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Copper Standards: Designation and Classification of Copper Alloys

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Copper Standards: Designation and Classification of Copper Alloys

Copper standards define the properties of copper and copper alloys and set out how the type, form, and condition of an alloy should be described. Just as importantly, they provide a common language shared by the producers, traders, and users of copper alloys. As the metals and manufacturing industries have become increasingly global, the ability to compare and cross-reference the various copper standards has become more valuable than ever. This article explains how the major systems are structured and how they relate to one another.

European Copper Standards (CEN)

In Europe, copper standards are unified through a system developed by the Comité Européen de Normalisation (CEN). This system uses a six-character alphanumeric designation. The first letter, "C", indicates a copper alloy. The second letter identifies the product form, as follows: B for ingots to be remelted into cast products, C for cast products, F for filler materials used in brazing and welding, M for master alloys, R for refined unwrought copper, S for scrap, W for wrought products, and X for non-standard materials. Three numbers then identify the material, and a final letter identifies the classification of individual copper material groups while extending the capacity of the designation system.

Coppers: Commercially Pure Grades

In North America, copper standards are unified through the Unified Numbering System (UNS), which is managed jointly by the American Society for Testing and Materials (ASTM) and the Society of Automotive Engineers (SAE). Under the UNS, coppers and copper alloys are designated by five-digit numbers preceded by the letter "C". These five-digit codes are based on, and supersede, an older three-digit system developed by the U.S. copper and brass industry.

The older system was administered by the Copper Development Association (CDA), and copper alloys are still identified by their "CDA numbers" in many documents and drawings. The UNS designations are simply two-digit extensions of the CDA numbers, created to accommodate new compositions. For example, free-cutting brass, once known as CDA Alloy No. 360, became UNS C36000. UNS designations have since been incorporated into the most relevant copper standards, including those of ASTM, ASME, and SAE.

Within the UNS, numbers from C10000 through C79999 denote wrought alloys, while cast alloy designations range from C80000 through C99999. Within these two categories, the compositions are grouped into distinct families, including the six major groups: coppers, high-alloy coppers, brasses, bronzes, copper-nickels, and nickel silvers. Alloys that do not fall into one of these six groups are classified either as "other copper-zinc alloys" among the wrought compositions or as "special alloys" among the cast compositions.

Japanese Copper Standards (JIS)

Japanese JIS copper standards are based primarily on ISO standards. A JIS specification begins with the prefix JIS, followed by the letter C for wrought copper and copper alloys and a four-digit number that indicates the alloying elements added.

For example, JIS C1020 contains 99.9% copper, JIS C2720 is a copper-zinc alloy (brass), JIS C5191 is a copper-tin-phosphorus alloy (phosphor bronze), JIS C3601 is a copper-zinc-lead alloy (lead-alloyed brass), JIS C6801 is a copper-zinc-aluminium alloy (brass), and JIS C4430 is a copper-zinc-tin brass.

Explore More in the Copper Series

This article covers the standards that govern copper alloy designation and classification. The other guides in the Copper series address what those standards define. Copper Specifications explains the regional designation systems in detail, while Copper Grades organises the metal into its six alloy families. Copper Properties covers the conductivity, corrosion resistance, and strength that distinguish one alloy from another. Together, they connect the standards framework with the designations, grades, and properties it underpins.

Frequently Asked Questions (FAQs)

Why are copper standards important?

Copper standards precisely define the type, form, and condition of an alloy, and they provide a common language for producers, traders, and users. In an increasingly global market, they also make it possible to compare and cross-reference alloys designated under different systems.

How does the UNS relate to the older CDA numbers?

The UNS five-digit codes are direct extensions of the older three-digit CDA numbers administered by the Copper Development Association. Each UNS number simply adds two digits to accommodate new compositions. For example, CDA Alloy No. 360 became UNS C36000.

How does the UNS distinguish wrought copper alloys from cast copper alloys?

Under the UNS, numbers from C10000 through C79999 denote wrought alloys, while numbers from C80000 through C99999 denote cast alloys. Both categories are further divided into the six major alloy families.

What are the six major families of copper alloys under the UNS?

The six major groups are coppers, high-alloy coppers, brasses, bronzes, copper-nickels, and nickel silvers. Alloys outside these groups are classed as "other copper-zinc alloys" (wrought) or "special alloys" (cast).

What is the basis of the Japanese JIS copper standards?

JIS copper standards are based primarily on ISO standards. Each designation uses the prefix JIS, the letter C for copper and copper alloys, and a four-digit number that reflects the alloying elements, as in JIS C1020 for 99.9% copper.