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LINEAR THERMAL EXPANSION COEFFICIENT OF COPPER AND COPPER ALLOYS
The linear thermal expansion coefficient (α) relates temperature change to dimensional change:
ΔL = α · L0 · ΔT. Typical room-temperature values for copper and widely used
copper alloys (brasses, bronzes) are listed below in 10⁻⁶/°C and 10⁻⁶/°F. Values vary with
alloy composition, temper, product form, and the applicable temperature range.
For a general comparison of thermal expansion coefficients across metals,
see the main reference:
Thermal Expansion Coefficient of Metals
.
|
Linear Thermal Expansion Coefficient Values for Copper Alloys
|
| Material |
Temp. |
Coefficient of Thermal Expansion |
| 10−6/°C |
10−6/°F |
| Wrought Coppers |
| Pure copper | 20 °C / 68 °F | 16.5 | 9.2 |
| Electrolytic tough pitch copper (ETP) | 20–100 °C / 68–212 °F | 16.8 | 9.4 |
| Free-machining copper, 0.5% Te or 1% Pb | 20–300 °C / 68–572 °F | 17.7 | 9.9 |
| Wrought Alloys |
| Commercial bronze, 90% | 20–300 °C / 68–572 °F | 18.4 | 10.3 |
| Red brass, 85% | 18.7 | 10.4 |
| Low brass, 80% | 19.1 | 10.6 |
| Cartridge brass, 70% | 19.9 | 11.1 |
| Yellow brass | 20.3 | 11.2 |
| Muntz metal | 20.8 | 11.5 |
| Leaded commercial bronze | 18.4 | 10.2 |
| Free-cutting brass | 20.5 | 11.4 |
| Forging brass | 20.7 | 11.5 |
| Naval brass | 21.2 | 11.8 |
| Manganese bronze (A) | 21.2 | 11.8 |
| Free-cutting phosphor bronze | 17.3 | 9.6 |
| Aluminum bronze (Class 1) | 16.8 | 9.4 |
| Beryllium copper | 17.8 | 9.9 |
Notes: Values are typical/representative for the temperature ranges shown. For design, use the
relevant material standards and design allowables when required.
Why copper alloys expand more than steel
Copper and copper-based alloys generally exhibit higher thermal expansion
than carbon and alloy steels because of their face-centered cubic (FCC)
crystal structure and lower elastic stiffness.
Typical copper alloys fall in the range of
16–21 × 10⁻⁶/°C, compared with approximately
10–12 × 10⁻⁶/°C for most carbon steels.
This difference is important in electrical busbars, heat exchangers,
and brazed joints where copper components are connected to steel or
stainless steel parts.
How to apply CTE
Estimate length change with temperature: ΔL = α · L₀ · ΔT.
Example: A 0.8 m brass (cartridge, α ≈ 19.9×10⁻⁶/°C) warmed by 45 °C expands by ΔL ≈ 19.9×10⁻⁶ × 0.8 × 45 ≈ 0.000716 m (0.72 mm).
Related
Reference
- Davis, J.R. Metals Handbook Desk Edition. ASM, 1998.