Friction stir welding of high-strength aerospace aluminum alloy and application in rocket tank manufacturing

Friction stir welding(FSW) has been widely adopted in aerospace industry for fabricating high-strength aluminum alloy structures, such as large volume fuel tanks, due to its exceptional advantages including low distortion, less defects and high mechanical properties of the joint. This article systematically reviews the key technical issues in producing large capacity aluminum alloy fuel tanks by using FSW,including tool design, FSW process optimization, nondestructive testing(NDT) techniques and defect repairing techniques, etc. To fulfill the requirements of Chinese aerospace industry, constant-force FSW,retractable tool FSW, lock joint FSW, on-line NDT and solid-state equal-strength FSW techniques, as well as a complete set of aerospace aluminum FSW equipment, have been successfully developed. All these techniques have been engineered and validated in rocket tanks, which enormously improved the fabrication ability of Chinese aerospace industry.