Alloy 800HT (Welding),Incoloy 800HT Other/Similar Specs,N08811,E FORU

British Specs:BS 3072 BS 3073 BS 3074 BS 3075 BS 3076 NA15，American Specs:AMS 5766 Bar and Forgings AMS 5871 Sheet, Strip and Plate ASTM B408 ASTM B564 ASTM A240 ASTM A480，German Specs:WS 1.4876 WS 1.4958 WS 1.4959

### **Technical Datasheet: Alloy 800HT / Incoloy 800HT / UNS N08811** #### **1. Overview** Alloy 800HT (commercially known as Incoloy 800HT) is a nickel-iron-chromium superalloy optimized for high-temperature service. The "HT" designation signifies "High Temperature," reflecting its enhanced creep rupture strength and superior resistance to carburization and oxidation compared to standard Alloy 800H. It is an austenitic, solid-solution strengthened alloy, stabilized with titanium and aluminum. The terms **Alloy 800HT (Welding)**, **Incoloy 800HT**, and **UNS N08811** all refer to this specific grade, which is defined by a critical chemistry balance and a mandatory high-temperature solution anneal. #### **2. Key Characteristics** * **Enhanced Creep & Stress-Rupture Strength:** Designed specifically for prolonged service at temperatures above 600°C (1112°F). * **Excellent Oxidation Resistance:** Suitable for continuous service up to 1150°C (2100°F) and cyclic service up to 1035°C (1900°F). * **Superior Carburization & Sulfidation Resistance:** Ideal for harsh environments in petrochemical processing. * **Good Metallurgical Stability:** Maintains its microstructure and properties over long-term exposure. * **Resistance to Chloride Stress Corrosion Cracking:** A key advantage over standard stainless steels. #### **3. Chemical Composition (Weight %)** The performance of 800HT is guaranteed by its tightly controlled chemistry, particularly the Aluminum and Titanium content. | Element | Minimum (%) | Maximum (%) | Key Function | | :--- | :--- | :--- | :--- | | **Nickel (Ni)** | 30.0 | 35.0 | Stabilizes the austenitic matrix and provides fundamental corrosion resistance. | | **Chromium (Cr)** | 19.0 | 23.0 | Forms a protective Cr₂O₃ scale for oxidation and corrosion resistance. | | **Iron (Fe)** | Balance | Balance | The base element of the alloy. | | **Carbon (C)** | 0.06 | 0.10 | Enhances high-temperature strength via carbide formation. | | **Aluminum (Al)** | 0.25 | 0.60 | Combined with Ti, it provides strengthening and aids oxidation resistance. | | **Titanium (Ti)** | 0.25 | 0.60 | Combined with Al, it is critical for high-temperature strength. | | **Aluminum + Titanium (Al+Ti)** | **0.85** | **1.20** | **This is the defining requirement for 800HT (vs. standard 800H).** | | **Manganese (Mn)** | - | 1.50 | Improves hot workability. | | **Copper (Cu)** | - | 0.75 | - | | **Silicon (Si)** | - | 1.00 | Enhances oxidation resistance. | | **Sulfur (S)** | - | 0.015 | - | #### **4. Physical Properties** | Property | Value | | :--- | :--- | | **Density** | 7.94 g/cm³ (0.287 lb/in³) | | **Melting Range** | 1350 - 1400 °C (2460 - 2550 °F) | | **Specific Heat (20°C)** | 455 J/kg·K | | **Thermal Conductivity** | 11.2 W/m·K (at 100°C) | | **Mean Coefficient of Thermal Expansion** | 14.4 μm/m·K (20 - 100°C) | | **Electrical Resistivity** | 0.99 μΩ·m | | **Modulus of Elasticity** | 200 GPa (29 x 10⁶ psi) | #### **5. International Standards & Specifications** The material is covered by a wide range of international standards for different product forms. **Standard Product Forms (Plate, Tube, Pipe, Bar):** * **ASTM B409 / ASME SB409:** Plate, Sheet, and Strip * **ASTM B163 / ASME SB163:** Seamless Condenser and Heat-Exchanger Tubes * **ASTM B407 / ASME SB407:** Seamless Pipe and Tube * **ASTM B564 / ASME SB564:** Forgings (This is the primary standard for Incoloy 800HT forgings) * **ASTM B366 / ASME SB366:** Wrought Fittings **Welding Products (Alloy 800HT Welding):** * **AWS A5.14 / SFA-5.14: ERNiFeCr-1** * This is the standard for bare welding electrode and rod for processes like GTAW (TIG), GMAW (MIG), and SAW. * **AWS A5.11 / SFA-5.11: ENiFeCr-1** * This is the standard for covered electrodes for Shielded Metal Arc Welding (SMAW/Stick). **Other/Similar National & International Specs:** * **UNS:** N08811 * **EN (Euronorm):** EN 10095 - Heat resisting steels and nickel alloys * **DIN:** 1.4959 (A similar, often referenced German material number; note: chemistry may not be identical). * **ISO:** ISO 6207 (For plate, sheet, and strip) * **GOST:** (Russian standards may have equivalents, but specific codes should be verified for project requirements). #### **6. Applications** Incoloy 800HT is specified for critical high-temperature components across industries: * **Petrochemical & Chemical Processing:** * Steam Methane Reformer (SMR) components: outlet pigtails, manifolds, transfer lines, and reformer tubes. * Ethylene cracking furnace tubes, radiant coils, and internals. * Components in hydrocracker and hydrotreater units. * **Power Generation:** * Superheater and reheater tubing in conventional and advanced fossil fuel power plants. * Heat exchangers and tubing in Heat Recovery Steam Generators (HRSGs). * **Industrial Furnaces:** * Radiant tubes, muffles, retorts, and furnace rollers. * Heat treatment trays and baskets. * **Nuclear Power:** * Heat exchangers and steam generator tubing in certain nuclear reactor designs. * **Aerospace:** * Engine components and structural parts in high-temperature zones. #### **7. Important Note on Heat Treatment** To achieve the specified high-temperature properties, Alloy 800HT **must** be solution annealed at a temperature of **minimum 1121°C (2050°F)**, followed by rapid cooling (water quenching is typical). This condition is a mandatory requirement per the material standards and is essential for dissolving carbides and achieving the correct Al+Ti solution strengthening. --- **Disclaimer:** This datasheet is for informational purposes. For design and procurement, always refer to the project-specific material requisition and the latest version of the relevant standards and certified mill test reports.

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 1933 gallon liquid totes Special package is available on request.