中高强度铝合金熔化焊接接头的缺陷容限评价方法

doi:10.3901/JME.2020.08.046

摘要/Abstract

摘要： 应用电子背散射衍射及高精度同步辐射X射线三维原位成像技术，结合高周疲劳试验与裂纹扩展速率试验，揭示了激光复合焊接的中高强度铝合金的微结构特征（如组织、缺陷等）对疲劳性能的影响。结果发现，激光复合焊接过程显著改变了铝合金接头各区的组织特征；焊缝中存在着大量气孔缺陷；接头的拉伸和疲劳性能均低于母材，软化严重；根据缺陷的极值统计与修正的Murakami公式，获得了接头的理论疲劳极限。绘制出熔焊接头Kitagawa-Takahashi图，通过高周疲劳极限值推证得到铝合金7020和7050激光复合焊接头的缺陷容限值分别为185 μm和311 μm。

关键词: 同步辐射X射线, 缺陷容限评价, 疲劳极限, 疲劳裂纹扩展, Kitagawa-Takahashi图

Abstract: The effects of microstructural features on fatigue behaviours of medium and high strength Al alloys jointed by hybrid laser welding are revealed by using electron backscatter diffraction, high-cycle fatigue, crack growth rate and high-resolution synchrotron radiation in situ X-ray 3D micro tomography. The results show that the grain morphology and size are obviously modified after the hybrid welding. A large number of pores are found in the softened joints in hardness. Compared with base material, the tensile and fatigue properties of weld joint present a significant reduction. Based on extreme value statistics of defects and modified Murakami equation, the predicted fatigue limit is compared with that from the experiments. By using the Kitagawa-Takahashi diagram, the corresponding defect tolerance of 7020 and 7050 Al alloy hybrid joints are 185 μm and 311 μm, respectively.

Key words: synchrotron radiation X-ray tomography, defects tolerance assessment, fatigue limit, fatigue crack growth, Kitagawa-Takahashi diagram

中图分类号:

TG405

吴圣川, 谢成, 胡雅楠, 吴正凯, 康国政. 中高强度铝合金熔化焊接接头的缺陷容限评价方法[J]. 机械工程学报, 2020, 56(8): 46-59.

WU Shengchuan, XIE Cheng, HU Yanan, WU Zhengkai, KANG Guozheng. Defect Tolerance Assessment Method of Fusion Welded Medium and High Strength Al Alloy Joints[J]. Journal of Mechanical Engineering, 2020, 56(8): 46-59.

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