7178-T6, T651 Aluminum alloy,Aluminum 7178-T6, T651 alloy，E FORU

### **7178-T6, T651 Aluminum Alloy: Ultra-High Strength Aerospace Alloy** **7178-T6 and 7178-T651** represent the peak-aged tempers of one of the strongest commercially available aluminum alloys. These tempers provide exceptional strength-to-weight ratio, making 7178 the preferred choice for highly stressed structural applications in aerospace, defense, and high-performance industries where maximum strength is required. --- #### **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 T6 and T651 Tempers** **T6 Temper:** - Solution heat-treated and artificially aged to peak strength - Maximum strength condition - May contain residual stresses from quenching **T651 Temper:** - Solution heat-treated, stress-relieved by stretching (1-3% permanent set), and artificially aged - Reduced residual stresses - Improved dimensional stability for machining - Preferred for critical applications requiring precise dimensions --- #### **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** | 120-140 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 | T6 Temper | T651 Temper | | :--- | :--- | :--- | | **Tensile Ultimate Strength** | 530 - 590 MPa (77 - 86 ksi) | 520 - 580 MPa (75 - 84 ksi) | | **Tensile Yield Strength (0.2% Offset)** | 470 - 530 MPa (68 - 77 ksi) | 460 - 520 MPa (67 - 75 ksi) | | **Elongation** | 5-10% | 6-11% | | **Compression Yield Strength** | 480 - 540 MPa (70 - 78 ksi) | 470 - 530 MPa (68 - 77 ksi) | | **Shear Strength** | 300 - 340 MPa (44 - 49 ksi) | 290 - 330 MPa (42 - 48 ksi) | | **Fatigue Strength** | 160 - 190 MPa (23 - 28 ksi) | 155 - 185 MPa (22 - 27 ksi) | | **Brinell Hardness** | 140 - 155 HB | 135 - 150 HB | --- #### **5. Product Applications** **7178-T6/T651** is used in the most demanding high-stress applications: * **Aerospace Structures:** * Aircraft wing skins and spars * Fuselage frames and bulkheads * Primary structural components * Helicopter rotor components * **Defense Applications:** * Military aircraft structural components * Missile and rocket components * Armored vehicle components * Defense system structures * **High-Performance Applications:** * Racing vehicle chassis and suspension * High-performance bicycle frames * Competition sports equipment * **Space Applications:** * Space launch vehicle structures * Satellite components * Spacecraft structural members --- #### **6. International Standards** | Standard Body | Designation | Specification | | :--- | :--- | :--- | | **Aluminum Association** | 7178-T6 / 7178-T651 | AA Teal Sheets | | **ASTM International** | 7178-T6 / 7178-T651 | ASTM B209 / B211 | | **Aerospace (AMS)** | 7178-T6 | AMS 4048 | | **Aerospace (AMS)** | 7178-T651 | AMS 4049 | | **European Norm** | EN AW-7178 T6 / T651 | EN 485-2 / EN 754-2 | | **Unified Numbering System** | A97178 | UNS Registry | --- #### **7. Key Characteristics** **Advantages:** - **Exceptional strength-to-weight ratio** (highest among commercial aluminum alloys) - **High fatigue strength** - **Good machinability** - **Excellent damage tolerance** - **Proven reliability** in critical applications **Limitations:** - **Lower corrosion resistance** than other aerospace alloys - **Limited formability** in aged condition - **Susceptible to stress corrosion cracking** - **Higher cost** than other aluminum alloys - **Requires specialized welding** techniques --- #### **8. Manufacturing Considerations** * **Machining:** Excellent machinability with proper tooling and techniques * **Forming:** Must be formed in annealed condition then heat-treated * **Welding:** Not generally recommended; requires specialized techniques * **Heat Treatment:** Solution treated at 460-475°C, aged at 115-130°C * **Surface Treatment:** Requires proper corrosion protection --- #### **9. Special Features** **7178-T6/T651** offers unique performance characteristics: * **Strength Comparison:** Approximately 10-15% stronger than 7075-T6 aluminum * **Weight Savings:** Significant advantage over lower strength alloys * **Performance Heritage:** Decades of proven performance in aerospace * **Quality Assurance:** Strict control of chemical composition and heat treatment **T651 vs T6 Advantages:** - Reduced distortion during machining - Better dimensional stability - Improved stress corrosion resistance - Preferred for complex, precision components --- #### **10. Performance in Service** - **Aerospace Reliability:** Proven performance in aircraft structures - **Fatigue Life:** Excellent resistance to cyclic loading - **Fracture Toughness:** Adequate for high-strength aluminum alloy - **Maintenance:** Requires proper corrosion protection in aggressive environments **7178-T6/T651 Aluminum Alloy** represents the ultimate in high-strength aluminum technology for applications where maximum strength and weight reduction are critical. Its extensive use in aerospace applications, particularly in highly stressed aircraft structures and components, demonstrates its capability to perform reliably in the most demanding environments. The T651 temper provides additional benefits for precision components where dimensional stability and reduced residual stresses are essential for performance and manufacturability. While requiring careful attention to corrosion protection, 7178 continues to be the material of choice for applications where the highest possible strength-to-weight ratio is required.

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 2198 gallon liquid totes Special package is available on request.