3D short fatigue crack closure behavior in Ti-6Al-4V alloy investigated using in-situ high resolution synchrotron X-ray tomography
3D short fatigue crack closure behavior in Ti-6Al-4V alloy investigated using in-situ high resolution synchrotron X-ray tomography
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DOI：
10.1016/j.engfracmech.2021.107755
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发表时间：
2021-04
影响因子：
5.4
通讯作者：
Valary Tubei;H. Toda;M. Hassanipour;Kyosuke Hirayama;O. Takakuwa;A. Takeuchi;M. Uesugi
中科院分区：
文献类型：
--
作者：
Valary Tubei;H. Toda;M. Hassanipour;Kyosuke Hirayama;O. Takakuwa;A. Takeuchi;M. Uesugi
利用同步辐射X射线显微层析技术原位研究了Ti-6Al-4V合金疲劳短裂纹的三维闭合行为。在1 µm的空间分辨率水平下，在两个短裂纹前沿拍摄断层扫描数据集，以观察闭合的时间演化行为（有时称为4D成像）。由于高的空间分辨率水平，复杂的三维裂纹形态，包括偏转，刻面路径和裂纹分支/重叠所造成的三维变化的微观结构特征，很容易观察到一起发生的裂纹闭合。本研究分离了近端和端后裂纹闭合的贡献，并观察了它们随裂纹扩展的行为。可以推断，随着裂纹长度的增加，尖端后闭合的演变主要影响短裂纹区域的整体闭合行为。裂纹前缘闭合行为的变化被认为是由于存在不同的裂纹路径形态，表现出不同程度的断裂表面粗糙度，由于模式II和模式III的位移。讨论了裂纹尖端张开位移范围（ΔCTOD）与裂纹扩展速率之间的关系。
In-situ synchrotron X-ray microtomography has been employed to investigate the three-dimensional (3D) closure behavior of short fatigue crack in Ti-6Al-4V alloy. At a spatial resolution level of 1 µm, tomography datasets were taken at two short crack fronts to observe the time evolution behavior of closure (sometimes called 4D imaging). Owing to the high spatial resolution level, the complex 3D crack morphology consisting of deflections, facet paths and crack branching/overlap caused by the 3D variation in the microstructural features were readily observed together with the occurrence of crack closure. This study separated the contributions of near-tip and behind-tip crack closure and observed their behavior with crack growth. It was deduced that the evolution of behind-tip closure with increase in crack length predominantly affects the overall closure behavior in the short crack regime. Crack front closure behavior variation was found to be attributable to the existence of different crack path morphologies which showed varied degree of fracture surface roughness due to Mode II and Mode III displacements. The relationship between closure, crack tip opening displacement range (ΔCTOD) and crack growth rate are also discussed.