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Aluminium 6061 vs. 7075:Which One is Best for Your Project

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Aluminium alloys play a pivotal role in various industries, offering a balance between strength, weight, and corrosion resistance. In the realm of aluminum, two popular alloys frequently compared are Aluminium 6061 and 7075. Understanding their differences is crucial for making informed decisions in material selection.
Aluminium 6061 vs. 7075

What is 6061 aluminum alloy?

Aluminium 6061 is a widely recognized alloy in the 6000 series, known for its versatility and balance between strength, weight, and workability. It primarily contains magnesium and silicon as its major alloying elements, which contribute to its favourable properties. This alloy is often referred to as a “structural” aluminum due to its ability to be used in structural applications where strength and durability are crucial.

What is 7075 aluminum alloy?

Aluminium 7075 stands out in the 7000 series as one of the highest-strength alloys available, primarily attributed to its zinc as the primary alloying element. This alloy is renowned for its excellent mechanical properties, particularly its high strength and toughness, making it a preferred choice for high-performance applications. Aluminium 7075 is also known for its use in applications requiring high stress and strain resistance.

6061 Vs 7075 aluminum: Chemical Composition

Here is a comparison table summarizing the chemical composition differences between Aluminum 6061 and 7075.

Chemical Elements 6061 Aluminum 7075 Aluminum
Magnesium 0.8-1.2% 2.1-2.9%
Silicon 0.4-0.8% Max 0.4%
Iron Max 0.7% Max 0.5%
Copper 0.15-0.4% 1.2-2.0%
Manganese Max 0.15% Max 0.3%
Chromium 0.04-0.35% 0.18-0.28%
Zinc Max 0.25% 5.1-6.1%
Titanium 0.15% 0.16%
Aluminum Remainder Remainder

Mechanical Properties

Property Aluminum 6061 Aluminum 7075
Tensile Strength 18,000 to 35,000 psi 33,000 to 78,000 psi
Yield Strength 8,000 to 30,000 psi 23,000 to 73,000 psi
Hardness (Brinell) 95 HB 150 HB
Elongation 10-15% in 2” 9-18% in 2”
Density 2.7 g/cm³ 2.81 g/cm³
Thermal Conductivity 167 W/m-K 130 W/m-K
Melting Point 582-652°C (1080-1205°F) 475-635°C (890-1175°F)
  • Strength: Aluminum 7075 is significantly stronger than 6061, both in terms of tensile and yield strength, primarily due to its higher zinc, magnesium, and copper content.
  • Hardness: With a Brinell hardness value significantly higher, 7075 is harder than 6061, making it more resistant to wear and tear.
  • Elongation: Both alloys show good ductility, but the specific elongation can vary depending on the temper and processing.
  • Thermal Conductivity: Aluminum 6061 has higher thermal conductivity than 7075, making it better suited for applications requiring efficient heat dissipation.
  • Density: There is a slight difference in density, with 7075 being a bit denser due to its higher content of alloying elements like zinc and copper.
  • Melting Point: The melting point of 6061 is generally higher, indicating different thermal stability under high temperatures.

Physical Properties

To complete the comparison, we’ll now focus on the physical properties of Aluminum 6061 and 7075. These properties include aspects such as weldability, corrosion resistance, formability, and machinability. Here’s how the two types of aluminum compare.

Property Aluminum 6061 Aluminum 7075
Weldability Excellent Fair to Good
Corrosion Resistance Good Good, but less than 6061
Formability Excellent Good, but less than 6061
Machinability Good Good
Conductivity Good electrical conductivity Lower than 6061
Coating/Finish Quality Excellent (clear anodic coatings) Good (can be more susceptible to stress corrosion cracking)
  • Weldability: Aluminum 6061 is known for its excellent weldability, making it ideal for applications involving welding. On the other hand, 7075 is weldable but requires more care and may not perform as well under the same conditions due to its higher susceptibility to cracking.
  • Corrosion Resistance: While both materials have good corrosion resistance, 6061 has a slight edge, especially in environments that are wet or corrosive. This makes 6061 a better choice for marine applications.
  • Formability: 6061 is easier to form into complex shapes and is ideal for projects requiring extensive machining or forming. Although 7075 can also be formed, it is generally considered less formable compared to 6061.
  • Machinability: Both alloys are considered to have good machinability, but the specific cutting conditions may vary due to the differences in their hardness and strength.
  • Conductivity: 6061 typically has better electrical conductivity, which can be advantageous in electrical and electronic applications.
  • Coating/Finish Quality: Aluminum 6061 typically achieves a better surface finish in anodizing processes, making it suitable for applications where aesthetics are important. While 7075 can also be anodized, it may be more prone to cosmetic flaws and stress corrosion cracking.
6061 vs 7075 aluminum

Applications of 7075 Aluminum vs 6061 Aluminum

Applications of both 7075 and 6061 aluminum alloys vary significantly due to their differing physical properties.

Applications of 6061 Aluminum

  1. General Fabrication: Due to its excellent weldability and formability, 6061 is widely used in structures requiring welding and complex shapes, including frames, brackets, and machinery components.
  2. Automotive Parts: It’s used in automotive parts that benefit from its good strength-to-weight ratio and corrosion resistance, such as wheels and chassis parts.
  3. Marine Construction: Its good corrosion resistance makes it suitable for marine applications, including boat hulls, gangways, and other marine structures.
  4. Electrical Components: Its good electrical conductivity allows it to be used in electrical fittings, connectors, and various components in electrical and electronic devices.
  5. Construction: Aluminum 6061 is used in construction for window frames, doors, roofing, and architectural trim due to its good strength, durability, and aesthetics.

Applications of 7075 Aluminum

  1. Aerospace Components: 7075’s high strength and lightweight make it ideal for aircraft structures, such as wing spars, fuselage frames, and other high-stress parts.
  2. Sporting Equipment: Its high strength-to-weight ratio is perfect for high-performance sporting equipment like bicycle frames, climbing equipment, and baseball bats.
  3. Military Applications: Due to its high strength, it is used in military applications, including armored vehicles and military grade weapons.
  4. Tooling and Mold Making: 7075’s hardness and strength make it suitable for molds, tooling, and other applications where wear resistance is critical.
  5. High-Stress Applications: Any application that requires a high strength-to-weight ratio and can tolerate the alloy’s lesser formability and weldability may benefit from using 7075.
6061 Aluminum

Choosing between 6061 and 7075 aluminum alloys requires evaluating the specific requirements of your project and balancing factors such as strength, weldability, formability, and corrosion resistance.

1. If your project requires high strength, but you can sacrifice some formability, choose 7075 aluminum. If medium strength meets the needs of your project, but formability is important, then 6061 aluminum is a better choice.

2. For projects involving a large number of welds or complex shapes, 6061 is preferred for its excellent weldability and formability. If the manufacturing process involves applications that require abrasion resistance or fewer welded parts, 7075 should be considered.

3. 6061 has better corrosion resistance and is better suited for applications in corrosive environments, such as marine applications.If corrosion resistance is not required or can be controlled by coatings and treatments, the high strength of 7075 may be advantageous.

EASIAHOME has a team with over 17 years of machining experience, as well as ISO 9001 certification, and is focused on assisting you in making an informed choice in your material selection. If you need professional services for CNC machining 6061 or 7075 aluminum, please feel free to contact us.

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