Compared with traditional friction stir spot welding

refill friction stir spot welding can produce perfect weld without exit hole

so it has bright future in some cases including termination hole repair of friction stir welds. New research progress of refill friction stir spot welding in the recent years has been reviewed

such as development of welding equipment

study of welding process and forming mechanism

analysis of weld microstructure and mechanical performance

and exploration of dissimilar materials

in addition

several important fields are indicated which include welding robot

keyhole closure process

weld fatigue and bonding between Al with other material.