8280-O Aluminum alloy,Aluminum 8280-O alloy，E FORU

### **Product Datasheet: 8280-O Aluminum Alloy** **1. General Overview** 8280-O Aluminum Alloy is a high-silicon, free-machining aluminum alloy supplied in the annealed ("O" temper) condition. The high silicon content gives it exceptional wear resistance and low thermal expansion, while the annealed temper provides maximum ductility and formability. It is primarily recognized for its superior machinability, making it an ideal choice for components requiring complex machining and a high-quality surface finish. **2. International Standards** The 8280 alloy is standardized under several major international systems, ensuring consistency and quality across global supply chains. * **UNS:** UNS A98280 * **ASTM:** ASTM B85 (Standard Specification for Aluminum-Alloy Die Castings) * **AA:** AA 8280 (Aluminum Association designation) * **EN (European Standard):** EN AC-48200 (Note: European designations may have variations; this is a common equivalent). **3. Chemical Composition (Weight %)** The chemical composition conforms to the standards set by the Aluminum Association for alloy 8280. | Element | Content (%) | | :--- | :--- | | **Silicon (Si)** | 9.5 - 12.5 | | **Iron (Fe)** | ≤ 1.3 | | **Copper (Cu)** | 2.0 - 3.5 | | **Zinc (Zn)** | ≤ 1.5 | | **Manganese (Mn)** | ≤ 0.55 | | **Magnesium (Mg)** | ≤ 0.10 | | **Nickel (Ni)** | ≤ 0.55 | | **Tin (Sn)** | ≤ 0.15 | | **Lead (Pb)** | ≤ 0.15 | | **Titanium (Ti)** | ≤ 0.20 | | **Other Elements** | ≤ 0.15 each; ≤ 0.05 total | | **Aluminum (Al)** | Balance | *Note: The high Silicon (Si) and Copper (Cu) content are the primary drivers of this alloy's key properties.* **4. Physical Properties** The physical properties of 8280-O are characteristic of high-silicon aluminum alloys. | Property | Value / Description | | :--- | :--- | | **Density** | ≈ 2.75 g/cm³ (0.099 lb/in³) | | **Melting Range** | ≈ 520 - 600 °C (968 - 1112 °F) | | **Coefficient of Thermal Expansion (20-100°C)** | 19.5 x 10⁻⁶/°C | | **Thermal Conductivity** | ≈ 125 W/m·K | | **Electrical Conductivity** | ≈ 35 % IACS (International Annealed Copper Standard) | | **Modulus of Elasticity** | ≈ 74 GPa (10.7 x 10⁶ psi) | **5. Mechanical Properties (Typical for O Temper)** The "O" (Annealed) temper signifies the softest and most ductile state of the alloy. | Property | Value | | :--- | :--- | | **Tensile Strength** | 180 - 220 MPa (26,000 - 32,000 psi) | | **Yield Strength (0.2% Offset)** | 90 - 120 MPa (13,000 - 17,000 psi) | | **Elongation at Break** | 8 - 15 % (in 50 mm / 2 inches) | | **Hardness, Brinell** | 50 - 65 HB | **6. Key Characteristics & Advantages** * **Excellent Machinability:** 8280-O is classified as a free-machining alloy. It allows for high-speed machining, producing small, broken chips and achieving excellent surface finishes. * **Outstanding Wear Resistance:** The hard, primary silicon particles dispersed throughout the aluminum matrix provide exceptional resistance to abrasion and wear. * **Low Thermal Expansion:** Its coefficient of thermal expansion is lower than that of most other aluminum alloys, making it stable under thermal cycling. * **Good Corrosion Resistance:** It exhibits good resistance to atmospheric corrosion. * **High Pressure Tightness:** It is well-suited for applications requiring pressure-tight components, such as hydraulic valve bodies. **7. Product Applications** 8280-O Aluminum Alloy is predominantly used in the manufacturing of complex, precision-machined components, especially where wear resistance is critical. * **Automotive Industry:** * Engine blocks and cylinder heads * Pistons * Transmission housings * Pump bodies and housings * **Hydraulics and Pneumatics:** * Valve bodies and manifolds * Compressor parts * **General Engineering:** * Bearing cages and housings * Gears and other wear-prone components * Machinery parts requiring intricate shapes and good dimensional stability. **8. Available Forms** 8280 alloy is most commonly supplied as: * **Die Castings** * **Permanent Mold Castings** * **Sand Castings** The "O" temper is achieved by a full anneal heat treatment after casting to relieve stresses and maximize ductility for subsequent machining operations. --- **Disclaimer:** The information provided herein is for reference purposes only. The properties are typical and can vary based on the specific casting process and section size. For critical applications, consultation with the material supplier is recommended to verify the properties for a specific lot or production run.

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 2273 gallon liquid totes Special package is available on request.