangential residual compressive stress at the hole edge. With the increase of the hole inclinations, the residual stress of the specimen was more uneven in radial direction, while more uniform in axial direction. The fatigue life of the strengthened all increased under three loading levels. The crack initiation zone moved near the entrance layer after ICE. Moreover, ICE increased the crack growth zone, and significantly inhibited the crack growth rate and stiffness degradation rate.

中文翻译：

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基于数值和实验方法的 GH4169 斜孔结构的冷膨胀疲劳性能研究


本文提出了高温合金裸孔结构的斜冷膨胀 （ICE） 方法，为航空发动机斜孔结构的寿命提高提供了有价值的见解。表征了带斜孔的 GH4169 试件的静态和疲劳性能的改善。此外，还进行了拉伸和疲劳试验，并通过数字图像相关 （DIC） 评估了表面应变。还讨论了 GH4169 斜孔试件的刚度退化和疲劳断裂行为。结果表明，ICE可引起斜孔结构的膨胀和凸起的扩大，导致孔边缘产生切向残余压应力。随着孔倾斜度的增加，试件的残余应力在径向上更不均匀，而在轴向上更均匀。强化后的疲劳寿命在 3 个载荷水平下均有所增加。裂缝起生区在 ICE 后移动到入口层附近。此外，ICE 增加了裂纹扩展区，并显着抑制了裂纹扩展速率和刚度退化速率。