Copper alloys

Copper alloys

Copper alloys are alloys with copper as their principal component. They have high resistance to corrosion.

Due to its high electric conductivity, pure electrolytic copper is used mostly for making of electrical cables.

Compositions

The similarity in external appearance of the various alloys, along with the different combinations of elements used when making each alloy, can lead to confusion when categorizing the different compositions. There are as many as 400 different copper and copper-alloy compositions loosely grouped into the categories: copper, high copper alloy, brasses, bronzes, copper nickels, copper–nickel–zinc (nickel silver), leaded copper, and special alloys. The following table lists the principal alloying element for four of the more common types, along with the name for each type.

Classification of copper and its alloys
Family Principal alloying element UNS numbers
Copper alloys, brass Zinc (Zn) C1xxxx–C4xxxx,C66400–C69800
Phosphor bronzes Tin (Sn) C5xxxx
Aluminium bronzes Aluminium (Al) C60600–C64200
Silicon bronzes Silicon (Si) C64700–C66100
Copper nickel, nickel silvers Nickel (Ni) C7xxxx

Some common Copper alloys

Name Nominal composition Form and condition Yield strength Tensile strength Elongation Hardness Comments
Copper (ASTM B1, B2, B3, B152, B124, R133) Cu 99.9 Annealed 10 32 45 42 Electrical equipment, roofing, screens
"
"
Cold-drawn 40 45 15 90
"
"
"
Cold-rolled 40 46 5 100
"
Gilding metal (ASTM B36) Cu 95.0, Zn 5.0 Cold-rolled 50 56 5 114 Coins, ammunition casings
Cartridge brass (ASTM B14, B19, B36, B134, B135) Cu 70.0, Zn 30.0 Cold-rolled 63 76 8 155 Good for cold-working; radiators, hardware, electrical
Phosphor bronze (ASTM B103, B139, B159) Cu 70.0, Sn 10.0, P 0.25 Spring temper 122 4 241 High fatigue-strength and spring qualities
Yellow or High brass (ASTM B36, B134, B135) Cu 65.0, Zn 35.0 Annealed 18 48 60 55 Good corrosion resistance
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"
Cold-drawn 55 70 15 115
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"
"
Cold-rolled (HT) 60 74 10 180
"
Manganese bronze (ASTM 138) Cu 58.5, Zn 39.2, Fe 1.0, Sn 1.0, Mn 0.3 Annealed 30 60 30 95 Forgings
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"
Cold-drawn 50 80 20 180
"
Naval brass (ASTM B21) Cu 60.0, Zn 39.25, Sn 0.75 Annealed 22 56 40 90 Resistance to salt corrosion
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Cold-drawn 40 65 35 150
"
Muntz metal (ASTM B111) Cu 60.0, Zn 40.0 Annealed 20 54 45 80 Condensor tubes
Aluminium bronze (ASTM B169 alloy A, B124, B150) Cu 92.0, Al 8.0 Annealed 25 70 60 80
"
"
Hard 65 105 7 210
"
Beryllium copper (ASTM B194, B196, B197) Cu 97.75, Be 2.0, Co or Ni 0.25 Annealed, solution-treated 32 70 45 B60 (Rockwell) Electrical, valves, pumps
"
"
Cold-rolled 104 110 5 B81 (Rockwell)
"
Free-cutting brass Cu 62.0, Zn 35.5, Pb 2.5 Cold-drawn 44 70 18 B80 (Rockwell) Screws, nuts, gears, keys
Nickel silver (ASTM B112) Cu 65.0, Zn 17.0, Ni 18.0 Annealed 25 58 40 70 Hardware
"
"
Cold-rolled 70 85 4 170
"
Nickel silver (ASTM B149) Cu 76.5, Ni 12.5, Pb 9.0, Sn 2.0 Cast 18 35 15 55 Easy to machine; ornaments, plumbing
Cupronickel (ASTM B111, B171) Cu 88.35, Ni 10.0, Fe 1.25, Mn 0.4 Annealed 22 44 45 Condensor, salt-water pipes
"
"
Cold-drawn tube 57 60 15
"
Cupronickel Cu 70.0, Ni 30.0 Wrought Heat-exchange equipment, valves
Red brass (ASTM B30 4A) Cu 85.0, Zn 5.0, Pb 5.0, Sn 5.0 Cast 17 35 25 60

Brasses

A brass is an alloy of copper with zinc. Brasses are usually yellow in color. The zinc content can vary between few % to about 40%; as long as it is kept under 15%, it does not markedly decrease corrosion resistance of copper.

Brasses can be sensitive to selective leaching corrosion under certain conditions, when zinc is leached from the alloy (dezincification), leaving behind a spongy copper structure.

Bronzes

A bronze is an alloy of copper and other metals, most often tin, but also aluminium and silicon.

  • Aluminium bronzes are alloys of copper and aluminium. The content of aluminium ranges mostly between 5-11%. Iron, nickel, manganese and silicon are sometimes added. They have higher strength and corrosion resistance than other bronzes, especially in marine environment, and have low reactivity to sulfur compounds. Aluminium forms a thin passivation layer on the surface of the metal.
  • Phosphor bronze
  • Nickel bronzes, e.g. nickel silver and cupronickel

Precious metal alloys

Copper is often alloyed with precious metals like silver and gold, to create, for example, Corinthian bronze, hepatizon, tumbaga and shakudo.

See also

References

  • Machinery's Handbook, Industrial Press Inc, New York, ISBN 0-8311-2492-X, Edition 24, page 501

External links

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