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Corrosion fatigue crack propagation behavior of A7N01P‐T4 aluminum alloy welded joints from high‐speed train underframe after 1.8 million km operation
Author(s) -
Lu Wei,
Ma Chuanping,
Gou Guoqing,
Fu Zhenghong,
Sun Weiguang,
Che Xiaoli,
Chen Hui,
Gao Wei
Publication year - 2021
Publication title -
materials and corrosion
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.487
H-Index - 55
eISSN - 1521-4176
pISSN - 0947-5117
DOI - 10.1002/maco.202012123
Subject(s) - materials science , corrosion , welding , base metal , metallurgy , crack closure , scanning electron microscope , corrosion fatigue , alloy , fracture mechanics , composite material , polarization (electrochemistry) , optical microscope , paris' law , chemistry
Using the potentiodynamic polarization analysis, the fatigue crack propagation behavior of A7N01P‐T4 aluminum alloy metal inert gas welded joints cut from a high‐speed train underframe after 1.8 million km operation was studied in air and in a 3.5 wt% NaCl solution. The fracture surface and crack growth path were analyzed using optical microscopy, scanning electron microscopy, and electron backscattered diffraction. The results reveal that the corrosion fatigue crack growth rate of an A7N01P‐T4 welded joint in a 3.5 wt% NaCl solution is higher than that in air. Furthermore, the corrosion fatigue crack growth rate is noted to be the fastest in the heat‐affected zone, followed by the base metal, whereas it is the slowest in the weld metal, which is consistent with the corrosion resistance of the A7N01P‐T4 joints. The second phase is observed to exhibit a significant influence on the corrosion fatigue crack propagation path. The cracks are noted to grow toward the soft orientation and have obvious plastic deformation during the propagation process, which indicates that the anodic dissolution is the main cause of the corrosion fatigue crack growth.