The Best Methods for Braze Welding Copper

Properties of Copper

• Copper is an important metal used for a variety of industrial and construction purposes because of its excellent electrical and thermal conductivity, its corrosion resistance and and its wear resistance. Copper and many copper alloys can be joined by welding, brazing and soldering, according to the Aufhauser website.

Copper Alloys

• Copper products may be up to 99.3 percent copper, or they may contain other elements, such as silicon, zinc, tin, nickel or aluminum. To some degree, these other elements may affect how well the material can be welded. The choice of method for welding, brazing or soldering of copper is determined by the type of material being joined, as well other components within the material.

Brazing Copper

• Brazing uses an oxy-acetylene gas to produce joints between two pieces of material, such as copper. The overlap between the two pieces need not be large to create a strong joint, according to TheFabricator.com. This condition occurs because effective brazing requires the braze material to flow uniformly into the gap between parts. Large overlaps spread out the material over a greater area, which can lead to trapped gas in the joint that creates weaknesses in the joint. Braze filler material must be heated to a fully liquid state, rather than a slushy consistency, to permeate the joint easily. Reaching this fully liquid state can be complicated by the alloy components in the material.

Welding Copper

• Surface preparation is an important part of the successful welding of copper materials. Surfaces should be free of grease, dirt and oil. Thick copper pieces should be preheated to a high heat to reduce the amount of conduction that occurs from the weld area to the rest of the material. The preferred welding method for joining copper is gas tungsten arc welding using argon gas, with silicon-bronze wire. Argon-helium mixtures of gas are also used. The built-up oxide layer should be removed between passes of welding. Hot peening -- tapping the material with a hammer while it is still warm from welding -- will help to reduce the chances that the copper will crack.