Aluminum alloys are highly valued for their strength-to-weight ratio, high relative strength, corrosion resistance and processability, making them a popular choice in a wide range of industries, including construction, aerospace, electronics, new energy, sports equipment and automobiles.
However, with such a wide variety of aluminum alloys available, it can be difficult to determine which alloy is best suited for a specific project. In this article, we will compare two of the most common alloys, 6061 and 7075, to help you make an informed decision.
What is 6061 aluminum ?
6061 is a 6000 series aluminum alloy mainly composed of magnesium and silicon, with a relatively low proportion of other components. This simple composition results in lower strength compared to 7005 aluminum, but also makes welding and pressing easier, resulting in lower cost.
The main alloying elements of 6061 are magnesium and silicon, which provide moderate strength. This alloy also has good resistance to corrosion, weldability and oxidation. It is commonly used in industrial structural parts that require a certain level of strength and corrosion resistance.
Due to its low cost, light weight and strength, 6061 is a widely used aluminum material. It is often used in construction and structural products, as well as in the aerospace and entertainment industries. It is also the most commonly used aluminum alloy.
Application of 6061 aluminum alloy in architecture
6061 aluminum alloy has good tensile strength, which can be improved through tempering, and also has excellent corrosion resistance, weldability and machinability. Its machinability makes it an ideal choice for many extrusion projects as it is easy to shape.
Given its low cost, the 6061 is widely used to produce a variety of precision parts in different shapes. Its versatility, combined with its good mechanical properties, makes it a popular choice for a variety of applications.
What is 7075 aluminum ?
7075 aluminum is known for being the lightest and strongest material in its class, but it comes at a high price. This alloy is comparable in strength to many types of steel, but has a much lower density, making it an excellent substitute for steel in high stress applications. Its exceptional resistance to fatigue stress makes it a reliable choice.
7075 aluminum plate is a cold-treated forged alloy with exceptional strength, surpassing that of carbon steel. It is one of the most powerful alloys in commercial use, possessing resistance to common corrosion, good mechanical properties and anodic reaction. Its fine grain structure improves deep drilling performance, increases tool wear resistance and provides a distinct advantage in thread rolling compared to heavier materials.
7075 is part of the Al-Zn-Mg-Cu series of super-hard aluminum and is widely used in the aviation industry, particularly in aircraft manufacturing. It has been used in industry since the late 1940s due to its ultra-high strength, good plasticity after solution treatment, and particularly its effective heat treatment strengthening effect.
However, 7075 aluminum has poor welding performance and a tendency to stress corrosion. To improve its resistance to stress corrosion cracking, two-stage aging may be necessary. Protective treatments such as aluminum coating are also necessary.
According to China's executive standard GB/T3880.2-2006, 7075 aluminum is stable in solid solution and has good plasticity after treatment, making it an excellent choice for strengthening by heat treatment. This super resistant material is also known as “steel”.
7075 aluminum alloy is a powerful material with strength comparable to many steels. Zinc is the main alloying element of this material, which gives it good fatigue resistance and average machinability. However, it has low corrosion resistance and is more susceptible to corrosion compared to other aluminum alloys.
This alloy belongs to the 7000 series of aluminum materials and has a similar composition to 7005, but with a higher zinc content. The hardness of 7075 is much higher than that of 6061 and even surpasses that of steel. Despite its high hardness, it is difficult to weld and press, which makes your work more challenging. Furthermore, its relatively high cost limits its use and makes it unsuitable for applications requiring more affordable alloys.
Related Reading: Common Aluminum Alloy Hardness Table
The 7075 aluminum alloy provides medium resistance to corrosion due to its small amount of copper in its chemical composition. It is also known to have good machinability but poor formability and weldability. This alloy has a higher cost compared to other aluminum alloys, making it less profitable in some applications.
Differences between 6061 and 7075
Comparison of the properties of alloys 6061 and 7075
| aluminum alloy 6061 | aluminum alloy 7075 |
| Aluminum is alloyed with silicon and magnesium. | Aluminum alloy alloyed mainly with zinc and a small amount of magnesium and copper. |
| Structural Grade Aluminum Alloy | Structural Grade Aluminum Alloy |
| Medium strength, can be very high after tempering. | High resistance, even greater after tempering. |
| High strength/weight ratio, low density. | The strength/weight ratio is very high even considering a density higher than 6061. |
| Good corrosion resistance. | Medium corrosion resistance. |
| Good weldability, machinability and machinability. Very suitable for DC machining and extrusion projects. | Conventional machinability, weldability and machinability are poor. |
| It has high versatility and can be used in different sectors. | High-strength applications, mainly in the aerospace industry |
1. Difference in composition:
6061 aluminum alloy is composed of 97.9% aluminum, 1% magnesium, 0.6% silicon, 0.28% copper and 0.2% chromium. These elements are combined to form a versatile and durable material.
7075 aluminum alloy, on the other hand, generally consists of 5.6-6.1% zinc, 2.1-2.5% magnesium, 1.2-1.6% copper and trace amounts of silicon, iron, manganese, titanium, chromium and other metals. This combination gives 7075 aluminum alloy high strength and durability, making it a popular choice for high-stress applications.
2. Hardness difference:
The hardness of 6061 is 90HB.
The hardness of 7075 can reach 150HB.
3. Series difference:
6061 is a 6000 series aluminum alloy.
7075 is a 7000 series aluminum alloy, which is an alloy of zinc and magnesium and aluminum.
4. Differences in mechanical properties:
| Aluminum Alloy Code | Harvest | Shear | Traction |
| 6061 | 7KSI | 10KSI | 13KSI |
| 7075 | 15KSI | 22KSI | 33KSI |
| 6061-T6 | 31KSI | 17KSI | 35KSI |
| 7075-T6 | 73KSI | 48 KSI | 83KSI |
5. Difference in purpose:
Typically, 7075 aluminum is 20-40% more expensive than 6061 aluminum. As a result, 6061 aluminum is commonly used in applications where a higher priced aluminum alloy is not required.
7075 and 7005 aluminum are often used in commercial industries such as aerospace due to their high hardness and low density.
Therefore, 7075 aluminum is often used as a commercial aluminum alloy.
6. Price difference:
The price of 6061 aluminum is usually 18 to 30 yuan per kilogram, while the price of 7075 aluminum is usually 40 to 60 yuan per kilogram. Due to its lower cost, 6061 aluminum has a relatively high sales volume, while 7075 aluminum has a relatively low sales volume due to its higher price.
7. Comparison of chemical components
|
Chemical composition, % by weight |
|||||||||
|
turns on |
Yes |
Faith |
Ass |
Mn |
mg |
Cr |
Zn |
Zr |
You |
|
6061 |
0.40-0.80 |
0.70 |
0.15-0.40 |
0.15 |
0.80-1.20 |
0.10 |
0.10 |
– |
0.10 |
|
7075 |
0.40 |
0.50 |
1.2-2.0 |
0:30 |
2.1-2.9 |
0.18-0.28 |
5.1-6.1 |
0.05 |
0.20 |
(The proportion of trace elements in the above figure is calculated based on the upper limit of the standard value)
The main trace elements of the alloy are magnesium and silicon, which form the Mg2Si phase. A limited amount of copper or zinc is added to increase the alloy's strength while maintaining its corrosion resistance.
However, the high proportion of trace elements results in a more expensive cost.
The main element of the alloy is zinc, and the addition of copper and magnesium creates the Al Zn Mg Cu alloy, which has the greatest strengthening effect among all aluminum alloys.
8. Comparison of important mechanical properties
7075 aluminum is often called aviation aluminum because of the material's exceptional performance. 7075-T6 is currently the highest strength aluminum alloy, surpassing even common steel.
| High strength, high hardness | Excellent resistance to external forces, especially suitable for small sizes and high demands. |
| Excellent wear resistance and good cutting performance | CNC is convenient for making workpieces, and the materials are compact, wear-resistant and durable. |
| High fatigue resistance and long service life | Increase the inspection interval of precision instruments and reduce maintenance cost. |
| High precision, high damage tolerance | More accurate, good toughness, not easy to deform under pressure or impact for a long time. |
Industrial manufacturing
7075 aluminum is often used in applications that have high standards and its advantages are clearly apparent.
It not only has a high level of accuracy, but also a longer service life, which enhances the product from multiple angles and is difficult to achieve by other methods.
Consumer Electronics:
Apple uses 7 series aluminum alloys extensively.
For example, Apple uses 7 series aluminum to manufacture the iPhone's middle frame and back cover.
Other products such as aluminum profiles are also made from 7 series aluminum alloys.
The middle frame of the Xiaomi 8 is also made of 7 series aluminum alloy.
Device materials:
Series 7 aluminum alloys present unique advantages in a variety of special applications.
For example, ski poles and golf club heads are often subjected to repeated and continuous external forces, making aviation aluminum a preferred material.
Currently, a growing number of industries are using aviation aluminum materials to improve the appearance and performance of their products, differentiating them from their competitors.
9. Comparison of processing performance
| Comparison Items | 6061 | 7075 |
| Machinability | great | Excellent+ |
| Weldability | Can be welded | Difficult to weld |
| Surface treatment | easily | difficulty |
| Corrosion resistance | great | difference |
Both 6061 and 7075 aluminum can be machined effectively using CNC machine tools.
6061 aluminum is weldable, while 7075 aluminum is more difficult to weld.
6061 aluminum is also easily subjected to surface treatments such as oxidation coloring, while 7075 aluminum has an inconsistent oxidation effect.
In terms of corrosion resistance, 6061 aluminum performs better when untreated compared to 7075 aluminum.
Materials 6061T6 and 7075T6 have a high degree of hardness and cannot be bent.
10. Application of 6061 and 7075 aluminum alloys
The following are some common applications for each of these leagues:
It is important for engineers to consider these typical applications when determining which alloy is best suited for a specific project.
| aluminum alloy 6061 | aluminum alloy 7075 |
| Construction Products | Aircraft wings and fuselage |
| Electrical products | Aerospace Parts |
| The Conduit | Gears and shafts |
| bicycle frame | Helical gear |
| furniture | Throttle |
| Auto parts | Fuse Parts |
Full assessment
In most cases, 7075 aluminum has superior properties compared to 6061 aluminum.
However, it is not correct to simply assume that 7075 is always better.
It is crucial to first consider the specific purpose and budget before reaching a conclusion.
6061 aluminum can generally meet the requirements of general industrial manufacturing.
7075 aluminum is typically used in high-demand applications such as aerospace, military supplies, precision equipment, high-end electronics, and high-end products.
Should you choose 6061 or 7075 aluminum alloy?
Both 6061 and 7075 aluminum alloys have a high strength-to-weight ratio and excel in specific applications.
Selecting which alloy to use depends on your intended use and budget.
When welding or forming is required, or when medium to high tensile strength and corrosion resistance are important factors, 6061 aluminum is the best choice. This is also an economical option for extrusion of complex shapes.
The defining characteristic of 7075 aluminum is its extremely high strength. As a result, it is best suited when exceptionally high tensile strength is required while maintaining a high strength-to-weight ratio and high fatigue resistance.
