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UNS C82800 (Alloy 275C) Beryllium Copper

C82800 copper is a lightly alloyed grade of copper, formulated for casting. C82800 is the UNS number for this material. Older literature may refer to this material as ASTM Alloy 275C or ASTM Alloy 275CT.

It has the lowest electrical conductivity among cast coppers. In addition, it has the lowest thermal conductivity and the highest embodied energy.

The properties of C82800 copper include two common variations. This page shows summary ranges across both of them. For more specific values, follow the links immediately below. The graph bars on the material properties cards further below compare C82800 copper to: cast 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 18 x 106 psi

Elongation at Break

1.0 to 20 %

Poisson's Ratio

0.33

Rockwell B Hardness

45 to 85

Shear Modulus

46 GPa 6.7 x 106 psi

Tensile Strength: Ultimate (UTS)

670 to 1140 MPa 97 to 170 x 103 psi

Tensile Strength: Yield (Proof)

380 to 1000 MPa 55 to 150 x 103 psi

Thermal Properties

Latent Heat of Fusion

240 J/g

Maximum Temperature: Mechanical

310 °C 580 °F

Melting Completion (Liquidus)

930 °C 1710 °F

Melting Onset (Solidus)

890 °C 1630 °F

Specific Heat Capacity

390 J/kg-K 0.092 BTU/lb-°F

Thermal Conductivity

120 W/m-K 71 BTU/h-ft-°F

Thermal Expansion

17 µm/m-K

Electrical Properties

Electrical Conductivity: Equal Volume

18 % IACS

Electrical Conductivity: Equal Weight (Specific)

19 % IACS

Otherwise Unclassified Properties

Density

8.7 g/cm3 540 lb/ft3

Embodied Carbon

12 kg CO2/kg material

Embodied Energy

190 MJ/kg 82 x 103 BTU/lb

Embodied Water

310 L/kg 37 gal/lb

Common Calculations

Resilience: Ultimate (Unit Rupture Work)

11 to 110 MJ/m3

Resilience: Unit (Modulus of Resilience)

590 to 4080 kJ/m3

Stiffness to Weight: Axial

7.8 points

Stiffness to Weight: Bending

19 points

Strength to Weight: Axial

21 to 36 points

Strength to Weight: Bending

20 to 28 points

Thermal Diffusivity

36 mm2/s

Thermal Shock Resistance

23 to 39 points

Alloy Composition

Among cast copper alloys, the composition of C82800 copper is notable for including cobalt (Co) and beryllium (Be). Cobalt is used to improve strength. Beryllium is used to permit precipitation hardening (which increases strength) without much effect on electrical conductivity, but at the cost of substantial toxicity.

Copper (Cu) 94.6 to 97.2
Beryllium (Be) 2.5 to 2.9
Cobalt (Co) 0.15 to 0.7
Silicon (Si) 0.2 to 0.35
Iron (Fe) 0 to 0.25
Nickel (Ni) 0 to 0.2
Aluminum (Al) 0 to 0.15
Titanium (Ti) 0 to 0.12
Chromium (Cr) 0 to 0.1
Tin (Sn) 0 to 0.1
Zinc (Zn) 0 to 0.1
Lead (Pb) 0 to 0.020
Residuals 0 to 0.5

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

Followup Questions

Similar Alloys

Further Reading

ASM Specialty Handbook: Copper and Copper Alloys, J. R. Davis (editor), 2001