Because of their excellent strength to weight ratio, high relative strength, corrosion resistance and processability, aluminum alloys are widely used in construction, aerospace, electronics, new energy, sports equipment and automobile industries.
Given the wide variety of aluminum alloys available, it may be a challenge to choose the right aluminum alloy for your project.
This article compares two common alloys 6061 and 7075 and will help you decide between them.
What is 6061 aluminum?
6061 is a 6000 series aluminum material, mainly composed of magnesium and silicon, with a low proportion of total components.
The strength is lower than 7005 aluminum.
However, due to the simple composition and low content of the alloy, the difficulty of welding and pressing is relatively low, so the price is also cheap.
The main alloying elements in 6061 alloy are magnesium and silicon, with moderate strength.
6061 alloy has good corrosion resistance, weldability and oxidation effect.
It is widely used in various industrial structural parts requiring certain strength and high resistance to antibiotics.
6061 is the most common aluminum material.
It is light, strong and economical.
It also has certain applications in structure and construction products as well as aerospace and entertainment industries.
Application of 6061 aluminum alloy in architecture
Aluminum alloy 6061 exhibits good tensile strength, which can be improved by tempering treatment, and has good corrosion resistance, weldability and machinability.
Its machinability makes it the right choice for many extrusion projects because it is easy to form.
This alloy is widely used at a relatively low cost and is a good choice for producing various precision parts of different shapes.
What is 7075 aluminum?
7075 is the lightest and strongest aluminum material, and the price is super expensive!
7075 is as strong as steel.
Its strength is comparable to many types of steel, but its density is much lower. This alloy is a good substitute for steel in high-stress applications.
It is also excellent in resisting fatigue stress, making it very reliable.
7075 aluminum plate is a cold treated forging alloy with high strength, far better than mild steel.
7075 is one of the most powerful alloys in commercial use.
It has common corrosion resistance, good mechanical properties and anode reaction.
The fine grain makes the deep drilling performance better, the wear resistance of the tool is enhanced, and the thread rolling is different from the heavy one.
The high-end 7075 aluminum plate belongs to the Al Zn Mg Cu Series superhard aluminum.
7075 alloy is an ultra-high strength deformed aluminum alloy which has been used in aircraft manufacturing since the late 1940s and is still widely used in the aviation industry.
It is characterized by good plasticity after solution treatment, especially good heat treatment strengthening effect, high strength below 150 ℃, and particularly good low temperature strength;
Poor welding performance;
There is a tendency of stress corrosion cracking;
Aluminum clad or other protective treatment is required.
The resistance to stress corrosion cracking can be improved by two-stage aging.
According to China’s executive standard: GB / T3880.2-2006, stable solid solution and good plasticity after treatment, are especially good for heat treatment strengthening effect, and super strength 7075 is also known as steel.
In aluminum alloy 7075, zinc is the main alloying element.
It is powerful, has strength comparable to many steels, and has good fatigue strength and average machinability, but has poor resistance and is easier to corrode than many other aluminum alloys.
Its relatively high cost limits its use, and cheap alloys are not suitable for applications.
7075 is also a 7000 series aluminum material.
The composition is the same as that of 7005, but the content is much higher.
The hardness is much higher than 6061 and exceeds the hardness of steel.
However, due to the large amount of alloy components and great hardness, it is very difficult to weld and press, and the price is far higher than 6061 and 7005.
7075 alloy provides only average corrosion resistance as a result of the small amount of copper contained in its chemical composition. It also has good machinability and poor formability and weldability.
Another disadvantage of this alloy is that it has a relatively high cost relative to other aluminum alloys.
Differences between 6061 and 7075
Comparison of properties of 6061 and 7075 alloys
|6061 aluminum alloy||7075 aluminum alloy|
|Aluminum is alloyed with silicon and magnesium.||Aluminum alloy mainly alloyed 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 strength, even higher after tempering.|
|High strength to weight ratio, low density.||The strength / weight ratio is very high even considering a higher density than 6061.|
|Good corrosion resistance.||Average corrosion resistance.|
|Good weldability, machinability and machinability. Very suitable for CC machining and extrusion projects.||Conventional machinability, weldability and machinability are poor.|
|It has high versatility and can be used in many industries.||High strength applications, mainly in the aerospace industry|
1. Composition difference:
In 6061 aluminum alloy, aluminum alloy element accounts for 97.9%, magnesium element accounts for 1%, silicon element accounts for 0.6%, and 0.28% copper and 0.2% chromium are added.
The composition of 7075 aluminum alloy generally includes 5.6-6.1% zinc, 2.1-2.5% magnesium, 1.2-1.6% copper, less than half a percentage point, and silicon, iron, manganese, titanium, chromium and other metals.
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 a zinc magnesium aluminum alloy.
4. Differences in mechanical properties:
|Aluminum alloy code||Yield||Shear||Tensile|
5. Purpose difference:
Under normal circumstances, the price of 7075 is about 20-40% higher than that of 6061.
Because of the price, 6061 can be used in all places where aluminum alloy materials are not required to be used.
7075 and 7005 are usually used in commercial applications such as aerospace, high hardness and low density.
Therefore, 7075 is also commonly used as commercial aluminum alloy.
6. Price difference:
The price of 6061 is generally 18-30 yuan / kg, while the price of 7075 is generally 40-60 yuan / kg. Therefore, the sales volume of 6061 is relatively high, while the sales volume of 7075 is relatively small due to the price.
7. Comparison of chemical components
Chemical composition, w%
(the proportion of trace elements in the above figure is calculated according to the upper limit of standard value)
The trace elements are mainly magnesium and silicon, and form Mg2Si phase.
A small amount of copper or zinc is added to improve the strength of the alloy without significantly reducing its corrosion resistance.
The proportion of trace elements is high and the cost is expensive.
The main element is zinc.
Adding copper and magnesium to form Al Zn Mg Cu alloy, the strengthening effect is greater in all aluminum alloys.
8. Comparison of important mechanical properties
7075 is known as aviation aluminum, which is very superior in material performance comparison. 7075-T6 is the aluminum alloy with the highest strength at present, better than ordinary steel.
|High strength, high hardness||Excellent resistance to external forces, especially suitable for small size and high requirements.|
|Excellent wear resistance and good cutting performance||CNC is convenient to make workpieces, and the materials are compact, wear-resistant and durable.|
|High fatigue resistance and long service life||Extend the inspection interval of precision instruments and reduce the maintenance cost.|
|High precision, high damage tolerance||More precise, good toughness, not easy to deform under pressure or impact for a long time.|
It is often used in occasions with high standards, and its advantages are self-evident.
It not only has a high degree of precision, but also has a longer service life, which improves the product from a multi-dimensional perspective, which is difficult to achieve by other methods.
7-series aluminum alloy is widely used by Apple.
Apple uses 7-series aluminum profiles to make the middle frame and back cover of iPhone.
The aluminum profiles are also made of 7-series aluminum alloy.
Xiaomi 8 is also a 7-series aluminum (Al) alloy middle frame.
It has irreplaceable advantages in many special fields.
For example, ski poles and golf heads need to be repeatedly and continuously subjected to external forces, so they prefer aviation aluminum.
At present, more and more fields try to use aviation aluminum materials to improve the appearance and performance of products, so as to achieve a difference with competitive products.
9. Comparison of processing performance
|Weldability||Can be welded||Difficult to weld|
In terms of machinability, both can be well milled on CNC machine tools.
6061 can be welded, while 7075 is difficult to weld.
6061 can easily conduct surface treatment such as oxidation coloring, and 7075 has unstable oxidation effect.
The corrosion resistance of 6061 is better when the two are not treated.
6061T6 and 7075T6 materials have high hardness and cannot be bent.
10. Application of 6061 and 7075 Aluminum Alloys
The following are some typical applications of each of these alloys.
It is worth considering that engineers usually use each alloy to better understand which alloy is more suitable for a given project.
|6061 aluminum alloy||7075 aluminum alloy|
|Construction products||Aircraft wings and fuselage|
|Electrical products||Aerospace parts|
|The Conduit||Gears and shafts|
|Bicycle frame||Worm gear|
|Auto parts||Fuse parts|
In most cases, 7075 aluminum material is superior to 6061 material.
However, we can not simply conclude that 7075 must be better.
Or you need to clarify your purpose and budget first.
In general, 6061 can basically meet the general industrial manufacturing requirements.
The 7075 is used in high demand occasions, such as aerospace, military supplies, precision equipment, high-end electronic equipment, high-end products, etc.
Should you choose 6061 or 7075 aluminum alloy?
Both alloys show high strength to weight ratio, and each has advantages in specific applications.
Therefore, which alloy is selected depends on the intended use and budget.
Aluminum 6061 will be a better choice when the product is to be welded or formed, requiring medium to high tensile strength or considering corrosion resistance.
This is also a better choice for extruding complex shapes or with limited budgets.
The very high strength of aluminum 7075 is its main feature.
Therefore, it is more suitable when an abnormally high tensile strength is required, while having a high strength to weight ratio and high fatigue resistance.