Defect repair of resistance spot welded aluminum alloy joint by friction stirring

For the defects such as crack and shrinkage in the resistance spot welded aluminum alloy joint, a repairing method based on the needleless friction stir thermal-mechanical coupling effect is proposed. By changing parameters such as rotational speed and dwell time, the repair effect and the influence factors on the defects were studied. The results showed that the bar type cracks could be repaired by single-side processing with a proper friction stir parameters, but the shrinkage defect still existed and there was no significant improvement in the performance of the repaired joint. The double-side processing could effectively repair the bar type crack and shrinkage, as a result, the maximum tensile shear was increased from 3.20 kN to 6.14 kN. The fracture mode of the joints after repairing was brittle failure, confirming that the proposed method is feasible and effective.