Copper-based Conductivity Materials

The original definition of brasses is copper-zinc alloys. This definition has been enlarged with additions of lead, aluminium, manganese, iron, tin, and nickel.

There are over twenty cast brasses listed in EN1982:2008, but this document refers only to the 3 brasses which may be used in current carrying applications, where a lower conductivity than that of pure copper (100% IACS) is permissible. They have conductivities in the region of 20% IACS which is considerably greater than cast iron, stainless steel or titanium.

They also have good mechanical properties, good corrosion resistance and excellent machinability; attributes combined with low cost.

History

The first alloy used by man was bronze, copper-tin (about 3000 BC). Brass came much later due to difficulty of introducing zinc into molten copper, since metallic zinc is volatile and was added as zinc carbonate (calamine process) which was melted under charcoal.

The Romans were the first to use brass on any significant scale, for armour, helmets, brooches, decorative metalwork and coins (hence the term “brass” for money).

Once the production of metallic zinc was achieved in 1738, brass with a high level of artistic and technical merit became available leading to an expansion in decorative, domestic and engineering applications.

The rise of the electrical industry at the end of the 19th century led to an increase in the use of brass both wrought and cast due to its good thermal and electrical conductivity, with castings being ideal for the production of complex, sound, low cost shapes to close tolerances.

Heat Treatment

Brass castings may be stress relieved from 250-400oC.

Properties

Property

CuZn35Mn2Al1Fe1-C

CuZn33Pb2-C

CuZn39Pb1Al-C

Tensile strength N/mm2

450-500

180

220-350

Proof strength N/mm2

170-200

70

80-250

Elongation %

18-20

12

4-15

Hardness HB

110-120

50

65-110

IACS %

22

20

18

Thermal conductivity W/moC

87

90

81

The mechanical properties depend on the casting method used, which may be sand, pressure die, continuous or centrifugal, see BS EN 1982:2008.

Fabrication

 Process Rating
 Cold formability
Not recommended
 Hot formability
Not recommended
 Soldering Excellent
 Brazing Good
 Oxyacetylene welding
Not recommended
 Gas shield arc welding
Not recommended
 Resistance welding
Not recommended

Machining

CuZn35Mn2Al1Fe1-C is rated at 30% which is good.

CuZn33Pb2-C and CuZn39Pb1Al-C are rated at 70% (because of the lead content), which is excellent.

This is compared to CuZn39Pb3 which has the best machinability of any metallic alloy and is rated at 100%.

Resistance to Corrosion

In common with the other copper-based alloys, cast brasses have excellent resistance to normal atmospheric corrosion. They gradually darken over a period of time due to a tarnish film which forms on the surface. This film is mainly oxide, but in locations where there is sulphur pollution, a proportion will be sulphide. This film eventually becomes stable and protective, and no further oxidation occurs. It is very thin and smooth and in no way interferes with the electrical function of a brass casting.

Resistance to Softening

The cast brasses should not be used in applications involving sustained stresses above 150oC.

Applications

For complex shaped components where the high conductivity of copper is not required, cast brasses with good mechanical properties, good machinability and corrosion resistance provide a cost effective option for engineers.

  • Electrical hardware
  • Lugs
  • Wiping glands
  • Eye bolts
  • Earthing rods
  • Earth bars
  • Terminal blocks
  • Terminal connectors

Available Forms

CuZn39Pb1Al-C, CuZn33Pb2-C, CuZn35Mn2Al1Fe1-C are available as centrifugal investment, pressure die castings and sand.

Specifications

Below are the specifications for Europe, USA and Asia. Note that for USA and Asia, some compositions are not identical. For equivalent standards from other countries visit the Copper Key website.

  • UK: DCB3 (CuZn39Pb1Al-C), SCB3 (CuZn33Pb2-C), HTB1 (CuZn35Mn2Al1Fe1-C) (British Standard BS designation). British Standards are superseded by European Standards.
  • Europe CC754S (CuZn39Pb1Al-C), CC750S (CuZn33Pb2-C), CC765S (CuZn35Mn2Al1Fe1-C) (European Standard EN designation).
  • USA: C85710, C85400, C86550 (American Society for Testing and Materials ASTM designation).
  • Japan: CACln301 (Japanese Industrial Standards JIS designation).

Further information on CuZn39Pb1Al-C, CuZn33Pb2-C, CuZn35Mn2Al1Fe1-C and other conductivity materials, is available at the Copper Alloys Knowledge Base.

Application Example 1: Electrical Components

Below is shown a collection of electrical hardware such as pins, connectors, earthing bolts and clamps which may be easily cast and machined. Brass is an excellent, cost effective choice where the high conductivity of pure copper is not required.

Application Example 2: Brass Terminal Connectors

These connectors with good electrical and thermal conductivities, are easily cast to shape and machined and are an excellent cost effective choice when the high conductivity of pure copper is not required.

Quick Facts

Properties

These alloys have the following combination of properties:
  • Tensile strength: 180-500 N/mm2
  • Proof strength: 70-250 N/mm2
  • % Elongation: 4-20
  • Hardness (HV): 50-120
  • Electrical conductivity: 18-22% IACS
  • Thermal conductivity: 81-90 W/m oC

Applications

  • Electrical hardware
  • Lugs
  • Wiping glands
  • Eye bolts
  • Earthing rods
  • Earth bars
  • Terminal blocks
  • Terminal connectors

Available Forms

CuZn39Pb1Al-C, CuZn33Pb2-C, CuZn35Mn2Al1Fe1-C are available as centrifugal investment, pressure die castings and sand.

Application Example 1: Electrical Components

Electrical Components (Courtesy of Jamnagar Brass Components).
Electrical components (Courtesy of Jamnagar Brass Components).

Application Example 2: Brass Terminal Connectors

Brass Terminal Connectors (Courtesy of Brass Terminal Connectors India).
Brass terminal connectors (Courtesy of Brass Terminal Connectors India).
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