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.

摘要

AA2024-T3铝合金采用搅拌摩擦焊与粘接相结合的混合工艺连接。焊接前将环氧酯胶均匀涂抹在板材表面。根据搭接界面不同区域胶粘剂的作用，搭接界面可分为完全FSW区（CWZ）、过渡区（TZ）和完全密封区（CSZ）。在拉伸剪切试验期间，负载最初由 CWZ 和 TZ 分担。随着外载荷的增加，裂纹首先在胶层处萌生，导致载荷-位移曲线快速下降。当CWZ单独承受载荷时，接头承载能力恢复，载荷-位移曲线再次增加，直至CWZ开裂断裂。混合接头裂纹扩展过程主要包括胶层开裂阶段和FSW界面开裂阶段。粘合剂层的开裂载荷高于常规接头的弹性极限载荷，因此粘合剂不影响设计载荷。TZ上的粘合层降低了应力，使应力分布均匀，CSZ上可以阻挡腐蚀介质。