No abstract

No abstract

No abstract

No abstract

The present article introduces the auxiliary energy assisted friction stir welding (FSW) processes purported to overcome the shortcomings of the conventional FSW process. The auxiliary energies used for this purpose are thermal energy from electric resistance heat, induction heat, laser, plasma, arc, etc. and mechanical energy in the form of ultrasonic vibration. The state-of-the-art, experimentation and progresses in these FSW variants are surveyed and compiled. The auxiliary energy assisted FSW processes exhibit great promise by having numerous advantages over the conventional FSW in terms improved process window, heat generation, material flow, reduced load on the tools and mechanical properties of joints. Such remarkable advantages would lead these processes to redefine many global technologies and markets in the twenty-first century. However, these variants are still in their preliminary stages of investigation, and more systematic investigations are necessary for their critical assessment. In this aspect, some unsolved issues and challenges are overlooked.

Ultrasonic vibration enhanced friction stir welding (UVeFSW) is a new variant of friction stir welding (FSW) in which a sonotrode transmits ultrasonic energy directly into the localised area of the workpiece near and ahead of the rotating tool. This study investigated the influence of ultrasonic vibration on the formation, microstructure and mechanical properties of butt welded 2024Al-T4 joints, and attempted to unveil the underlying mechanism of UVeFSW by experimental methods. Morphology inspection, X-ray detection and metallographic inspection of the welds revealed that ultrasonic vibration can improve the weld formation at higher welding speeds. The stir zone in the UVeFSW broadened, while the grains in the heat affected zone had no obvious growth contrary to that in the base metal. Results of the mechanical tests indicated that the tensile strength and elongation of joints, and the microhardness value in the stir zone increased at the same welding parameters.

No abstract

No abstract