Mechanical Properties Analysis and Texture Characterization of Friction Stir Welding Joints of 2024 and 5083 Dissimilar Aluminum Alloys Based on Thermal–Mechanical Coupling Effect

Aluminum alloys 2024 and 5083 are critical for lightweight engineering, yet their reliable dissimilar joining remains challenging. This study employs friction stir welding (FSW) to fabricate 2024/5083 joints, integrating multicharacterization (optical microscopy, scanning electron microscopy, electron backscatter diffraction (EBSD)) and thermal simulation to elucidate heat input's: 600–1200 rpm; 20–80 mm min −1 regulation on microstructures and properties. Novelty lies in identifying 600 rpm (20–40 mm min −1 ) as the optimal parameters: the nugget zone (NZ) undergoes full continuous dynamic recrystallization, forming fine equiaxed grains (≈6.06 μm) with high‐angle grain boundaries (>65%) and uniform dispersion of Al‐Cu/Mg phases. This yields an ultimate tensile strength (UTS) of 295.61 MPa (surpassing both base metals) and 12.85% elongation. In contrast, 800 rpm induces excessive heat, triggering static recrystallization grain growth, bimodal NZ microstructures, Mg segregation, and defects—drastically reducing UTS to <180 MPa and elongation to <0.5%. EBSD verifies optimal parameters suppress texture anisotropy, while thermal simulation underpins the “heat input–recrystallization–performance” correlation. This work establishes a multiscale “defect‐microstructure‐property” chain, advancing FSW parameter optimization for dissimilar Al alloys by clarifying 600 rpm as the critical threshold for balancing thermomechanical effects.