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Aluminum alloys are renowned for their high strength-to-weight ratio. Their lightweight and corrosion-resistance abilities make them a preferred choice in the automotive, aerospace, sports, electrical, and construction industries. Among the available alloys, the debate often centers around 6061 vs. 7075 Aluminum. So, in this article, we will break down the technical differences between these two alloys and help you determine which is best suited for your specific needs.
What is Aluminum 6061 Alloy?
Aluminum 6061 is one of the most used alloys of Aluminum, particularly in the automotive space. It belongs to the famous Aluminium 6000 series, where magnesium and silicon are key alloying elements.
Aluminum 6061 is easy to machine, weldable, and can undergo heat treatment and anodizing. It’s desired in applications where you need a lightweight and stylized structure with moderate loads.
What is Aluminum 7075 Alloy?
Aluminum 7075 belongs to the alloy series 7000, with zinc, magnesium, and copper as the alloying elements. The presence of these two elements imparts strength and toughness to the material.
Aluminum 7075 is one of the highest-strength aluminum alloys, particularly used in military and aerospace applications.
6061 vs 7075 Aluminum Alloy: 9 Differences Explained
We have broken down the comparison between 6061 and 7075 aluminum alloys into mechanical, chemical, and machining aspects to offer a clear, in-depth view of their differences
1. Alloy Composition
The chemical difference is apparent in their name; 6061 is from the aluminum 6xxx series, while 7075 is from the 7xxx series. Aluminum 6061 has magnesium and silicon as the main alloying elements. Whereas 7075 contains Zinc, Copper, and magnesium in relatively larger amounts.
The presence of these different alloying elements impacts their physical and chemical properties, as you will see in the subsequent comparisons.
| Element | 6061 Aluminum (T6) | 7075 Aluminum (T6) |
| Aluminum (Al) | 95.8-98.6% | 87.1-91.4% |
| Magnesium (Mg) | 0.8-1.2% | 2.1-2.9% |
| Silicon (Si) | 0.4-0.8% | 0.0-0.4% |
| Zinc (Zn) | 0.0-0.25% | 5.1-6.1% |
| Copper (Cu) | 0.15-0.4% | 1.2-2.0% |
| Chromium (Cr) | 0.04-0.35% | 0.18-0.28% |
| Manganese (Mn) | 0.0-0.15% | 0.0-0.3% |
2. Physical Properties
7075 aluminum has a slightly higher density than 6061 aluminum. One reason is that the collective atomic mass of magnesium (24.3u) and silicon (28.1u) is even less than zinc (65.4u). This higher density contributes to its greater tensile strength but makes it marginally heavier. The melting temperature of both alloys differs as well, with 6061 having a lower melting point.
| Physical Property | 6061 Aluminum (T6) | 7075 Aluminum (T6) |
| Density | 2.70 g/cm³ | 2.81 g/cm³ |
| Melting Temperature | 582-652°C | 477-635°C |
3. Chemical Properties
Both the alloys are corrosion resistant due to Aluminum presence. When exposed to air, it forms a protective aluminum oxide layer that shields the underlying metal from further corrosion. However, the inner composition can affect the quality of resistance.
For instance, the 6061 has a higher copper content, which in certain conditions, can pose a corrosion threat to Aluminum. That’s why 6061 is less corrosion-resistant than Aluminum 7071 and some other alloy series.
| Chemical Property | 6061 Aluminum (T6) | 7075 Aluminum (T6) |
| Oxide Layer Formation | Present (Al2O3) | Present (Al2O3) |
| Corrosion Resistance | Higher | Moderate |
4. Mechanical Properties
The different alloying elements in 6061 and 7075 largely impact their mechanical properties. Below, we compare key mechanical characteristics.
- Yield Strength: Yield strength is the maximum stress a material can endure before it permanently deforms. Since Aluminum 7075 has a higher zinc content, it has superior yield strength than aluminum 6061.
- Thermal Conductivity: Thermal conductivity is the material’s ability to conduct heat. Conductivity is largely dependent on similar material composition. Aluminum 6061 has higher thermal conductivity due to its lower alloy content and simpler structure.
- Elasticity Modulus: The elasticity modulus (also known as Young’s modulus) measures the stiffness of a material i.e. how much it will deform under stress. In that aspect, both have very close values.
- Hardness: Hardness is the material’s resistance to scratching. 7075 Aluminum is harder than 6061 because of the stronger alloying structure of zinc.
| Physical Property | 6061 Aluminum (T6) | 7075 Aluminum (T6) |
| Yield Strength | 240 MPa | 503 MPa |
| Thermal Conductivity | 167 W/m·K | 130 W/m·K |
| Elastic Modulus | 68.9 GPa | 71.7 GPa |
| Hardness (Brinell) | 95 | 150 |
5. Surface Properties
Anodizing is an electrochemical process to add a thin layer on the surface to prevent corrosion, improve hardness, and add aesthetic appearance to it.
6061 Aluminum is known for its excellent anodizing properties. It forms a transparent oxide layer that protects the surface and allows for a high-quality finish.
7075 aluminum, though also suitable for anodizing, has a slightly different behavior. Due to its higher zinc content, there’s a chance the oxide layer may turn brown, particularly if the zinc content is high.
| Surface Property | 6061 Aluminum (T6) | 7075 Aluminum (T6) |
| Anodizing Quality | Excellent | Good |
| Oxide Layer Transparency | Transparent | Transparent to brown (if high zinc) |
| Surface Protection | High | High |
6. Machinability
7075 aluminum is challenging to machine due to its toughness and higher stiffness. It produces greater tool wear and requires specialized tools to achieve precise machining.
In contrast, 6061 aluminum is much easier to machine. Its relatively lower hardness, coupled with the presence of magnesium and silicon, makes it more workable without excessive tool wear.
| 6061 Aluminum (T6) | 7075 Aluminum (T6) | |
| Machinability | Excellent | Moderate to Low |
| Tool Wear | Low | High |
| Chip Formation | Better | More difficult |
7. Fabrication Properties
6061 aluminum has good weldability. Its magnesium and silicon content contribute to better fusion during welding.
On the other hand, 7075 aluminum is not well-suited for welding due to its high zinc and copper content, which are prone to cracking. A special technique, friction stir welding, can be used to to weld this alloy.
8. Applications
Due to its lower strength, 6061 aluminum is also more formable. It can be easily shaped and bent without cracking. This makes it ideal for applications that require complex shapes or forming processes, such as tubing or extrusions. The automotive sector is one of the largest beneficiaries of this material. Besides it’s a part of multiple consumer goods.
Aluminum 7075’s limited formability makes it more suitable for machined components rather than formed or bent structures. It is one of the toughest grades, used for aerospace, sports, and military-grade applications.
| 6061 Aluminum Applications | 7075 Aluminum Applications |
| Automotive: Vehicle frames and panels | Aerospace: Aircraft wings and fuselages |
| Construction: Architectural frameworks | Military: Missile components |
| Electrical: Connectors | Industrial: Gears and shafts |
9. Cost Differences
6061 is a common material, largely used in many industries. So, it’s ideal to source and get. In contrast, 7075 is a material you need for very specialized applications, military or aerospace, so it’s slightly on the expensive side. As per an estimate, Aluminum 6061 costs 20 to 25% higher than Aluminum 7075.
Aluminum 6061 vs 7075: Which One to Choose?
Material choice is a crucial part of manufacturing and one has to decide based on utility and costs. We have compared two aluminum alloys, 6061 and 7075, and observed they largely differ in chemical and physical properties. So, their choice must be made based on that.
Use 6061 aluminum when you need good formability, medium strength, and welding capabilities. It’s best for general applications like automotive parts, construction, and marine equipment.
Choose 7075 Aluminum when strength is your priority, especially in high-stress environments, like aerospace and military. It may be tougher to machine, but its strength-to-weight ratio is exceptional.
Richconn is a professional CNC machining manufacturer, experienced in producing parts from various materials. If your project requires the use of 6061 or 7075 aluminum, feel free to contact us for a free quote.
