Overview of laser-welded thin-walled joints fatigue performance and a statistical method for defect analysis

Welding always has a deteriorating effect on fatigue strength in structures under dynamic loading. Weld joints induce discontinuity in structure geometry and the microstructure. Welding induced discontinuity, and defects allow for potential fatigue cracks that lead to the failure of welded parts or structures. The laser welding process differs from conventional arc welding in process and joint type. The most significant advantage in laser welding comes from the deep penetrating mode of welding, which also brings challenges to the soundness of the weld. The benefits of laser welding are most evident in the manufacture of sheet metal products such as sandwich panels. In literature, laser welding is generally dealt with by using different parts of the overall process without taking the fatigue point of view into account. In this article, the process of laser welding is discussed, while keeping fatigue strength in perspective. The fatigue data of laser welded joints is studied in order to find defect distribution that explains fatigue strength distribution in tests. The suitability of traditional fatigue assessment for laser welding is also discussed.

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