When it comes to aluminum alloys, two of the most popular and widely used grades are 6061 and 7075. Both belong to the family of high-performance aluminum alloys, offering lightweight strength, corrosion resistance, and excellent machinability. However, when engineers, fabricators, and designers ask, “Which is stronger, 6061 or 7075 aluminum?”, the answer depends on the specific application and the type of strength being evaluated.
In this article, we will provide a detailed comparison of 6061 vs 7075 aluminum, covering composition, mechanical strength, corrosion resistance, weldability, cost, and their suitability for aerospace, automotive, marine, and industrial uses.
As a leading manufacturer and supplier of premium aluminum products, SASAALUMINUM offers both 6061 and 7075 grades certified to international aerospace and engineering standards.
1. Understanding the Basics: 6061 and 7075 Aluminum
Both 6061 and 7075 are heat-treatable aluminum alloys, but they belong to different alloy series with distinct properties.
| Property | 6061 Aluminum | 7075 Aluminum |
|---|---|---|
| Alloy Series | 6xxx (Al-Mg-Si) | 7xxx (Al-Zn-Mg-Cu) |
| Main Alloying Elements | Magnesium, Silicon | Zinc, Magnesium, Copper |
| Heat Treatable | Yes | Yes |
| Typical Tempers | T4, T6, T651 | T6, T651 |
| Applications | General engineering, aerospace structures, frames | Aerospace, military, high-performance parts |
The key difference lies in the alloying elements — 7075’s addition of zinc and copper gives it far higher strength than 6061, but at the expense of corrosion resistance and weldability.
2. Chemical Composition
| Element | 6061 (%) | 7075 (%) |
|---|---|---|
| Aluminum (Al) | 95.8–98.6 | 87.1–91.4 |
| Magnesium (Mg) | 0.8–1.2 | 2.1–2.9 |
| Silicon (Si) | 0.4–0.8 | ≤0.4 |
| Zinc (Zn) | ≤0.25 | 5.1–6.1 |
| Copper (Cu) | 0.15–0.4 | 1.2–2.0 |
| Chromium (Cr) | 0.04–0.35 | 0.18–0.28 |
| Iron (Fe) | ≤0.7 | ≤0.5 |
| Titanium (Ti) | ≤0.15 | ≤0.2 |
From this composition, it’s easy to see that 7075 aluminum has a much higher percentage of zinc and copper, which dramatically boosts its tensile strength and hardness.
3. Mechanical Properties Comparison
| Property | 6061-T6 | 7075-T6 |
|---|---|---|
| Tensile Strength | 310 MPa (45 ksi) | 572 MPa (83 ksi) |
| Yield Strength | 276 MPa (40 ksi) | 503 MPa (73 ksi) |
| Elongation | 12% | 11% |
| Brinell Hardness | 95 HB | 150 HB |
| Density | 2.70 g/cm³ | 2.81 g/cm³ |
7075 aluminum is significantly stronger — nearly twice the strength of 6061 in both tensile and yield performance. However, 6061 still provides ample strength for many structural applications, particularly where weldability and corrosion resistance are more important than ultimate strength.
4. Strength Analysis: Which Is Stronger?
If we are comparing purely on mechanical strength, 7075 aluminum is the stronger alloy.
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Tensile Strength: 7075 exceeds 6061 by around 85–90%.
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Yield Strength: 7075’s yield limit is almost double that of 6061, meaning it can withstand greater stresses before permanent deformation.
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Hardness: The higher Brinell hardness of 7075 (150 HB vs 95 HB) means it resists wear and abrasion more effectively.
In aerospace or defense applications where every gram counts and mechanical loads are extreme, 7075 aluminum is often the alloy of choice.
5. Corrosion Resistance
While 7075 offers superior strength, 6061 aluminum outperforms it in corrosion resistance.
6061 Corrosion Performance
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Excellent resistance in marine, chemical, and humid environments.
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Forms a natural oxide layer that protects against corrosion.
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Ideal for outdoor structures, boats, and aircraft fuselage components.
7075 Corrosion Performance
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Susceptible to stress corrosion cracking (SCC) and pitting, especially in saltwater environments.
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Requires protective coatings, anodizing, or paint to maintain surface integrity.
Thus, for long-term exposure to moisture or marine conditions, 6061 aluminum is the better choice.
6. Weldability and Machinability
| Property | 6061 | 7075 |
|---|---|---|
| Weldability | Excellent | Poor (crack-prone) |
| Machinability | Excellent | Good |
| Formability | High | Moderate |
| Workability | Easy to extrude, bend, and shape | More brittle and harder to form |
6061 Aluminum
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Renowned for outstanding weldability using TIG and MIG processes.
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Suitable for complex structures requiring welded joints (e.g., aircraft frames, vehicle chassis).
7075 Aluminum
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Difficult to weld due to zinc and copper content, which can cause cracking.
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Generally machined or fastened mechanically rather than welded.
Therefore, 6061 aluminum is far more versatile for fabrication and repair work.
7. Heat Treatment and Temper Designations
Both 6061 and 7075 are heat-treatable alloys, and their properties can vary significantly depending on temper.
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T6 Temper: Solution heat-treated and artificially aged for high strength.
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T651 Temper: Same as T6 but stress-relieved by stretching for better dimensional stability.
For structural aerospace-grade use, the T6 and T651 conditions are the most common for both alloys.
7075-T651, in particular, delivers exceptional strength used in aircraft wing spars, fuselage frames, and landing gear components.
8. Fatigue Strength and Impact Resistance
| Property | 6061-T6 | 7075-T6 |
|---|---|---|
| Fatigue Strength | 96 MPa (14 ksi) | 160 MPa (23 ksi) |
| Impact Toughness | High | Moderate |
7075 aluminum exhibits higher fatigue resistance, making it suitable for repetitive load environments such as aircraft structures. However, 6061 offers better ductility and impact resistance, providing more flexibility under sudden stresses or impacts.
9. Cost and Availability
| Factor | 6061 | 7075 |
|---|---|---|
| Cost per kg | Lower | Higher |
| Availability | Widely available | Slightly limited |
| Processing Cost | Lower (easier to machine and weld) | Higher (more tool wear, harder to process) |
Because 7075 contains expensive alloying elements like zinc and copper, it costs more per unit weight. 6061 remains the most cost-effective and widely available option for large-scale manufacturing.
10. Applications Comparison
6061 Aluminum Applications
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Aircraft fuselage and frames
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Automotive wheels, chassis, and suspension components
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Marine structures and boat hulls
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Bicycles and sporting equipment
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General structural and architectural use
7075 Aluminum Applications
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Aircraft wing spars and landing gear
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Aerospace and defense-grade fasteners
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High-performance automotive and motorcycle parts
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Sporting goods (rifle receivers, climbing gear)
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Military and space-grade structural components
While 7075 is the go-to alloy for aerospace and defense applications, 6061 is preferred in general aviation, transportation, and industrial equipment due to its balance of strength, weldability, and cost.
11. Summary: 6061 vs 7075 Aluminum Strength and Performance
| Category | 6061 Aluminum | 7075 Aluminum |
|---|---|---|
| Tensile Strength | 310 MPa | 572 MPa |
| Yield Strength | 276 MPa | 503 MPa |
| Hardness (HB) | 95 | 150 |
| Corrosion Resistance | Excellent | Moderate |
| Weldability | Excellent | Poor |
| Machinability | Excellent | Good |
| Fatigue Strength | Good | Excellent |
| Cost | Low | High |
| Best For | Marine, automotive, general aerospace | High-stress aerospace, defense, racing |
Verdict:
If strength is the only concern, 7075 aluminum is undeniably stronger than 6061.
However, if versatility, corrosion resistance, weldability, and cost efficiency are equally important, 6061 aluminum remains the best all-around choice.
12. SASAALUMINUM – Your Reliable Partner in Aerospace and Industrial Aluminum
SASAALUMINUM is a professional manufacturer and exporter specializing in high-grade aluminum alloys, including 6061-T6, 6061-T651, 7075-T6, and 7075-T651 for aerospace, defense, marine, and industrial applications.
Why Choose SASAALUMINUM:
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Certified materials under AMS, ASTM, and EN standards
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Full traceability with EN 10204 3.1 / 3.2 certificates
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Global supply chain and fast delivery
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Customized cutting, machining, and surface finishing
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Technical support for alloy selection and performance optimization
Our 6061 and 7075 aluminum products are trusted by aircraft manufacturers, automotive engineers, and precision fabricators worldwide for their quality, consistency, and mechanical integrity.
Conclusion
The answer to “Which is stronger, 6061 or 7075 aluminum?” is clear: 7075 aluminum is significantly stronger, with superior tensile, yield, and fatigue strength. It’s the alloy of choice for aerospace and military applications that demand the highest possible performance under extreme conditions.
However, 6061 aluminum continues to dominate in applications where corrosion resistance, weldability, and affordability are key — making it one of the most versatile and widely used alloys in the world.
Ultimately, the right choice depends on your specific project requirements:
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Choose 7075 for maximum strength and performance.
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Choose 6061 for versatility, corrosion resistance, and cost efficiency.
For both materials, SASAALUMINUM provides premium aerospace-grade aluminum alloys manufactured to global quality standards — ensuring strength, precision, and reliability for every application.
Post time: Oct-23-2025