7068-T76; 7068-T76511 Aluminum alloy,Aluminum 7068-T76; 7068-T76511 alloy，E FORU

### **7068-T76 / 7068-T76511 Aluminum Alloy: High-Strength with Enhanced Corrosion Resistance** **7068 Aluminum Alloy** in T76 and T76511 tempers represents an optimized version of this ultra-high strength aluminum-zinc-magnesium-copper alloy, offering an improved balance between mechanical strength and corrosion resistance for demanding aerospace and defense applications. --- #### **1. Chemical Composition** | Element | Content (%) (Typical) | Role in the Alloy | | :--- | :--- | :--- | | **Zinc (Zn)** | 7.3 - 8.3 | Primary strengthening element through formation of MgZn₂ precipitates | | **Magnesium (Mg)** | 2.5 - 3.3 | Enhances strength and work hardening characteristics | | **Copper (Cu)** | 1.6 - 2.4 | Improves strength and stress corrosion cracking resistance | | **Zirconium (Zr)** | 0.05 - 0.15 | Controls grain structure and inhibits recrystallization | | **Iron (Fe)** | ≤ 0.15 | Impurity - controlled for improved toughness | | **Silicon (Si)** | ≤ 0.12 | Impurity - controlled for improved ductility | | **Manganese (Mn)** | ≤ 0.10 | - | | **Chromium (Cr)** | ≤ 0.05 | - | | **Titanium (Ti)** | ≤ 0.10 | - | | **Other Elements** | ≤ 0.05 each; ≤ 0.15 total | - | | **Aluminum (Al)** | Balance | Base metal | --- #### **2. Understanding the T76 and T76511 Tempers** **T76 Temper:** - Solution heat-treated and artificially over-aged - Enhanced corrosion resistance compared to T6 temper - Good balance of strength and corrosion resistance - Improved stress corrosion cracking resistance **T76511 Temper:** - Solution heat-treated, stress-relieved by stretching, and artificially over-aged - Specifically for extruded products - Improved dimensional stability - Enhanced exfoliation corrosion resistance - Maintains high strength while providing better corrosion performance --- #### **3. Physical Properties** | Property | Value / Description | | :--- | :--- | | **Density** | 2.85 g/cm³ (0.103 lb/in³) | | **Melting Range** | 475°C - 635°C (887°F - 1175°F) | | **Electrical Conductivity** | 38-43% IACS | | **Thermal Conductivity** | 120-135 W/m·K | | **Coefficient of Thermal Expansion** | 23.5 × 10⁻⁶/°C (20-100°C) | | **Modulus of Elasticity** | 71 GPa (10.3 × 10⁶ psi) | --- #### **4. Mechanical Properties (Typical)** | Property | T76 Temper | T76511 Temper | | :--- | :--- | :--- | | **Tensile Ultimate Strength** | 570 - 610 MPa (83 - 88 ksi) | 560 - 600 MPa (81 - 87 ksi) | | **Tensile Yield Strength (0.2% Offset)** | 520 - 560 MPa (75 - 81 ksi) | 510 - 550 MPa (74 - 80 ksi) | | **Elongation** | 10-13% | 11-14% | | **Compression Yield Strength** | 510 - 550 MPa (74 - 80 ksi) | 500 - 540 MPa (73 - 78 ksi) | | **Shear Strength** | 320 - 350 MPa (46 - 51 ksi) | 310 - 340 MPa (45 - 49 ksi) | | **Fatigue Strength** | 170 - 190 MPa (25 - 28 ksi) | 165 - 185 MPa (24 - 27 ksi) | | **Brinell Hardness** | 145 - 160 HB | 140 - 155 HB | --- #### **5. Product Applications** **7068-T76/T76511** is used in applications requiring both high strength and good corrosion resistance: * **Aerospace Structures:** * Upper wing components * Fuselage frames * Wing ribs and spars * Structural brackets * **Marine & Offshore:** * Marine aircraft components * Ship structures * Offshore platform components * **Defense Applications:** * Military vehicle components * Naval equipment * Defense system structures * **Industrial Applications:** * High-strength structural components * Machinery parts * Material handling equipment --- #### **6. International Standards** | Standard Body | Designation | Specification | | :--- | :--- | :--- | | **Aluminum Association** | 7068-T76 / 7068-T76511 | AA Teal Sheets | | **ASTM International** | 7068-T76 / 7068-T76511 | ASTM B221 | | **Aerospace (AMS)** | 7068 | AMS 4338 | | **European Norm** | EN AW-7068 T76 / T76511 | EN 755-2 | | **Unified Numbering System** | A97068 | UNS Registry | --- #### **7. Key Characteristics** **Advantages:** - **High strength** with improved corrosion resistance - Excellent exfoliation corrosion resistance - Good stress corrosion cracking resistance - Enhanced dimensional stability (T76511) - Good fatigue performance - Superior strength-to-weight ratio **Limitations:** - Slightly lower strength than T6 temper - Higher cost than conventional alloys - Requires controlled heat treatment - Limited formability in aged condition --- #### **8. Manufacturing Considerations** * **Machining:** Good machinability with proper tooling * **Forming:** Best formed in annealed condition * **Welding:** Requires specialized techniques * **Heat Treatment:** Precise control required for optimal properties * **Corrosion Protection:** Good inherent resistance but may require protection in severe environments --- #### **9. Special Notes** The T76 and T76511 tempers provide an excellent compromise between mechanical strength and corrosion resistance: - **T76511** is particularly suitable for extruded products requiring precise machining and dimensional stability - The over-aging process improves corrosion resistance while maintaining high strength - These tempers are preferred for applications where both mechanical performance and durability in corrosive environments are important - The alloy maintains good fracture toughness and damage tolerance characteristics **7068-T76/T76511** offers a superior balance of properties for applications where the ultra-high strength of 7068-T6 is required, but additional corrosion resistance is necessary for long-term service in demanding environments.

Packing of Standard Packing: Typical bulk packaging includes palletized plastic 5 gallon/25 kg. pails, fiber and steel drums to 1 ton super sacks in full container (FCL) or truck load (T/L) quantities. Research and sample quantities and hygroscopic, oxidizing or other air sensitive materials may be packaged under argon or vacuum. Solutions are packaged in polypropylene, plastic or glass jars up to palletized 2161 gallon liquid totes Special package is available on request.