LAUSR

Friction stir welding (FSW) and gas tungsten arc welding (GTAW) were employed to manufacture the spiral pipes by a double-sided synchronization approach. The fatigue crack growth properties for base metal (BM) and welded metal (WM) in FSW and GTAW were studied using standard compact tension specimens manufactured from the welded pipes of the AA 5754 aluminum alloys. The highest crack growth rate occurred in WM of GTAW specimen, while WM of FSW specimen showed the lowest crack growth rate. Moreover, the crack growth rate of BM specimen fell in between them. This was because of the combination of the coarse grains and a high residual stress in WM of GTAW in comparison with WM of FSW and BM. The increase in fatigue crack rate matched well with the variation in the plastic region at the crack tip.