Weldability of interlocked-end friction stir welding of aluminum alloy: single and double-sided welding

The weldability of the interlocked-end friction stir welding (IFSW) of aluminum plates was studied via the use of single and double-sided welding procedures. The abutting ends of the Al plates were milled into equidistant slots (with 5 mm rise and 10 mm span) and an interlocked/meshed end profile was formed when two slotted plates were brought together. The friction stir welding of the interlocked end of the plates was carried out at different tool rotational (700 – 1120 rpm) and traverse (21 – 63 mm/min) speeds while the structure, tensile strength, and fracture behaviors of the resultant welds were examined. The results showed the presence of flow-induced defects in the welds irrespective of the adopted welding procedure. Relative to the single-sided welds, the severity of the weld defect was significantly reduced in the double-sided welds due to dual material plasticization, material consolidation, and twofold recrystallization advantages. Improved tensile strength (from 39.6 to 69.1 MPa), reduced area fraction of flow-induced defect, and a large area with ductile features are obtained in the double-sided IFSW weld. A double-sided welding procedure is recommended for the interlocked-end friction stir welding process.