What is 7075 aluminum alloy?
What Is 7075 Aluminum?
7075 aluminum is a heat-treatable aluminum alloy known for its high strength as its core advantage. It is an aerospace-grade material whose primary alloying element is zinc, along with magnesium and copper. Belonging to the 7xxx series, it is one of the most representative grades in this category. It features high strength and light weight, and is mainly used in the manufacturing of aircraft structural components, aerospace parts, bicycle frames, golf club heads, and molds
7075 Aluminum Composition (Typical Chemical Composition (wt.%))
| Element | Content (%) |
|---|---|
| Zinc (Zn) | 5.6 – 6.1 |
| Magnesium (Mg) | 2.1 – 2.5 |
| Copper (Cu) | 1.2 – 1.6 |
| Chromium (Cr) | 0.18 – 0.28 |
| Iron (Fe) | ≤ 0.50 |
| Silicon (Si) | ≤ 0.40 |
| Aluminum (Al) | Balance |
7075 Aluminum Mechanical Properties (Yield strength/tensile strength)
| Temper | Thickness (mm) | Tensile Strength (Rm, MPa) | Yield Strength (Rp0.2, MPa) |
|---|---|---|---|
| T6 | 1.5–25 | ≥540 | ≥470 |
| 25–50 | ≥530 | ≥460 | |
| 50–60 | ≥525 | ≥440 | |
| 60–80 | ≥495 | ≥420 | |
| 80–90 | ≥490 | ≥390 | |
| 90–100 | ≥460 | ≥360 | |
| 100–120 | ≥410 | ≥300 | |
| 120–150 | ≥360 | ≥260 | |
| 150–200 | ≥360 | ≥240 | |
| T651 | 1.5–25 | ≥540 | ≥470 |
| 25–50 | ≥530 | ≥460 | |
| 50–60 | ≥525 | ≥440 | |
| 60–80 | ≥495 | ≥420 | |
| 80–90 | ≥490 | ≥390 | |
| 90–100 | ≥460 | ≥360 | |
| 100–120 | ≥410 | ≥300 | |
| 120–150 | ≥360 | ≥260 | |
| 150–203 | ≥360 | ≥240 | |
| T73 | 1.5–12.5 | ≥460 | ≥385 |
| 12.5–50 | ≥475 | ≥390 | |
| 50–60 | ≥455 | ≥360 | |
| 60–80 | ≥440 | ≥340 | |
| 80–100 | ≥430 | ≥340 | |
| T7351 | 1.5–12.5 | ≥460 | ≥385 |
| 12.5–50 | ≥475 | ≥390 | |
| 50–60 | ≥455 | ≥360 | |
| 60–80 | ≥440 | ≥340 | |
| 80–100 | ≥430 | ≥340 | |
| 100–120 | ≥420 | ≥320 | |
| 120–203 | ≥400 | ≥300 | |
| T76 | 1.5–6 | ≥500 | ≥425 |
| 6–12.5 | ≥490 | ≥415 | |
| T7651 | 1.5–6 | ≥500 | ≥425 |
| 6–12.5 | ≥490 | ≥415 |
7075 Aluminum Density/Melting point
Density: ~2.81 g/cm³
Elastic Modulus: ~71 GPa
Thermal Conductivity: ~155 W/m·K
Electrical Conductivity: ~33% IACS
Melting Pointing: 475--635℃
These values reflect the balance between high mechanical strength and relatively low density that defines 7075 aluminum.
Machining of 7075 Aluminum in Different Tempers
Although all 7075 aluminum tempers share the same alloy chemistry, heat treatment significantly changes their strength, dimensional stability, corrosion resistance, and machining behavior. Selecting the correct temper is often more important than choosing the alloy itself, especially for aerospace and precision CNC components.
The following comparison focuses on the machining characteristics of the six most common aerospace tempers.
7075-T6 — Maximum Strength, Maximum Residual Stress
7075-T6 is the peak-aged condition, delivering the highest strength and hardness available for standard 7075 aluminum. The trade-off is high internal residual stress, particularly in thick rolled plate.
From a machining perspective, T6 is the temper most likely to distort after large amounts of material are removed. Warping, twisting, and dimensional drift frequently appear during finish machining because the internal stresses are released as the part is cut.
For this reason:
Avoid removing large amounts of material from only one side.
Rough machine both sides whenever possible to maintain stress balance.
Leave sufficient stock for finish machining after roughing.
Do not attempt flame straightening or localized heating after machining, as heat will alter the temper and permanently change mechanical properties.
T6 remains an excellent choice for high-strength structural parts, but it is generally not the first choice for thin-wall precision aerospace components where dimensional stability is critical.
7075-T651 — The Standard Choice for Precision Aerospace Machining
T651 begins as T6 but undergoes a controlled stretching process to relieve residual stress before artificial aging. The strength remains essentially the same as T6, while machining distortion is dramatically reduced.
For most aerospace plate applications, T651 is the industry standard because it offers the best combination of strength and dimensional stability.
Recommended machining practices include:
Perform symmetrical machining whenever possible.
Remove material in multiple passes instead of one heavy cut.
Allow large parts to rest between roughing and finishing to release any remaining internal stress.
Leave a small, consistent finish allowance before the final pass.
Because corrosion resistance is still similar to T6, finished parts exposed to marine or humid environments should receive protective surface treatments such as hard anodizing or chromate conversion coating.
Like all high-strength 7xxx alloys, T651 should not be repaired by conventional fusion welding.
7075-T73 and T7351 — Lower Strength, Outstanding Corrosion Resistance
T73 and T7351 are overaged tempers developed specifically to improve resistance to stress corrosion cracking (SCC). Compared with T6, tensile strength typically decreases by approximately 8–10%, but long-term durability in corrosive environments improves significantly.
From a machining standpoint, these tempers are generally more forgiving than T6.
Typical advantages include:
Better dimensional stability during machining.
Lower risk of cracking around sharp corners or threaded features.
More predictable cutting behavior during long machining cycles.
These tempers are widely used for aircraft structures operating in marine, coastal, or high-humidity environments where corrosion resistance is more important than achieving maximum strength.
Although machining is generally smoother, sharp carbide tooling and adequate coolant are still essential to maintain excellent surface finish and avoid built-up edge.
7075-T76 and T7651 — The Best Balance Between Strength and Durability
T76 and T7651 represent a moderate overaged condition positioned between T651 and T7351.
They retain higher strength than T73 while providing substantially better corrosion resistance than T6 or T651.
For many aerospace manufacturers, these tempers offer one of the best overall balances of:
Mechanical strength
Stress corrosion resistance
Dimensional stability
Machining consistency
T7651 further benefits from stress relief by stretching before aging, making it particularly suitable for large precision plates, structural aerospace components, and high-volume CNC production.
Where minimizing scrap rate and achieving consistent dimensional accuracy are priorities, T7651 is often preferred over standard T6.
General Machining Guidelines for All 7075 Tempers
Regardless of temper, several machining principles apply to every 7075 aluminum component.
Avoid Conventional Fusion Welding
7075 aluminum is generally unsuitable for TIG, MIG, or other fusion welding processes because hot cracking and significant strength loss are difficult to avoid. When joining is required, aerospace manufacturers typically use friction stir welding (FSW), mechanical fastening, or structural adhesives instead.
Minimize Cold Forming
All heat-treated 7075 tempers have relatively limited ductility. Tight-radius bending, aggressive cold straightening, or forceful reshaping can introduce microscopic cracks that may not be immediately visible but can reduce fatigue life.
Use Sharp Cutting Tools and Effective Cooling
High-performance carbide tools, polished flutes designed for aluminum, and abundant coolant or mist lubrication help prevent built-up edge, reduce cutting temperature, and improve surface finish.
Never Apply Localized Heat After Machining
Localized heating, flame straightening, or uncontrolled thermal repair can destroy the carefully controlled aging condition, resulting in hardness variation, dimensional instability, and permanent loss of mechanical performance.
7075 Aluminum Typical Products
7075 aluminum sheet plate: 7075 t7351 aircraft plate
7075 aluminum bar: 7075 T6 T6511 cold drawn bar
7075 aluminum tube: 7075 T6 seamless tube
7075 aluminum price is generally on the higher end among aluminum alloys, and depends on several factors, so if you want more accurate price, pls contact sales of Shenzhen Chinalcometal.
What is 7075 aluminum used for?
7075 aluminum alloy is widely used in high-performance applications where require high strength, low weight, and reliability. In the aerospace field, it is commonly used for aircraft structural components such as wing spars, fuselage frames, bulkheads, and landing gear parts, as well as spacecraft structural assemblies where high load-bearing capability is required. Beyond aerospace, it is also used in high-end bicycle frames, mountain bike components, and sports equipment, where lightweight design and stiffness are necessary. In addition, it is used in high-precision mechanical parts such as molds, tooling fixtures, jigs, and automotive performance components. Its combination of strength, machinability, and durability makes it a preferred material for demanding structural and engineering applications.
7075 Aluminum vs 6061 Aluminum Properties
| Property | 7075 Aluminum Alloy | 6061 Aluminum Alloy |
|---|---|---|
| Main Alloying Elements | Zn – Mg – Cu (Al-Zn-Mg-Cu system) | Mg – Si (Al-Mg-Si system) |
| Density | ~2.81 g/cm³ | ~2.70 g/cm³ |
| Tensile Strength (T6) | ~500–600 MPa | ~250–310 MPa |
| Strength Level | Very high (near steel-level for some applications) | Medium, general-purpose structural strength |
| Corrosion Resistance | Moderate (needs surface protection) | Good |
| Weldability | Poor | Excellent |
| Machinability | Moderate | Good |
| Relative Cost | High (premium material) | Low to medium (economical) |
6061 Aluminum vs 7075 Aluminum Applications
7075 Aluminum Alloy
Aerospace structural components (wing spars, fuselage frames, bulkheads)
High-performance bicycle frames and sports equipment
High-stress mechanical parts (gear components, load-bearing shafts)
Molds, tooling fixtures, and precision aerospace components
6061 Aluminum Alloy
General structural and engineering components
Automotive parts and frames
Construction materials (profiles, brackets, structural supports)
Pipes, tubing, and welded assemblies
General-purpose machined parts and housings
FAQ About 7075 Aluminum
Can 7075 Aluminum Be Welded?
7075 aluminum is generally not recommended for welding. Its high zinc and copper content increases the risk of hot cracking, and welding significantly reduces mechanical strength in the heat-affected zone. Mechanical fastening or alternative alloys are usually preferred.
Can You Anodize 7075 Aluminum?
Yes, 7075 aluminum can be anodized. However, due to its copper content, the anodized surface may appear darker or less uniform compared to alloys such as 6061. For functional anodizing, this is typically acceptable, while decorative finishes may be more challenging.
Can You Bend 7075 Aluminum?
Bending 7075 aluminum is limited, especially in T6 and T651 tempers, where cracking can occur. Softer conditions such as annealed or T73 may allow limited forming, but tight bend radii are generally not recommended.
How Strong Is 7075 Aluminum?
7075-T6 aluminum offers tensile strength up to approximately 580 MPa, approaching that of some low-carbon steels while weighing roughly one-third as much. This makes it one of the strongest commercially available aluminum alloys.
Is 7075 aluminum better than 6061?
When answering the question “Is 7075 aluminum better than 6061?”, it cannot be simply judged as “better or worse,” because the two alloys are designed for different purposes and performance priorities. A more accurate way to understand them is whether they are suitable for a specific application. 7075 aluminum alloy is primarily optimized for high strength and high stiffness. Its main advantage lies in its excellent mechanical properties and very high strength-to-weight ratio. However, this comes at the expense of relatively poorer machinability, weldability, corrosion resistance, and higher cost. Therefore, it is typically used in applications requiring extreme structural performance, such as aerospace components, high-load mechanical structures, and high-performance sports equipment.
In contrast, 6061 aluminum alloy focuses on a balance of overall properties. It offers a well-rounded combination of strength, machinability, weldability, and corrosion resistance. Although its strength is significantly lower than that of 7075, it is more than sufficient for most general engineering applications, while also being more cost-effective and easier to manufacture. Therefore, in practical material selection, 7075 is preferred when maximum performance and lightweight structural efficiency are the primary goals, whereas 6061 is a more suitable choice when manufacturing ease, cost efficiency, and environmental adaptability are more important.