Is 7068 stronger than 7075?

Yes, 7068 is stronger than 7075.

7068 aluminum offers higher strength and better fatigue resistance than 7075, but with slightly reduced ductility and corrosion resistance.

• 7068 excels in ultimate strength and hardness, but it sacrifices ductility, corrosion resistance, and machinability. It is ideal for niche, high-stress applications.
• 7075 strikes a balance between strength, machinability, and cost, making it a versatile choice for aerospace and structural applications.

Both 7068 and 7075 are part of the 7xxx series (aluminum-zinc-magnesium-copper alloys) and are known for their high strength. While 7075 aluminum has long been the primary material in aerospace and high-performance applications, 7068 aluminum has emerged as the next-generation alloy, offering higher strength and fatigue resistance. However, these improvements come at the cost of increased processing complexity and, in some cases, reduced corrosion resistance.

• Strength and Fatigue: 7068 aluminum outperforms 7075, with tensile strength about 35% higher and better fatigue resistance, making it ideal for high-stress, critical load-bearing applications.
• Machining: The increased strength of 7068 requires stricter machining and fastening practices; its weldability is inferior to 7075, and alternative assembly methods are typically needed.

While both alloys are prominent in aerospace and high-performance fields, 7068 is favored in areas where maximum strength and weight reduction are crucial, even at the expense of higher production complexity and cost.

While 7075 remains the industry standard for many high-performance applications, 7068 represents an evolution for situations with extremely high strength and durability requirements, especially where fatigue resistance and an excellent strength-to-weight ratio are vital.

7068 vs 7075 aluminum Chemical Composition

7068 vs 7075 Aluminum Mechanical Properties

7068 vs 7075 Aluminum Corrosion Resistance

Both alloys have moderate corrosion resistance, which is typical for the 7xxx series.

7075 is typically protected using coatings (e.g., aluminum cladding). 7068, with its higher alloy content, may have further reduced corrosion resistance, requiring protective measures.

7068 vs 7075 Aluminum Manufacturing and Processing

Machinability:

Both alloys are difficult to machine due to their high strength. However, 7068 has higher strength, meaning machining requires sharper tools, higher speeds, and efficient cooling methods to avoid excessive tool wear or workpiece damage.

Weldability:

Welding high-strength 7xxx series alloys is generally problematic. Particularly, 7068 is more prone to cracking and embrittlement during welding. Therefore, mechanical fastening or adhesive bonding methods are generally preferred.

Due to the weakening of the heat-affected zone, both alloys have poor weldability. 7075 has slightly better formability than 7068.

7068 vs 7075 Aluminum Heat Treatment

Both alloys can be heat treated (T6 temper is common). 7068 may require precise aging processes to reach peak strength.

Both alloys benefit from specific heat treatments. While 7075 is typically available in the T6 temper, 7068 can be processed in T6511 (maximum static strength) or T76/T76511 (balanced strength and improved fracture toughness) tempers. The chosen temper not only affects the final mechanical properties but also influences the material’s resistance to stress corrosion cracking.

7068 vs 7075 Aluminum Cost and Availability

• 7075: Widely available and cost-effective for high-performance applications.
• 7068: Less common and more expensive due to special composition and processing methods.

7068 vs 7075 Aluminum Applications

• 7075: Aerospace frames, bicycle components, military equipment, automotive parts.
• 7068: Extreme stress applications (e.g., aerospace fasteners, high-performance automotive systems, professional sports equipment).

7075 Aluminum:

Due to its high strength and availability, 7075 is widely used in aerospace, automotive, and sports equipment. It is a reliable choice for applications such as aircraft fuselage components, bicycle frames, and other load-bearing structures.

7068 Aluminum:

Designed for the most demanding applications where an extremely high strength-to-weight ratio is crucial. Its superior mechanical properties make it especially suitable for aerospace structural components, defense parts, and high-performance engine components in racing or advanced machinery. Despite its many advantages, the machining challenges and cost of 7068 may limit its usage compared to the more readily available 7075.

7068 and 7075 Aluminum Selection Guide

Choose 7068 for maximum strength where cost and corrosion resistance are secondary. Choose 7075 for a balance of performance, availability, and corrosion resistance.