Influence mechanism of pin thread in friction stir welding of magnesium alloys based on the relationship between microstructure and mechanical properties

Xie, Liangwen; Xiong, Xiang; Zhu, Xianyong; Fan, Yuexiang; Jiang, Cheng; Song, Yulai

doi:10.1016/j.jmatprotec.2023.117870

Cited by 9 publications

(2 citation statements)

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“…The structure of the weld is typical for welds made with a tool with a cylindrical pin. In the cross-section, the weld nugget and the thermomechanically affected zone are less visible compared to other test results of FSW welds of Mg alloys: AZ91 [61], AZ31 [62], or with the alloy addition Sn (ATZ511) [63]. However, a significant difference was observed between the areas at the weld face and the rest of the thermomechanically affected zone (TMAZ).…”

Section: Discussionmentioning

confidence: 68%

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Comprehensive Research of FSW Joints of AZ91 Magnesium Alloy

et al. 2023

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For the friction stir welding (FSW) of AZ91 magnesium alloy, low tool rotational speeds and increased tool linear speeds (ratio 3.2) along with a larger diameter shoulder and pin are utilized. The research focused on the influence of welding forces and the characterization of the welds by light microscopy, scanning electron microscopy with an electron backscatter diffraction system (SEM-EBSD), hardness distribution across the joint cross-section, joint tensile strength, and SEM examination of fractured specimens after tensile tests. The micromechanical static tensile tests performed are unique and reveal the material strength distribution within the joint. A numerical model of the temperature distribution and material flow during joining is also presented. The work demonstrates that a good-quality joint can be obtained. A fine microstructure is formed at the weld face, containing larger precipitates of the intermetallic phase, while the weld nugget comprises larger grains. The numerical simulation correlates well with experimental measurements. On the advancing side, the hardness (approx. 60 HV0.1) and strength (approx. 150 MPa) of the weld are lower, which is also related to the lower plasticity of this region of the joint. The strength (approx. 300 MPa) in some micro-areas is significantly higher than that of the overall joint (204 MPa). This is primarily attributable to the macroscopic sample also containing material in the as-cast state, i.e., unwrought. The microprobe therefore includes less potential crack nucleation mechanisms, such as microsegregations and microshrinkage.

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Section: Discussionmentioning

confidence: 68%

“…A clear asymmetry of the FSW joint is also shown in [69]. On the other hand, in [62,63], the zone near the shoulder is distinguished as a mixing zone or shoulder-affected zone due to significant stirring. Literature analysis shows that this joint area is created in more challenging conditions than other areas.…”

Section: Discussionmentioning

confidence: 89%