Friction Stir Weld of AZ91 Magnesium Alloy With and Without Nano-SiC Particle

In this article, the influence of SiC nanoparticles on the friction stir welding of AZ91 magnesium alloy has been studied. For this purpose, a groove was designed to incorporate the nanoparticles into the weldment without requiring any additional tool to cover the weld surface. The welding process was carried out with and without nanoparticles in different process conditions. The mechanical properties and microstructure of the prepared joints were also studied. The results indicated that without using the nanoparticles, the minimum grain size of 2.79 µm along with the strength of 99% of the base metal can be achieved by applying the highest examined welding traverse speed and the lowest rotational speed. By using the SiC nanoparticles, in addition to annealing and dynamic recrystallization (DRX) mechanisms, the weld microstructure is also affected by pinning and aggregation mechanisms. Furthermore, it was realized that an increase in the rotational and traverse speeds adversely affects the mean grain size of the welded joints in the presence of nanoparticles. For the welded samples with nanoparticles, the grain size can be refined to 1.06 µm at the lowest traverse speed and the highest rotational speed.