Microstructure and texture evolution in bobbin tool friction stir welded 16mm-thick 6061-T4 aluminum alloy: Investigation into the correlation with mechanical behavior

This study systematically investigates the texture evolution and its impact on the mechanical properties of 16 mm-thick 6061-T4 aluminum alloy joint fabricated via bobbin tool friction stir welding (BT-FSW). The results reveal significant regional differences in texture formation due to variations in thermal cycling and material flow. Multiple symmetrical textures aligned with the {011} crystal plane were formed, enhancing hardness and strain accommodation. Dynamic recrystallization (DRX) and grain rotation promote the formation of E texture in SZ Middle , where the texture strength is higher than in SZ Top and SZ Bottom . Distinct shear textures, including Brass, Copper, and S components, emerge during welding, further shaping the overall texture characteristics. Additionally, geometric and continuous DRX (GDRX and CDRX) in the thermal-mechanically affected zone (TMAZ) contribute to texture heterogeneity. Digital Image Correlation (DIC) analysis confirms that texture strengthening enhances the strain accommodation capacity of SZ Middle , improving deformation resistance . This study provides new insights into the role of texture evolution in BT-FSW and establishes a foundation for optimizing welding parameters to enhance the structural integrity and mechanical performance of hollow-section thick aluminum alloy joints, with potential applications in aerospace and structural engineering.