Comparative Analysis of Three Different Probe Designs for Reducing Hook Defects in FSW of AA6005-T6 Aluminum Alloy

Abstract

Hook defects are common in FSW butt–lap joints, resulting in a significant safety hazard for the parts that suffer cyclic load. In this study, a numerical simulation based on the Euler–Lagrange coupling method was conducted to investigate the formation process of hook defect during FSW of AA6005-T6 aluminum alloy. The simulation results were validated with experimental data, showing good agreement. The formation of the hook defect is caused by the threads on the probe promoting material flow in the thickness direction. In order to further study the effect of probe morphology on hook defects, three kinds of probe models with different morphology were established and numerically simulated by the CEL method. The simulation results show that all three kinds of probes can reduce the size of the hook. The welds obtained using the left–left probe (LLP) and the three-plane probe (TPP) both exhibit void defects, while the welds obtained by a right–left probe (RLP) have no internal void defects. The experimental results show the same characteristics as the simulation results, and the size of the hook defect is reduced to 58 μm.