Defect Tolerance Assessment Method of Fusion Welded Medium and High Strength Al Alloy Joints

doi:10.3901/JME.2020.08.046

Abstract

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

CLC Number:

TG405

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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