COPPERS AND COPPER ALLOYS Machinery's Handbook, 31st Edition
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Coppers and CopperAlloys Pure copper is a reddish, highly malleable metal, and was one of the first to be found and utilized. Copper and its alloys are widely used because of their excellent electrical and thermal conductivities, outstanding resistance to corrosion, ease of fabrication, and broad ranges of obtainable strengths and special properties. Almost 400 commercial copper and copper-alloy compositions are available from mills as wrought products (rod, plate, sheet, strip, tube, pipe, extrusions, foil, forgings, and wire) and from foundries as castings. Copper alloys are grouped into several general categories according to composition: coppers and high-copper alloys
brasses bronzes copper nickels copper-nickel-zinc alloys (nickel silvers) leaded coppers special alloys
The designation system originally developed by the US copper and brass industry for identifying copper alloys used a three-digit number preceded by the letters CA. These designations have now been made part of the Unified Numbering System (UNS) simply by expanding the numbers to five digits preceded by the letter C. Because the old numbers are embedded in the new UNS numbers, no confusion results. UNS C10000 to C79999 are assigned to wrought compositions, and UNS C80000 to C99999 are assigned to castings. The designation system is not a specification but a method for identifying the composition of mill and foundry products. The precise technical and quality assurance requirements to be satisfied are defined in relevant standard specifications issued by the federal govern ment, the military, and the ASTM. Table 1. Classification of Coppers and Copper Alloys Family Principal Alloying Element UNS Numbers a Coppers, high-copper alloys C1xxxx Brasses Zn C2xxxx, C3xxxx, C4xxxx, C66400 to C69800 Phosphor bronzes Sn C5xxxx Aluminum bronzes Al C60600 to C64200 Silicon bronzes Si C64700 to C66100 Copper nickels, nickel silvers Ni C7xxxx a Wrought alloys. Cast Coppers and Copper Alloys.— Generally, casting permits greater latitude in the use of alloying elements than in the fabrication of wrought products, which requires either hot or cold-working. The cast compositions of coppers and high-copper alloys have a designated minimum copper content and may include other elements to impart special properties. The cast brasses are comprised of copper-zinc-tin alloys (red, semired, and yellow brasses); manganese bronze alloys (high-strength yellow brasses); leaded manga- nese bronze alloys (leaded high-strength yellow brasses); and copper-zinc-silicon alloys (silicon brasses and bronzes). The cast bronze alloys have four main families: copper-tin alloys (tin bronzes); copper- tin-lead alloys (leaded and high-leaded tin bronzes); copper-tin-nickel alloys (nickel-tin bronzes); and copper-aluminum alloys (aluminum bronzes). The cast copper-nickel alloys contain nickel as the principal alloying element. The leaded coppers are cast alloys containing 20 percent or more lead. Table 2 lists the properties and applications of common cast copper alloys.
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