Copper alloy

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Copper alloys are alloys with copper as the main component and other metals or semi-metals in different proportions. Alloys that do not contain copper as a main component (such as Corten steel ) are called copper- containing alloys.

They are considered to be the first man-made alloys. Above all, bronze (copper-tin) and brass (copper-zinc) play a bigger role in human history . Its characteristic properties are high strength, ductility, strain hardening, corrosion resistance and good sliding properties.

Copper-tin alloys ( bronze )

Tin bronzes are deoxidized with phosphorus . They therefore contain residual phosphorus and are often incorrectly referred to as phosphor bronze. When designating or ordering semi-finished products, e.g. B. sheets, rods, wires, pipes, condition descriptions according to DIN EN 1173 can be added. The term bronze is no longer standardized today and is used for a number of high-alloy copper materials with tin (up to 12%), nickel (nickel bronze up to over 20% Ni), aluminum ( aluminum bronze up to 10% Al) and others.

Copper-zinc alloys ( brass )

In the solid state, copper dissolves up to 30% zinc as a mixed crystal . The alloys built up from these mixed crystals are called α-brass. As the zinc content increases, the tensile strength and yield strength of the α-brass increase. The cause of the increasing solidification is the increasing number of stacking faults in the brass, limited by dislocations, which occur during plastic deformation with the zinc content.

With zinc contents above about 30%, β-brass is produced. The β-phase consists of mixed crystals at high temperatures and of the very brittle intermetallic phase CuZn at low temperatures .

The γ-phase, which is technically unusable due to its high brittleness, consists of the intermetallic phase Cu 5 Zn 8 .

Material designation
according to DIN EN 1412		 Abbreviation MS sign Tensile strength
in N / mm²		 Yield strength
in N / mm²		 Elongation
at break in%		 Hardness
HB 10		 Notes on properties
and use
CW509L CuZn40 MS60 240 ... 470 240 ... 390 43… 12 80 ... 140 Good hot and cold formable (forged brass,
coin metal); suitable for bending, riveting,
upsetting and flanging as well as in the soft state
for embossing and also for deep drawing;
easy to machine on machines with the addition of lead.
CW612N CuZn39Pb2 MS58 360… 590 250 ... 540 40… 9 85… 175 Slightly cold formable through bending, riveting and
flanging; easy to punch; easy to machine (drilling and milling quality);
Watch brass for wheels and plates
CW614N CuZn39Pb3 MS58 380 ... 610 300… 570 35… 8 90 ... 180 Well formable after heating. Slightly formable without
heating. Alloys for all machining processes;
Form turned parts of all kinds, engraving brass; Watch brass for
wheels and plates, for precisely drawn bar profiles.
CW617N CuZn40Pb2 MS58 360… 570 200… 520 25… 4 80… 170 Very well suited for machining and for forming
by hot pressing and forging. Manufacture
of mass parts for the electrical engineering, precision mechanics
and optical industry; as well as for complicated profile shapes.
CW708R CuZn31Si - 440… 490 200 ... 290 22… 15 120… 160 For sliding loads even with high loads,
bearing bushings, guides and other sliding elements.
Sheet brass
consists of α mixed crystals and is brittle at 400 ° C to 500 ° C, soft at room temperature, easily deformable and difficult to machine.
Straight brass
consists of α + β mixed crystals and can be easily thermoformed and easily machined at room temperature.
Pure γ / α and γ + β brass is technically unusable due to its excessive brittleness.

Alloying other metals creates special brass .

Alloy element Effect in brass
nickel increases the notched impact strength
manganese improves corrosion resistance and refines the grain
iron refines the grain
tin improves seawater resistance
aluminum increases hardness and yield strength without reducing toughness

Copper-zinc alloys (copper content> 80%)

Also referred to as tombac , silicon tombac having the greatest structural relevance.

Copper-silver alloys

To increase the strength through solid solution formation , between 0.03% and 0.12% silver is added to the copper. The achievable tensile strength values ​​are a maximum of 270 N / mm². These alloys are used in electrical engineering for collector rings, contacts and commutator bars.

Copper-magnesium alloys

The magnesium content is between 0.2% and 0.8%. These alloys are used for cables in telecommunications technology ("post bronze"). They are also used as cold-drawn contact wires in overhead contact lines for high speeds.

Copper-nickel alloys

Copper-nickel alloys with typical nickel contents between 10% and 30% are called cupronickel . An alloy with 25% nickel is widely used as coin metal.

Copper-beryllium alloys ( beryllium copper )

Copper-beryllium alloys contain between 1.6% and 2.1% beryllium. The solubility of copper for beryllium decreases with falling temperature. It is 1.55% Be at 605 ° C and less than 0.1% Be at room temperature. For this reason, beryllium bronzes are hardenable , i. H. Their strength properties can be increased by quenching from 800 ° C in water followed by a longer holding to 300 ° C (= aging). After strong cold deformation before aging for one hour, the tensile strength is up to 1550 N / mm², the hardness is 365 HB and the elongation at break is 2%. Application examples are: parts exposed to heavy wear, e.g. B. transmission parts , bearings and leaf springs , slot terminals and highly stressed components that must be non-magnetic. Spark-free tools for mining, drilling rigs and production platforms as well as for the chemical industry are important applications.

Another hardenable copper alloy is created by adding tellurium . The resulting Cu 2 Te particles improve the machinability considerably with only a slight impairment of the conductivity.

literature

  • Martin Klein: Introduction to the DIN standards . Vieweg + Teubner Verlag, 2007, ISBN 3-8351-0009-2
  • Eduard Vinaricky: Electrical contacts, materials and applications: fundamentals, technologies, test methods . Springer, 2002, ISBN 3-540-42431-8
  • Heinrich Cornelius: Copper in technical iron . J. Springer, 1940
  • Ernst Brunhuber: Casting from copper alloys: Casting copper-base alloys . Fachverlag Schiele & Schoen, 1986, ISBN 3-7949-0444-3 , google books
  • Stephan Hasse, Ernst Brunhuber: Giesserei Lexikon . Fachverlag Schiele & Schoen, 2001, ISBN 3-7949-0655-1 google books
  • Heinz M. Hiersig : Lexicon production engineering, process engineering . Springer, 1995, ISBN 3-18-401373-1

Web links

Individual evidence

  1. ↑ Heinz M. Hiersig: Lexikon production engineering, process engineering . Springer, 1995, ISBN 3-18-401373-1 , p. 565 ff., Google books .
  2. ↑ Eduard Vinaricky: Electrical contacts, materials and applications: fundamentals, technologies, test methods . Springer, 2002, ISBN 3-540-42431-8 , pp. 285 ff., Google books .
  3. ↑ Martin Klein: Introduction to the DIN standards . Vieweg + Teubner Verlag, 2007, ISBN 3-8351-0009-2 , p. 226 ff., Google books .
  4. ↑ https://www.kupferinstitut.de/wp-content/uploads/2019/09/i5.pdf
  5. ↑ Deutsches Kupferinstitut: Material data sheets: CuZn40Pb2 . German Copper Institute, 2005, data sheet .