Mechanical Properties of Friction Stir Welded 2024 Aluminum Alloy Joint

2024-T351 aluminum alloy plate with 5 mm thickness was friction stir welded using two kinds of probe shape which are a left screw (LS) and cone with the curvature (CR). The microstructures and mechanical properties of the welded joint were investigated. Regardless of both welding conditions and probe shapes, the microstructures of stirred zone showed finer than that of the base metal. Hardness of weld zone of both joints showed lower than that of the base metal. The hardness of stir zone was restored 80%~100% of base metal. Tensile strength of LS joint showed about 90% of the base metal, and its CR joint showed about 70% of the base metal. The fatigue limit of LS joint showed about 90% of the base metal, and its CR joint showed about 80% of the base metal.