The Unified Numbering System
The Unified Numbering System (UNS) is the accepted alloy designation system in North America for wrought and cast copper and copper alloy products. The three-digit system developed by the U.S. copper and brass industry was expanded to five digits following the prefix letter C and made part of the Unified Numbering System for Metals and Alloys. UNS designations are simply expansions of the former designations. For example, Copper Alloy No. 377 (forging brass) in the original three-digit system became C37700 in the UNS System. The UNS is managed jointly by the American Society for Testing and Materials (ASTM) and the Society of Automotive Engineers (SAE). Because these old numbers are embedded in the new UNS numbers, no confusion need result. This designation system is also used in Canada.
The designation system is an orderly method of defining and identifying coppers and copper alloys; it is not a specification. It eliminates the limitations and conflicts of alloy designations previously used and at the same time provides a workable method for the identification marking of mill and foundry products.
In the designation system, numbers from C10000 through C79999 denote wrought alloys. Cast alloys are numbered from C80000 through C99999. Within these two categories, the compositions are grouped into the following families of coppers and copper alloys:| Coppers | Metals which have a designated minimum copper content of 99.3% or higher. |
|---|---|
| High Copper Alloys | For the wrought products, these are alloys with designated copper contents less than 99.3% but more than 96% which do not fall into any other copper alloy group. The cast high copper alloys have designated copper contents in excess of 94%, to which silver may be added for special properties. |
| Brasses | These alloys contain zinc as the principal alloying element with or without other designated alloying elements such as iron, aluminum, nickel and silicon. The wrought alloys comprise three main families of brasses: copper-zinc alloys; copper-zinc-lead alloys (leaded brasses); and copper-zinc-tin alloys (tin brasses). The cast alloys comprise four main families of brasses: copper-tin-zinc alloys (red, semi-red and yellow brasses); "manganese bronze" alloys (high strength yellow brasses); leaded "manganese bronze" alloys (leaded high strength yellow brasses); copper-zinc-silicon alloys (silicon brasses and bronzes); and cast copper-bismuth and copper-bismuth-selenium alloys. Ingot for remelting for the manufacture of castings may vary slightly from the ranges shown. |
| Bronzes | Broadly speaking, bronzes are copper alloys in which the major alloying element is not zinc or nickel. Originally "bronze" described alloys with tin as the only or principal alloying element. Today, the term is generally used not by itself but with a modifying adjective. For wrought alloys, there are four main families of bronzes: copper-tin-phosphorus alloys (phosphor bronzes); copper-tin- lead-phosphorus alloys (leaded phosphor bronzes); copper-aluminum alloys (aluminum bronzes); and copper-silicon alloys (silicon bronzes).
The cast alloys have four main families of bronzes: 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 family of alloys known as "manganese bronzes," in which zinc is the major alloying element, is included in the brasses, above. |
| Copper-Nickels | These are alloys with nickel as the principal alloying element, with or without other designated alloying elements. |
| Copper-Nickel-Zinc Alloys | Known commonly as "nickel silvers," these are alloys which contain zinc and nickel as the principal and secondary alloying elements, with or without other designated elements. |
| Leaded Coppers | These comprise a series of cast alloys of copper with 20% or more lead, sometimes with a small amount of silver, but without tin or zinc. |
| Special Alloys | Alloys whose chemical compositions do not fall into any of the above categories are combined in "special alloys." |
Designations for the most widely used coppers and copper alloys are shown in bold-face type in the tables of composition. For each of these, a standard data sheet appears in either Part 2 (wrought products) or Part 7 (cast products) of the CDA Standards Handbook.
The use of these standard designations by any member or non-member of the Copper Development Association Inc. is voluntary. These standard designations do not preclude any member or non-member from manufacturing or supplying products which do not conform to these standard designations.
The standard designation composition limits do not preclude the possible presence of other unnamed elements. However, analysis shall regularly be made only for the minor elements listed in the table, plus either copper or zinc or plus all major elements except one. The major element that is not analyzed shall be determined by difference between the sum of those elements analyzed and 100%. By agreement between producer or supplier and consumer, analysis may be required and limits established for elements not cited. Percentage content of elements shown as "Remainder" (Rem.) is normally calculated by difference.
Chemical Symbols
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Standard Chemical Composition Limits
The composition limits in this listing of Standard Designations for Copper and Copper Alloys are presented according to the following numerical convention, wherever practicable.
| Constituent | Convention For Expressing Composition Limits |
|---|---|
| Copper Nos. C10000 - C15999 (wrought) and C80000 - C81199 (cast): | |
| Copper | XX.XX |
| Alloying elements and impurities: | |
| 1/10 and over | .XX |
| 1/100 and less than 1/10 | .0XX |
| 1/1000 and less than 1/100 | .00X |
| less than 1/1000 | .000X |
| Copper Alloy Nos. C16000 - C79999 (wrought) and C81300 - C99999 (cast): | |
| Copper | XX.X |
| Alloying elements and impurities: | |
| 6/10 and over | .X |
| 1/10 and less than 6/10 | .XX |
| 1/100 and less than 1/10 | .0X |
| 1/1000 and less than 1/100 | .00X |
| less than 1/1000 | .000X |
| CDA assumes no responsibility or liability of any kind in connection with this publication or its use by any person or organization and CDA makes no warranties of any kind hereby or with respect to any of the information or data contained herein. This publication shall not be construed as a recommendation of any patented or proprietary application that may be involved. For additional information on how to register new copper alloys, visit the UNS Copper Alloys site. |
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