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The brazing of brass has its own characteristics due to the evaporation of hot zinc and the formation of a surface oxide film. In brasses, which contain up to 15% of zinc, the oxide film consists of bonded particles of ZnO and CuO. In copper alloys with large amounts of zinc, the oxide layer consists mainly of ZnO, which is more difficult to remove than copper oxide.

Fluxes and solders

When soldering with tin-lead etc. low temperature solder it is necessary to remove the oxide layer from the brass surface. Rosin-alcohol or more active fluxes are used. For example soldering of brasses L63, LS59-1-1 are fluxes with zinc chloride base with additives. Brass, unlike copper, is much less soluble in lead-tin solder melts. Thus, intermetallic layers grow slowly in the brazing process, which positively influences the mechanical properties of the brazed seam. The compounds obtained by soldering L63 with lead-tin solders have a lower tensile strength compared to copper under the same conditions. For example, the ultimate strength of tin-soldered butt joints of copper is 90 MPa, that of brass is not more than 59 MPa.

When brazing brasses with high copper content silver brazing alloys of brands are used: PSr40, PSr72, PSr45, PSr12, PSr25 as well as copper-phosphorous brass and brass with low melting point. When soldering brasses with high zinc content (L68, L63) solder PSr40 is used. Phosphorous solders are not suitable for them, as there appear low ductility solder joints. This can be explained by the fact that very brittle zinc phosphides are formed in the solder seam.

For those joints that are not exposed to dynamic and vibration loads, PMC48 and PMC36 solders are used. During soldering with copper-phosphorous and silver solders, the brass starts to dissolve intensively. Therefore to reduce the contact of solid metal and liquid solder they should be soldered at high heating rates. Brass of L63 grade dissolves intensively in solders PSr45, PSr40 and PSr15 and much less in solders PSr50KD and PSr37.5.

Temperature conditions

Parts made of brass can be brazed at temperatures of 850-870°C and in salt baths. To improve the flow of solder in the bath solution in the gap adds 4-5% flux, which contains borax or potassium fluoroborate. In the process of heating the parts in ovens and in the flame of gas burners is also oxidation and evaporation of zinc, thereby worsening the flow of solder. When brazing brass with a burner, the oxidation and evaporation of zinc in the reducing flame can be slightly reduced. Porosity in the solder joints at the same time is reduced.

Buy, price

Evek GmbH sells products of deformed and foundry brass ina widerange at an optimal price. We supply fluxes and solders of various grades. All products are certified. Quality meets GOST and international standards requirements. Lead time is minimal. The price depends on the order volume and additional terms of delivery. Preferential discounts are offered to our wholesale customers.