Effect of connection process on mechanical properties of aluminum alloy structure

7B04 aluminum alloy was chosen as the experimental material. The static and fatigue properties of 7B04 aluminum alloy structure joined by refill friction stir spot welding (Refill FSSW) were conducted, and they were compared with that joined by riveting. Results show that the compression static load of the typical structure connected by riveting and refill FSSW fluctuated in the range of 117 —124 kN, and the shear load was in the range of 89 —95 kN. Welds spacing had a small influence on the static load of the structures joined by refill FSSW. However, the fatigue life of structures of riveting was lower than that joined by refill FSSW. For the welded structure, the heterogeneous microstructures of welding joint led to the uneven microhardness, and meanwhile the hook in the lap interface bends upwards. These factors made the fatigue structures failure along the path that sleeve moves.