Applications of Aircraft Grade Aluminum 7175 Sheet in Aerospace Structures

In the aerospace industry, materials are constantly challenged by the need for high strength, low weight, and excellent fatigue resistance. Engineers must select alloys that can endure intense pressure, temperature fluctuations, and dynamic loads while maintaining strict weight limitations. Among the most advanced materials available, Aircraft Grade Aluminum 7175 Sheet stands out as one of the most trusted alloys used in aircraft structures, wings, and landing gear components.

As an improved version of the 7075 series, Aluminum Alloy 7175 offers a refined microstructure, higher fracture toughness, and superior performance under fatigue loading. Its balance of strength, toughness, and corrosion resistance makes it an essential material for aerospace applications where reliability and precision are critical.

This article explores the key characteristics, advantages, and major applications of Aircraft Grade Aluminum 7175 Sheet in modern aerospace structures and highlights why SASAALUMINUM continues to be a leading global supplier of this premium alloy.

1. Understanding Aircraft Grade Aluminum 7175

Aluminum Alloy 7175 is a high-strength, heat-treatable aluminum-zinc-magnesium-copper alloy developed specifically for aerospace structural use. It is derived from the well-known 7075 alloy but processed under more controlled conditions to achieve better mechanical uniformity and improved fracture toughness.

Typical Chemical Composition (%):

• Zinc (Zn): 5.6–6.1

• Magnesium (Mg): 2.4–2.9

• Copper (Cu): 1.2–1.6

• Chromium (Cr): 0.18–0.28

• Aluminum (Al): Balance

The alloy’s microstructure and heat-treatment response make it highly suitable for forged and machined structural components, particularly in aircraft and defense systems where strength-to-weight ratio is a top priority.

2. Key Properties of Aluminum 7175 Sheet

Aircraft Grade Aluminum 7175 Sheet is recognized for its remarkable combination of strength, toughness, and durability. Its performance is optimized through precision heat treatment processes such as T7351 or T73651.

Mechanical Properties (Typical):

• Tensile Strength: 540–580 MPa

• Yield Strength: 460–510 MPa

• Elongation: 8–11%

• Density: 2.81 g/cm³

• Hardness: 150–160 HB

• Fatigue Strength: ~240 MPa

These properties give 7175 aluminum an exceptional strength-to-weight ratio, which is why it’s frequently used in aircraft structures, landing gear supports, and wing spars.

3. Advantages of Using Aluminum 7175 in Aerospace Structures

The aerospace sector demands materials that can withstand extreme operational environments while reducing overall airframe weight. Aluminum 7175 meets these requirements through its outstanding performance characteristics:

3.1 High Strength-to-Weight Ratio

Compared to many other aerospace alloys, 7175 aluminum offers similar strength to steel but at one-third the weight, allowing aircraft designers to achieve lighter and more efficient airframes.

3.2 Excellent Fatigue Resistance

Aircraft components experience repeated stress cycles during flight operations. 7175 aluminum’s fine-grained structure and improved fracture toughness ensure superior fatigue life, reducing the risk of crack propagation and in-service failure.

3.3 Corrosion and Stress-Corrosion Resistance

Unlike earlier versions of 7075, the T7351 temper of 7175 aluminum exhibits excellent resistance to stress-corrosion cracking (SCC), a crucial advantage for parts exposed to moist or marine environments.

3.4 Good Machinability and Surface Finish

The alloy machines cleanly and allows for tight tolerances in aerospace components. It also provides a smooth surface finish that is ideal for anodizing and protective coatings.

3.5 Thermal Stability

7175 aluminum maintains its mechanical properties across a wide temperature range, ensuring stable performance during altitude changes and thermal cycling.

4. Major Applications in Aerospace Structures

Because of its outstanding combination of mechanical strength and fracture toughness, Aircraft Grade Aluminum 7175 Sheet is extensively used in the aerospace industry for both primary and secondary structural applications.

4.1 Fuselage Frames and Bulkheads

7175 aluminum is used in aircraft fuselage frames where high compressive strength and toughness are required to absorb flight stresses while keeping the structure lightweight.

4.2 Wing Spars and Ribs

Wing components must resist bending and torsion forces. The high strength and fatigue resistance of 7175 aluminum make it ideal for wing spars, ribs, and reinforcement plates that endure continuous cyclic loads.

4.3 Landing Gear Components

The alloy’s superior yield strength and toughness under impact make it perfect for landing gear fittings, struts, and support brackets, which experience dynamic loads during takeoff and landing.

4.4 Engine Mounts and Pylons

Engine supports require materials capable of handling vibration and temperature variation. Aluminum 7175’s high fatigue limit and stability ensure safe operation in these critical systems.

4.5 Structural Panels and Reinforcement Plates

7175 sheets are also used in aircraft skin reinforcements, seat tracks, and connecting structures that must balance rigidity with weight efficiency.

5. Comparison: 7175 vs 7075 Aluminum in Aerospace Use

While both alloys belong to the 7000 series, 7175 aluminum offers several improvements over 7075 due to its optimized manufacturing and heat treatment processes.