Comparison of fatigue properties between friction stir welds and TIG welds for Al alloy

The effect of welding processes friction stir welds(FSW)and tungsten inert gas welding (TIG)on fatigue properties of LF2 aluminum welded joints was analyzed,and the S-N curves of the welded joints were established.The results show that the fatigue properties of FSW welded joints are better than that of TIG welded joints.Fatigue strength of friction stir welds is 59-65 MPa under N=10~6. The microstructures of joints are comparatively fine grain and narrow HAZ zone in the FSW welds which inhibit the growth of crack and produce high fatigue life compared to that of the TIG welds.Fracture morphologies of TIG welds show that the fatigue fracture occurs from weld defects.