Different Attempt to Improve Friction Stir Brazing: Effect of Mechanical Vibration and Rotational Speed

A developed version of friction stir brazing (FSB) entitled friction stir vibration brazing (FSVB) was presented to fabricate low carbon steel joint using %67wt Sn-%33wt Pb alloy as a braze metal. This attempt aims to analyze the role of mechanical vibration and rotational speed on microstructure and mechanical behaviors of the brazed samples. Furthermore, the thermal analysis, the thickness of intermetallic compounds (IMCs) layers, and void volume percentage at the joint interface were studied. It was concluded that the temperature during the joining process increased and the coherency of the joint interface enhanced while FSVB was applied instead of FSB. In addition, the grains in the joint zone under the FSVB process were smaller than those produced under the conventional FSB process. The results also showed that the mechanical performance, namely hardness, and shear strength increased and the thickness of the IMCs layer along with the void volume percentage in the brazed sample decreased as rotational speed increased from 850 to 1150 rpm. The results indicated that rotational speeds over 1150 rpm had detrimental effects on mechanical properties. This is related to the effect of high heat input and induced temperature on brazing flow and filler-base metal interaction. Graphic abstract