Abstract
Keyhole at the end of a conventional friction stir welded (FSW) joint is one of the major concerns in certain applications. To address this issue, a novel keyhole refilling technique was developed for conventional friction stir spot welding (FSSW) using resistance spot welding (RSW). A three-phase secondary rectifier resistance welder was adapted for the refill of the keyhole in the 1.5 mm + 1.5 mm friction stir spot welded 2024-T4 aluminum alloy joint. The microstructure and tensile shear fracture behavior were compared for both the unfilled and refilled specimens. The results show that the plug and keyhole are dominated by solid state welding with some localized zones by fusion welding. The refill process significantly improved the maximum load capacity in tensile shear testing as the corona ring is enlarged leading to a larger bonding area. Moreover, the tensile shear fracture occurs in the refilled FSSW specimens at the corona bonding zone, while the fracture occurs at the hook zone in the unfilled keyhole.
Highlights
Friction stir welding (FSW) is a patented welding technique developed by The Welding Institute (TWI) in 1991 [1]
Five friction stir spot welding (FSSW) specimens with refilled holes for each welding condition with different welding currents (28 kA, 31 kA, 34 kA, 37 kA, and 40 kA respectively) along with five groups FSSW with unfilled keyholes with same FSSW parameters were selected for static TS testing at room temperature
A novel keyhole refill technique is developed for friction stir spot welding (FSSW) using resistance spot welding (RSW) and is applied successfully to refill a keyhole generated in friction stir spot welded
Summary
Friction stir welding (FSW) is a patented welding technique developed by The Welding Institute (TWI) in 1991 [1]. As a solid-state welding process, the metallurgical properties of the weldment could be partly maintained or even be better than those of the parent material. This technique could be applied to join materials that exhibit an adverse reaction during conventional fusion welding, such as metal matrix composites, dissimilar materials, rapidly solidified materials, etc. A novel refill technique is developed for friction stir spot welding (FSSW) using resistance spot welding (RSW), which is a popular manufacturing method in aerospace and automotive industries [16,17]. A detailed comparative study was carried out with a focus on the microstructure and tensile shear fracture behavior of the unfilled and refilled friction stir spot welded joints
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
