825 Cast UNS N08826 Severe Corrosion and Heat Resistant Alloy,Cast UNS N08826; 1

### **Product Introduction: Alloy 825 Cast (UNS N08826 / CU5MCuC) Severe Corrosion Resistant Alloy** **Overview** Cast Alloy 825, designated as UNS N08826 and known by the cast grade **CU5MCuC**, is a nickel-iron-chromium alloy fortified with molybdenum and copper. It is the cast equivalent of the widely used wrought alloy UNS N08825 (INCOLOY® 825). This alloy is specifically engineered to resist corrosion in a wide range of severe environments, including sulfuric and phosphoric acids, and is highly resistant to chloride-induced stress corrosion cracking and pitting. Its balanced composition makes it a versatile and reliable choice for handling corrosive process streams in the chemical process, petrochemical, and oil and gas industries. --- #### **Chemical Composition (Typical % by Weight, per ASTM A494)** The composition of CU5MCuC is meticulously balanced to combat a broad spectrum of corrosive media. | Element | Content (%) | Role & Benefit | | :--- | :--- | :--- | | **Nickel (Ni)** | 38.0 - 46.0 | Provides inherent resistance to chloride-ion stress-corrosion cracking and corrosion by reducing environments. | | **Chromium (Cr)** | 19.5 - 23.5 | Imparts resistance to oxidizing environments such as nitric acid, nitrates, and oxidizing salts. | | **Iron (Fe)** | Balance | Forms the base of the alloy matrix, contributing to cost-effectiveness. | | **Molybdenum (Mo)** | 2.5 - 3.5 | Enhances resistance to pitting and crevice corrosion in chloride-containing solutions and provides protection against reducing acids. | | **Copper (Cu)** | 1.5 - 3.0 | A critical addition that provides exceptional resistance to sulfuric acid and phosphoric acid, especially in non-oxidizing conditions. | | **Manganese (Mn)**| 1.00 max | Aids in castability and controls sulfur. | | **Silicon (Si)** | 1.00 max | A deoxidizer used in the casting process. | | **Carbon (C)** | 0.05 max | Kept to a low level to minimize carbide precipitation during welding or thermal exposure, which helps prevent sensitization and intergranular attack. | | **Titanium (Ti)** | 0.60 - 1.20 | Acts as a stabilizer. It combines with carbon to form stable carbides, preventing chromium depletion at grain boundaries (sensitization) and thus enhancing intergranular corrosion resistance. | | **Sulfur (S)** | 0.03 max | A detrimental element kept to a minimum to prevent hot cracking and maintain ductility. | *Note: "INCOLOY" is a registered trademark of Special Metals Corporation.* --- #### **Physical & Mechanical Properties (Typical)** | Property | Value / Condition | | :--- | :--- | | **Density** | 8.14 g/cm³ (0.294 lb/in³) | | **Melting Range** | 1370 - 1400 °C (2500 - 2550 °F) | | **Specific Heat** | 440 J/kg·K (0.105 BTU/lb·°F) @ 20°C | | **Thermal Conductivity**| 10.5 W/m·K (72.7 BTU·in/hr·ft²·°F) @ 100°C | | **Thermal Expansion** | 14.0 μm/m·°C (7.8 μin/in·°F) @ 20-100°C | | **Tensile Strength** | 586 MPa (85 ksi) min | | **Yield Strength (0.2% Offset)** | 241 MPa (35 ksi) min | | **Elongation** | 25% min | --- #### **International Standards and Specifications** Cast Alloy 825 (CU5MCuC) is recognized by key international standards for corrosion-resistant cast components. * **Cast Product Standards:** * **ASTM A494 / A494M:** Standard Specification for Castings, Nickel and Nickel Alloy. (Grade CU5MCuC) * **UNS N08826:** Unified Numbering System designation for the cast alloy. * **Wrought Equivalent:** * **UNS N08825 (INCOLOY 825):** The standard wrought form of this alloy (e.g., plate, sheet, tube). * **ASTM B423 / B424 / B425:** Standards for UNS N08825 seamless pipe and tube, plate, sheet, and strip. * **NACE MR0175/ISO 15156:** Approved for use in sour service (H₂S-containing) environments in the oil and gas industry. --- #### **Product Applications** CU5MCuC cast components are essential in industries where resistance to complex corrosive mixtures is required. 1. **Chemical Process Industry (CPI):** * Pumps, valves, and impellers for handling sulfuric and phosphoric acids. * Mixing tanks, reactors, and heat exchangers for organic and inorganic chemical production. * Piping and fittings for corrosive service. 2. **Oil & Gas Production:** * Wellhead components, Christmas tree parts, and downhole tool assemblies for sour service (H₂S) applications. * Pump casings and valve bodies for production and injection systems. 3. **Pollution Control & Scrubbers:** * Scrubber towers, ducting, and fan housings in Flue Gas Desulfurization (FGD) systems. * Components exposed to sulfurous and sulfuric acid condensates. 4. **Pharmaceutical and Acid Production:** * Equipment for pickling, acid production, and uranium processing. #### **Key Advantages** * **Versatile Corrosion Resistance:** Excellent resistance to a wide range of corrosive environments, including sulfuric acid, phosphoric acid, and seawater. * **Resistance to Localized Attack:** High levels of chromium and molybdenum provide strong resistance to pitting and crevice corrosion. * **Resistance to Stress Corrosion Cracking (SCC):** The high nickel content makes it highly resistant to chloride-induced stress corrosion cracking. * **Stabilized Chemistry:** The addition of titanium stabilizes the alloy against sensitization, ensuring excellent intergranular corrosion resistance in the as-welded condition. **Conclusion** Cast Alloy 825 (UNS N08826 / CU5MCuC) is a highly versatile and robust nickel-iron-chromium alloy designed for severe corrosive service. Its unique balance of nickel, chromium, molybdenum, and copper makes it exceptionally effective in handling sulfuric and phosphoric acids, chlorides, and complex chemical streams. For critical components in chemical processing, oil and gas, and pollution control equipment, CU5MCuC offers a proven and cost-effective solution, fully backed by international standards like ASTM A494.

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 3403 gallon liquid totes Special package is available on request.