Specific Heat Capacity of Aluminum: 6061, 7075, 2024 & 5052
At about 20°C, these four wrought aluminum alloys cluster near 0.88–0.90 J/(g·K). Their difference is small, so specific heat alone rarely decides the best alloy.
What should you remember?
Four facts prevent most calculation and buying mistakes.
Only a small spread
The room-temperature reference values differ by roughly 2.5% from lowest to highest.
Density changes the result
Use volumetric heat capacity, ρcp, when parts occupy the same space.
cp is not conductivity
Specific heat stores energy. Conductivity controls how readily heat moves.
Verify the real condition
Attach temperature, temper, product form and source to every design value.
6061, 7075, 2024 and 5052 specific heat compared
| Alloy | Typical cp near 20°C | J/(g·K) | BtuIT/(lb·°F) | Data confidence |
|---|---|---|---|---|
| 6061 | 897 J/(kg·K) | 0.897 | 0.2142 | Direct NIST-hosted ASM reference value. |
| 7075 | 893 J/(kg·K) | 0.893 | 0.2133 | Direct NIST-hosted ASM reference value. |
| 2024 | 875 J/(kg·K) | 0.875 | 0.2090 | Direct NIST-hosted ASM reference value. |
| 5052 | About 880 J/(kg·K) | About 0.880 | About 0.2102 | Estimated/common reference; confirm for critical work. |
Room-temperature reference: NIST-hosted ASM wrought-aluminum properties. Conversion factor: NIST Guide to the SI. Values are typical references, not guaranteed lot properties.
Why does 7075 sometimes appear as 960 J/(kg·K)?
Kaiser publishes 960 J/(kg·K) for 7075 in a table labeled at 100°C. That value is useful at its stated temperature, but it should not be mixed into a room-temperature ranking. Specific heat changes with temperature, so both 893 near 20°C and 960 at 100°C can be reasonable within their own source conditions.
What does specific heat capacity mean?
Specific heat capacity, written cp, tells you how much energy is needed to raise one kilogram of material by one degree. A value of 897 J/(kg·K) means that an ideal one-kilogram 6061 sample needs about 897 joules for a one-kelvin temperature rise when that value fits the temperature range.
- Specific heat cp: energy stored per unit mass and degree.
- Part heat capacity C = mcp: energy stored by the whole component per degree.
- Volumetric heat capacity ρcp: energy stored per unit volume and degree.
- Thermal conductivity k: how readily heat moves through the material.
- Thermal diffusivity α = k/(ρcp): how quickly a temperature pattern spreads.
Hardness and strength are different again
Heat treatment can change the strength of 6061 or 7075 greatly while changing room-temperature specific heat much less. Do not use cp to predict yield strength, weld strength or corrosion resistance.
Convert aluminum specific heat without losing a factor of 1,000
Keep the units beside every number. The arithmetic is simple; most errors come from mixing prefixes or mass units.
897 J/(kg·K) becomes 0.897 J/(g·K).
897 J/(kg·K) becomes 0.897 kJ/(kg·K).
897 becomes about 0.2142 BtuIT/(lb·°F).
A rise of 75°C is a temperature difference of 75 K.
Q = m × cp × ΔTUse for a modest range when one constant cp is accurate enough.
Cvol = ρ × cpUse when two candidate parts occupy the same envelope instead of having the same mass.
t ≈ Q ÷ PabsorbedUse net power absorbed by the part—not simply the heater nameplate rating.
Specific heat is a temperature-dependent property
A single cp number is a shortcut for a curve. When temperature rises, aluminum generally needs more heat for each additional degree. A room-temperature value may be good for a small excursion and too simple for an oven, hot-forming cycle or cryogenic system.
Use a constant when the range and risk are modest
For an early estimate around room temperature, Q = mcpΔT is easy to audit. State the chosen cp and run a sensitivity check if published values differ.
Use a curve when the range is wide
For temperature-dependent data, calculate Q = m∫cp(T)dT. If the aluminum melts, add latent heat and use valid solid- and liquid-phase data. A room-temperature constant does not cover a phase change.
Temper and product form still belong in the record
The effect of temper on cp near room temperature is often modest compared with its effect on strength or conductivity. “Modest” does not mean zero. Record the full condition, such as T6, T651, T3, T351 or H32, whenever the model is controlled.
The cp values are close. The real trade-offs are not.
Choose an alloy from the full mechanical, thermal, corrosion and manufacturing requirement—not one column in a property table.
Balanced thermal manufacturing choice
Often the practical starting point for heat sinks, cold plates, housings, machine parts and fixtures.
- Useful conductivity in common tempers
- Good availability and machinability
- Extrudable and generally weldable
Strength-led selection
Useful for highly loaded and weight-sensitive parts, but not automatically the best thermal-spreading alloy.
- High mechanical strength
- Lower k than 6061-T6 in common high-strength conditions
- Joining and corrosion strategy need care
Aerospace structural trade-offs
Fatigue, damage tolerance, product specification and corrosion protection usually matter more than its small cp difference.
- Established aerospace applications
- Condition and product form matter
- Do not borrow 6061 conductivity data
Forming and corrosion choice
Common for sheet-metal enclosures, tanks, marine components and weldments.
- Good formability and weldability
- Strong corrosion resistance
- The stated cp is an estimate; verify when critical
How much energy is needed to heat the part?
These examples isolate sensible heat stored in the metal. They do not include convection, radiation, fixtures, coolant, contact losses or heater inefficiency.
Define the part
Use actual mass—or calculate it from geometry and alloy density.
Set the temperature rise
Subtract the starting temperature from the target temperature.
Select cp
Match alloy, temperature range, condition and confidence level.
Add the real system
Account for losses, fixtures, fluids, interfaces and absorbed power.
| 10 kg part heated by 75 K | cp used | Q = mcpΔT | Difference from 6061 |
|---|---|---|---|
| 6061 | 897 J/(kg·K) | 672.75 kJ | Reference |
| 7075 | 893 J/(kg·K) | 669.75 kJ | 3.00 kJ lower |
| 2024 | 875 J/(kg·K) | 656.25 kJ | 16.50 kJ lower |
| 5052 | About 880 J/(kg·K) | About 660.00 kJ | About 12.75 kJ lower |
Estimate warm-up time without overpromising the result
The ideal time is easy to calculate. The useful estimate comes from separating energy stored in the aluminum from every other load and loss in the machine.
Start with absorbed power
The 10 kg 6061 example needs 672.75 kJ for a 75 K rise. At a constant 2.0 kW absorbed by the part, the ideal time is 672.75 kJ ÷ 2 kJ/s, or about 336 seconds (5.6 minutes).
Nameplate power is not net power
If only 65% of a 2.0 kW heater reaches the part, net absorbed power is about 1.3 kW. The same idealized rise becomes roughly 517 seconds (8.6 minutes), before temperature-dependent losses are added.
Heat more than the workpiece
Fixtures, clamps, trays, coolant and nearby machine structure may warm during the cycle. Add their heat capacities separately, then account for changing convection, radiation, contact resistance and control behavior.
| Question | Input to collect | Why it changes the answer |
|---|---|---|
| What is heated? | Part, fixture, fasteners, fluid and insulation | Every heated mass stores energy; omitting a fixture can make the predicted cycle too short. |
| How is heat delivered? | Heater contact, induction, oven, laser or hot fluid | The transfer route changes absorbed power, surface losses and temperature uniformity. |
| What result matters? | Average, surface, core or minimum temperature | A part can reach the right average temperature while still having a damaging hot spot or cold center. |
| How is the cycle controlled? | Sensor position, ramp, soak, duty cycle and feedback delay | The controller may reduce power near the target, so constant-power time is only a first estimate. |
Use ρcp when the part envelope is fixed
Two one-kilogram samples answer a mass-based question. Two one-liter parts answer a packaging question. Because density changes the mass inside one liter, the ranking can change.
| Alloy | Density used | Volumetric heat capacity ρcp | Energy for 1 L and 75 K |
|---|---|---|---|
| 6061 | 2,700 kg/m³ | 2.42 MJ/(m³·K) | 181.6 kJ |
| 7075 | 2,800 kg/m³ | 2.50 MJ/(m³·K) | 187.5 kJ |
| 2024 | 2,770 kg/m³ | 2.42 MJ/(m³·K) | 181.8 kJ |
| 5052 | 2,680 kg/m³ | About 2.36 MJ/(m³·K) | About 176.9 kJ |
Which alloy heats fastest?
There is no answer from cp alone. Under the same absorbed power, a lower total heat capacity can raise average temperature faster. But local temperature and uniformity also depend on conductivity, geometry, heat-source footprint, contact, convection and control history.
Higher specific heat does not make a better heat sink
A heat sink must move heat from the source into fins and then reject it to air or coolant. Specific heat helps determine transient temperature change, but conductivity and the surrounding heat-transfer path often control the working temperature.
Illustrative diffusivity comparison
Using condition-specific conductivity values with the volumetric heat capacities above gives approximate thermal diffusivities of 69 mm²/s for 6061-T6, 52 for 7075-T6/T651, 50 for 2024-T3/T4, and 59 for 5052-O. These are screening examples because conductivity changes strongly with temper and source.
- Use cp for energy storage per mass.
- Use ρcp for energy storage per volume.
- Use k and the full geometry for steady heat flow.
- Use α with boundary conditions for transient spreading.
Choose the alloy by the job it must do
The best selection combines thermal response with strength, corrosion, forming, welding, machining, product availability and total cost.
Start with 6061
Evaluate conductivity, channels, interfaces, flow, flatness, joining and leak testing—not cp alone.
Compare 2024 and 7075
Strength, fatigue, toughness, corrosion, fasteners, service temperature and approved allowables lead the choice.
Consider 5052
Formability, weldability, corrosion resistance, gauge, finish, sealing and the H-temper matter most.
Model the whole cycle
Include warm-up energy, temperature uniformity, stiffness, expansion, wear, sensors and control stability.
Use ρcp
Density changes how much mass and stored heat fit inside the available package.
Represent the joint
Local thermal history can change temper, conductivity and mechanical properties around the weld.
When should you test specific heat?
Handbook values are usually enough for concept design and sensitivity work. Testing becomes worthwhile when a small thermal margin, a wide temperature range, qualification, material variation or a contractual requirement makes the source uncertainty important.
ASTM E1269-24
This method uses differential scanning calorimetry to determine specific heat capacity for thermally stable solids and liquids. Its normal operating range is −100°C to 600°C, subject to equipment and specimen limits.
ASTM E1461-13(2022)
The flash method primarily measures thermal diffusivity. Under strict conditions, related cp data may also be determined; conductivity can then be derived from α, density and cp. Each measured or assumed input adds uncertainty.
- Define alloy, full temper, product form, thickness and lot.
- Set the temperature range and requested data spacing.
- Name the method, calibration, sampling and uncertainty.
- State whether the result is informational or an acceptance requirement.
Record the assumption so another engineer can reproduce it
A traceable model is more valuable than a table with many unsupported decimal places.
What exactly is being bought?
- Alloy and complete temper
- Sheet, plate, extrusion, bar or tube
- Thickness, coating, cladding or anodizing
- Welded, bonded or heat-treated condition
What must the model predict?
- Start and target temperatures
- Heat load, duration and duty cycle
- Warm-up, cool-down and uniformity target
- Airflow, coolant, contacts and insulation
How certain must the value be?
- Handbook assumption or supplier value
- Temperature-dependent curve
- Lot-specific measured data
- Method, uncertainty and acceptance rule
Seven common mistakes in aluminum heat-capacity calculations
| Mistake | Why it fails | Better practice |
|---|---|---|
| Using 7075 = 960 at room temperature | The Kaiser value is labeled at 100°C. | Use a room-temperature source or state 100°C clearly. |
| Calling cp “thermal conductivity” | Heat storage and heat flow are different. | Model cp, k, density, geometry and boundaries separately. |
| Mixing J and kJ | This creates a 1,000× error. | Write units beside every input and result. |
| Comparing equal-size parts using cp alone | Different densities change the part mass. | Use ρcp or calculate actual mass. |
| Assuming highest cp means coolest part | Conductivity and heat rejection may control temperature. | Solve the complete heat path and energy balance. |
| Using Q = mcpΔT through melting | The formula omits latent heat and phase-specific properties. | Integrate cp(T) and add phase-change enthalpy. |
| Treating a typical value as guaranteed | A handbook number may not represent the purchased lot. | Specify method, temperature, sampling and acceptance criteria. |
Send the thermal duty—not only the alloy name.
Share the alloy and temper, product form, dimensions or mass, temperature range, heat load, cycle time, environment, joining route, quantity and certification needs. That gives our team enough information to compare manufacturing and thermal risk on the same basis.
Related aluminum engineering guides
Aluminum specific heat FAQ
What is the specific heat capacity of 6061 aluminum?
A NIST-hosted ASM reference lists 897 J/(kg·K), or 0.897 J/(g·K), near 20°C. Use it as a typical reference rather than a guaranteed property for every temper, product form and lot.
What is the specific heat capacity of 7075 aluminum?
A NIST-hosted ASM reference lists 893 J/(kg·K) near 20°C. Kaiser lists 960 J/(kg·K) at 100°C, which explains why both numbers appear online.
What is the specific heat of 2024 aluminum?
A useful typical reference near 20°C is 875 J/(kg·K), equal to 0.875 J/(g·K) or about 0.209 BtuIT/(lb·°F).
What value should I use for 5052 aluminum?
About 880 J/(kg·K) is a common estimate for early work. Because the accessible value is estimated rather than a certified condition-specific result, obtain supplier data or test representative stock when the margin is tight.
Can I use 0.9 J/(g·K) for a quick aluminum calculation?
Yes, for a rough room-temperature estimate across these four alloys. Record the assumption and use alloy-specific or temperature-dependent data when a few percent matters.
Does temper change aluminum specific heat?
It can, because heat treatment changes the material's phase and solute state. Near room temperature, the cp effect is often modest compared with the strength or conductivity change, but critical models should still match the exact condition.
Does higher specific heat make a better heat sink?
No. Higher cp means more energy is needed to change each kilogram by one degree. Heat-sink performance also depends strongly on thermal conductivity, geometry, interfaces, airflow or coolant, and heat-source distribution.
How do I convert J/(kg·K) to Btu/(lb·°F)?
Divide the J/(kg·K) value by 4,186.8 for the International Table Btu. For example, 897 J/(kg·K) is about 0.2142 BtuIT/(lb·°F).
Does a mill certificate guarantee specific heat?
Usually not. Mill certificates commonly report chemistry and mechanical properties required by the product specification. If cp must be guaranteed, add the temperature, method, sampling, uncertainty and acceptance rule to the contract.
Can Q = mcpΔT be used near aluminum melting?
Not by itself. Near and through melting, use temperature-dependent properties and include latent heat. Also confirm the alloy's solidus and liquidus range rather than assuming one pure-metal melting point.
Sources behind the engineering guidance
Always verify the current document and the purchased material condition before qualification or contract release.
- NIST-hosted ASM — Properties of Wrought Aluminum and Aluminum Alloys: room-temperature reference properties for 6061, 7075 and 2024.
- Kaiser Aluminum — 6061 Sheet, Coil and Plate: typical 100°C specific heat and condition-dependent conductivity.
- Kaiser Aluminum — 7075 Sheet, Coil and Plate: typical 100°C specific heat and 20°C conductivity.
- Kaiser Aluminum — 2024 Sheet, Coil and Plate: typical physical-property reference data.
- NIST — Aluminum 6061-T6: temperature-dependent cryogenic specific-heat correlation from 4 K to 300 K.
- NIST Guide to the SI, Appendix B.8: Btu, joule, pound and kelvin conversion factors.
- ASTM E1269-24: specific heat capacity by differential scanning calorimetry.
- ASTM E1461-13(2022): thermal diffusivity by the flash method and related thermal-property context.