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UNS C18400 Chromium Copper

C18400 copper is a lightly alloyed grade of copper, formulated for primary forming into wrought products. It can have a moderately high ductility among the wrought coppers in the database.

The properties of C18400 copper include five 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 C18400 copper to: wrought coppers (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

120 GPa 17 x 106 psi

Elongation at Break

13 to 50 %

Poisson's Ratio


Rockwell B Hardness

16 to 84

Shear Modulus

44 GPa 6.3 x 106 psi

Shear Strength

190 to 310 MPa 27 to 44 x 103 psi

Tensile Strength: Ultimate (UTS)

270 to 490 MPa 40 to 71 x 103 psi

Tensile Strength: Yield (Proof)

110 to 480 MPa 16 to 69 x 103 psi

Thermal Properties

Latent Heat of Fusion

210 J/g

Maximum Temperature: Mechanical

200 °C 390 °F

Melting Completion (Liquidus)

1080 °C 1970 °F

Melting Onset (Solidus)

1070 °C 1960 °F

Specific Heat Capacity

390 J/kg-K 0.093 BTU/lb-°F

Thermal Conductivity

320 W/m-K 190 BTU/h-ft-°F

Thermal Expansion

17 µm/m-K

Electrical Properties

Electrical Conductivity: Equal Volume

80 % IACS

Electrical Conductivity: Equal Weight (Specific)

81 % IACS

Otherwise Unclassified Properties

Base Metal Price

31 % relative


8.9 g/cm3 560 lb/ft3

Embodied Carbon

2.6 kg CO2/kg material

Embodied Energy

41 MJ/kg 18 x 103 BTU/lb

Embodied Water

310 L/kg 37 gal/lb

Common Calculations

Resilience: Ultimate (Unit Rupture Work)

63 to 120 MJ/m3

Resilience: Unit (Modulus of Resilience)

54 to 980 kJ/m3

Stiffness to Weight: Axial

7.3 points

Stiffness to Weight: Bending

18 points

Strength to Weight: Axial

8.5 to 15 points

Strength to Weight: Bending

10 to 16 points

Thermal Diffusivity

94 mm2/s

Thermal Shock Resistance

9.6 to 17 points

Alloy Composition

Among wrought copper alloys, the composition of C18400 copper is notable for including chromium (Cr) and arsenic (As). Chromium additions permits certain types of heat treatment to improve mechanical strength. Arsenic is used to protect the alloy against dezincification.

Copper (Cu)Cu 97.2 to 99.6
Chromium (Cr)Cr 0.4 to 1.2
Zinc (Zn)Zn 0 to 0.7
Iron (Fe)Fe 0 to 0.15
Silicon (Si)Si 0 to 0.1
Phosphorus (P)P 0 to 0.050
Lithium (Li)Li 0 to 0.050
Calcium (Ca)Ca 0 to 0.0050
Arsenic (As)As 0 to 0.0050
Residualsres. 0 to 0.5

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

Followup Questions

Similar Alloys

Further Reading

Copper Alloys: Preparation, Properties and Applications, Michael Naboka and Jennifer Giordano (editors), 2013