The aerospace and defense industries constantly demand materials that can perform reliably under extreme mechanical stress, temperature variation, and corrosive environments — all while maintaining the lightest possible weight. One alloy that meets these demanding requirements is the Aircraft Grade Aluminum 7175 Sheet, a member of the high-strength 7000 series aluminum family.
Renowned for its exceptional mechanical properties, heat-treatable nature, and lightweight efficiency, Aluminum 7175 plays a crucial role in manufacturing aircraft structural components, landing gear parts, and high-performance engineering applications.
This article provides a comprehensive overview of the mechanical properties and heat treatment processes that make Aluminum 7175 Sheet one of the most reliable materials for aerospace structures, along with insights into why SASAALUMINUM is a leading global supplier of high-quality aircraft-grade aluminum materials.
Introduction to Aluminum 7175
Aluminum Alloy 7175 is a high-strength aluminum-zinc-magnesium-copper (Al-Zn-Mg-Cu) alloy designed for critical structural applications that require excellent strength-to-weight ratio, fatigue resistance, and toughness.
It belongs to the same alloy family as 7075 aluminum, but it has been metallurgically optimized for superior fracture toughness and better stress corrosion resistance through refined processing and controlled heat treatment.
Available primarily in sheet, plate, and forging forms, Aircraft Grade Aluminum 7175 Sheet is typically supplied in T6 and T7351 tempers, offering engineers flexibility to tailor mechanical properties to specific application needs.
Chemical Composition of Aluminum 7175
| Element | Content (%) | Function |
|---|---|---|
| Zinc (Zn) | 5.6 – 6.1 | Increases strength through precipitation hardening |
| Magnesium (Mg) | 2.3 – 2.9 | Enhances hardness and contributes to the formation of strengthening phases |
| Copper (Cu) | 1.2 – 1.9 | Improves machinability and contributes to age-hardening |
| Chromium (Cr) | 0.18 – 0.28 | Prevents grain boundary corrosion and refines grain structure |
| Iron (Fe) | ≤ 0.20 | Controlled impurity to maintain strength and surface quality |
| Silicon (Si) | ≤ 0.10 | Improves casting and machining properties |
| Manganese (Mn) | ≤ 0.10 | Enhances toughness and ductility |
| Titanium (Ti) | ≤ 0.06 | Promotes fine grain structure |
| Aluminum (Al) | Balance | Provides corrosion resistance and light weight |
This precise chemical formulation results in a fine-grain microstructure that provides the strength and durability required for aerospace-grade performance.
Mechanical Properties of Aluminum 7175 Sheet
The mechanical properties of Aluminum 7175 Sheet depend largely on its temper condition and heat treatment process. Below are the typical properties in the T7351 condition, the most commonly used for aerospace applications.
| Property | Typical Value (T7351 Temper) |
|---|---|
| Tensile Strength | 510 – 570 MPa |
| Yield Strength | 440 – 500 MPa |
| Elongation | 7 – 11% |
| Modulus of Elasticity | 71 GPa |
| Hardness | 155 – 170 HB |
| Density | 2.81 g/cm³ |
| Fatigue Strength | 160 – 180 MPa |
| Fracture Toughness | > 35 MPa√m |
| Operating Temperature | -50°C to 120°C |
Key Strength Highlights
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High Tensile and Yield Strength comparable to that of structural steels but at less than one-third the weight.
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Excellent Fatigue Resistance ensures durability under cyclic loading typical in aircraft operation.
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Superior Fracture Toughness reduces the risk of crack propagation under high stress.
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Good Ductility provides a balance between strength and formability for manufacturing complex aerospace parts.
Comparison: Aluminum 7175 vs. Aluminum 7075
| Property | Aluminum 7175 | Aluminum 7075 |
|---|---|---|
| Tensile Strength | 510–570 MPa | 480–540 MPa |
| Yield Strength | 440–500 MPa | 410–480 MPa |
| Fracture Toughness | Higher | Moderate |
| Stress Corrosion Resistance | Excellent | Good |
| Fatigue Life | Excellent | Very Good |
| Typical Temper | T7351 | T651 |
| Common Applications | Landing gear, wing spars | Fittings, frames |
Aluminum 7175 provides better fracture toughness and greater resistance to stress corrosion cracking than 7075, making it preferred for high-stress, load-bearing structures.
The Role of Heat Treatment in Aluminum 7175 Performance
The heat treatment process is what truly defines the performance of Aircraft Grade Aluminum 7175 Sheet. Through precise thermal control, engineers can modify the alloy’s internal structure to achieve desired levels of strength, toughness, and corrosion resistance.
Main Heat Treatment Stages
1. Solution Heat Treatment
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Temperature: 465°C – 480°C
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Purpose: Dissolves alloying elements (Zn, Mg, Cu) into a single-phase solid solution.
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Cooling: Rapid quenching in water to retain solute atoms within the aluminum matrix.
This step ensures a homogeneous microstructure, preparing the material for the next hardening stage.
2. Quenching Process
After solution treatment, the sheet is rapidly cooled to prevent premature precipitation.
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Water Quenching: Common for thick sheets to retain uniform structure.
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Air Quenching: Used for thinner sections to minimize distortion.
Rapid cooling “freezes” the elements in solid solution, maintaining maximum potential for strength development during aging.
3. Artificial Aging (Precipitation Hardening)
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Temperature: 120°C – 160°C
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Duration: 8 – 24 hours
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Purpose: Promotes controlled precipitation of strengthening phases such as MgZn₂ (η’ phase).
This step significantly increases strength by forming fine, coherent precipitates that block dislocation movement.
Two primary temper conditions result from artificial aging:
| Temper | Description | Characteristics |
|---|---|---|
| T6 | Solution heat treated and artificially aged | Highest strength but lower stress corrosion resistance |
| T7351 | Solution heat treated, stress relieved, and artificially aged | Slightly lower strength but much better toughness and corrosion resistance |
For aerospace applications, T7351 is most preferred due to its balanced strength, toughness, and environmental resistance.
Microstructural Evolution During Heat Treatment
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As-Quenched State: Supersaturated solid solution with high internal energy.
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Early Aging: Fine GP zones (Guinier–Preston zones) form, strengthening the matrix.
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Intermediate Aging: Formation of η’ (MgZn₂) phase — the main hardening phase.
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Over-Aging (T7351): Controlled coarsening of precipitates for improved stress corrosion resistance and fracture toughness.
Through this process, Aluminum 7175 Sheet achieves its remarkable combination of strength and ductility, essential for safe and durable aerospace components.
Corrosion Resistance and Surface Protection
Although aluminum naturally forms a protective oxide layer, Aircraft Grade Aluminum 7175 offers enhanced stress corrosion cracking resistance, especially in the T7351 condition.
To further improve corrosion protection, the following surface treatments are often applied:
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Anodizing – Creates a dense oxide film that enhances oxidation resistance.
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Alclad Coating – Applies a thin layer of pure aluminum to improve surface protection without affecting strength.
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Chromate Conversion Coating – Provides electrochemical protection for aerospace environments.
These treatments ensure that 7175 aluminum sheets maintain long-term integrity even in humid, salt-laden, or fuel-exposed environments.
Applications of Aluminum 7175 Sheet
The exceptional mechanical and thermal characteristics of Aircraft Grade Aluminum 7175 Sheet make it ideal for high-stress structural applications.
Aerospace Industry
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Wing spars, fuselage frames, and bulkheads
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Landing gear components and brackets
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Engine mounts and pressurized cabin structures
Defense and Military Systems
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Missile and rocket body structures
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Aircraft armor plating and fasteners
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Helicopter rotor attachments
High-Performance Engineering
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Precision machine parts
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Automotive racing components
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Marine and offshore structural panels
In each of these applications, Aluminum 7175 Sheet delivers consistent reliability under extreme mechanical loading, ensuring both safety and performance.
Key Advantages of Aluminum 7175 Sheet
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High Strength-to-Weight Ratio – Provides superior load-bearing capacity with minimal weight.
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Excellent Fatigue and Creep Resistance – Withstands repetitive stress over long service life.
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Superior Fracture Toughness – Resists crack growth and sudden failure.
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Outstanding Corrosion Resistance – Particularly effective in T7351 condition.
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Good Machinability and Formability – Facilitates precision manufacturing of complex aerospace parts.
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Heat-Treatable Flexibility – Mechanical properties can be tailored through controlled heat treatment.
These advantages make Aircraft Grade Aluminum 7175 Sheet one of the most trusted materials in modern aerospace design.
Why Choose SASAALUMINUM for Aluminum 7175 Sheet
At SASAALUMINUM, we specialize in producing premium-quality 7175 aluminum sheets that meet international aerospace standards such as AMS 4048, ASTM B209, and MIL-DTL-46027.
Our advanced production facilities use precision rolling, vacuum melting, and heat treatment technologies to ensure uniform microstructure and tight mechanical tolerances. Every batch undergoes strict quality inspections, including:
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Chemical composition analysis
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Tensile and hardness testing
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Ultrasonic inspection for internal flaws
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Corrosion and fatigue performance evaluation
Whether you require material for aircraft components, defense systems, or industrial engineering projects, SASAALUMINUM guarantees consistent performance, dimensional accuracy, and superior durability.
By choosing SASAALUMINUM, you partner with a supplier committed to innovation, reliability, and excellence in every sheet produced.
Conclusion
The Aircraft Grade Aluminum 7175 Sheet combines high strength, outstanding fatigue performance, and tailored heat treatment flexibility, making it a cornerstone of modern aerospace engineering. Its mechanical superiority, achieved through precise heat treatment control, enables it to perform reliably under extreme stress and environmental conditions.
From landing gear and wing spars to missile components and engine mounts, Aluminum 7175 Sheet continues to define the standards for aerospace-grade performance.
At SASAALUMINUM, we are proud to supply world-class 7175 aluminum materials that meet the most demanding specifications for global aerospace applications. Our products reflect precision, quality, and innovation — ensuring your designs achieve both strength and efficiency without compromise.
Post time: Oct-31-2025