After we introduced Common Aluminum alloys used for machining. Today, we continue to introduce Specifically two aluminum grades 6061 Aluminum and 7075 Aluminum which are mostly used in precision machining. in this article, we will explain the differences between these two aluminum alloys and how to choose when you design an aluminum product.
What Is 6061 Aluminum Grade?
Aluminum grade 6061 is one of the most commonly used aluminum alloys. it is the most famous member of the 6000 series of aluminum alloys. Due to the perfect balance of hardness and machinability, 6061 aluminum alloy is referred to as structural aluminum. it is Composed primarily of aluminum(97.9%) and magnesium, silicon, copper, chromium, and a tiny amount of other elements.
What Is 7075 Aluminum Grade?
Aluminum 7075 is a high-strength heat-treatable aluminum alloy used for highly stressed structural parts. it is a member of the 7000 series aluminum alloys. As a primarily zinc-based aluminum alloy, It contains 5.6% zinc, 2.1% magnesium, and 1.2% copper.
Differences Between Aluminum 6061 and 7075
6061 Vs. 7075 Aluminum: Chemical Composition Comparison
Below is a table to show the Chemical Composition of both materials and you will find how each Chemical affects the performance of the materials.
| Element | Property Affected | Aluminum 6061 Composition (%) | Aluminum 7075 Composition (%) |
| Aluminum (Al) | Strength, Hardness | Approximately 97.9 | Balance (Over 90%) |
| Silicon (Si) | Machinability | 0.4 – 0.8 | 0.4 |
| Magnesium (Mg) | Strength, Corrosion Resistance | 0.8 – 1.2 | 2.1 – 2.9 |
| Zinc (Zn) | Strength | 0.25 | 5.1 – 6.1 |
| Copper (Cu) | Corrosion Resistance., Strength | 0.15 – 0.4 | 1.2 – 2.0 |
| Iron (Fe) | Strength | 0.7 | 0.5 |
| Manganese (Mn) | Strength, Machinability | 0.15 | 0.3 |
| Chromium (Cr) | Corrosion Resistance | 0.04 – 0.35 | 0.18 – 0.28 |
| Titanium (Ti) | 0.15 | 0.2 |
6061 vs. 7075 Aluminum: mechanical properties comparison
A comparison table is below for the mechanical properties of both materials.
| Property | Aluminum 6061 | Aluminum 7075 |
| Tensile Strength (MPa) | 276 | 572 |
| Yield Strength (MPa) | 241 | 503 |
| Hardness (Brinell HB) | 95 | 150 |
| Fatigue Strength (MPa) | 96 | 159 |
| Shear Strength (MPa) | 207 | 331 |
| Young’s Modulus (GPa) | 69 | 71 |
| Poisson’s Ratio | 0.33 | 0.33 |
| Thermal Conductivity (W/m·K) | 167 | 130 |
| Electrical Resistivity (Ω·mm²/m) | 0.036 | 0.0003 |
| Elasticity | Good | Good |
| Temperature Resistance | Up to 300°C | Up to 160°C |
| Corrosion Resistance | Good | Average |
Tensile Strength
This property measures a material’s resistance to a longitudinal pulling force. Aluminum 7075 is very good in this aspect, making it ideal for applications where high strength is critical, such as aerospace components.
Yield Strength
Yield strength indicates the point at which a material begins to deform plastically. Aluminum 7075 has a higher yield strength compared to 6061, which means its superior ability to withstand deformation.
Hardness
Hardness means a material’s resistance to surface indentation or abrasion. Aluminum 7075’s hardness is higher than that of aluminum 6061, making it more resistant to wear and damage.
Elongation
Elongation measures how far a material can stretch before breaking. Aluminum 6061 is more ductile in this aspect, meaning it can deform significantly before reaching its breaking point compared to 7075.
Young’s Modulus(Modulus of Elasticity)
This property defines a material’s stiffness and its ability to return to its original shape after deformation. Both alloys have similar values, but 6061 is slightly more elastic, making it better suited for applications requiring flexibility.
Thermal Conductivity
It means how efficiently a material conducts heat. Aluminum 6061 has higher thermal conductivity, making it suitable for heat dissipation applications like heat sinks.
Electrical Resistivity
This property quantifies a material’s opposition to electrical current flow. 7075 has slightly lower electrical resistivity, making it better for electrical conductivity applications.
Elasticity
Elasticity reflects a material’s ability to deform and regain its original shape under applied stress. Aluminum 6061 has higher elasticity, allowing it to flex more without permanent deformation.
Temperature Resistance
This property indicates how well a material can withstand elevated temperatures. Aluminum 7075 is better in high-temperature environments due to its higher melting point.
Corrosion Resistance
It shows a material’s ability to withstand deterioration when exposed to corrosive substances. Both alloys have good corrosion resistance, but aluminum 6061 is better.
6061 vs. 7075 Aluminum: machinability comparison
CNC Machinability
Aluminum 6061 is easy to machine, and used for producing longer, continuous chips during CNC Aluminum machining. On the other hand, Aluminum 7075 is also machinable, but it generates shorter, segmented chips. so, for CNC machinability, 6061 aluminum will be better.
Weldability
In terms of weldability, Aluminum 6061 is better. It is adaptable to various welding techniques, including TIG and MIG welding with a good result. Although Aluminum 7075 is weldable, it demands more expertise and careful control of welding parameters.
Bending
For bending operations, Aluminum 6061 is highly formable and can be bent to various angles without the risk of cracking or distortion. In contrast, Aluminum 7075 is less ductile and possible to crack during bending.
Sawing
Both alloys can be cut effectively, but Aluminum 6061 is easier to cut. Standard sawing equipment can easily cut 6061, ensuring precise and clean cuts. Aluminum 7075 requires specialized sawing equipment for optimal cutting results.
EDM (Electrical Discharge Machining)
Wire EDM is not commonly used on Aluminum 6061 due to its excellent machinability using conventional methods. For Aluminum 7075, EDM is a viable option, especially in cases demanding high-precision components.
Tool Wear
Tool wear is a key consideration during machining. Aluminum 6061 shows low tool wear. Aluminum 7075, while still machinable has high tool wear due to its high hardness.
Surface Finish
Aluminum 6061 generally delivers a smooth surface finish, making it an excellent choice when aesthetics is important. Aluminum 7075 can also achieve a satisfactory surface finish, but it may require more effort due to its high hardness.
6061 VS 7075 Aluminum: How To Choose?
With the answer to the following three questions, you will know how to choose.
Which One is Stronger: 6061 or 7075 Aluminum?
7075 aluminum alloy has a higher yield strength compared to 6061 aluminum, So it can withstand impacts better than 6061.
Which One is Easier to Machine: 6061 or 7075 Aluminum?
6061 aluminum has lower tensile strength and hardness compared to 7075 aluminum. So, 6061 aluminum is easier to machined and shaped.
Which One is More Cost-Effective?
The raw material cost and machining expenses for 7075 are higher. So Aluminum 6061 is more cost-effective.
When to choose: 6061 or 7075 Aluminum
According to the comparison above, we summarize a when list to help you decide how to choose.
Aluminum 6061 can be considered for use in the following situations:
- When parts require a lot of welding process.
- When there’s a high demand for corrosion resistance.
- When a lower cost is a priority.
7075 aluminum is more suitable for the following situation:
- When achieving a high strength-to-weight ratio is needed.
- When parts need to withstand high temperatures.
- When parts will be subjected to high stress.
- When the budget allows for higher material costs.
Conclusion
6061 and 7075 Aluminum alloys are both wonderful in the machining process. if you can not decide well, Contact a professional aluminum machining supplier. KUSLA is a manufacturer of precision aluminum machining in China. Feel free to get in touch with us for your aluminum machining projects.
You may also interested in other comparisons:
FAQ
How much more expensive is 7075 than 6061?
Generally speaking, 7075 aluminum’s price is around 20% higher than 6061. but this depends on the local market price, it can vary at different times.
What grade in 6061 aluminum is used for machining?
6061-T6 is the most popular aluminum alloy for CNC machining.
