In the modern aerospace and defense industries, the pursuit of materials that combine superior strength, lightweight efficiency, and long-term durability is never-ending. Engineers are continually challenged to design components that can withstand extreme mechanical stress, temperature fluctuations, and corrosive environments without compromising on weight or reliability.
Among all aluminum alloys developed for such demanding applications, the Aircraft Grade Aluminum 7175 Sheet stands out as one of the most high-performance materials available today. It is renowned for its exceptional strength-to-weight ratio, fatigue resistance, and fracture toughness, making it an ideal choice for aerospace structures, defense systems, and advanced engineering applications.
This article explores in depth the high-performance characteristics of Aircraft Grade Aluminum 7175 Sheet, covering its composition, mechanical properties, corrosion resistance, and typical applications, as well as how SASAALUMINUM ensures the highest quality standards in manufacturing and global supply.
Introduction to Aluminum Alloy 7175
Aluminum Alloy 7175 is a heat-treatable, high-strength aluminum-zinc-magnesium-copper (Al-Zn-Mg-Cu) alloy belonging to the 7000 series, a family known for its use in aircraft structures and military applications.
It was specifically designed to provide higher fracture toughness and better stress corrosion resistance than its predecessor, 7075, while retaining similar levels of ultimate tensile strength. This balance of strength, durability, and corrosion resistance makes 7175 aluminum a preferred choice for critical load-bearing components in aircraft and high-stress mechanical assemblies.
Its typical tempers — T6 (for maximum strength) and T7351 (for optimized toughness and corrosion resistance) — allow flexibility in design according to application requirements.
Chemical Composition of Aluminum 7175
| Element | Content (%) | Function |
|---|---|---|
| Zinc (Zn) | 5.6 – 6.1 | Primary strengthening element; contributes to high tensile strength |
| Magnesium (Mg) | 2.3 – 2.9 | Enhances hardness and improves aging response |
| Copper (Cu) | 1.2 – 1.9 | Contributes to precipitation hardening and improves machinability |
| Chromium (Cr) | 0.18 – 0.28 | Increases corrosion resistance and refines grain structure |
| Iron (Fe) | ≤ 0.20 | Controlled impurity |
| Silicon (Si) | ≤ 0.10 | Controlled impurity; improves surface finish |
| Manganese (Mn) | ≤ 0.10 | Enhances ductility and impact resistance |
| Titanium (Ti) | ≤ 0.06 | Assists in grain refinement during solidification |
| Aluminum (Al) | Balance | Provides lightweight characteristics and oxidation resistance |
This carefully balanced chemistry ensures that Aircraft Grade Aluminum 7175 Sheet offers a unique blend of mechanical strength, toughness, and environmental stability suited for aerospace and defense use.
Mechanical Properties of Aluminum 7175 Sheet
| Property | Typical Value (T7351 Temper) |
|---|---|
| Tensile Strength | 510 – 570 MPa |
| Yield Strength | 440 – 500 MPa |
| Elongation | 7 – 11% |
| Modulus of Elasticity | 71 GPa |
| Fatigue Strength | 160 – 180 MPa |
| Hardness | 155 – 170 HB |
| Density | 2.81 g/cm³ |
| Fracture Toughness | > 35 MPa√m |
| Operating Temperature | -50°C to 120°C |
These values highlight why 7175 aluminum is widely chosen for aerospace-grade applications. Its tensile and yield strength rival those of structural steels — yet at just one-third the density — giving engineers a significant advantage in weight reduction.
1. Exceptional Strength-to-Weight Ratio
One of the defining high-performance characteristics of Aircraft Grade Aluminum 7175 Sheet is its remarkable strength-to-weight ratio. With a density of only 2.81 g/cm³, it is nearly three times lighter than steel but provides comparable mechanical strength.
This lightweight strength translates directly to higher fuel efficiency, increased payload capacity, and improved aircraft maneuverability. In aerospace design, reducing even a few kilograms can lead to enormous performance and cost savings.
Advantages of Lightweight Strength
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Reduces structural mass without sacrificing load-bearing capacity.
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Enhances fuel economy and flight range.
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Allows for more efficient aerodynamic designs.
Such benefits make Aluminum 7175 Sheet indispensable for airframes, wings, and structural assemblies where weight savings are crucial.
2. Superior Fatigue Resistance
Aircraft and spacecraft experience millions of stress cycles during operation — from takeoff and landing to rapid temperature and pressure changes. Materials that cannot handle cyclic loading will fail prematurely through fatigue cracking.
Aluminum 7175 Sheet is engineered with a fine-grained microstructure and precipitation-hardened matrix (MgZn₂ phase) that provide superior fatigue resistance. It withstands repetitive stress without microcrack formation, ensuring long-term structural integrity.
Fatigue Resistance Highlights
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Maintains structural performance over long service cycles.
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Prevents crack initiation and propagation under cyclic stress.
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Ensures safety and reliability in dynamic aerospace environments.
This makes 7175 aluminum ideal for landing gear fittings, wing spars, and fuselage joints, where both static and dynamic loads are high.
3. Excellent Fracture Toughness
Fracture toughness measures a material’s ability to resist crack propagation once a flaw occurs — a critical property in aerospace components subjected to constant stress.
Through precise control of alloy chemistry and heat treatment, Aluminum 7175 Sheet achieves exceptional fracture toughness, especially in the T7351 temper. The balance between strength and ductility enables it to absorb impact energy and prevent catastrophic failure.
Key Advantages
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Enhanced crack resistance and damage tolerance.
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Greater safety margin in critical aircraft parts.
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Extended fatigue life and reduced maintenance frequency.
For aircraft manufacturers, this translates into longer service intervals and increased operational reliability — critical factors for both performance and cost efficiency.
4. Outstanding Corrosion and Stress Corrosion Resistance
Aerospace materials must withstand moisture, humidity, and fuel exposure without suffering degradation. Unlike other high-strength alloys that may be prone to stress corrosion cracking (SCC), Aluminum 7175 Sheet, especially in T7351 condition, exhibits excellent corrosion resistance.
This is achieved through:
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Controlled chromium addition that stabilizes grain boundaries.
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Optimized over-aging treatment that reduces internal stress.
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Formation of a protective oxide layer that prevents oxidation.
Benefits in Service
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Long-term performance in marine, coastal, and humid environments.
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Resistance to chemical attack from aviation fuels and de-icing fluids.
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Compatibility with surface treatments such as anodizing and Alclad coating for extra protection.
As a result, Aircraft Grade Aluminum 7175 Sheet maintains its mechanical integrity even under the most challenging environmental conditions.
5. Heat Treatment Advantages
The outstanding strength and toughness of 7175 aluminum are achieved through precise heat treatment processes, which include:
Solution Heat Treatment
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Heated to ~470°C to dissolve solute elements (Zn, Mg, Cu).
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Quenched rapidly to create a supersaturated solid solution.
Aging Treatment (Precipitation Hardening)
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Reheated to 120–160°C for several hours to allow fine precipitation of MgZn₂ particles.
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These precipitates obstruct dislocation movement, significantly increasing strength.
Common Tempers
| Temper | Description | Characteristics |
|---|---|---|
| T6 | Solution heat treated and artificially aged | Maximum strength and hardness |
| T7351 | Solution heat treated, stress-relieved, and over-aged | Better corrosion resistance and toughness |
6. High Machinability and Formability
Despite its high strength, Aircraft Grade Aluminum 7175 Sheet maintains excellent machinability and formability. It can be precisely milled, cut, or formed into complex aerospace shapes without cracking or warping.
Processing Benefits
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Suitable for CNC machining, cold forming, and precision drilling.
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Stable during heat treatment and welding, minimizing distortion.
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Compatible with advanced joining methods such as friction stir welding (FSW).
These attributes make it a top choice for precision aerospace components where both performance and dimensional accuracy are critical.
7. Thermal Stability and Performance Under Stress
Aluminum 7175 Sheet maintains its structural integrity across a wide range of temperatures — from -50°C (high altitude) to 120°C (engine and aerodynamic heating zones). Its low thermal expansion coefficient ensures dimensional stability, while its thermal conductivity helps dissipate heat efficiently.
Advantages
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Reliable in fluctuating temperature environments.
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Prevents thermal fatigue cracking.
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Suitable for engine mounts, structural skins, and pressurized components.
This thermal stability ensures that 7175 aluminum can endure long operational lifetimes without deformation or performance loss.
Typical Applications of Aluminum 7175 Sheet
Thanks to its high performance, Aircraft Grade Aluminum 7175 Sheet is widely used in both aerospace and industrial sectors:
Aerospace Applications
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Aircraft wing spars, fuselage frames, and landing gear components
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Engine mounts, bulkheads, and pressurized cabins
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Military aircraft structures requiring high damage tolerance
Defense and Space Applications
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Missile components and rocket motor cases
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Helicopter rotor hubs and weapon system brackets
Automotive and Marine Applications
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High-performance racing frames and suspension arms
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Marine structural panels needing corrosion and fatigue resistance
Industrial Equipment
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Precision machine bases, robotic arms, and high-load mechanisms
In all these areas, Aluminum 7175 Sheet delivers the ideal combination of lightweight strength, reliability, and long-term endurance.
Advantages Summary
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Exceptional Strength-to-Weight Ratio – Reduces mass without compromising strength.
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Superior Fatigue and Creep Resistance – Ensures durability in cyclic stress conditions.
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Excellent Fracture Toughness – Enhances safety and damage tolerance.
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Outstanding Corrosion Resistance – Performs well in moisture and chemical exposure.
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Customizable Heat Treatment Options – Provides flexibility between strength and toughness.
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High Machinability – Ideal for precision aerospace and industrial manufacturing.
Why Choose SASAALUMINUM for Aluminum 7175 Sheet
At SASAALUMINUM, we are dedicated to producing high-quality aircraft-grade aluminum materials that meet the most demanding aerospace and defense standards, including AMS 4048, ASTM B209, and MIL-DTL-46027.
Our 7175 aluminum sheets are manufactured using advanced melting, rolling, and heat treatment technologies to ensure optimal grain structure, mechanical consistency, and dimensional precision. Each batch undergoes:
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Chemical composition analysis
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Tensile and hardness testing
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Ultrasonic flaw detection
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Corrosion and fatigue evaluation
With years of expertise and cutting-edge equipment, SASAALUMINUM supplies materials that consistently deliver strength, toughness, and reliability — ensuring your aerospace and industrial projects perform flawlessly.
By choosing SASAALUMINUM, you are selecting a partner committed to precision, performance, and long-term quality assurance in every product we deliver.
Conclusion
The Aircraft Grade Aluminum 7175 Sheet exemplifies the perfect fusion of strength, toughness, and lightweight performance, making it one of the most advanced materials used in aerospace today. Its exceptional fatigue resistance, fracture toughness, and corrosion stability enable it to perform in the most demanding environments — from the skies to defense systems and beyond.
Through precise heat treatment and metallurgical control, Aluminum 7175 achieves mechanical excellence that ensures safety, efficiency, and reliability for years of operation.
At SASAALUMINUM, we are proud to provide premium 7175 aluminum sheets that meet international aerospace standards, supporting innovation and performance across industries.
Post time: Oct-31-2025