Identification of the mechanical properties and surface morphology of the friction still welding on aluminum alloy specimens

The fracture behavior of lap-shear joints manufactured by the friction stir welding (FSW) technique is examined in this paper. Two aluminum sheets, 6 mm and 10 mm in thickness, were welded using different process parameters to form a lap-shear joint. A special tool was designed and fabricated for the stir-spot welding process. The microhardness of the joint’s surface was analyzed with regard to the evolution of different parameters: the thickness and rotating speed of the tool. Static tensile tests were performed to determine the behavior of the welded joint using the two sheets. The three-point bending (TPB) and fatigue parameters of the weld were determined to characterize the fracture behavior. The effect of different main process-controlling parameters, such as the tool probe pin rotating speed, duration of action time, and sinking/penetration depth into the lower welded sheet on the weld’s fracture behavior, has been investigated through an intensive experimental program. Optical and scanning electron microscope fractographs were obtained to examine the weld fracture modes in different situation. The results show that higher frictional heat due to a relatively higher tool probe pin rotational speed and penetration depth into the lower sheet produces improved joint static strength and toughness.