This study examines the effects of ultrasound-enhanced friction stir welding (USE-FSW) on the mechanical properties and microstructural characteristics of aluminum alloy AA6082-T6, commonly used in automotive, aerospace, and construction industries. The investigation included tensile and bending tests, as well as detailed microstructural evaluations using scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and energy-dispersive X-ray spectroscopy (EDS). The results indicate that USE-FSW led to an approximately 26% increase in tensile strength compared to similar samples produced by conventional friction stir welding (CFSW). Additionally, the elongation at break improved by around 52%, indicating better ductility. Flexural strength also showed a notable improvement of over 70%. Microstructural analysis revealed a finer grain structure in the stir zone, contributing to these mechanical enhancements. However, the changes in texture and grain orientation were relatively modest, as shown by EBSD and Kernel Average Misorientation (KAM) analyses. Overall, USE-FSW offers incremental improvements in weld quality and mechanical performance, making it a promising technique for producing joints with slightly enhanced strength and ductility.

This study presents a comparative analysis between conventional friction stir welding (CFSW) and flexible ultrasonic-enhanced friction stir welding (FLEX-USE-FSW) applied to 3-mm-thick AA6082-T6 aluminum alloy. A novel ultrasonic system integrated into the tool holder was employed to introduce axial ultrasonic vibrations during welding. Mechanical testing, microstructural characterization, electron backscatter diffraction (EBSD), process force monitoring, and laser vibrometry were conducted to evaluate the influence of ultrasonic excitation on weld quality and process behavior. The results show that ultrasonic assistance reduces axial and traverse forces by up to 20%, broadens the operational window for tensile strength and elongation, and enhances material plasticization. EBSD analysis revealed a higher fraction of low-angle boundaries and modified grain texture in the ultrasonic-assisted stir zone (SZ), suggesting a change in recrystallization dynamics. Cross-sectional imaging indicated a larger and more homogeneous stirred zone in FLEX-USE-FSW, with reduced defect formation at elevated welding speeds. Additionally, laser vibrometry measurements showed improved energy transmission in specimens oriented parallel to the rolling direction. The findings demonstrate that ultrasonic excitation positively affects weld morphology, mechanical properties, and microstructural evolution, particularly under high-speed and low-heat input conditions.

This study presents a comparative analysis between conventional friction stir welding (CFSW) and flexible ultrasonic-enhanced friction stir welding (FLEX-USE-FSW) applied to a 3-mm-thick AA6082-T6 aluminum alloy. A novel ultrasonic system integrated into the tool holder was employed to introduce axial ultrasonic vibrations during the welding process. Mechanical testing, microstructural characterization, electron backscatter diffraction (EBSD), process force monitoring, and laser vibrometry were conducted to evaluate the influence of ultrasonic excitation on weld quality and process behavior. The results show that ultrasonic assistance reduces axial and traverse forces by up to 20%, broadens the operational window for tensile strength and elongation, and enhances material plasticization. EBSD analysis revealed a higher fraction of low-angle boundaries and modified grain texture in the ultrasonic-assisted stir zone (SZ), suggesting a change in recrystallization dynamics. Cross-sectional imaging revealed a larger and more homogeneous stirred zone in FLEX-USE-FSW, accompanied by reduced defect formation at elevated welding speeds. Additionally, laser vibrometry measurements showed improved energy transmission in specimens oriented parallel to the rolling direction. The findings demonstrate that ultrasonic excitation has a positive effect on weld morphology, mechanical properties, and microstructural evolution, particularly under high-speed and low-heat input conditions.