Effect of friction-stir weld parameters on hybrid bonded joints

ABSTRACT

This research compares the mechanical behaviour of adhesive bonded (AB), friction stir spot welded (FSSW) and hybrid joints (H). The H joints were performed using both AB and FSSW. The influence of tool geometry, tool rotational speed and tool penetration depth on the joint strength were examined. The analysis of the mechanical performance of the joints was done using metallographic, hardness and tensile testing. In order to determine the local strains an optical extensometer with digital image correlation was used. Adhesive bonded joints displayed higher strength than welded or weld-bonded joints. Penetration of the tool pin into the lower plate increases the strength of the welded joint, although it has an unfavourable influence on defect formation. The weld-bonded (hybrid) joints have lower strength than adhesive-bonded joints or welded joints, as the uncured adhesive makes welding difficult, and the heat generated in the welding harms the adhesive.

KEYWORDS:

• Aluminium and alloys
• damage mechanics
• epoxy/epoxides
• joint design
• friction-stir welding

Acknowledgements

This research is sponsored by FEDER funds through the program COMPETE – Programa Operacional Factores de Competitividade – and by national funds through FCT – Fundação para a Ciência e a Tecnologia –, under the project UID/EMS/00285/2020.