Exit-hole repairing in friction stir welding of AA5456 pipe using consumable pin

ABSTRACT

Filling Friction Stir Welding (FFSW) is an FSW completing process, in which the exit-holes at the end of friction stir welded lines are filled by a rotational semi-consumable pin. In the present study, combined 7.5 mm thick AA5456 rolled plates (5 mm) and pipes (2.5 mm) were successfully welded and filled by FFSW using a semi-consumable similar pin (5456) and semi-consumable dissimilar pins (7075 and 2024) on lap joint specimens. The effects of filling parameters, pin geometry, rotation speed and plunge velocity on the mechanical properties and microstructure of the joints were investigated by tensile and hardness tests. Optical Microscopy (OM) and Scanning Electron Microscopy (SEM) were implemented to study the microstructure and interfaces of the filled holes. Furthermore, preheating assessment was studied to cover technological issues. Finite element method was applied for FFSW simulation using DEFORM-3D commercial package. The optimized process parameters for AA5456 were obtained as the pin rotation speed of 800 rpm, plunge velocity of 50 mm/min and a similar material (AA5456) pin of cone angle 8°.

KEYWORDS:

• Filling
• friction
• stir
• welding
• FFSW
• consumable
• pin
• pipe
• exit-hole
• lap
• AA5456

Acknowledgments

The authors would like to acknowledge the laboratories of Iran University of Science and Technology for providing the experiments facilities. Also, technical support of M. Safarkhanian, D. Gholami, E. Yaghubi, F. Allafchi and M. Rahimi-Chegeni is greatly acknowledged.