When selecting an aluminum alloy for a structural or fabrication application, engineers are often faced with choosing between 2024, 7075 and 6061, each with their own set of advantages and limitations. This article examines the key differences between 2024, 7075 and 6061 aluminum alloys, providing guidance on their most suitable uses to help with material selection decisions.
What’s 2024 Aluminum?
2024 aluminum is a heat-treatable alloy comprised predominantly of aluminum along with 3-5% copper and up to 1.5% magnesium. The addition of these alloying elements, particularly copper, gives 2024 aluminum significantly greater strength than pure aluminum or other common alloys such as 6061. Through a process of solution heat treatment and artificial aging, the alloy’s properties can be optimized to achieve a tensile strength approaching 500 MPa.
What’s 6061 Aluminum?
6061 aluminum is a precipitation-hardened aluminum alloy containing about 0.6-1.2% copper, 0.6-1.2% magnesium, and 0.4-0.8% silicon as its major alloying elements. Compared to other heat-treatable alloys like 2024, 6061 aluminum has moderate strength but excellent corrosion resistance due to a protective oxide layer that forms on its surface. With a tensile strength of around 310 MPa, 6061 is easier to machine, form, and join than high-strength alloys, making it a popular choice when good weldability, corrosion protection and moderate strength are required.
What’s 7075 Aluminum?
7075 aluminum is a high-strength aluminum alloy containing significant amounts of zinc (5.1-6.1%) and magnesium (2.1-2.9%) to provide stronger mechanical properties than other common heat-treatable alloys like 2024 and 6061. Through proper heat treatment, 7075 aluminum can achieve tensile strengths exceeding 500 MPa, making it suitable for applications requiring maximum load-bearing capabilities. However, its high zinc composition also makes 7075 aluminum fairly brittle and difficult to machine compared to other alloys.
2024 vs 6061, What’s the Difference?
Composition:
2024 contains 3.8-4.9% copper which gives it higher strength properties. 6061 contains 0.6-1.2% copper. 6061 contains 1.2% magnesium and 0.6% silicon which provide better corrosion resistance than 2024.
Mechanical Properties:
2024 has a tensile strength of around 485 MPa compared to 6061’s 310 MPa. 6061 has lower strength but greater ductility (about 10% elongation) than 2024 (5-10% elongation). 2024 can significantly increase strength through heat treatment processes while 6061’s properties are more static.
Corrosion Resistance:
2024 has lower corrosion resistance due to its higher copper content. Requires protective coatings. 6061 forms a protective aluminum oxide layer and has good resistance to atmospheric and many chemical exposures.
Machinability:
2024 work hardens more during machining so is more difficult to machine than 6061. 6061 cuts more smoothly and holds a sharper edge through machining processes.
Applications:
2024 is used where high strength is critical like aircraft structures. 6061 is better for general fabrication and architectural/industrial applications needing strength and corrosion resistance. 6061 is less expensive to produce and fabricate compared to heat treatable 2024 alloy.
2024 vs 7075, What’s the Difference?
Composition:
2024 contains 3.8-4.9% copper as the primary strengthening element. 7075 contains significantly more zinc (5.1-6.1%) and magnesium (2.1-2.9%) as its main alloying constituents.
Mechanical Properties:
7075 has higher tensile strength, typically around 500 MPa vs 485 MPa for 2024. 7075 has slightly lower ductility, around 5% elongation vs 5-10% for 2024. Both alloys are heat treatable to optimize properties.
Corrosion Resistance:
2024 has lower corrosion resistance than 7075 due to higher copper content. Requires protection. 7075 forms a protective oxide layer and is more resistant to environmental damage.
Machinability:
7075 is tougher to machine than 2024 due to work hardening from its zinc content. 2024 cuts cleaner but requires lubricants for machining 7075 alloy.
Applications:
2024 is commonly used in airframes and other airborne structures. 7075 is found in high-strength structures like helicopter gearboxes requiring durability. 7075 is more costly to produce but favored where ultimate strength is critical.
The Key Differences Between Aluminum Alloys 2024, 7075 & 6061
2024, 7075 and 6061 aluminum alloys each have their own distinct material properties and suitability for different applications. Of the three, 7075 aluminum delivers the highest strength but at the expense of machinability and formability. 2024 provides excellent strength-to-weight performance along with good workability, making it well-adapted for structural uses. The 6061 alloy strikes a favorable balance of properties with above-average strength combined with outstanding corrosion resistance and ease of fabrication. Overall, 6061 aluminum is generally the most versatile and cost-effective choice for multi-purpose manufacturing. Meanwhile, specialized designs requiring absolute maximum strength properties may necessitate 7075 alloy. And when high performance strength is prioritized, 2024 aluminum offers viable advantages. The right alloy selection depends on the specific performance needs and limitations of the intended product or component design.
| Property | 2024 AL | 7075 AL | 6061 AL |
| Composition | 4-5% Cu | 4-5% Cu | 4-5% Cu |
| Tensile Strength (MPa) | ~485 | ~500 | ~310 |
| Elongation (%) | 5-10% | 5% | 10% |
| Hardness (HB) | 95-120 | 110-150 | 80-95 |
| Density (g/cm3) | 2.77 | 2.81 | 2.7 |
| Corrosion Resistance | Low, requires protection | Moderate | Good, forms oxide layer |
| Machinability | Good | Poor, work hardens | Excellent |
| Fatigue Strength | High | Very high | Moderate |
| Formability | Good | Limited | Good |
| Welding | Good for thin sheets | Difficult | Easy |
| Typical Applications | Airframes, structural parts | Gearboxes, rotors | General fabrication, automotive |
| Cost | Moderate | High | Low |
| Heat Treatability | Yes, increases strength | Yes, increases strength | Minimal strengthening |