Wire-based Friction Stir Additive Manufacturing (W-FSAM) is an emerging solid-state additive manufacturing technique for the fabrication of large-scale aluminum components. Compared to fusion-based additive processes, W-FSAM eliminates melting, thereby preventing solidification-related defects such as hot cracking, porosity, and oxidation [1]. The solid-state material deposition enables the formation of dense and defect-free structures with refined microstructures and promising mechanical properties. These characteristics make W-FSAM particularly suitable for medium- and high-strength aluminum alloys, including the EN AW-2xxx, EN AW-6xxx, and EN AW-7xxx series, which are typically difficult to process using conventional fusion-based AM technologies [1, 2].

The fundamentals of the W-FSAM process are presented, ranging from the basic operating principle and initial feasibility studies using commercially pure aluminum to investigations on high-strength 2000-series aluminum alloys. The microstructural evolution and mechanical performance are investigated for both the model material EN AW-1050 and the high-strength alloy EN AW-2014, with detailed tensile and fatigue testing carried out on specimens extracted from the additively manufactured wall structures. For EN AW-2014, additional tensile and fatigue specimens are taken from all three principal directions (X, Y, and Z) to assess anisotropic behavior. The results show significantly enhanced tensile strength and fatigue resistance relative to the base material, demonstrating the capability of W-FSAM to produce high-performance aluminum structures.

The 3D microstructural morphology is analyzed with a focus on recrystallization behavior along the build height caused by continuous heat accumulation during layer-by-layer deposition. Electron backscatter diffraction (EBSD) is employed to quantify grain orientation, grain size distribution, and recrystallized fractions. Complementary light and scanning electron microscopy reveal a remarkable grain refinement in the deposited material compared to the wrought base material, indicating dynamic recrystallization induced by intensive plastic deformation during processing.

Overall, this work highlights the potential of W-FSAM as a viable manufacturing route for high-strength aluminum alloys and provides insights into process–structure–property relationships for future industrial application.

References

[1] S. Donaubauer, S. Weihe, M. Werz, Influence of Stirring Pin Geometry on Weld Appearance and Microstructure in Wire-Based Friction-Stir Additive Manufacturing of EN AW-6063 Aluminium. J. Manuf. Mater. Process. 2025, 9, 306. https://doi.org/10.3390/jmmp9090306

[2] H. Chen, N. Zou, Y. Xie, X. Meng, Xiaotian Ma, N. Wang, Y. Huang, Wire-based friction stir additive manufacturing of AlCu alloy with forging mechanical properties, Journal of Manufacturing Processes, Volume 133, 2025, Pages 354-366, https://doi.org/10.1016/j.jmapro.2024.11.037.