Characterization of microstructure evolution and weld geometry in micro-friction stir spot welding of lightweight AZ31B magnesium alloy

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Agus Widyianto, Edwar Yazid, Aan Yudianto, Herminarto Sofyan, Gunadi

2025 Results in Engineering Vol. 26 Article Cited by 5 Quartile

Abstract

The micro-friction stir spot welding (µFSSW) procedure is investigated in this study. The process is used for magnesium alloy AZ31B with different thicknesses of 0.3 mm and 0.5 mm. This study examines the impact of varying plunge depths and dwell times on the geometry of welds and their mechanical performance and microstructural features. The results of the welding experiments showed that the ideal mechanical properties were achieved at a dwell duration of 500 ms and a plunge depth of 600 µm. This resulted in a maximum shear load of 326 ± 37 N and a cross-tensile load of 88 ± 2 N. The weld geometry study revealed that increasing the plunge depth and the dwell duration contributed to an increase in the weld nugget size and the thermo-mechanically affected zone (TMAZ). The results of the microhardness tests showed that the stir zone (SZ) had a higher level of hardness, generating an inverted “V” distribution with a peak of 118 HV. Metallographic investigations demonstrated that SZ included smaller grains due to dynamic recrystallization. On the other hand, the TMAZ contained coarser grains, and the heat affected zone (HAZ) contained granules that had partially recrystallized. Based on the study's findings, it can be concluded that µFSSW is a viable approach for joining thin sheets of AZ31B. The study also highlights that dwell duration and plunge depth are crucial parameters that influence the integrity of the weld. © 2025 The Author(s)

Affiliations

Department of Mechanical and Automotive Engineering, Faculty of Vocational, Universitas Negeri Yogyakarta, Kampus UNY Wates 55652, Indonesia; Research Center for Smart Mechatronics, National Research and Innovation Agency (BRIN), Bandung, Indonesia; Department of Mechanical, Aerospace and Civil Engineering, The University of Manchester, United Kingdom; Department of Automotive Engineering Education, Faculty of Engineering, Universitas Negeri Yogyakarta, Kampus UNY Karang Malang 55281, Indonesia