Understanding Copper Alloys

As copper alloys were developed, the Copper Development Association (CDA) established a numbering system based on the composition of each alloy. These numbers were then adopted by the SAE and ASTM (who added an additional two digits to the codes) and are used to identify various copper alloys. Below is a breakdown of the copper grade numbering system to help you understand copper alloys and the characteristics of each series.

C100 Series (Coppers)

100 series coppers are considered pure coppers, having a minimum copper content of 99.3%. High copper alloys which contain a copper content between 99.3% and 96% also fit into the 100 series. These grades possess high electrical conductivity and can contain additional alloying elements such as beryllium, cadmium, chromium, cobalt, nickel, or iron help to improve the strength without affecting electrical conductivity.

C200 Series (Brasses)

The 200 series grades are copper-zinc alloys that possess fair electrical characteristics and can be drawn or formed while maintaining good strength.

C300 Series (Leaded Brasses)

The 300 series are brass alloys containing 1% to 3% lead by weight which allows for ease of machining, milling, sawing and shearing.

C400 Series (Tin Brasses)

The 400 series alloys contain 1% to 2% tin, along with copper and zinc for greater corrosion resistance and strength. These grades are commonly used in electrical applications including terminals and connectors.

C500 Series (Phosphor Bronzes)

The 500 series alloys include leaded phosphor bronzes designed for performance under load conditions. These grades also possess greater resistance to alternating or cycling stress common in spring or bellows applications.

C600 Series (Bronzes)

The 600 series includes aluminum bronzes with 2% to 3% aluminum by weight which provides greater strength while maintaining formability. These alloys are commonly used for bearings, wear plates and hydraulic valve parts.

C700 Series (Nickel Silvers)

The 700 series alloys possess high strength, good formability and increased corrosion resistance. This includes alloys of copper, nickel and lead.

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