Abstract The residual stresses of Ti-3Al-2.5V tubing have effects on both fatigue performance and stress corrosion resistance. The inner surface, which directly contacts the hydraulic fluid of the aircraft, is the working surface of Ti-3Al-2.5V aerospace hydraulic tubing and fatigue cracks probably initiate on the inner surface. However, measuring residual stresses on the inner surface of small caliber tubing is difficult using X-ray diffraction at diffraction angles (2θ) of higher than 120° because the X-rays would be shaded by the outer surface. In this work, the as-received Ti-3Al-2.5V tubing was transversely cut using an electric discharge machine to obtain a sample having a length that was suitable for subsequent measurements and as long as possible to avoid stress relief. Then a diffractometer with Cu Kα radiations was used to scan the lattice planes {103} at the 2θ of 70.631° for the inner surface stresses of the sample. In particular, to avoid shading effects, we let the incident X-rays enter from one end of the sample and let the diffracted radiations exit from the other end. This work is of theoretical significance and application value for optimizing stress relief annealing process and for X-ray stress analysis of titanium and other metallic tubing.

中文翻译：

---

X射线衍射法对小口径Ti-3Al-2.5V管内表面残余应力分析的试验方法

摘要 Ti-3Al-2.5V管材的残余应力对疲劳性能和抗应力腐蚀性能都有影响。与飞机液压油直接接触的内表面是Ti-3Al-2.5V航空航天液压油管的工作面，疲劳裂纹很可能起源于内表面。然而，在衍射角 (2θ) 高于 120° 的情况下，使用 X 射线衍射很难测量小口径管内表面的残余应力，因为 X 射线会被外表面遮蔽。在这项工作中，使用电火花机横向切割原样的 Ti-3Al-2.5V 管，以获得长度适合后续测量的样品，并尽可能长以避免应力释放。然后使用具有 Cu Kα 辐射的衍射仪扫描 2θ 为 70.631° 的晶格平面 {103} 以获得样品的内表面应力。特别是，为了避免阴影效应，我们让入射 X 射线从样品的一端进入，而让衍射辐射从另一端出射。该工作对优化去应力退火工艺和钛等金属管材的X射线应力分析具有理论意义和应用价值。