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 SiO 2 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 SiO 2 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.

In the current investigation, a new version of brazing entitled FSVB (friction stir vibration brazing) is developed. In this process, the adjoining samples are vibrated normally to the brazing line while FSB is performed. Low carbon steel sheets are lap joined together using FSB and FSVB methods while SiO2 nanoparticles are incorporated in the joint. The microstructure and mechanical behaviors of the joints developed under different conditions are analyzed. %67wt Sn-%33wt Pb alloy is used as braze metal. The results show that the strength of the FSV brazed specimen is higher than that of the FS brazed sample (about 30%); additionally, the presence of SiO2 nanoparticles increases the strength of joints made by FSVB. Second-phase particles reduce the mobility of dislocations and strengthen the braze material. The vibration of adjoining specimens, during FSVB, increases the stirring of the molten braze metal between the adjoining specimens and the molten fills the space thoroughly. Workpiece vibration during FSVB also leads to the production of higher heat and temperature compared to those when using FSB. The higher temperature results in a higher fluidity of molten and it enhances the homogeneity of second-phase particle distribution and as a result, the joint strength increases. The results show that the strength and hardness of FSV brazed samples increase by 16% and 18%, respectively, and the thickness of the intermetallic component decreases as vibration frequency increases from 20 Hz to 50 Hz.