Comparative study on fatigue properties between AA2024-T4 friction stir welds and base materials

The comparative study on fatigue properties between AA2024-T4 friction stir welds and base materials have been performed and the influence of zigzag-curve defects across weld section on the fatigue properties of FSW joints were investigated. It was shown that the zigzag-curve defects were the inherent feature existed in the friction stir nugget and could make the characteristic fatigue strength decrease from 96.19 MPa for base material to 73.71 MPa for welded joints with a reduction of 23.4%. Although the lower fatigue strength than the corresponding base material, the FSW joints of AA2024-T4 Al alloy achieved higher fatigue strength compared to the traditional fusion design curves IIW FAT40 and Draft Eurocode 9 design category 55-6 for structural aluminum alloy components.