7178-O Aluminum alloy,Aluminum 7178-O alloy，E FORU

### **7178-O Aluminum Alloy: Annealed Ultra-High Strength Alloy** **7178-O Aluminum Alloy** is the annealed (soft) temper of one of the highest strength commercially available aluminum alloys from the Al-Zn-Mg-Cu series. In the O temper condition, this alloy offers maximum formability and ductility, making it ideal for severe forming operations prior to final heat treatment to achieve its renowned ultra-high strength properties. --- #### **1. Chemical Composition** | Element | Content (%) (Typical) | Role in the Alloy | | :--- | :--- | :--- | | **Zinc (Zn)** | 6.3 - 7.3 | Primary strengthening element through formation of MgZn₂ precipitates | | **Magnesium (Mg)** | 2.4 - 3.1 | Enhances strength and age-hardening response | | **Copper (Cu)** | 1.6 - 2.4 | Improves strength and stress corrosion cracking resistance | | **Chromium (Cr)** | 0.18 - 0.28 | Controls grain structure and improves toughness | | **Iron (Fe)** | ≤ 0.50 | Impurity - controlled for improved consistency | | **Silicon (Si)** | ≤ 0.40 | Impurity - controlled for improved ductility | | **Manganese (Mn)** | ≤ 0.30 | - | | **Titanium (Ti)** | ≤ 0.20 | - | | **Other Elements** | ≤ 0.05 each; ≤ 0.15 total | - | | **Aluminum (Al)** | Balance | Base metal | --- #### **2. Understanding the O Temper** The O temper designation indicates: - **Fully annealed condition** - **Softest state** with maximum ductility - **Recrystallized microstructure** - **Lowest strength** condition - **Ideal for severe forming operations** **Key Characteristics:** - Maximum formability for complex shaping - Homogeneous, stress-relieved microstructure - Base condition for subsequent heat treatment - Uniform mechanical properties --- #### **3. Physical Properties** | Property | Value / Description | | :--- | :--- | | **Density** | 2.82 g/cm³ (0.102 lb/in³) | | **Melting Range** | 477°C - 638°C (890°F - 1180°F) | | **Electrical Conductivity** | 32-36% IACS | | **Thermal Conductivity** | 115-135 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 | Typical Value | | :--- | :--- | | **Tensile Ultimate Strength** | 240 - 280 MPa (35 - 41 ksi) | | **Tensile Yield Strength (0.2% Offset)** | 120 - 160 MPa (17 - 23 ksi) | | **Elongation** | 10-14% | | **Compression Yield Strength** | 115 - 155 MPa (17 - 22 ksi) | | **Shear Strength** | 165 - 195 MPa (24 - 28 ksi) | | **Fatigue Strength** | 95 - 125 MPa (14 - 18 ksi) | | **Brinell Hardness** | 70 - 85 HB | *Note: After solution heat treatment and aging to T6 temper:* - *Tensile Strength: 530-590 MPa (77-86 ksi)* - *Yield Strength: 470-530 MPa (68-77 ksi)* --- #### **5. Product Applications** **7178-O** is primarily used as the starting material for components requiring severe forming: * **Aerospace Components:** * Aircraft structural parts requiring complex forming * Wing components * Fuselage frames * Military aircraft parts * **High-Performance Applications:** * Racing components * High-stress structural parts * Critical machinery components * **Defense Applications:** * Military vehicle components * Armor plates (before final heat treatment) * Defense system structures * **Specialized Applications:** * High-performance sports equipment * Specialized tooling * High-strength fixtures --- #### **6. International Standards** | Standard Body | Designation | Specification | | :--- | :--- | :--- | | **Aluminum Association** | 7178-O | AA Teal Sheets | | **ASTM International** | 7178-O | ASTM B209 / B211 | | **Aerospace (AMS)** | 7178-O | AMS 4046 | | **European Norm** | EN AW-7178 O | EN 485-2 / EN 754-2 | | **Unified Numbering System** | A97178 | UNS Registry | --- #### **7. Key Characteristics** **Advantages:** - **Maximum formability and ductility** - **Ultra-high strength potential** after heat treatment - Good machinability after aging - **Exceptional strength-to-weight ratio** (after heat treatment) - Proven reliability in aerospace applications - Suitable for complex forming operations **Limitations:** - **Lowest strength** in O temper condition - Requires subsequent heat treatment for high-strength applications - Limited use in final applications without heat treatment - Higher cost than other aluminum alloys - Lower corrosion resistance than some other alloys --- #### **8. Manufacturing Considerations** * **Forming:** Excellent - suitable for deep drawing and severe forming operations * **Heat Treatment:** Requires solution treatment and aging for ultra-high strength * **Machining:** Good machinability after heat treatment * **Welding:** Can be welded in O temper, but requires re-heat treatment after welding * **Surface Treatment:** Good for anodizing and other surface treatments --- #### **9. Heat Treatment Process** **Typical Sequence for Achieving Ultra-High Strength:** 1. **Form component** in O temper condition 2. **Solution heat treat** at 460-475°C (860-890°F) 3. **Rapid quench** in water or polymer 4. **Artificial age** at 115-130°C (240-265°F) for 24 hours **Resulting Properties (T6 Temper):** - Tensile Strength: 530-590 MPa - Yield Strength: 470-530 MPa - Elongation: 5-10% --- #### **10. Special Notes** **7178-O Aluminum Alloy** serves as the foundational material for manufacturing ultra-high-strength components that require significant forming during fabrication. The O temper condition allows manufacturers to create complex shapes and severe contours that would be impossible to form in the high-strength T6 condition. The alloy is particularly valuable for applications where: - Complex forming operations are required - Final ultra-high strength properties are needed after forming - Maximum weight reduction is critical - Reliability and performance are paramount **7178-O** represents the essential first step in manufacturing the highest-performance components that will ultimately achieve the exceptional strength properties that make 7178 aluminum one of the strongest commercially available alloys. Its use is typically reserved for the most critically stressed aerospace and defense applications where every kilogram of weight savings translates directly into improved performance and capability.

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 2197 gallon liquid totes Special package is available on request.