AL 800AT™ Nickel-Base Alloy, UNS N08811,1

### **Product Datasheet: AL 800AT™ / INCOLOY® 800AT (UNS N08811)** **A Nickel-Iron-Chromium Alloy Optimized for Advanced High-Temperature Applications** --- #### **1. Overview** **AL 800AT™**, commercially referenced as **INCOLOY® 800AT** (UNS N08811), represents an advanced evolution of the standard 800 series alloys. This nickel-iron-chromium alloy is specifically engineered with tighter compositional controls and enhanced high-temperature stability for superior performance in demanding thermal applications. The "AT" designation indicates "Advanced Technology," reflecting improvements in high-temperature strength, creep resistance, and microstructural stability. The alloy maintains excellent resistance to oxidation, carburization, and sulfidation, making it particularly suitable for prolonged service in temperatures ranging from 600°C to 1150°C (1110°F to 2100°F). --- #### **2. Chemical Composition (Typical Weight %)** | Element | Content (%) | Role in the Alloy | |---------|-------------|-------------------| | **Nickel (Ni)** | ~30.0-34.0 | Provides austenitic matrix stability | | **Chromium (Cr)** | ~19.0-23.0 | Confers oxidation resistance | | **Iron (Fe)** | Balance (~39.5) | Primary alloy matrix element | | **Carbon (C)** | ~0.06-0.10 | Optimized for creep strength | | **Aluminum (Al)** | ~0.25-0.45 | Enhanced stabilization | | **Titanium (Ti)** | ~0.25-0.45 | Improved grain boundary control | | **Manganese (Mn)** | ≤ 1.25 | Controlled residual | | **Silicon (Si)** | ≤ 0.75 | Controlled residual | | **Copper (Cu)** | ≤ 0.75 | Residual element | | **Sulfur (S)** | ≤ 0.015 | Controlled impurity | --- #### **3. Physical Properties (Typical)** | Property | Value / Condition | |----------|-------------------| | **Density** | 7.94 g/cm³ (0.286 lb/in³) | | **Melting Range** | 1350-1400 °C (2460-2550 °F) | | **Thermal Expansion Coefficient** | 14.2 μm/m·°C (20-1000°C) | | **Thermal Conductivity** | 11.5 W/m·K (at 100°C) | | **Modulus of Elasticity** | 198 GPa (28.7×10⁶ psi) | | **Electrical Resistivity** | 0.98 μΩ·m | | **Specific Heat Capacity** | 510 J/kg·K (at 20°C) | --- #### **4. Mechanical Properties** **Room Temperature (Annealed Condition):** * **Tensile Strength**: 520-650 MPa (75-94 ksi) * **Yield Strength (0.2% Offset)**: 220-350 MPa (32-51 ksi) * **Elongation**: 35-45% **High-Temperature Performance (650°C/1200°F):** * **Tensile Strength**: ~380 MPa (55 ksi) * **Creep Rupture Strength**: Significantly improved over standard 800/800H * **Stress Rupture Life**: Enhanced by optimized Ti/Al ratio --- #### **5. Enhanced Characteristics** **Superior to Standard 800/800H Alloys:** * Improved microstructural stability * Enhanced creep and stress rupture properties * Better long-term aging characteristics * Optimized Ti/Al ratio for superior performance * Tighter compositional controls --- #### **6. Product Applications** **Petrochemical Industry:** * Steam methane reformer tubes * Ethylene cracking furnace coils * Hydrocarbon pyrolysis tubes * Catalyst carrier grids **Power Generation:** * Superheater and reheater tubes * Heat exchanger components * Steam generator tubing * High-temperature piping systems **Heat Processing:** * Radiant tubes and furnace muffles * Heat treatment retorts and fixtures * Annealing furnace components * Roller hearth furnace parts **Nuclear Applications:** * Intermediate heat exchangers * Steam generator tubing * High-temperature reactor components --- #### **7. International Standards** * **UNS**: N08811 * **DIN/Werkstoff Nr.**: 1.4958 * **ASTM/ASME Specifications**: * **ASTM B-409 / ASME SB-409**: Plate, Sheet, and Strip * **ASTM B407**: Seamless Pipe and Tube * **ASTM B408**: Rod and Bar * **Aerospace Material Specification**: * **AMS 5871**: Sheet, Strip, and Plate * **Additional Certifications**: * ASME Boiler and Pressure Vessel Code * ISO 6208 for wrought nickel alloys * European Pressure Equipment Directive (PED) * Nuclear quality assurance standards --- **Technical Note:** AL 800AT exhibits significantly improved high-temperature mechanical properties compared to standard 800/800H alloys, particularly in creep rupture strength and microstructural stability. The optimized Ti/Al ratio and tighter compositional controls contribute to its enhanced performance in demanding high-temperature applications. *INCOLOY is a registered trademark of Special Metals Corporation. AL 800AT is understood to be a related trademark for this advanced alloy composition.*

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 3387 gallon liquid totes Special package is available on request.