Issue 77

T. Jiao et alii, Fracture and Structural Integrity, 77 (2026) 362-385; DOI: 10.3221/IGF-ESIS.77.21

Influence mechanism of defects in aluminum alloy friction stir welding on fatigue life

Ting Jiao Aircraft Strength Research Institute of China, Xi'an 710065, PR China 296513713@qq.com, https://orcid.org/0000-0002-6377-2150 Junling Fan Aircraft Strength Research Institute of China, Xi'an 710065, PR China National Key Laboratory of Strength and Structural Integrity, Xi'an 710065, PR China Fanjunling623@163.com, https://orcid.org/0000-0002-2093-8632 Xinwei Li, Xiangrui Meng

Aircraft Strength Research Institute of China, Xi'an 710065, PR China 1768390804@qq.com, https://orcid.org/0009-0006-7626-5410 15929909078@163.com, https://orcid.org/0009-0000-0746-9635 Yongbin Ma School of Mechanics and Transportation Engineering, Northwestern Polytechnical University, Xi'an 710072, PR China mayb@nwpu.edu.cn, https://orcid.org/0000-0002-3770-4824

Citation: Jiao, T., Fan, J., Li, X., Meng, X., Ma, Y., Influence mechanism of defects in aluminum alloy friction stir welding on fatigue life, Fracture and Structural Integrity, 77 (2026) 362-385.

A BSTRACT . By controlling welding parameters and adjusting process conditions, three typical defects-oxide inclusions, tunnel defects, and lack-of penetration defects-were intentionally introduced during the friction stir welding (FSW) of aluminum alloys. A comparative analysis of fatigue S - N curves between sound joints and joints with the three types of defects was conducted to systematically evaluate the impact of different defect types on the fatigue performance of welded joints. The results demonstrated that all three defects significantly reduce the fatigue life of the joints, with lack-of penetration defects having the most pronounced effect, followed by tunnel defects and oxide inclusions. Fracture surface analysis using SEM, EDS, and Microhardness testing confirmed that defects act as the primary crack initiation sites—the sound joint initiated cracks at the arc-textured surface, whereas cracks in all defective joints originated from the defect regions.

Received: 22.04.2026 Accepted: 29.05.2026 Published: 05.06.2026 Issue: 07.2026

Copyright: © 2026 This is an open access article under the terms of the CC-BY 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

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