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UNS C21000 (CW500L) Gilding Brass

C21000 brass is a brass formulated for primary forming into wrought products. CW500L is the EN numeric designation for this material. C21000 is the UNS number. Additionally, the EN chemical designation is CuZn5. The British Standard (BS) designation is CZ125. And the common industry name is 95-5 Gilding Brass.

It has a moderately high melting temperature among wrought brasses. In addition, it can have the lowest tensile strength and has the highest thermal conductivity.

The properties of C21000 brass include nine common variations. This page shows summary ranges across all of them. For more specific values, follow the links immediately below. The graph bars on the material properties cards further below compare C21000 brass to: wrought brasses (top), all copper alloys (middle), and the entire database (bottom). A full bar means this is the highest value in the relevant set. A half-full bar means it's 50% of the highest, and so on.

Mechanical Properties

Elastic (Young's, Tensile) Modulus

110 GPa 17 x 106 psi

Elongation at Break

2.9 to 50 %

Poisson's Ratio


Rockwell B Hardness

36 to 73

Rockwell Superficial 30T Hardness

44 to 68

Shear Modulus

43 GPa 6.2 x 106 psi

Shear Strength

180 to 280 MPa 26 to 40 x 103 psi

Tensile Strength: Ultimate (UTS)

240 to 450 MPa 34 to 65 x 103 psi

Tensile Strength: Yield (Proof)

69 to 440 MPa 10 to 63 x 103 psi

Thermal Properties

Latent Heat of Fusion

200 J/g

Maximum Temperature: Mechanical

190 °C 370 °F

Melting Completion (Liquidus)

1070 °C 1950 °F

Melting Onset (Solidus)

1050 °C 1920 °F

Specific Heat Capacity

390 J/kg-K 0.092 BTU/lb-°F

Thermal Conductivity

230 W/m-K 140 BTU/h-ft-°F

Thermal Expansion

18 µm/m-K

Electrical Properties

Electrical Conductivity: Equal Volume

56 % IACS

Electrical Conductivity: Equal Weight (Specific)

57 % IACS

Otherwise Unclassified Properties

Base Metal Price

30 % relative


8.8 g/cm3 550 lb/ft3

Embodied Carbon

2.6 kg CO2/kg material

Embodied Energy

42 MJ/kg 18 x 103 BTU/lb

Embodied Water

310 L/kg 37 gal/lb

Common Calculations

Resilience: Ultimate (Unit Rupture Work)

13 to 100 MJ/m3

Resilience: Unit (Modulus of Resilience)

21 to 830 kJ/m3

Stiffness to Weight: Axial

7.2 points

Stiffness to Weight: Bending

18 points

Strength to Weight: Axial

7.4 to 14 points

Strength to Weight: Bending

9.6 to 15 points

Thermal Diffusivity

69 mm2/s

Thermal Shock Resistance

8.1 to 15 points

Alloy Composition

Among wrought copper alloys, the composition of C21000 brass is notable for containing comparatively high amounts of iron (Fe) and lead (Pb). Iron is used to increase strength inexpensively. Lead is used to improve machinability and bearing properties, at the cost of toxicity.

Copper (Cu)Cu 94 to 96
Zinc (Zn)Zn 3.7 to 6.0
Iron (Fe)Fe 0 to 0.050
Lead (Pb)Pb 0 to 0.030
Residualsres. 0 to 0.2

All values are % weight. Ranges represent what is permitted under applicable standards.

Followup Questions

Similar Alloys

Further Reading

ASTM B134: Standard Specification for Brass Wire

ASTM B36: Standard Specification for Brass Plate, Sheet, Strip, And Rolled Bar

Copper: Its Trade, Manufacture, Use, and Environmental Status, Gunter Joseph, 2001

Properties and Selection: Nonferrous Alloys and Special-Purpose Materials, ASM Handbook vol. 2, ASM International, 1993