Characteristics and strength of hybrid friction stir welding and adhesive bonding lap joints for AA2024-T3 aluminium alloy

ABSTRACT

A hybrid process combining friction stir welding with adhesive bonding is used to connect AA2024-T3 aluminum alloy. The epoxy ester adhesive was evenly smeared on the sheet surface prior to welding. Regarding the function of the adhesive in different regions at the lap interface, the lap interface can be divided into a completely FSW zone (CWZ), transition zone (TZ) and completely sealed zone (CSZ). During the tensile-shear test, the load is initially shared by the CWZ and TZ. With the increase of the external load the cracks first initiate at the adhesive layer, leading to the fast decrease of load–displacement curves. When the CWZ bears the load alone, the joint recovers the load-carrying capacity and the load–displacement curves increase again until the CWZ cracks and fractures. The crack propagation process of the hybrid joint mainly includes adhesive layer cracking stage and FSW interface cracking stage. The cracking load of the adhesive layer is higher than the elastic limit load of the conventional joint, and thus the adhesive does not influence the design load. The adhesive layer on the TZ reduces the stress and makes the stress distribution uniform, and on the CSZ can block the corrosion media.

Keywords:

• friction stir welding
• adhesive bonding
• AA2024-T3 aluminum alloy
• joint characteristics
• load-carrying capacity

Nomenclature

Table

Acknowledgements

We appreciate that Beijing FSW Technology Co., Ltd provides the welding equipment for us. Meanwhile, thanks to AVIC Manufacturing Technology Institute for providing tensile-shear test and metallographic experiments.

Disclosure statement

The authors declare that they have no conflict of interest.