Effect of SnAg1.0Cu0.5 on the wettallity of Ag30CuZnSn flux cored brazing filler and mechanical properties of its brazed joints

Adding SnAg1.0Cu0.5 powder into flux cored powder, the effect of different SAC105 content on the microstructure and properties of brazed joint obtained by Ag30CuZnSn flux cored brazing filler metal and stainless steel was studied. The results show that the addition of SAC105 can significantly improve the wetting and spreading properties of Ag30CuZnSn flux cored brazing filler metal on the surface of stainless steel. With the increase of SAC105 content, its wetting spreading area increased. This is mainly because the increase of Sn can significantly reduce the melting temperature of brazing filler metal, thus increasing the superheat of the liquid metal, reducing the viscosity of the liquid metal and enhancing the fluidity of the liquid metal. Finally, the wetting and spreading properties of the Ag30CuZnSn flux cored brazing filler metal on the surface of 304 stainless steel was improved. When the addition of SAC105 was 20 wt.%, the microstructure of brazed joint has the fine grain, which was mainly composed of interwoven Ag-based solid solution. The shear strength of the corresponding brazed joint was up to the maximum value of 453 MPa, which increased by 29.9%.