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.
| Cu | 94.6 to 97.2 | |
| Be | 2.5 to 2.9 | |
| Co | 0.15 to 0.7 | |
| Si | 0.2 to 0.35 | |
| Fe | 0 to 0.25 | |
| Ni | 0 to 0.2 | |
| Al | 0 to 0.15 | |
| Ti | 0 to 0.12 | |
| Cr | 0 to 0.1 | |
| Sn | 0 to 0.1 | |
| Zn | 0 to 0.1 | |
| Pb | 0 to 0.020 | |
| res. | 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