Alclad 7475-T761 Aluminum alloy,Aluminum 7475-T761 alloy，E FORU

### **Product Introduction: Alclad 7475-T761 Aluminum Alloy** **Alclad 7475-T761** is a premium aerospace-grade aluminum product engineered for critical applications requiring an exceptional combination of **high fracture toughness**, **superior fatigue performance**, and **maximum resistance to exfoliation and stress corrosion cracking (SCC)**. It consists of a high-strength **7475 aluminum alloy core** that is clad on both surfaces with a thin, metallurgically bonded layer of pure aluminum or a low-potential alloy. The **T761 temper** is a specific over-aged condition that prioritizes corrosion resistance and stability, making it ideal for thick sections and long-term service in demanding environments. --- ### **1. Chemical Composition** The properties are defined by the core alloy's tightly controlled composition and the protective Alclad cladding. **A. Core Alloy: 7475 Chemical Composition (% by Weight)** | Element | Content | | :--- | :--- | | **Aluminum (Al)** | Balance | | **Zinc (Zn)** | 5.2 - 6.2 | | **Magnesium (Mg)** | 1.9 - 2.6 | | **Copper (Cu)** | 1.2 - 1.9 | | **Chromium (Cr)** | 0.18 - 0.25 | | **Iron (Fe)** | ≤ 0.12 | | **Silicon (Si)** | ≤ 0.10 | | **Manganese (Mn)** | ≤ 0.06 | | **Titanium (Ti)** | ≤ 0.05 | | **Other Impurities** | ≤ 0.05 each; ≤ 0.15 total | *Key Point: 7475 is a controlled-toughness variant of 7075, with stricter limits on impurities (Fe, Si) to maximize fracture toughness and fatigue resistance.* **B. Alclad Cladding:** The core is clad on both sides with a layer of high-purity aluminum or a dedicated anode alloy (e.g., 7072). This layer, typically 1.5-5% of the total thickness per side, acts as a **sacrificial anode**, corroding in preference to the strong, high-copper core, thereby providing superior corrosion protection. --- ### **2. Physical Properties** The physical properties are dominated by the core 7475 alloy. | Property | Metric Value | Imperial Value | | :--- | :--- | :--- | | **Density** | ~2.80 g/cm³ | ~0.101 lb/in³ | | **Melting Range** | ~ 475 - 635 °C | ~ 887 - 1175 °F | | **Electrical Conductivity** | ~ 35-40% IACS | - | | **Thermal Conductivity** | ~ 130 W/m·K | - | | **Modulus of Elasticity** | 71 GPa | 10.3 x 10⁶ psi | --- ### **3. Mechanical Properties** The **T761 temper** is critical. It indicates the material has been: * **Solution Heat Treated** * **Stress-Relieved by Stretching** (typically to a permanent set of 1.5-3% for plate) * **Artificially Over-Aged** to a specific condition that provides excellent exfoliation and stress corrosion cracking resistance. This over-aging results in a slight sacrifice in strength compared to the T6 temper, but a significant gain in corrosion resistance and stability. **Typical Room Temperature Mechanical Properties (Plate - T761 Temper)** | Property | Value (Metric) | Value (Imperial) | | :--- | :--- | :--- | | **Tensile Ultimate Strength** | 510 - 538 MPa | 74 - 78 ksi | | **Tensile Yield Strength (0.2% Offset)** | 441 - 469 MPa | 64 - 68 ksi | | **Elongation at Break** | 11 - 13% | 11 - 13% | | **Compressive Yield Strength** | ~ 441 MPa | ~ 64 ksi | | **Fracture Toughness (K꜀)** | Very High | Very High | *The hallmark of 7475 is its exceptional fracture toughness, which is retained even in the over-aged T76 temper, making it superior to 7075 in damage tolerance.* --- ### **4. International Standards** Alclad 7475-T761 is specified in key aerospace standards, particularly for plate product forms. * **Aerospace Material Specifications (AMS):** * **AMS 4204:** This standard often covers Alclad 7475 plate in various tempers, including the T76 range. The specific revision of the standard will call out the T761 temper requirements for properties and corrosion resistance. * **ASTM International:** * **ASTM B209:** Standard Specification for Aluminum and Aluminum-Alloy Sheet and Plate. This is the overarching standard that defines the requirements for 7475 alloy products. * **OEM Standards:** * It is widely used and specified under proprietary material standards from major aerospace manufacturers like **Boeing (BMS)** and **Airbus**, which will have detailed requirements for the T761 temper. --- ### **5. Product Applications** Alclad 7475-T761 is selected for the most critical damage-tolerant structures where long-term corrosion resistance is mandatory. * **Aerospace Structures:** * **Lower Wing Skins and Panels:** Where high tensile loads, superior fatigue life, and resistance to corrosive environments are paramount. * **Fuselage Skins:** Especially for areas prone to fatigue cracking or operating in marine environments. * **Bulkheads and Frame Members:** In thick sections where through-thickness corrosion resistance is critical. * **Military Aircraft Structural Components.** * **Other High-Performance Applications:** * **Critical components in space launch vehicles** where reliability and resistance to stress corrosion are non-negotiable. --- ### **6. Key Characteristics & Advantages** * **Excellent Resistance to Exfoliation and Stress Corrosion Cracking (SCC):** The **T761 over-aged temper** is the primary advantage, making it suitable for thick sections and service in severe environments. * **Exceptional Fracture Toughness:** The 7475 core alloy provides superior resistance to crack propagation compared to other 7xxx series alloys at similar strength levels. * **Superior Corrosion Protection:** The Alclad layer provides sacrificial (cathodic) protection, effectively isolating the core from corrosive attack. * **Excellent Fatigue Performance:** The combination of a tough core and a smooth, crack-inhibiting Alclad surface results in outstanding fatigue life. ### **Considerations** * **Strength vs. T6 Temper:** The T761 temper offers lower mechanical strength than the peak-aged T61 temper. The selection is a trade-off favoring corrosion resistance over maximum strength. * **Cladding:** The soft Alclad layer must be considered in machining and design, but it is essential for the product's corrosion and fatigue performance. * **Weldability:** Generally not recommended for fusion welding; components are typically joined with mechanical fasteners. * **Cost:** A premium, specialty aerospace material, it is more expensive than standard alloys. ### **Conclusion** **Alclad 7475-T761 Aluminum Alloy** is a high-reliability material designed for the most demanding damage-tolerant aerospace applications where environmental durability is a critical design constraint. It provides an optimal balance of high toughness, excellent fatigue life, and maximum corrosion resistance, making it an indispensable choice for primary aircraft structures like lower wings and fuselages that must endure decades of service under tensile loads and in corrosive conditions. The T761 temper specifically ensures long-term structural integrity by prioritizing resistance to exfoliation and stress corrosion cracking.

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 2213 gallon liquid totes Special package is available on request.