In the field of aerospace and high-performance engineering, 2219 aluminum alloy is known as one of the most reliable high-strength, heat-resistant materials. It is used in rocket fuel tanks, aircraft fuselages, and cryogenic systems — wherever materials must combine strength, stability, and excellent thermal performance.
Two of its most important physical properties — density and thermal conductivity — play a critical role in determining its performance in these demanding applications.
In this detailed article, SASAALUMINUM explains the density and thermal conductivity of 2219 aluminum, how they compare with other alloys, and why these properties make the alloy so valuable to the aerospace industry.
1. Introduction to 2219 Aluminum Alloy
2219 aluminum is a wrought aluminum-copper alloy (Al–Cu–Mn system) that offers a unique combination of high strength, excellent weldability, and good corrosion resistance at elevated temperatures.
It belongs to the 2000 series aluminum alloys, where copper is the main alloying element, providing significant strengthening through precipitation hardening.
This alloy is most commonly used in high-temperature aerospace structures, cryogenic fuel tanks, and spacecraft pressure vessels, where mechanical stability and heat management are both essential.
2. Chemical Composition of 2219 Aluminum
| Element | Content (%) | Function |
|---|---|---|
| Copper (Cu) | 5.8 – 6.8 | Strength and heat resistance |
| Manganese (Mn) | 0.20 – 0.40 | Grain refinement |
| Iron (Fe) | ≤ 0.30 | Impurity control |
| Silicon (Si) | ≤ 0.20 | Strength improvement |
| Zinc (Zn) | ≤ 0.10 | Minimizes stress corrosion |
| Vanadium (V) | 0.05 – 0.15 | Thermal stability |
| Titanium (Ti) | ≤ 0.15 | Grain structure control |
| Aluminum (Al) | Balance | Base metal |
This carefully balanced composition gives 2219 aluminum its ability to maintain both mechanical and thermal stability across a wide temperature range — from cryogenic conditions (-253°C) to high service temperatures (~300°C).
3. Density of 2219 Aluminum
The density of a metal defines its mass per unit volume. For engineers, it directly affects weight calculations, material selection, and structural performance.
3.1 Standard Density
The typical density of 2219 aluminum is:
2.84 g/cm³ (2840 kg/m³)
This value is slightly higher than most aluminum alloys because of its relatively high copper content (around 6%).
3.2 Density Comparison with Other Aluminum Alloys
| Alloy | Density (g/cm³) | Density (kg/m³) | Main Alloying Element |
|---|---|---|---|
| 1050 (Pure Aluminum) | 2.70 | 2700 | None |
| 6061 | 2.70 | 2700 | Mg, Si |
| 2219 | 2.84 | 2840 | Cu |
| 7075 | 2.81 | 2810 | Zn, Mg, Cu |
Because copper is denser than magnesium, silicon, or zinc, 2219 aluminum has a slightly higher density. However, its superior strength-to-weight ratio and thermal stability make it much more efficient than other alloys for aerospace use.
4. Effect of Density on Engineering Applications
The slightly higher density of 2219 aluminum offers several engineering advantages:
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Improved Structural Rigidity:
Higher atomic packing provides better stiffness and vibration resistance, crucial for spacecraft and aircraft structures. -
Excellent Dimensional Stability:
The alloy resists deformation under heat or stress due to its stable crystal structure. -
Optimal Balance of Strength and Weight:
Even though 2219 is denser than 6061, it achieves higher strength at a similar weight, reducing overall structural mass when designed efficiently.
For aerospace engineers, density data is essential for calculating total mass, fuel efficiency, and flight load distribution.
5. Thermal Conductivity of 2219 Aluminum
Thermal conductivity measures a material’s ability to transfer heat. It determines how quickly heat moves through a component, influencing design for cooling, heat shields, and fuel tanks.
5.1 Standard Thermal Conductivity Value
At room temperature (25°C), 2219 aluminum has a thermal conductivity of:
120 – 135 W/m·K
This is lower than pure aluminum (237 W/m·K) because alloying with copper and other elements reduces free electron movement. However, it still provides excellent thermal conduction compared to steel, titanium, or nickel-based alloys.
5.2 Comparison with Other Alloys
| Alloy | Thermal Conductivity (W/m·K) | Thermal Efficiency |
|---|---|---|
| Pure Aluminum (1050) | 237 | Very High |
| 6061 Aluminum | 167 | High |
| 2219 Aluminum | 125 | Moderate-High |
| 7075 Aluminum | 130 | Moderate-High |
| Stainless Steel | 15 | Low |
| Titanium | 22 | Low |
As shown, 2219 aluminum has lower conductivity than 6061, but much higher than steel or titanium — ideal for components requiring controlled heat flow rather than extreme heat dissipation.
6. Temperature Dependence of Thermal Conductivity
The thermal conductivity of 2219 aluminum varies slightly with temperature:
| Temperature (°C) | Thermal Conductivity (W/m·K) |
|---|---|
| 25 | 130 |
| 100 | 128 |
| 200 | 122 |
| 300 | 117 |
As temperature rises, conductivity decreases slightly due to increased lattice vibration (phonon scattering). Despite this, 2219 remains thermally stable and predictable — critical for precise aerospace thermal control systems.
7. Why Density and Thermal Conductivity Matter
7.1 In Aerospace Applications
Both density and thermal conductivity determine how an aluminum alloy behaves in flight:
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Density affects total mass, inertia, and energy efficiency.
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Thermal conductivity governs how quickly heat from engines, friction, or solar radiation dissipates through the structure.
For example, in rocket fuel tanks, 2219 aluminum prevents thermal fatigue and heat distortion, while maintaining a manageable weight.
7.2 In Cryogenic Applications
At extremely low temperatures, 2219 aluminum retains ductility and fracture toughness, and its predictable thermal behavior ensures stable containment of liquid hydrogen or oxygen in cryogenic vessels.
8. Mechanical Properties Related to Thermal Performance
| Property | 2219-T851 (Typical) | Units |
|---|---|---|
| Tensile Strength | 480 | MPa |
| Yield Strength | 380 | MPa |
| Modulus of Elasticity | 73 | GPa |
| Density | 2.84 | g/cm³ |
| Thermal Conductivity | 120–135 | W/m·K |
| Specific Heat | 0.88 | J/g·K |
| Coefficient of Expansion | 22.8 × 10⁻⁶ | /°C |
These combined properties make 2219 aluminum both mechanically strong and thermally efficient, ensuring consistent performance under wide temperature fluctuations.
9. Comparison with 6061 and 7075 Aluminum
| Property | 2219 | 6061 | 7075 |
|---|---|---|---|
| Density (g/cm³) | 2.84 | 2.70 | 2.81 |
| Thermal Conductivity (W/m·K) | 125 | 170 | 130 |
| Max Service Temp (°C) | 300 | 200 | 150 |
| Weldability | Excellent | Excellent | Poor |
| Strength (MPa) | High | Medium | Very High |
| Corrosion Resistance | Moderate | Excellent | Fair |
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6061: Better heat conduction, but not suitable for high-temperature aerospace use.
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7075: Stronger at room temperature, but loses stability under heat.
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2219: The best balance between heat resistance, weldability, and strength retention, ideal for rocket and aircraft structures.
10. Thermal Expansion and Dimensional Stability
The coefficient of thermal expansion of 2219 aluminum is approximately:
22.8 × 10⁻⁶ /°C
This value represents the alloy’s expansion per degree Celsius of temperature increase. It ensures that components such as fuel tanks, pressure domes, and aerospace panels expand uniformly during heating, avoiding structural misalignment or cracking.
11. Influence of Heat Treatment on Thermal Properties
2219 aluminum is available in several heat-treated tempers (T31, T37, T62, T81, T851). Heat treatment affects microstructure and therefore density and thermal performance.
| Temper | Thermal Conductivity (W/m·K) | Description |
|---|---|---|
| T31 | 135 | Soft, formable, highest conductivity |
| T37 | 130 | Intermediate strength |
| T62 | 125 | Fully aged, standard aerospace condition |
| T81 | 122 | Cold worked, high strength |
| T851 | 120 | Stress relieved, best stability |
Although thermal conductivity decreases slightly with strength, all conditions maintain excellent thermal reliability and predictable behavior.
12. Applications Requiring Controlled Density and Heat Flow
2219 aluminum is the preferred material in environments where thermal control, stability, and light weight are critical:
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Rocket and spacecraft fuel tanks (liquid oxygen, hydrogen)
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Cryogenic storage vessels
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Aerospace structural frames and panels
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Missile and defense systems
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High-temperature tooling and heat exchangers
Its consistent density and moderate conductivity help maintain uniform temperature gradients, reducing thermal stress and preventing localized expansion.
13. Behavior Under Thermal Cycling
In aerospace missions, components experience repeated heating and cooling. 2219 aluminum demonstrates:
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Minimal warping during rapid temperature changes
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Excellent fatigue resistance under cyclic stress
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Stable microstructure without phase cracking
This performance ensures reliability for reusable launch systems and long-term satellite components.
14. Weight Efficiency in Aerospace Design
Density determines total mass, which directly influences payload capacity and fuel efficiency.
A simple comparison:
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1 m³ of 2219 aluminum weighs 2840 kg.
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1 m³ of 6061 aluminum weighs 2700 kg.
Although slightly heavier, 2219 compensates with 30–40% higher tensile strength, allowing engineers to design thinner, lighter structures without compromising safety.
15. Cryogenic and High-Temperature Dual Performance
Few alloys perform well at both extremes — but 2219 aluminum does:
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Retains fracture toughness at -253°C (liquid hydrogen temperature)
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Maintains strength and stability up to 300°C (570°F)
This dual performance capability makes it a preferred choice for rocket fuel systems and launch vehicle structures, where temperatures fluctuate drastically between space and combustion zones.
16. Standards and Specifications
SASAALUMINUM supplies 2219 aluminum conforming to international standards such as:
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AMS 4066 / AMS 4068 – Sheet, plate, and strip
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AMS 4162 / AMS 4163 – Bars and forgings
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ASTM B209 / B221 – General aluminum alloy standards
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EN 573-3 / EN 485-2 – European mechanical and dimensional standards
All materials are certified with EN 10204 3.1 or 3.2 mill test certificates, ensuring traceability and quality assurance.
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17. SASAALUMINUM Quality and Capabilities
At SASAALUMINUM, we specialize in the production and supply of aerospace-grade 2219 aluminum alloy in multiple forms:
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Plates and Sheets – up to 200 mm thickness
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Rods and Bars – solution treated or aged
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Forgings and Rings – customized per drawing
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Extrusions and Tubes – for aerospace assemblies
We provide full heat treatment, ultrasonic testing, and dimensional inspection, ensuring consistent mechanical and thermal performance.
18. Comparison with Other Aerospace Alloys
| Alloy | Density (g/cm³) | Thermal Conductivity (W/m·K) | Max Service Temp (°C) | Weldability |
|---|---|---|---|---|
| 2024 | 2.78 | 121 | 150 | Poor |
| 2219 | 2.84 | 125 | 300 | Excellent |
| 6061 | 2.70 | 167 | 200 | Excellent |
| 7075 | 2.81 | 130 | 150 | Poor |
The table highlights 2219’s unique high-temperature capability with excellent thermal balance — a combination unmatched by other aluminum alloys.
19. Advantages of 2219 Aluminum in Thermal Design
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High Heat Capacity: Absorbs and redistributes heat efficiently.
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Stable Density: Prevents distortion under mechanical or thermal stress.
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Predictable Conductivity: Ensures reliable thermal modeling.
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Compatible with Welding and Heat Treatment: No property loss in joints.
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Excellent Structural Integrity: Maintains tight tolerances in extreme environments.
These advantages make 2219 aluminum a top-tier material for engineers seeking performance and precision in advanced designs.
20. Conclusion
The density and thermal conductivity of 2219 aluminum — approximately 2.84 g/cm³ and 120–135 W/m·K, respectively — define its reputation as a high-performance aerospace alloy.
Its unique ability to maintain strength, stability, and consistent heat transfer from cryogenic to 300°C makes it an indispensable material for rocket, spacecraft, and high-temperature engineering applications.
Compared with other alloys like 6061 and 7075, 2219 stands out for its heat resistance, weldability, and structural integrity, proving its reliability across the most challenging environments.
At SASAALUMINUM, we are proud to supply certified 2219 aluminum materials globally, supporting innovation in aerospace, defense, and energy sectors.
Post time: Oct-29-2025