Study on Wettability and Brazing Properties of Ag30CuZnSn Flux Cored Brazing Filler Metal

The flux cored brazing filler metal was made up of Ag30CuZnSn brazing filler strip and powders containing B2O3, KBF4and KF through the method of strip rolling. The wettability of Ag30CuZnSn cored brazing filler metal on the surface of T1 copper was studied. T1 copper was brazed by flame brazing using Ag30CuZnSn cored brazing filler metal. The microstructure of brazed seam was observed and the mechanical properties of the Ag30CuZnSn/T1 copper brazed joints was tested. The properties were compared to these of joints brazed by Ag30CuZnSn filler metal+FB102. The results show that the spreading area obtained by Ag30CuZnSn cored brazing filler metal was slightly higher than that obtained by Ag30CuZnSn filler metal+FB102. The mechanical properties of Ag30CuZnSn/T1 copper brazed joints formed by flame brazing can meet the use requirements. The shear fracture positions are all located in the base metal. The microstructure of brazed joint is mainly composed of CuZn phase, Ag-based solid solution and Cu-based solid solution, which is consistent with the microstructure of brazed joint obtained by Ag30CuZnSn filler metal+FB102.