When choosing an aluminum alloy for aerospace, automotive, or industrial applications, engineers often compare 2219, 6061, and 7075 — three of the most widely used grades in the aluminum family. Each alloy has unique characteristics that make it suitable for specific environments, from cryogenic fuel tanks to aircraft frames and high-stress mechanical parts.
In this detailed analysis, SASAALUMINUM explores the differences between 2219, 6061, and 7075 aluminum alloys, comparing their composition, mechanical properties, heat resistance, corrosion behavior, and applications. Whether you are designing a rocket tank or a lightweight aircraft component, understanding these alloys will help you choose the right material for your project.
1. Introduction to Aluminum Alloys
Aluminum alloys are categorized by series based on their major alloying elements:
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2000 Series (e.g., 2219) → Aluminum-Copper alloys
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6000 Series (e.g., 6061) → Aluminum-Magnesium-Silicon alloys
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7000 Series (e.g., 7075) → Aluminum-Zinc-Magnesium-Copper alloys
Each series offers distinct advantages. The 2000 series focuses on high-temperature strength and weldability, the 6000 series on versatility and corrosion resistance, and the 7000 series on ultimate tensile strength.
2. Chemical Composition Comparison
| Alloy | Main Alloying Elements | Typical Composition (%) |
|---|---|---|
| 2219 | Al–Cu–Mn | Cu 6.3, Mn 0.3, V 0.1, Ti 0.1, balance Al |
| 6061 | Al–Mg–Si | Mg 1.0, Si 0.6, Cu 0.3, Cr 0.2, balance Al |
| 7075 | Al–Zn–Mg–Cu | Zn 5.6, Mg 2.5, Cu 1.6, Cr 0.2, balance Al |
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The copper-rich 2219 alloy offers superior heat resistance.
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6061, with magnesium and silicon, provides corrosion protection and easy fabrication.
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7075, strengthened with zinc and magnesium, delivers the highest tensile strength but lower corrosion resistance.
3. Mechanical Properties (Typical for Common Tempers)
| Property | 2219-T851 | 6061-T6 | 7075-T6 |
|---|---|---|---|
| Tensile Strength (MPa) | 480 | 310 | 570 |
| Yield Strength (MPa) | 380 | 275 | 505 |
| Elongation (%) | 9 | 12 | 11 |
| Brinell Hardness (HB) | 130 | 95 | 150 |
| Density (g/cm³) | 2.84 | 2.70 | 2.81 |
At first glance, 7075-T6 appears strongest, but 2219-T851 maintains its strength at much higher service temperatures — a key advantage in aerospace and space applications.
4. Heat Resistance and Service Temperature
4.1 2219 Aluminum
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Designed for high-temperature service up to 300°C (570°F).
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Retains 70% of its strength at 300°C.
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Ideal for rocket tanks, fuel vessels, and engine structures.
4.2 6061 Aluminum
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Maximum service temperature around 200°C (390°F).
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Loses significant strength beyond this range.
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Used where moderate heat exposure occurs (e.g., automotive frames, marine parts).
4.3 7075 Aluminum
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Starts losing strength above 150°C (300°F).
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Suitable for room-temperature or low-heat structural components.
Summary:
2219 aluminum offers the best high-temperature stability, while 7075 provides peak strength at ambient conditions and 6061 delivers balanced general performance.
5. Weldability and Fabrication
| Alloy | Weldability | Comments |
|---|---|---|
| 2219 | Excellent | Retains strength after welding and post-aging; used for aerospace tanks. |
| 6061 | Excellent | Easiest to weld; widely used for fabrication. |
| 7075 | Poor | Prone to hot cracking; not recommended for welding applications. |
2219 aluminum has a major advantage in aerospace fabrication because it maintains mechanical properties even after high-temperature welding and heat cycles, which is critical for pressurized fuel systems.
6. Corrosion Resistance
| Alloy | Corrosion Resistance | Notes |
|---|---|---|
| 2219 | Moderate | May require surface treatment or anodizing. |
| 6061 | Excellent | Natural oxide film resists marine and atmospheric corrosion. |
| 7075 | Fair to Poor | Susceptible to stress-corrosion cracking, especially in humid environments. |
While 6061 excels in corrosion resistance, 2219 can achieve good durability through cladding or anodizing, which is standard for aerospace parts.
7. Machinability and Workability
| Alloy | Machinability | Formability | Comments |
|---|---|---|---|
| 2219 | Good | Moderate | Machines well in T31 or T37 tempers. |
| 6061 | Excellent | Excellent | Ideal for extrusion and machining. |
| 7075 | Good | Limited | High hardness may cause tool wear. |
6061 aluminum is the easiest to machine and form, while 2219 is typically machined in solution-treated conditions before aging to final hardness.
8. Fatigue and Creep Resistance
Fatigue resistance determines how well an alloy withstands cyclic loading — crucial in aerospace and automotive parts.
| Alloy | Fatigue Strength (MPa) | Creep Resistance | Comments |
|---|---|---|---|
| 2219 | 160 | Excellent | Retains strength at 300°C; used in long-duration missions. |
| 6061 | 95 | Moderate | Suitable for medium-load structures. |
| 7075 | 160 | Poor | Strong but prone to fatigue under stress. |
2219 aluminum offers superior long-term stability under heat and cyclic stress, making it ideal for rocket and satellite structures that undergo thermal cycling between cryogenic and high-temperature conditions.
9. Density and Strength-to-Weight Ratio
| Alloy | Density (g/cm³) | Strength-to-Weight Ratio |
|---|---|---|
| 2219 | 2.84 | High |
| 6061 | 2.70 | Moderate |
| 7075 | 2.81 | Very High |
Although 6061 is the lightest, 2219 and 7075 both provide higher specific strength, making them preferable for weight-sensitive aerospace applications.
10. Thermal Conductivity and Expansion
| Property | 2219 | 6061 | 7075 |
|---|---|---|---|
| Thermal Conductivity (W/m·K) | 120 | 170 | 130 |
| Coefficient of Expansion (×10⁻⁶ /°C) | 22.8 | 23.6 | 23.5 |
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6061 conducts heat most efficiently, suitable for heat sinks or structural parts.
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2219 has lower thermal conductivity but better dimensional control under heat.
This means 2219 parts remain dimensionally stable in fluctuating temperatures — a vital factor in aerospace assemblies.
11. Cost and Availability
| Alloy | Relative Cost | Availability | Comments |
|---|---|---|---|
| 2219 | High | Moderate | Specialized aerospace alloy. |
| 6061 | Low | Excellent | Most commonly available grade. |
| 7075 | Medium-High | Good | Popular for aircraft and military components. |
While 6061 is cost-effective for general manufacturing, 2219 justifies its higher price with exceptional high-temperature and weld performance.
12. Typical Applications by Alloy
| Alloy | Common Applications |
|---|---|
| 2219 | Rocket tanks, spacecraft structures, cryogenic vessels, aircraft bulkheads, pressure domes |
| 6061 | Automotive frames, marine parts, pipelines, structural extrusions, consumer products |
| 7075 | Aircraft wings, landing gear, bicycle frames, firearm components, racing parts |
Each alloy dominates its field: 2219 in aerospace, 6061 in structural engineering, and 7075 in high-stress mechanical design.
13. Performance Comparison Summary
| Feature | 2219 | 6061 | 7075 |
|---|---|---|---|
| Strength | High | Moderate | Very High |
| Heat Resistance | Excellent (up to 300°C) | Good (up to 200°C) | Fair (below 150°C) |
| Weldability | Excellent | Excellent | Poor |
| Corrosion Resistance | Moderate | Excellent | Poor |
| Fatigue Resistance | Excellent | Good | Fair |
| Machinability | Good | Excellent | Good |
| Cost | High | Low | Medium |
| Main Use | Aerospace / Spacecraft | General Industry | Aircraft / Defense |
For high-performance or mission-critical applications, 2219 aluminum remains unmatched due to its balance of strength, heat resistance, and weldability.
19. SASAALUMINUM – Your Reliable Aerospace Aluminum Supplier
SASAALUMINUM is a professional manufacturer and exporter of high-performance aluminum alloys including 2219, 6061, and 7075, serving industries across aerospace, marine, and automotive sectors.
Our advantages include:
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Supply of certified alloys per AMS, ASTM, and EN standards
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Custom heat treatments (T31, T62, T81, T851, T6, T73, etc.)
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Precision cutting, machining, and inspection
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Full traceability and EN 10204 3.1/3.2 certification
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We ensure consistent quality, on-time delivery, and full technical support for clients worldwide.
20. Conclusion
The comparison between 2219, 6061, and 7075 aluminum alloys highlights one simple truth — each alloy excels in its own domain.
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2219 aluminum leads in high-temperature strength, weldability, and aerospace reliability.
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6061 aluminum offers excellent versatility and corrosion resistance at a low cost.
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7075 aluminum delivers the highest strength-to-weight ratio for mechanical parts but is limited by poor weldability and heat tolerance.
For demanding aerospace, defense, and space applications, 2219 aluminum remains the preferred choice due to its unique combination of strength, heat stability, and fabrication flexibility.
At SASAALUMINUM, we are committed to providing top-quality aluminum alloys that meet global standards for performance, precision, and safety.
Post time: Oct-29-2025