Alloy 825,Incoloy 825 ,UNS N08825,E FORU

British Specs:BS 3072 BS 3073 BS 3074 BS 3075 BS 3076 NA16，American Specs:ASTM B425 ASTM B424 ASTM B163 (Tube *)，German Specs:WS 2.4858

### **Technical Datasheet: Alloy 825 / Incoloy 825 / UNS N08825** --- #### **1. Overview** **Alloy 825** (commercially known as **Incoloy® 825**) is a nickel-iron-chromium alloy with additions of molybdenum and copper, specifically designed for exceptional corrosion resistance in a wide range of aggressive environments. Unlike the high-temperature-focused Alloy 800HT, Alloy 825 is optimized for service in reducing acids, oxidizing chemicals, and stress-corrosion cracking media. It is stabilized with titanium to prevent sensitization and intergranular corrosion. The designations **Alloy 825**, **Incoloy 825**, and **UNS N08825** all refer to this versatile, corrosion-resistant nickel-base alloy. --- #### **2. Key Characteristics** * **Excellent General Corrosion Resistance:** Performs well in both oxidizing and reducing environments. * **Superior Resistance to Reducing Acids:** Outstanding resistance to sulfuric and phosphoric acids. * **Excellent Resistance to Stress Corrosion Cracking (SCC):** Highly resistant to chloride-induced SCC. * **Pitting and Crevice Corrosion Resistance:** The high molybdenum and chromium content provides strong resistance to localized attack. * **Stabilized against Sensitization:** The titanium addition prevents the formation of harmful chromium carbides during welding or high-temperature exposure, safeguarding against intergranular attack. --- #### **3. Chemical Composition (Weight %)** The corrosion resistance of Alloy 825 is derived from its carefully balanced chemistry. | Element | Minimum (%) | Maximum (%) | Key Function | | :--- | :--- | :--- | :--- | | **Nickel (Ni)** | 38.0 | 46.0 | Provides inherent resistance to corrosion and reducing environments. | | **Chromium (Cr)** | 19.5 | 23.5 | Confers resistance to oxidizing media (e.g., nitrates, oxidizing salts). | | **Iron (Fe)** | 22.0 min | Balance | The base element of the alloy. | | **Molybdenum (Mo)** | 2.5 | 3.5 | Enhances resistance to pitting, crevice corrosion, and reducing acids. | | **Copper (Cu)** | 1.5 | 3.0 | Provides resistance to reducing acids, particularly sulfuric acid. | | **Titanium (Ti)** | 0.6 | 1.2 | Stabilizes the alloy by forming TiC, preventing chromium carbide precipitation (sensitization). | | **Carbon (C)** | - | 0.05 | Kept low to minimize carbide formation. | | **Manganese (Mn)** | - | 1.00 | - | | **Sulfur (S)** | - | 0.03 | - | | **Silicon (Si)** | - | 0.05 | - | --- #### **4. Physical Properties (Typical)** | Property | Value | | :--- | :--- | | **Density** | 8.14 g/cm³ (0.294 lb/in³) | | **Melting Range** | 1370 - 1400 °C (2500 - 2550 °F) | | **Specific Heat (20°C)** | 440 J/kg·K | | **Thermal Conductivity** | 10.8 W/m·K (at 100°C) | | **Mean Coefficient of Thermal Expansion** | 14.0 μm/m·K (20 - 100°C) | | **Electrical Resistivity** | 1.12 μΩ·m | | **Modulus of Elasticity (Elastic Modulus)** | 196 GPa (28.4 x 10⁶ psi) | --- #### **5. Mechanical Properties (Typical at Room Temperature)** * **Tensile Strength:** 655 MPa (95 ksi) min * **Yield Strength (0.2% Offset):** 275 MPa (40 ksi) min * **Elongation:** 30% min --- #### **6. International Standards & Specifications** Alloy 825 is covered by a comprehensive set of international standards for various product forms. | Product Form | Key International Standards | | :--- | :--- | | **Plate, Sheet, & Strip** | ASTM B424 / ASME SB424, EN 10095 | | **Seamless Pipe & Tube** | ASTM B423 / ASME SB423, ASTM B163 / ASME SB163 | | **Welded Tube** | ASTM B704 / ASME SB704, ASTM B705 / ASME SB705 | | **Welding Filler Metal** | **AWS A5.14: ERNiFeCr-3** / **SFA-5.14: ERNiFeCr-3**
**AWS A5.11: ENiFeCr-3** / **SFA-5.11: ENiFeCr-3** | | **Bar, Rod & Wire** | ASTM B425 / ASME SB425, ASTM B164 / ASME SB164 | | **Forgings & Fittings** | ASTM B564 / ASME SB564 (Forgings), ASTM B366 / ASME SB366 (Fittings) | **Common Trade Names:** Incoloy® 825 (a registered trademark of Special Metals Corporation). **Other/Similar National Specs:** * **UNS:** N08825 * **EN (Euronorm):** EN 2.4858 (NiCr21Mo) * **DIN:** 2.4858 * **GOST:** (Russian standards may have equivalents, but specific codes should be verified). --- #### **7. Applications** Alloy 825 is widely used across industries where severe corrosion is a primary concern: * **Chemical Processing:** * Pickling tanks, heating coils, and reaction vessels handling sulfuric and phosphoric acid. * Components in acid production, fertilizer industry, and polymer production. * **Oil & Gas Industry:** * Downhole and surface equipment (e.g., tubing strings, liners, valves) in sour service (H₂S-containing) environments. * Process piping and heat exchangers in refineries. * **Pollution Control & Waste Processing:** * Flue gas desulfurization (FGD) systems, scrubbers, and ducting. * Equipment for incineration and waste acid recovery. * **Marine and Offshore:** * Seawater cooling systems, ballast tanks, and propeller shafts. * Components exposed to brackish water and marine atmospheres. * **Acid Production and Handling:** * Equipment for producing, storing, and transporting sulfuric acid. * **Nuclear Fuel Reprocessing:** Used in various components due to its resistance to nitric acid and other chemicals. --- #### **8. Important Note on Heat Treatment** Alloy 825 is typically supplied in the solution annealed condition at a temperature range of **900-980°C (1650-1800°F)**, followed by rapid cooling (water quenching). This heat treatment ensures that the carbon is in solution with titanium and that the alloy is in its most corrosion-resistant state, free from harmful precipitates. --- **Disclaimer:** 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 1936 gallon liquid totes Special package is available on request.