Vibration-Assisted Friction Stir Welding of AA 2024-T3 Plates

Abstract

Abstract In this research, the weldability of AA 2024-T3 plates using vibration-assisted friction stir welding (VaFSW) is primarily inspected. The vibration imparted to the fixture holding the specimens in VaFSW differentiates this state-of-art process from the conventional friction stir welding (FSW) technique. For large-scale welding applications, it is ideal to vibrate the tool with the required amplitude and frequency for optimum performance. Due to limitation in applying vibration to the tool in a milling machine, the vibration is imparted to a custom-designed fixture and rig setup. The fixture, which holds the plates rigidly, is mechanically shaken during the friction stir welding process to boost the material strain in the weld region. The VaFSW is performed with 1800 rpm tool rotational speed, 16 mm/min travel speed and at four intermittent levels of vibrational frequencies (10.11 Hz, 13.56 Hz, 16.67 Hz, 25.17 Hz). The welding morphology and mechanical characteristics of joints produced using VaFSW and FSW are presented in the current work. Finally, the results of VaFSW are compared with conventional FSW. Results show that the tensile strength and, hardness in each of the zones — Nugget zone, heat affected zone, and base metal increased with the increase in the vibrational frequency in the vibration-assisted friction stir welding process. In addition, the ductility of the joints increased by the vibration in the vibration-assisted friction stir welding process due to excessive plasticized material resulting in a greater grain dislocation. Moreover, the mechanical characteristics of weld joints enhanced with the increase in the vibrational frequency. However, the tensile strength and hardness of conventional FSWed joint are slightly higher than the joint produced using VaFSW at 10.11 Hz. This study is promising for finding the capability of VaFSW over FSW to produce quality weld joints.