North American Copper Alloys

In North America, copper and copper alloys are designated and classified using the Unified Numbering System (UNS). This system uses a combination of a letter prefix C and a five-digit number to identify specific alloys.

Here's a more detailed breakdown:

• Prefix "C": All copper alloys are designated with the letter "C" at the beginning of their UNS number.

• Five-Digit Number: Following the "C" is a five-digit number.

• Wrought vs. Cast:

  • Numbers from C10000 through C79999 denote wrought alloys.

  • Numbers from C80000 through C99999 denote cast alloys.

• Alloy Families: Within the wrought and cast categories, the UNS numbers are grouped to represent different families of copper alloys based on their primary alloying elements:

  • North American Wrought Copper Alloys:

    • Coppers: C10100 - C15999

    • High Copper Alloys: C16000 - C19999

    • Brasses: C20000 - C49999

    • Bronzes: C50000 - C69999

    • Copper Nickels: C70000 - C73499

    • Nickel Silvers: C73500 - C79999

  • North American Cast Copper Alloys:

    • Coppers: C80000 - C81399

    • High Copper Alloys: C81400 - C83299

    • Brasses: C83300 - C89999

    • Bronzes: C90000 - C95999

    • Copper Nickels: C96000 - C96999

    • Nickel Silvers: C97000 - C97999

    • Leaded Coppers: C98000 - C98999

    • Special Alloys: C99000 - C99999

• Expansion of Older System: The UNS system is an expansion of an older three-digit system previously used by the U.S. copper and brass industry. The older three-digit numbers are embedded within the UNS numbers. For example, Copper Alloy No. 464 (naval brass) became C46400 in the UNS system. 

Important Points:

• The UNS designation is an identification system, not a specification.

• It provides a way to define and identify coppers and copper alloys, eliminating confusion caused by different previous designations.

• The UNS system is managed jointly by the American Society for Testing and Materials (ASTM) and the Society of Automotive Engineers (SAE).