7075 aluminum is one of the most renowned high-strength aluminum alloys, widely used in aerospace, defense, and high-performance engineering applications. Belonging to the 7XXX series (aluminum-zinc-magnesium-copper alloys), it is recognized for combining exceptional strength with a relatively low weight, making it a preferred choice for critical structural components.
Its superior mechanical properties—high tensile strength, excellent fatigue resistance, and good machinability—position 7075 aluminum as a top-tier material in demanding industries such as aircraft structures, automotive performance parts, sports equipment, and defense hardware.
This article explores the core questions surrounding this alloy: What is 7075 aluminum? What are its properties? By understanding its composition, physical and mechanical characteristics, and key advantages, engineers and procurement specialists can make informed decisions for their high-stress, weight-sensitive applications.
What Is 7075 Aluminum?
7075 aluminum is a high-strength aluminum alloy from the 7XXX series, primarily composed of aluminum, zinc, magnesium, and copper. It was originally developed for the aerospace industry and remains one of the strongest commercially available aluminum alloys today. The addition of zinc and magnesium provides exceptional tensile strength, while copper enhances hardness and machinability.
Key Characteristics:
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Exceptional Strength: Among the highest of all aluminum alloys, comparable to many steels in tensile strength.
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Moderate Corrosion Resistance: Lower than 5XXX or 6XXX series alloys due to copper content, but can be improved with coatings or anodizing.
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Good Machinability: Well-suited for CNC machining, aerospace fittings, and high-stress components.
Comparison – 6061 vs. 7075 Aluminum:
| Property | 6061 Aluminum | 7075 Aluminum |
| Tensile Strength (MPa) | ~310 | ~570 (T6) |
| Corrosion Resistance | Excellent | Moderate |
| Machinability | Good | Very Good |
| Cost | Lower | Higher |
| Applications | Structural components, general engineering | Aerospace, defense, high-performance equipment |
Common Forms of 7075 Aluminum:
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Plates and Sheets – Aircraft panels, defense structures
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Bars and Rods – High-load shafts, automotive parts
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Profiles and Tubes – Sporting goods, aerospace frames
This combination of high strength, relatively low weight, and good machinability makes 7075 aluminum ideal for demanding engineering and structural applications where performance matters more than cost.
Chemical Composition of 7075 Aluminum
| Element | Content (%) |
| Aluminum (Al) | Balance |
| Zinc (Zn) | 5.1–6.1 |
| Magnesium (Mg) | 2.1–2.9 |
| Copper (Cu) | 1.2–2.0 |
| Chromium (Cr) | 0.18–0.28 |
| Iron (Fe) | ≤0.5 |
| Silicon (Si) | ≤0.4 |
| Manganese (Mn) | ≤0.3 |
| Titanium (Ti) | ≤0.2 |
Key Insights
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High Zinc-Magnesium-Copper Content: This combination dramatically increases tensile and yield strength, making 7075 one of the strongest aluminum alloys available.
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Chromium Addition: Improves toughness and stress-corrosion resistance.
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Lower Corrosion Resistance: Compared to 5XXX and 6XXX series alloys, the copper content slightly reduces natural corrosion resistance but can be mitigated with anodizing or protective coatings.
Comparison With 6061 Aluminum
| Property | 6061 Aluminum | 7075 Aluminum |
| Zinc Content (%) | 0 | 5.1–6.1 |
| Magnesium Content (%) | 0.8–1.2 | 2.1–2.9 |
| Copper Content (%) | 0.15–0.40 | 1.2–2.0 |
| Strength | Medium | Very High |
| Corrosion Resistance | Excellent | Moderate |
This composition makes 7075 aluminum ideal for aerospace, defense, and high-performance applications where strength is the primary requirement.
Physical Properties of 7075 Aluminum
| Property | 7075 Aluminum | 6061 Aluminum | Typical Aluminum Alloys |
| Density (g/cm³) | 2.81 | 2.7 | 2.70–2.80 |
| Melting Point Range (°C) | 477–635 | 582–652 | 500–660 |
| Thermal Conductivity (W/m·K at 25°C) | ~130–160 | ~167 | 130–235 |
| Electrical Conductivity (% IACS at 20°C) | ~33 | ~43 | 35–60 |
| Coefficient of Thermal Expansion (µm/m·°C, 20–100°C) | 23.5 | 23.6 | 22–24 |
Key Insights
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Density: At about 2.81 g/cm³, 7075 aluminum is only slightly heavier than 6061 but offers much higher strength-to-weight ratios.
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Melting Point: 7075 has a slightly lower melting range due to its high zinc and copper content.
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Thermal and Electrical Conductivity: Lower than 6061 because of the high alloying element content; this is typical of high-strength aluminum alloys.
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Thermal Expansion: Very similar to other aluminum alloys, making it predictable in structural applications exposed to temperature changes.
Comparison With 6061 and Other Alloys
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6061 Aluminum: Offers higher thermal and electrical conductivity but lower strength.
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5XXX Series (like 5052/5083): Higher corrosion resistance and better conductivity but significantly lower strength.
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7075 Advantage: The combination of relatively low density with very high strength makes it ideal for aerospace, defense, and performance-critical components where weight savings are crucial.
Mechanical Properties of 7075 Aluminum
7075 aluminum is one of the highest-strength aluminum alloys available. It is widely known as aircraft-grade aluminum due to its exceptional strength-to-weight ratio. Below are its key mechanical properties compared to 6061 aluminum.
| Property (at 20 °C unless noted) | 7075 Aluminum | 6061 Aluminum |
| Thermal Conductivity (W/m·K) | ~130–150 W/m·K | ~167 W/m·K |
| Coefficient of Thermal Expansion (µm/m·°C) | ~23.6 µm/m·°C | ~23.6 µm/m·°C |
| Specific Heat Capacity (J/kg·K) | ~960 J/kg·K | ~896 J/kg·K |
| Melting Point (°C) | 477–635 °C | 582–652 °C |
| Typical Operating Temperature Range | −200 °C to +120 °C (depends on application) | −200 °C to +150 °C |
Key Insights
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Tensile Strength: 7075-T6 offers almost double the tensile strength of 6061-T6, making it ideal for aerospace, defense, and high-performance automotive applications.
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Yield Strength: Its yield strength is also significantly higher, allowing for superior load-bearing capacity in critical structural components.
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Hardness: The Brinell hardness of 7075-T6 is much higher, indicating better wear resistance.
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Elongation: While still ductile enough for machining and forming, its elongation is slightly lower than 6061, reflecting its higher strength and hardness.
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Elastic Modulus: Similar to other aluminum alloys, providing predictable stiffness in engineering designs.
Why 7075 Aircraft Aluminum Stands Out
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High Strength-to-Weight Ratio: Essential for aircraft frames, defense systems, and performance vehicles.
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Fatigue Resistance: Ideal for cyclic load environments such as aircraft wings, landing gear, and high-performance sporting equipment.
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Machining Capability: Although harder than 6061, it machines well with the right tooling and parameters.
Thermal Properties of 7075 Aluminum
7075 aluminum exhibits good thermal conductivity and a moderate coefficient of thermal expansion, making it suitable for aerospace and high-performance applications where dimensional stability under temperature changes is critical. However, compared to 6061 aluminum, it has a slightly lower thermal conductivity due to its higher zinc and copper content.
| Property (at 20 °C unless noted) | 7075 Aluminum | 6061 Aluminum |
| Thermal Conductivity (W/m·K) | ~130–150 W/m·K | ~167 W/m·K |
| Coefficient of Thermal Expansion (µm/m·°C) | ~23.6 µm/m·°C | ~23.6 µm/m·°C |
| Specific Heat Capacity (J/kg·K) | ~960 J/kg·K | ~896 J/kg·K |
| Melting Point (°C) | 477–635 °C | 582–652 °C |
| Typical Operating Temperature Range | −200 °C to +120 °C (depends on application) | −200 °C to +150 °C |
Key Takeaways
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Thermal Conductivity: 7075's thermal conductivity is lower than 6061 due to its higher zinc, magnesium, and copper content.
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Thermal Expansion: Both alloys have similar coefficients of thermal expansion, ensuring comparable dimensional changes under heat.
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Operating Temperature Range: 7075 maintains its mechanical strength at low temperatures but is not ideal for continuous service above ~120 °C due to potential overaging or loss of strength.
Common Tempers of 7075 Aluminum: T6, T651, and T73
Like many high-strength aluminum alloys, 7075 aluminum is available in several heat-treated tempers. Each temper provides a balance between strength, stress resistance, and corrosion resistance, making it suitable for different engineering applications.
7075-T6 Aluminum
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Overview: The most widely used temperature of 7075.
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Characteristics: High tensile and yield strength, excellent hardness.
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Applications: Aerospace fasteners, military equipment, high-performance automotive parts.
7075-T651 Aluminum
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Overview: Derived from T6, but with stress-relief stretching.
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Characteristics: Retains nearly the same strength as T6 but reduces internal stresses, making it less prone to warping or distortion.
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Applications: Large structural components such as aircraft frames, tooling plates, and precision engineering parts.
7075-T73 Aluminum
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Overview: Overaged condition compared to T6.
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Characteristics: Lower strength than T6/T651 but significantly improved stress-corrosion cracking resistance and better toughness.
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Applications: Aerospace components in environments where corrosion resistance is critical, such as marine and humid conditions.
Comparative Table of 7075 Tempers
| Property / Temper | 7075-T6 | 7075-T651 | 7075-T73 |
| Tensile Strength (MPa) | ~570 | ~570 | ~505 |
| Yield Strength (MPa) | ~500 | ~500 | ~435 |
| Hardness (HB) | ~150 | ~150 | ~140 |
| Corrosion Resistance | Moderate | Moderate | High |
| Stress Resistance | Standard | Improved (stress-relieved) | Improved |
| Common Applications | Fasteners, gears, defense parts | Large aerospace structures, tooling plates | Marine and aerospace parts requiring corrosion resistance |
Key Insight:
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7075-T6: Maximizes strength, widely used where peak performance is required.
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7075-T651: Best for large or precision-machined parts needing dimensional stability.
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7075-T73: Preferred when corrosion resistance outweighs maximum strength.
Fabrication and Heat Treatment of 7075 Aluminum
Machinability
7075 aluminum is well-known for its excellent machinability, making it highly suitable for CNC machining and aerospace component manufacturing. Due to its high strength, cutting tools should be sharp and rigid, and cutting parameters (speed, feed, and depth) should be optimized to reduce tool wear and maintain dimensional accuracy.
Forming
7075 aluminum has only moderate formability at room temperature. Cold forming operations should be limited to simpler shapes. For more complex forms, hot forming at carefully controlled temperatures is recommended to prevent cracking and ensure proper shaping.
Welding
7075 aluminum is generally not recommended for conventional welding due to its poor weldability, especially in the T6 condition. Mechanical fastening or brazing is preferred when joining components. Specialized techniques such as friction stir welding may be used in some cases, but with caution.
Heat Treatment
7075 aluminum achieves its ultra-high strength through heat treatment. Artificial aging treatments such as T6 and T651 are most common, providing high strength and improved dimensional stability. Additional overaging processes (such as T73) can enhance corrosion resistance when required.
Surface Finishing
Although 7075 aluminum has moderate corrosion resistance, surface treatments can significantly improve its durability. Common options include anodizing, chemical conversion coatings, and powder coating, which enhance both corrosion resistance and aesthetic appearance.
Key Insight: With proper machining, forming, heat treatment, and surface finishing, 7075 aluminum can deliver superior performance in demanding applications such as aerospace, defense, and high-performance industrial equipment.
Applications of 7075 Aluminum
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Aerospace components: wings, landing gear, fuselage structures
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Military equipment: armor plates, structural components
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High-end bicycles and motorcycle frames
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Tooling and molds for precision manufacturing
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Sports equipment: ski poles, golf club heads
7075 aluminum is chosen in these applications for its ultra-high strength-to-weight ratio, excellent fatigue resistance, and dimensional stability under demanding conditions.
Surface Finishing and Corrosion Resistance of 7075 Aluminum
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Natural corrosion resistance: Relatively low compared to 6XXX series alloys
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Surface treatments: Anodizing, chemical conversion coatings, and protective paints can significantly enhance corrosion resistance
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Comparison with 6061 aluminum: 7075 has lower inherent corrosion resistance, so additional surface protection is often required
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Applications in harsh environments: Coatings or sealants are recommended for outdoor, marine, or high-humidity conditions to maintain durability and longevity
Standards and Specifications of 7075 Aluminum
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ASTM B209 – Aluminum and Aluminum-Alloy Sheet and Plate
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ASTM B221 – Aluminum and Aluminum-Alloy Extruded Bars, Rods, Wire, Profiles, and Tubes
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EN 573 / EN 485 – European standards for chemical composition and mechanical properties
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SAE AMS-QQ-A-250/12 – Aerospace material specification for 7075 aluminum
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International equivalents: 7075-T6 and T651 generally correspond across ASTM, EN, and AMS standards for high-strength aerospace and structural applications
Advantages and Limitations of 7075 Aluminum
Advantages
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Extremely high strength-to-weight ratio, superior to most aluminum alloys
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Excellent machinability for precision components
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Suitable for high-stress structural applications
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Can be strengthened through heat treatment (T6, T651)
Limitations
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Corrosion resistance lower than 6XXX series alloys
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Poor weldability, especially in T6 condition
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Higher material cost compared to common aluminum alloys
Related Alloys and Alternatives
Comparison of 7075 with Other Aluminum Alloys
| Property / Alloy | 7075-T6 | 6061-T6 | 2024-T3 |
| Tensile Strength (MPa) | 572–638 | 290–310 | 414–469 |
| Yield Strength (MPa) | 503–538 | 241–276 | 324–350 |
| Corrosion Resistance | Moderate | High | Moderate |
| Weldability | Poor | Excellent | Limited |
| Machinability | Good | Excellent | Good |
| Typical Applications | Aerospace, military, high-stress components | Automotive, structural, marine | Aerospace, automotive, structural |
7075 aluminum offers the highest strength among these common alloys, making it ideal for aerospace and high-stress applications, while 6061 provides better corrosion resistance and weldability for general structural use. 2024 serves as a high-strength alternative with moderate corrosion resistance, suitable for aerospace and automotive components.
Conclusion
7075 aluminum stands out for its exceptionally high strength-to-weight ratio, making it a preferred choice for applications requiring both strength and lightweight performance. Compared with 6061 and 2024 aluminum, 7075 excels in aerospace and high-stress structural components, offering superior mechanical properties. Its combination of strength, machinability, and potential for heat treatment makes it suitable for both industrial and high-performance consumer applications, including aerospace structures, military equipment, and specialized transportation and sports equipment.
FAQs
What is 7075 aluminum?
7075 aluminum is a high-strength aluminum alloy in the 7XXX series, primarily alloyed with zinc, magnesium, and copper. It is widely used in aerospace, military, and high-stress structural applications due to its excellent mechanical properties.
What are 7075 aluminum properties?
7075 aluminum offers very high tensile and yield strength, good machinability, and moderate corrosion resistance. It is lightweight and can be heat-treated to further enhance strength.
What is the chemical composition of 7075 aluminum?
The main elements are zinc (5.1–6.1%), magnesium (2.1–2.9%), copper (1.2–2.0%), and small amounts of chromium, iron, silicon, manganese, and titanium, with aluminum as the balance.
What are common tempers for 7075 aluminum?
Typical tempers include T6 (high strength), T651 (stress-relieved T6), and T73 (improved corrosion resistance with slightly lower strength).
How does 7075 aluminum compare with 6061 aluminum?
7075 aluminum has significantly higher strength than 6061 but lower corrosion resistance and more limited weldability. 6061 is easier to machine and weld, making it suitable for applications where corrosion resistance and fabrication flexibility are more important.
Can 7075 aluminum be welded?
Welding 7075 aluminum, especially in T6 condition, is generally not recommended due to loss of strength. Mechanical fastening or brazing is often preferred.
What are typical applications of aluminum 7075?
It is used in aerospace components (wings, fuselage, landing gear), military equipment, high-performance sports equipment, bicycle and motorcycle frames, and precision tooling.
What is 7075 aircraft aluminum?
7075 aircraft aluminum refers to the T6 or T651 tempers of 7075 specifically used in aerospace applications, valued for their combination of high strength, lightweight, and reliability in critical structural components.
About the Author: Gavin Xia
This article was written by engineers from the RAPID PROTOS team. Gavin Xia is a professional engineer and technical expert with 20 years of experience in rapid prototyping, metal parts, and plastic parts manufacturing.
