AWS WHC-5.03:2015

Copper and Copper Alloys
Scope : Among the highly valued properties of copper and copper alloys are excellent electrical and thermal conductivity, corrosion resistance, metal-to-metal wear resistance, and a distinctive aesthetic appearance. Copper and copper alloys are important to many industries, including automotive, communications, electrical and electronics, refrigeration, transportation, and highenergy physics, and also to the manufacturers of numerous consumer products. Copper is a favored material used in artistic and architectural applications. Corrosion resistance, high electrical conductivity, and low maintenance are especially important when copper is used in electrical connections. These properties contribute to the most significant use of copper: the manufacturing of electrical equipment. Copper is the electrical conductivity standard of the engineering world, with the rating of 100%, as determined by the International Annealed Copper Standard (IACS), which was developed by the International Electrotechnical Commission and published in 1913.1 The electrical conductivity of all materials is compared to the IACS standard. Some specially processed copper forms can reach an IACS rating of 103%, which is very close to the theoretical limit for pure copper. Copper and many copper alloys have a face-centered cubic crystal structure, which accounts for the characteristics of good formability and malleability. In pure form, copper has a density of 8.94 Mg/m3 (milligrams per cubic meter) (0.32 lb/in.3 [pounds per cubic inch]), about three times that of aluminum. The electrical and thermal conductivity of copper is slightly lower than that of silver, but about 1.5 times higher than that of aluminum. Copper is resistant to oxidation, water, salt water, alkaline solutions, and many organic chemicals. Characteristically good corrosion resistance makes copper alloys ideally suited for water tubing, valves, fittings, heat exchangers, chemical processing equipment, and bearings. Copper reacts with sulfur and ammonia compounds; ammonium hydroxide solutions rapidly attack copper and copper alloys. The pleasant color, relatively good strength, and good formability of copper and copper alloys make them highly favored for architectural applications, such as roofing and decorative accents. The naturally occurring, greenish, weathered corrosion productâ??called patina or verdigrisâ??is often used as a decorative feature. When joining these materials, the patina must be removed and reapplied after the operation. Copper and most copper alloys can be joined by welding, brazing, and soldering.2 The major classes of copper alloys, the metallurgy and processing of copper, and how alloying elements affect the joining characteristics of welding, brazing, and soldering are described in this chapter.