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6061 VS 7075 Aluminum, What is The Difference?

6061-vs-7075-aluminum-what-is-the-difference
Austin Peng
Published 24 Jun 2024

When selecting an aluminum alloy for a project, the properties required for the end application need to be considered - whether it is corrosion resistance, strength, weight, electrical conductivity or a combination of properties.

As the two most commonly used grades of aluminum are 6061 and 7075, let's explore the distinct differences between 6061 vs 7075 aluminum. In this article, you'll learn more about how they differ in terms of performance, industry applications, and more so that you can more effectively choose the best material for your project.

What is 6061 Aluminum Grade?

6061-custom-aluminum-parts

Aluminum 6061 is a 6xxx series aluminum alloy, which is mainly alloyed with magnesium and silicon (composition: 95.8% to 98.6% aluminum, 0.8% to 1.2% magnesium, and 0.4% to 0.8% silicon), and also contains trace elements such as copper and chromium.

Originally known as "Alloy 61S," this grade of aluminum was developed in 1935 and is one of the most commonly used grades of aluminum. It has excellent mechanical properties, high strength, corrosion resistance, excellent heat treatability and weldability. In addition, it can be anodized to provide a thin layer of various colors to protect your parts. AL6061 is available in a variety of forms, including aluminum sheet, block, bar, and tube.

What is 7075 Aluminum Grade?

Anodize-Aluminum-CNC-milling

Aluminum 7075 is a 7xxx series aluminum alloy, primarily a zinc-magnesium alloy (composition: 5.6 to 6.1% zinc, 2.1 to 2.5% magnesium), with 1.2 to 1.6% copper and elements such as silicon, iron, manganese, titanium, and chromium.

It was originally developed in secret by a Japanese company in 1936 and later introduced by Alcoa in 1943. 7075 aluminum alloy is one of the strongest aluminum alloys with an excellent strength-to-weight ratio, excellent mechanical properties, good fatigue resistance and ductility, and is widely used in high-stress applications and aircraft structural components.

What Differentiates Between Aluminum 6061 and Aluminum 7075?

Customized-Aluminum-Machined-Parts(1)

Through a brief introduction, we have learned about the grades of 6061 and 7075 aluminum. Next, we will have a deeper study on the types, chemical composition, mechanical properties and applications of the alloy series.

6061 vs. 7075 Aluminum: Alloy Tempers

6061 Aluminum: F, O, T4, T451, T42, T5, T6, T651, T6511, H112

7075 Aluminum: F, O, T6, T651, T62, T652, T76, T7651, T73, T7351, T7451, H112

6061 vs. 7075 Aluminum: Chemical Components

Custom-Aluminum-Machined-Parts(1)

The following table contains a complete breakdown of the chemical composition of 6061 and 7075 aluminum:

Element 6061 Aluminum 7075 Aluminum
Aluminum 95.85 - 97.90 % 86.90 – 91.40 %
Silicon 0.40 - 0.80 % 0.00 - 0.40 %
Zinc 0.00 – 0.25 % 5.6 – 6.10 %
Magnesium 0.80 - 1.20 % 2.1 - 2.50 %
Manganese (Mn) 0.00 – 0.15 % 0.00 - 0.30 %
Chromium 0.04 - 0.35 % 0.07 - 0.23 %
Copper 0.15 - 0.40 % 1.20 - 1.60 %
Iron (Fe) 0.00 – 0.70 % 0.00 – 0.50 %
Titanium (Ti) 0.00 – 0.15 % 0.00 – 0.2 %
Zirconium - 0.00 – 0.25 %
Residuals 0.00 – 0.15 % 0.00 – 0.15 %

6061 vs. 7075 Aluminum: Mechanical Properties

In order to compare the mechanical properties, we mainly distinguish 6061 and 7075 aluminum in terms of yield strength, elasticity, thermal conductivity,electrical resistivity, material hardness,melting point and machinability.

Yield Strength

The yield strength of 7075 aluminum is 503 MPa, while that of 6061 aluminum is 276 MPa. This means that 7075 aluminum has a higher resistance to deformation than 6061 aluminum, indicating that 7075 aluminum can withstand higher impacts and pressures without deformation. In addition, the yield strength of 276 MPa means that 6061 aluminum is not completely fragile.

Elasticity

Elasticity helps you to understand the elasticity of a material and its ability to resist deformation, and is also related to the stiffness of a material. 6061 aluminum has a coefficient of elasticity of 68.9 GPa, while 7075 aluminum has a coefficient of elasticity of 71.7 GPa, and both react similarly to elastic deformation.

Thermal Conductivity

Aluminum alloys are generally good conductors of heat. 6061 aluminum has a thermal conductivity of 167 W/m-K, compared to 130 W/m-K for 7075 aluminum, and it is clear that 6061 aluminum has a slightly higher thermal conductivity than 7075 aluminum. Therefore, it is an excellent material for heat exchangers that require heat dissipation.

Electrical Resistivity

Metals-Aluminum

Both 7075 and 6061 aluminum have low resistivity, 3.99 x 10-⁸ Ω-m for 6061 and 5.10 x 10-⁸ Ω-m for 7075, which indicates that they are both good conductors of electricity and are suitable for use in the electrical industry. In contrast to 7075 aluminum, 6061 has the lowest resistivity. Therefore, it is a better conductor of electricity than 7075 aluminum.

Material Hardness

The hardness of a material determines its ability to resist indentation, penetration, or other deformation. 6061 aluminum has a hardness of 95 HB, and 7075 aluminum has a hardness of 150 HB, which means that both alloys are hard enough to resist pressure without cracking or deforming.

Melting Point

Melting points are reported as a range due to the unique phase state of tempering and variations in the chemical composition of the material. 6061 aluminum has a melting point of 582 to 652°C, and 7075 aluminum has a melting point of 477 to 635°C, which shows that 7075 aluminum has a lower melting point than 6061, which is important for heat treating.

Machinability Comparison Table

The machinability of the material is an important engineering parameter for machining. You can learn about the multiple coefficients of 6061 and 7075 aluminum in the following table to choose a more suitable model for your project.

Properties 6061 Aluminum 7075 Aluminum
Units Imperial Metric Imperial Metric
Yield Strength 40,000 psi 276 MPa 73,000 psi 503 MPa
Melting Point 1080 to 1205°F 582 to 652°C 477 to 635°F 477 to 635°C
Thermal conductivity 1160 BTU-in/hr- ft²-°F 167 W/m-K 900 BTU-in/hr- ft²-°F 130 W/m-K
Elasticity Modulus 10,000 ksi 68.9GPa 10,400 ksi 71.7 Gpa
Electrical Resistivity 3.99 x 10⁻⁸ Ω·m 5.10 x 10⁻⁸ Ω·m
Machinability Good Fair
Hardness (Brinell) 95 150

6061 vs 7075 Aluminum: Applications

6061 and 7075 aluminum alloys overlap somewhat in applications, with both alloys being used to make automotive parts, aerospace components, and consumer products. However, their specific applications differ.

6061 aluminum is a better choice when the product needs to be welded or formed, requires moderate to high tensile strength, or corrosion is a concern, whereas 7075 aluminum is more appropriate when extremely high tensile strength, a high strength-to-weight ratio, and high fatigue resistance are required.

6061 Aluminum Applications

  • Aircraft parts
  • Ship parts
  • Valve parts
  • Camera parts
  • Electrical products
  • Architectural applications

7075 Aluminum Applications

  • Aircraft structures
  • Landing gear
  • Gears and shafts
  • Regulating valves
  • Bearing components of spacecraft

6061 vs 7075 Aluminum FAQs

6061 vs 7075 Aluminum, Which One is More Corrosion Resistant?

6061 aluminum is more corrosion resistant than 7075 aluminum because the copper content in the 7075 alloy is higher than in 6061. Since copper is more reactive to the environment, the higher the content, the more corrosive it is, and 6061 aluminum has more applications in industries where corrosiveness is a concern than 7075 aluminum.

6061 vs 7075 Aluminum, Which One is Heavier?

In terms of weight, 7075 aluminum has a higher strength-to-weight ratio than 6061 aluminum. They are preferred for lightweight applications, such as making lightweight frames for better handling and greater combat range. In terms of strength-to-weight ratio, 6061 aluminum is rated at 115 KN-m/Kg, while 7075 aluminum is rated at 196 KN-m/Kg.

What Are the Prices of 6061 and 7075 Aluminum?

6061 aluminum is more cost-effective, moderately strong, and easy to work with, while 7075 aluminum is very strong and usually has a smoother surface, but costs more. 6061 aluminum is used more frequently than 7075 aluminum, primarily because of the cost difference.

How Weldable Are 6061 and 7075 Aluminum?

In terms of welding performance, 6061 aluminum is weldable, while 7075 is generally considered difficult to weld and machine. Because of its lower hardness and tensile stress, 6061 aluminum alloy may have an advantage in scenarios that require good machining performance and welding performance.

Which Aluminum Responds Better to Anodizing?

The 6XXX series alloys are ideal for anodizing. The oxide layer after the anodizing process is clear and provides excellent protection, and 6061 aluminum is the first choice of many machine shops when parts need to be hard anodized in a variety of colors. 7075 aluminum is also very suitable for anodizing, but if the zinc content is too high, they may anodize to gray, blue-gray, or brown (mottled color).

How Strong Are They?

When looking at both alloys in the "T6 temper," it is noted that the tensile strength of 7075-T6 aluminum is almost twice that of 6061-T6 aluminum. It is estimated that the shear strength of 7075-T6 is 1.5 times that of 6061-T6. Therefore, 7075 T6 aluminum is also significantly harder than 6061-T6.

Conclusion

After reading this blog, I believe you have a basic understanding of 6061 and 7075 aluminum, but if you need to consider which material is more suitable for your project, you may not be sure for a while, because this requires a lot of knowledge and rich experience.

As an ISO 9001 certified processing shop, DEK can help you complete the material selection. If you have a 6061 and 7075 aluminum project, or you are looking for CNC machining aluminum services, please feel free to contact us.

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Austin Peng
Co-founder of DEK
AUTHOR
Hello! I'm Austin Peng. I manage a factory that specializes in CNC machining, injection molding, and sheet metal fabrication for small quantity production and rapid prototyping solutions. When I'm not immersed in work, I love diving into football matches, exploring new travel destinations, enjoying music, and staying updated on the latest tech trends. Feel free to chat with me about anything, whether it's work or life!

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