Alclad 2024-T81, T851 Aluminum alloy,Aluminum 2024-T81, T851 alloy,E FORU

### **Alclad 2024-T81/T851 Aluminum Alloy Product Introduction** **Overview** Alclad 2024-T81/T851 represents a premium class of high-strength aluminum-copper alloys that combine solution heat treatment, cold working, and artificial aging to achieve superior strength and stress-corrosion resistance. The T81/T851 tempers indicate the material has been solution heat-treated, cold worked (typically by stretching for stress relief), and then artificially aged to develop optimal mechanical properties. Combined with the sacrificial protection of Alclad cladding, this material offers an exceptional balance of strength, durability, and corrosion resistance for demanding aerospace applications. --- #### **1. Chemical Composition** **Core Material: 2024 Alloy** | Element | Content (%) | |---------|-------------| | **Aluminum (Al)** | Balance | | **Copper (Cu)** | 3.8 - 4.9 | | **Magnesium (Mg)** | 1.2 - 1.8 | | **Manganese (Mn)** | 0.30 - 0.9 | | **Iron (Fe)** | ≤ 0.20 | | **Silicon (Si)** | ≤ 0.15 | | **Zinc (Zn)** | ≤ 0.10 | | **Other Elements** | ≤ 0.15 total | **Cladding Material** - **Alloy:** 1230, 1050, or 1060 series aluminum - **Purity:** ≥99.0% aluminum content - **Coating Thickness:** Typically 1.5-5% per side of total thickness - **Protection Method:** Sacrificial cathodic protection --- #### **2. Physical Properties** | Property | Value / Description | |----------|---------------------| | **Density** | 2.78 g/cm³ (0.100 lb/in³) | | **Melting Range** | 500°C - 638°C (932°F - 1180°F) | | **Electrical Conductivity** | 30-35% IACS | | **Thermal Conductivity** | 121 W/m·K (at 25°C) | | **Coefficient of Thermal Expansion** | 23.2 × 10⁻⁶/°C (20-100°C) | | **Modulus of Elasticity** | 73.1 GPa (10,600 ksi) | --- #### **3. Mechanical Properties** **Typical Mechanical Properties:** | Property | T81 Value | T851 Value | |----------|------------|-------------| | **Tensile Strength** | 450-485 MPa (65-70 ksi) | 455-490 MPa (66-71 ksi) | | **Yield Strength (0.2% Offset)** | 325-360 MPa (47-52 ksi) | 330-365 MPa (48-53 ksi) | | **Elongation in 2 inches** | 6-10% | 5-9% | | **Shear Strength** | 275-295 MPa (40-43 ksi) | 280-300 MPa (41-44 ksi) | | **Fatigue Strength** | 138 MPa (20 ksi) | 145 MPa (21 ksi) | | **Brinell Hardness** | 125-135 HB | 130-140 HB | *Note: T851 typically refers to plate product forms with additional stress-relieving operations.* --- #### **4. International Standards** | Standard System | Designation | Product Form | |-----------------|-------------|--------------| | **ASTM** | ASTM B209 | Sheet & Plate | | **AMS** | AMS 4037 | Sheet (T81) | | **AMS** | AMS 4081 | Plate (T851) | | **MIL** | MIL-DTL-6075 | Sheet | | **EN** | EN AW-2024A [T81/T851] | Sheet/Plate | --- #### **5. Product Applications** **Aerospace Primary Structures:** - Aircraft lower wing skins and panels - Fuselage frames and stringers - Aircraft bulkheads and ribs - Wing spar caps and components **Defense Applications:** - Military aircraft structural components - Missile airframes and components - Armored vehicle protection panels - Military satellite structures **High-Performance Applications:** - Space launch vehicle components - Racing car chassis and components - High-stress structural applications - Precision machined aircraft parts --- #### **6. Key Advantages & Considerations** **Advantages:** - ✅ **Enhanced Strength Properties:** Superior yield strength compared to T3/T4 tempers - ✅ **Improved Stress-Corrosion Resistance:** Better SCC resistance than T6 temper - ✅ **Excellent Fatigue Performance:** Superior fatigue strength for long-life applications - ✅ **Dimensional Stability:** Cold working provides stable mechanical properties - ✅ **Corrosion Protection:** Alclad coating ensures long-term environmental durability - ✅ **Predictable Performance:** Consistent properties through controlled processing **Considerations:** - ⚠️ **Reduced Ductility:** Lower elongation compared to T3/T4 tempers - ⚠️ **Limited Formability:** Minimal capability for post-heat treatment forming - ⚠️ **Higher Cost:** Additional processing steps increase manufacturing cost - ⚠️ **Machining Challenges:** Requires appropriate techniques for high-strength material - ⚠️ **Welding Limitations:** Poor weldability restricts joining methods --- **Processing Characteristics** **T81/T851 Heat Treatment Process:** 1. Solution heat treatment at 490-500°C (915-932°F) 2. Rapid quenching to room temperature 3. Permanent cold working (1.5-3% stretching for stress relief) 4. Artificial aging at 180-195°C (355-383°F) for 8-12 hours **Material Performance Benefits:** - Optimized combination of strength and toughness - Reduced residual stresses from manufacturing - Improved resistance to stress-corrosion cracking - Stable properties for precision applications - Consistent performance in cyclic loading conditions **Conclusion** Alclad 2024-T81/T851 Aluminum Alloy represents the pinnacle of 2024 series aluminum performance, offering an optimal balance of high strength, excellent fatigue resistance, and improved stress-corrosion cracking resistance. The combination of cold working and artificial aging produces mechanical properties that are essential for primary aircraft structures and other critical applications where reliability and performance cannot be compromised. While the material demands careful manufacturing consideration and comes at a higher cost, its proven performance in the most demanding aerospace applications makes it an indispensable material for engineers designing structures where failure is not an option. The additional protection provided by the Alclad coating ensures long-term durability in corrosive environments, making this material system particularly valuable for aircraft that operate in marine and aggressive atmospheric conditions.

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 1539 gallon liquid totes Special package is available on request.