Effects of fluxes on distribution of SiC particles and microstructures and mechanical properties of nanoparticles strengthening A-TIG (NSA-TIG) welded magnesium alloy joints

Abstract

The effects of fluxes and the size of SiC particles on the morphologies, microstructures and mechanical properties of tungsten inert gas welded AZ31 magnesium alloy joints were investigated. The results showed that addition of SiC particles in the activating fluxes led to the decrease in all the weld penetrations while the surface appearance of welded joints improved in the case of TiO₂ activating flux was adopted. Grain refinement was obtained in the welded seams with the addition of SiC particles in TiO₂ flux and the effect of nanosized SiC particles on grain refinement is found to be more impressive than that of microsized SiC particles. The microhardness of the fusion zone and ultimate tensile strength of the welded joints increased with the addition of SiC particles in TiO₂ activating flux and nanosized particles have more strong efficiency on the improvement of mechanical properties compared with microsized SiC particles. SiC particles did not improve the mechanical properties of A-TIG welded joints with CaF₂ activating flux.