Alloy 800HT (Welding),Incoloy 800HT Forgings,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 (commonly known as Incoloy 800HT) is a nickel-iron-chromium superalloy designed for high-temperature service. The "HT" stands for "High Temperature," indicating its optimized composition for improved creep rupture strength and carburization resistance at temperatures exceeding 600°C (1112°F). It is a stable, austenitic solid-solution strengthened alloy. The designations **Alloy 800HT** (for welding products), **Incoloy 800HT Forgings** (for wrought forged components), and **UNS N08811** (the Unified Numbering System code) all refer to the same base material, which must meet specific chemistry and heat treatment requirements as defined by international standards. #### **2. Key Characteristics** * **Excellent High-Temperature Strength:** Superior creep and stress-rupture properties compared to standard Alloy 800/800H. * **Outstanding Oxidation Resistance:** Resists scaling and oxidation in continuous service up to 1150°C (2100°F) and in cyclic service up to 1035°C (1900°F). * **Excellent Carburization & Sulfidation Resistance:** Performs well in carburizing and sulfidizing atmospheres, making it ideal for petrochemical processing. * **Good Metallurgical Stability:** Maintains its structure and properties over long periods of exposure at high temperatures. * **Resistance to Chloride Stress Corrosion Cracking:** Unlike standard stainless steels, it is highly resistant to this form of attack. #### **3. Chemical Composition (Weight %)** The key to 800HT's performance is its tightly controlled chemistry and the required Al + Ti content. | Element | Minimum (%) | Maximum (%) | Key Function | | :--- | :--- | :--- | :--- | | **Nickel (Ni)** | 30.0 | 35.0 | Austenite stabilizer, provides strength & corrosion resistance. | | **Chromium (Cr)** | 19.0 | 23.0 | Forms protective Cr₂O₃ scale for oxidation & corrosion resistance. | | **Iron (Fe)** | Balance | Balance | Base element of the alloy. | | **Carbon (C)** | 0.06 | 0.10 | Enhances high-temperature strength through carbide formation. | | **Aluminum (Al)** | 0.25 | 0.60 | Combined with Ti, forms γ' phase for strengthening; aids oxidation resistance. | | **Titanium (Ti)** | 0.25 | 0.60 | Combined with Al, crucial for high-temperature strength. | | **Aluminum + Titanium (Al+Ti)** | **0.85** | **1.20** | **This is the critical 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) | | **Thermal Expansion Coefficient** | 14.4 μm/m·K (20 - 100°C) | | **Electrical Resistivity** | 0.99 μΩ·m | | **Modulus of Elasticity (Elastic Modulus)** | 200 GPa (29 x 10⁶ psi) | #### **5. Mechanical Properties (Typical at Room Temperature)** * **Tensile Strength:** 655 MPa (95 ksi) min * **Yield Strength (0.2% Offset):** 310 MPa (45 ksi) min * **Elongation:** 30% min *Note: For high-temperature mechanical properties (e.g., creep rupture strength), refer to specific ASTM data sheets or manufacturer's literature for time-temperature-stress values.* #### **6. Product Forms & International Standards** The material is supplied in various forms, each governed by specific international standards. | Product Form | Key International Standards | | :--- | :--- | | **Plate, Sheet, & Strip** | ASTM B409, ASME SB409, EN 10095 | | **Seamless Pipe & Tube** | ASTM B163, ASTM B407, ASME SB163/SB407 | | **Welding Filler Metal (Alloy 800HT Welding)** | **AWS A5.14: ERNiFeCr-1** / **SFA-5.14: ERNiFeCr-1**
*This is the standard specification for bare wire used in GTAW, GMAW, SAW, etc.* | | **Forged Bar & Incoloy 800HT Forgings** | ASTM B564 (Standard Specification for Nickel Alloy Forgings) | | **Bar & Rod** | ASTM B408 | | **Fittings & Flanges** | ASTM B366 (Wrought Fittings) | **Common Trade Names:** Incoloy® 800HT (a registered trademark of Special Metals Corporation), Nicrofer 3220 HT (ThyssenKrupp). #### **7. Applications** Incoloy 800HT is selected for demanding high-temperature applications across multiple industries: * **Petrochemical & Chemical Processing:** * Steam methane reformer (SMR) components (e.g., pigtails, outlet manifolds, transfer lines). * Ethylene furnace tubing, radiant tubes, and internals. * Components in hydrocracker and hydrotreater units. * **Power Generation:** * Heat exchangers, superheater and reheater tubing in advanced fossil fuel plants. * Components in heat recovery steam generators (HRSGs). * **Industrial Furnaces:** * Radiant tubes, muffles, retorts, and furnace fixtures. * Trays and baskets for heat treating. * **Nuclear Power:** * Heat exchangers and intermediate heat transfer systems in some reactor types. * **Aerospace:** * Certain engine and airframe components requiring high-temperature strength. #### **8. Important Note on Heat Treatment** To develop its optimal high-temperature properties, Alloy 800HT **must** be solution annealed at a temperature of **minimum 1121°C (2050°F)**, followed by rapid cooling (water quenching or rapid air cooling) to prevent carbide precipitation. This condition is a mandatory requirement per the material standards (e.g., ASTM B409). --- This document provides a general overview. For critical applications, always consult the specific material certification and the latest version of the relevant standards.

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 1932 gallon liquid totes Special package is available on request.