Higher Strength 7xxx Options

Q: Are there any higher strength 7xxx alternatives to 7075-T6 plate and extrusions?

A: According to Aluminum Standards and Data, the minimum tensile yield strength for 7075-T62 and T651 plate varies from 54.0 ksi to 67.0 ksi, depending on thickness, with the lower value applying to the thickest (4.000”) plate for which properties are registered.  The minimum ultimate tensile strength for 7075-T6, T62, T6510 and T6511 extrusions varies from 68.0 ksi to 72.0 ksi, again depending on thickness.

There are a number of 7xxx plate and extrusion products having higher strengths that have been registered with the Aluminum Association by Alcan (and former Pechiney), Alcoa, Aleris, and Universal Alloy Corporation.  For plate products, a tensile yield strength minimum as high as 86 ksi and an ultimate tensile strength as high as 89 ksi have been registered.  For extrusions, a tensile yield strength minimum as high as 95 ksi and an ultimate tensile strength as high as 99 ksi have been registered.

Tables 1 and 2, below, summarize the longitudinal tensile properties registered for various high strength 7xxx plate and extruded products, respectively.  Actual registrations provide a single value for minimum ultimate tensile strength, tensile yield strength and elongation for a specific thickness range.  In the summary tables below, for simplicity, ranges are given for the entire registered range of production.

Table 1.  Minimum Longitudinal Tensile Properties for High Strength 7xxx Plate Products

Table 2.  Minimum Longitudinal Tensile Properties for High Strength 7xxx Extruded Products

 (a)  Pechiney is now owned by Alcan.

To obtain minimum values for a particular thickness, for transverse minimum properties and for specific notes concerning the resistance to stress corrosion cracking, exfoliation corrosion or fracture toughness, please refer to the publication, Yellow Sheets - Tempers for Aluminum and Aluminum Alloy Products or to specification sheets from the individual producers: 

• Alcoa's 7055 Alloy - T7751 Plate and T77511 Extrusions

• Kaiser's Tube and Pipe Alloy 7068

Other sources of information on these materials are available online.

• "Latest Alloy Development Activities at Universal Alloy Corporation" (abstract only available online for Aeromat 2007 paper on 7136-T76511 & T73511)

• "Airbus and Current Aircrafts Metal Technologies" (K.–H. Rendigs presentation for 8th MMPDS, Sept, 2005 with information on 7449)

* "High Strength Corrosion Resistant 7449-T7651 Alloy for Intermediate Gauge Plates” (Ph. Lequeu et. al. presentation on 7449-T7651 for Aeromat 2003)

*  "Advanced Metallic & Hybrid Structural Concepts" (R. J. Bucci presentation for USAF Structural Integrity Program Conference (ASIP 2006), San Antonio, TX, November 29, 2006, covering Alcoa’s recent programs on advanced structural concepts for wing and fuselage applications and mentioning 7085)

• "Modeling of 7081 Plate Applications for High Performance-Cost Efficient Aircraft Structures" (abstract only available online for Aeromat 2007 paper on Aleris’ 7081-T7651 and T7451)

• "Improved Aluminium Sheet and Plate Alloys for Aircraft Fuselage, Wing and Integrated Structures" (abstract only available online for Aeromat 2007 paper on Aleris’ 7081-T7651 and T7451)

Related Links