Research progress in friction stir welding of 7xxx high strength aluminum alloys

According to research status of friction stir welding of 7xxx high strength aluminum alloy, the problems existed in welding process of 7xxx high strength aluminum alloy were described in detail from aspects of welding defects, selecting of tool profiles, softening of welded joints, fatigue property and corrosion resistance, stress and deformation. For friction stir welding (FSW) of 7xxx high strength aluminum alloy, welding defects and low formation quality of weld could lead to softening of welded joints, low fatigue life and poor corrosion resistance of welded joints. Optimizing FSW parameters, reducing welding defects and improving formation quality of weld were beneficial to reduce softening degree of welded joints, improve fatigue life and corrosion resistance of welded joints. Selecting tool pin profiles to FSW of 7xxx high strength aluminum alloy was beneficial to improve mechanical properties of welded joints. Surface mechanical rolling treatment and ultrasonic impact treatment on the surface of FSWed joints could improve stress state on the surface of welded joints, which was beneficial to improve fatigue property of welded joints. Appropriate post-welding heat treatment was carried out on FSWed joints to improve shape, distribution of strengthening phase and characteristics of grain, which was beneficial to improve corrosion resistance of welded joints.