Effect of Welding Parameter on Dynamic Fracture Properties of 2024-T3 Aluminum Friction Stir Welded Joints

Friction stir welding is widely used in the aerospace structure. It is important to study mechanical response of aluminum welded joints under dynamic loading. This paper aims to investigate the effect of welding parameter on rate-dependent dynamic tensile properties of 2024 aluminum welded joints. Samples in different weld zones were designed and dynamic tests with different strain rates were performed. It is observed that as the non-uniform heat and plastic flow during welding, yield strength of the heat-affected zone (513MPa) is much higher than the stirred zone (370MPa) and the thermo-mechanically zone (336MPa). Under the rotation speed of 400rmp, the heat affected zone and the stirred zone show much better tensile ductility, which is 25% higher than that of samples welded with the 600rmp rotation speed. The strain rate strengthening effect is obviously obtained. Furthermore, 2024 aluminum has been considered to have low strain rate sensitivity. The fracture morphology of specimens shows that as the function of rotating tool, equiaxed and fine grains help to enhance the strength.