When connecting copper to steel, which brazing filler alloy is recommended?

When connecting copper to steel, the use of a brazing filler alloy with a higher silver content, such as the 15 percent silver alloy, is beneficial. This alloy provides a strong, durable joint that is essential for the differing thermal expansion and contraction rates of these two metals. The elevated silver content enhances the flow and wettability of the filler material, helping to achieve a reliable bond.

Silver in the brazing alloy also contributes to improved corrosion resistance and mechanical strength, which is particularly important in applications where the joint may be subjected to mechanical stress or harsh environmental conditions. The higher percentage of silver tends to produce cleaner joints and requires lower brazing temperatures, which can prevent warping or damaging the base metals during the joining process.

While options with lower percentages of silver may be suitable for some applications, they may not provide the optimal properties needed for a robust connection between copper and steel, which is critical in HVAC systems and other applications where these two materials are commonly used together.