Brass brazing alloys are copper-based alloys with zinc as their main element. Zinc content level is the main determinant of brass brazing alloys’ mechanical properties and melting point. With the assistance of a borax or boric acid flux, brass brazing alloys can be used to braze materials such as copper, copper alloys, nickel, nickel-base alloys and stainless steel with the torch and induction brazing processes, where corrosion resistance is not a requirement. Other minor elements such as tin, silicon, manganese or nickel can be added to enhance brass brazing alloys’ fluidity and corrosion resistance; these minor elements can also ensure a higher strength and leak-tightness of the resulting braze joints, so as to satisfy various technical requirements based on its application.
BCu60ZnSn(Si) is a typical product of the brass brazing alloy range, which contains a small amount of Sn and Si. These minor elements not only prevent the evaporation of Zn during brazing, but also improves the brazing alloy’s wetting properties; as a result, this product is very widely applied in manufacturing. BCu58ZnSn(Ni)(Si)(Mn) is another common product. While Sn and Si in this product play the same functional roles as mentioned above, Mn increases hardness and strength of the braze joints, and Ni improves their toughness. Due to these attributes, this product is mainly used in scenarios where the requirement for brazing alloys’ performance and strength of the braze joints are high.
When using brass brazing alloy, it is important to avoid overheating, otherwise the evaporation of zinc will cause voids in the joints, which will affect its compactness and brazing performance. Moreover, residues should be cleansed at once after brazing, so as to prevent any negative impact on the joints. Sandblasting mechanical method is a relatively effective method for residue cleaning. For parts which allow quenching, one can also cool them immediately in water, as the impact of stress will cause residue to crack and therefore removed.