7278A Aluminum alloy,Aluminum 7278A alloy，E FORU

### **Product Introduction: 7278A Aluminum Alloy** **Aluminum 7278A** is a premium, high-strength alloy within the Al-Zn-Mg-Cu (7xxx series) family. It is an evolution of the standard 7278 alloy, typically characterized by tighter compositional controls and enhanced properties to meet the demanding requirements of modern aerospace and defense applications. It offers an exceptional strength-to-weight ratio, making it a critical material for the most heavily loaded structures. --- ### **1. Chemical Composition** The chemical composition of 7278A is precisely controlled to ensure superior performance and consistency. The "A" variant often implies stricter limits on impurities and minor alloying elements to enhance toughness and corrosion resistance. **Typical Composition (% by Weight)** | Element | Content | | :--- | :--- | | **Aluminum (Al)** | Balance | | **Zinc (Zn)** | 5.2 - 6.2 | | **Magnesium (Mg)** | 2.0 - 2.8 | | **Copper (Cu)** | 1.8 - 2.4 | | **Chromium (Cr)** | 0.18 - 0.28 | | **Zirconium (Zr)** | (May be present as an alternative to Cr) | | **Iron (Fe)** | ≤ 0.12 | | **Silicon (Si)** | ≤ 0.10 | | **Manganese (Mn)** | ≤ 0.05 | | **Titanium (Ti)** | ≤ 0.05 | | **Other Impurities** | ≤ 0.05 each; ≤ 0.15 total | *Note: The use of Zirconium (Zr) instead of or in combination with Chromium (Cr) is common in advanced 7xxx alloys to improve quench sensitivity and through-thickness properties in thick sections.* --- ### **2. Physical Properties** The physical properties of 7278A are consistent with other high-strength aluminum alloys. | Property | Metric Value | Imperial Value | | :--- | :--- | :--- | | **Density** | 2.85 g/cm³ | 0.103 lb/in³ | | **Melting Range** | ~ 477 - 635 °C | ~ 890 - 1175 °F | | **Electrical Conductivity** | ~ 30-35% IACS | - | | **Thermal Conductivity** | ~ 130 W/m·K | - | | **Modulus of Elasticity (E)** | 71 GPa | 10.3 x 10⁶ psi | --- ### **3. Mechanical Properties** Mechanical properties are highly dependent on the temper (heat treatment condition). The T651 temper is common for peak strength, while T76/T74 and T73 are over-aged tempers for improved corrosion resistance. **Typical Room Temperature Mechanical Properties (Plate - T651 Temper)** | Property | Value (Metric) | Value (Imperial) | | :--- | :--- | :--- | | **Tensile Ultimate Strength** | 620 - 665 MPa | 90 - 96 ksi | | **Tensile Yield Strength (0.2% Offset)** | 570 - 610 MPa | 83 - 88 ksi | | **Elongation at Break** | 8 - 11% | 8 - 11% | | **Hardness (Brinell)** | ~ 170 HB | ~ 170 HB | *Note: The T77 temper (a thermomechanical process) may also be applicable, offering an excellent combination of strength, toughness, and corrosion resistance without the significant strength loss associated with traditional over-aging.* --- ### **4. International Standards** 7278A is specified in several key international standards, which define its requirements for aerospace and other high-performance industries. * **Aerospace Material Specifications (AMS):** * **AMS 4203:** This is a primary specification for 7278 alloy plate and sheet. The "A" version may be called out by specific revisions or customer-specific requirements within this standard, often with tighter controls. * **ASTM International:** * **ASTM B209:** Standard Specification for Aluminum and Aluminum-Alloy Sheet and Plate. This standard covers the 7278 alloy, with the "A" designation typically referring to a specific, controlled version per this standard. * **European Standards (EN):** * It may be covered under **EN 485** (Sheet, strip and plate) but is more commonly specified by proprietary or aerospace-specific standards like **AMS**. * **Other:** It is often procured to specific OEM (Original Equipment Manufacturer) standards from major aerospace companies (e.g., Airbus, Boeing), which impose additional stringent requirements. --- ### **5. Product Applications** 7278A is engineered for the most critical and highly stressed components, primarily in: * **Aerospace Structures:** * **Upper Wing Skins:** For commercial and military aircraft, where compression strength is paramount. * **Fuselage Frames and Bulkheads:** Providing high strength and damage tolerance. * **Spar Caps and Stringers:** In wing and empennage structures. * **Defense Applications:** * **Military Aircraft Landing Gear Components** (typically as die forgings). * **Armored Vehicle Structures:** Where a high strength-to-weight ratio is critical for mobility and protection. * **High-Performance Industrial & Sporting Goods:** * Critical components in auto-racing suspensions. * High-end bicycle frames and components. * Equipment for mountaineering and other extreme sports. --- ### **6. Key Characteristics & Advantages** * **Ultra-High Strength:** Provides one of the highest strength levels available in aluminum alloys. * **Superior Strength-to-Weight Ratio:** Essential for reducing weight in aerospace and mobility applications. * **Good Fracture Toughness:** Resists crack propagation, a critical property for aerospace structural integrity. * **Enhanced Property Consistency:** The "A" designation and tighter controls ensure more uniform properties throughout the product form. * **Good Fatigue Performance:** Withstands cyclic loading well, which is crucial for dynamic structures like aircraft wings. ### **Considerations** * **Corrosion Resistance:** In the peak-strength T6-type temper, it is susceptible to stress corrosion cracking. For applications in corrosive environments, the use of over-aged tempers (T76, T73, T74) or the advanced T77 temper is mandatory. * **Weldability:** Generally considered poor for arc welding; components are typically joined using mechanical fasteners (rivets, bolts). * **Machinability:** It machines well in the T6 temper, but its high strength requires robust machinery and appropriate tooling. * **Cost:** A premium alloy, it is more expensive than standard 7xxx series alloys like 7075 due to its specialized processing and stringent quality controls. ### **Conclusion** **Aluminum 7278A alloy** represents the high-end of aluminum structural materials. Its optimized chemistry and controlled processing make it the go-to choice for engineers designing the most critical, weight-sensitive, and heavily loaded components in the aerospace and defense sectors, where maximizing performance and safety is non-negotiable.

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 2209 gallon liquid totes Special package is available on request.