Microstructures and mechanical properties of friction stir welded(FSW) joint and friction stir processed(FSP) specimen of AZ91D magnesium alloy diecast were investigated. Regardless of welding conditions, the microstructures of stirred zone both of FSW joint and FSP specimen showed finer than that of the base metal. The microstructure of stirred zone of FSP specimen were finer than that of the FSW joint. Hardness of stir zone of both FSW joint and FSP specimen showed as same as that of the base metal. Joint efficiency of tensile strength of FSW joint showed 110% of the base metal. Tensile strength of FSP specimen showed as same as the base metal. Bending property of FSP specimen was more satisfactory than FSW joint.
High-strength Al-Cu based alloy is a low-weldability material with many technical problems to be solved in order to improve its weld properties. This reseach was performed to evaluate various joining processes and determine a satisfactory process in terms of the properties of Al-Cu alloy sheet of 0.8mm in thickness. YAG laser, disk laser and plasma welding were considered as high-energy beam joining processes. Furhtermore, we also considered FSW which was classified as solid-state welding. The properties of high-strength aluminum alloy welds produced with high energy beam welding and FSW were satisfactory, and reliable welded joints with higher tensile strengths coule be obtained. When evaluating the weld characteristics in the drop impact test, the YAG laser and disk laser welded joints did not fracture along the joined line and the fracture chracteristics were satisfactory. FSW and disklaser welding displayed good properties, and it was evident that a reliable joint could be obtained by control of the heat source. In the case of FSW, the relationship between tensile and drop impact properties of the joints was not elucidated.