Synergistic effect of SiC nano-reinforcement and vibrator assistance in micro-friction stir welding of dissimilar AA5052-H32/AA6061-T6

Several studies have reported methods for improving the weldability in micro-friction stir welding (mu-FSW). Among them, the use of nano-reinforcement in FSW enhances the mechanical properties of the material. The particles are dispersed via micro-friction stir processing (mu-FSP) several times via reinforcement particle aggregation. In this study, a long processing time and non-uniform particle dispersion are the disadvantages of mu-FSP. Experiments were conducted to compare the microstructure and mechanical properties of SiC nano-reinforcement addition and vibration-assisted mu-FSW. To reduce the welding time, the vibration-assisted mu-FSP was performed using four magnetically attached coin-type vibrators on the material for reinforcement particle dispersion. Particle aggregation occurred only under SiC nano-reinforcement addition. However, the SiC particle dispersion was uniform under vibration assistance. Additionally, SiC nano-reinforcement dispersion led to more dislocations in the plasticized material due to the assisted vibration. The ultimate tensile strength and elongation were the highest, and a uniform hardness graph was obtained. Therefore, SiC-nano-reinforced and vibration-assisted mu-FSW not only makes the particle size of the weld relatively small and uniform, but also increases the dispersion range of the SiC particles, improving the mechanical properties and shortening the processing time two fold.