Effect of pin length and welding speed on lap joint quality of friction stir welded dissimilar aluminum alloys

Hook and cold lap are the key factors which can affect the friction stir lap welding (FSLW) joint performance. Pin length has also an important effect on the morphologies of the hook and cold lap. Joints of AA7075 and AA2024 which are frequently used in aircraft structural elements mainly adopt lap joint configuration. The effect of pin length on dissimilar AA7075 and AA2024 lap joints has not been reported. Current paper intends to provide some further insights on this subject by discussing the relations among pin length, welding speed, and the corresponding tensile shear strength. It is interesting to find that the joint with high strength can be obtained when the harder material is placed as the upper sheet.