Investigation on Intermetallic Compounds Formation and Effect of Reinforcing Particles during Friction Stir Vibration Brazing

In this paper, low carbon steel sheets were joined by the application of friction stir brazing (FSB) and friction stir vibration brazing (FSVB) processes while %67wt Sn-%33wt Pb alloy was used as filler material and SiO2 nanoparticles were utilized as reinforcing particles. The microstructure and mechanical properties of the developed joints were compared. The results indicated that the presence of mechanical vibration in FSVB promoted metallurgical reaction between the filler and base metals due to the enhanced thermal effect. Shear force for fracture and the joint hardness increased about 25 and 20%, respectively, as FSVB was replaced by FSB. The results also showed that the presence of vibration in FSVB led to the grain size decrease in the joint and enhanced the homogeneity of SiO2 particles distribution. According to fracture analyses, the number of dimples increased and the plasticity of the joint enhanced as FSVB was applied. Wetting of molten filler on substrate steels enhanced while vibration frequency increased. A continuous intermetallic compound layer with a fair thickness was formed as FSVB with a high-frequency value (50 Hz) was applied.