Selecting the right aluminum alloy requires balancing strength, cost, availability, manufacturability, and application requirements. Here's how 7068 compares to the more widely-used 7075 and the cost-effective 6061:
7068 Aluminum represents the pinnacle of commercial aluminum strength, but comes with trade-offs in cost, availability, and workability. 7075 offers an excellent balance of strength and availability, making it the industry standard for aerospace applications. 6061 provides good strength with superior formability, weldability, and corrosion resistance at a lower cost point.
The choice depends on your specific requirements: if maximum strength is non-negotiable and budget is secondary, 7068 may be justified. For most aerospace applications, 7075 provides sufficient strength with better availability. For general industrial applications where extreme strength isn't critical, 6061 offers the best value proposition.
Aluminum Alloy Comparison: 7068 vs 7075 vs 6061
| Property | 7068-T6511 | 7075-T6 | 6061-T6 |
|---|
| Ultimate Tensile Strength | 710 MPa | 572 MPa | 310 MPa |
| Yield Strength | 683 MPa | 503 MPa | 276 MPa |
| Elongation at Break | 8-10% | 11% | 12-17% |
| Density | 2.85 g/cm³ | 2.81 g/cm³ | 2.70 g/cm³ |
| Corrosion Resistance | Fair | Fair | Good |
| Weldability | Poor | Poor | Excellent |
| Machinability | Fair | Good | Good |
| Formability | Limited | Limited | Good |
| Cost (Relative) | Highest | High | Moderate |
| Availability | Limited | Wide | Very Wide |
| Typical Lead Time | 4-8 weeks | 2-4 weeks | 1-2 weeks |
Comparative data from aerospace-aluminum.com, Wikipedia, and industry sources
[2][4]Key Differentiators:
Strength: 7068 delivers approximately 35% higher tensile strength than 7075, and 129% higher than 6061. This makes 7068 suitable for applications where weight savings are critical and stress levels exceed 7075's capabilities [4].
Cost: 7068 commands a significant price premium due to:
- Limited production volume (economies of scale favor 7075)
- More complex manufacturing process
- Specialized heat treatment requirements
- Higher raw material costs (increased zinc and magnesium content)
Buyers should expect to pay 30-50% more for 7068 compared to 7075, and 2-3 times more than 6061, depending on form, quantity, and supplier.
Availability: 7075 is widely stocked by distributors globally, while 7068 often requires mill-direct orders with longer lead times. 6061 is the most readily available aluminum alloy, stocked by virtually every metal distributor.
Manufacturing Considerations:
Welding: Both 7068 and 7075 have poor weldability due to hot cracking susceptibility. Mechanical fastening or adhesive bonding is preferred. 6061 excels in weldability, making it preferable for fabricated assemblies.
Machining: 7075 machines well with proper tooling. 7068 is more challenging due to higher strength and work hardening tendency. 6061 offers the best machinability of the three.
Heat Treatment: All three alloys are heat-treatable, but 7068 requires more precise control to achieve optimal properties.
7068 has greater strength than 7075, but 7075 is more widely available and cost-effective for most applications. The 35% strength advantage of 7068 must be weighed against 30-50% higher cost and limited availability. [4]
