Alloy 260,,UNS N03260，EFORU

### **Alloy 260 / UNS N03260 - Technical Datasheet** --- #### **1. Overview** **Alloy 260** (UNS N03260) is a nickel-cocium alloy designed specifically for handling molten caustic and other highly corrosive alkaline environments. This alloy offers exceptional resistance to stress corrosion cracking and general corrosion in caustic solutions across a wide range of concentrations and temperatures. Its optimized composition provides superior performance in some of the most challenging chemical processing applications. --- #### **2. Chemical Composition (Weight %)** The composition is engineered for maximum caustic corrosion resistance. | Element | Content (%) | Role & Benefit | |---------|-------------|----------------| | **Nickel (Ni)** | ≥ 93.0 | Base element providing fundamental corrosion resistance | | **Copper (Cu)** | ≤ 0.25 | Controlled residual element | | **Iron (Fe)** | ≤ 0.50 | Controlled to minimize detrimental phases | | **Manganese (Mn)** | ≤ 0.50 | Deoxidizer and sulfur control | | **Carbon (C)** | ≤ 0.15 | Controlled for optimal strength and fabricability | | **Calcium (Ca)** | 0.02 - 0.10 | Key alloying element for enhanced caustic resistance | | **Silicon (Si)** | ≤ 0.50 | Deoxidizer and strength enhancement | | **Sulfur (S)** | ≤ 0.015 | Controlled to minimize hot cracking susceptibility | | **Magnesium (Mg)** | 0.01 - 0.10 | Sulfur control and grain refinement | --- #### **3. Physical Properties** The physical properties support its use in high-temperature applications. | Property | Value | |----------|-------| | **Density** | 8.89 g/cm³ (0.321 lb/in³) | | **Melting Point** | 1435-1445°C (2615-2635°F) | | **Specific Heat (20°C)** | 444 J/kg·K | | **Thermal Conductivity** | 67 W/m·K (at 20°C) | | **Mean Coefficient of Thermal Expansion** | 13.5 × 10⁻⁶/°C (20-300°C) | | **Electrical Resistivity** | 0.098 μΩ·m | | **Modulus of Elasticity** | 186 GPa (27 × 10⁶ psi) | | **Magnetic Properties** | Essentially non-magnetic | --- #### **4. Mechanical Properties** The alloy maintains good strength at elevated temperatures. **Annealed Condition:** | Property | Value | |----------|-------| | **Tensile Strength** | 450-550 MPa (65-80 ksi) | | **Yield Strength (0.2% Offset)** | 170-240 MPa (25-35 ksi) | | **Elongation** | 35-45% | | **Hardness** | 70-85 HRB | **Elevated Temperature Properties (300°C/570°F):** | Property | Value | |----------|-------| | **Tensile Strength** | 380 MPa (55 ksi) | | **Yield Strength** | 150 MPa (22 ksi) | | **Creep Strength** | 80 MPa (12 ksi) | --- #### **5. Product Applications** **Alloy 260** serves critical roles in caustic and alkaline environments: - **Chemical Processing:** - Caustic evaporators and concentrators - Molten salt reactors - Alkaline digestion vessels - Caustic soda handling systems - **Pulp and Paper Industry:** - Digester vessels and components - Black liquor recovery boilers - Pulp bleaching equipment - Chemical recovery systems - **Petrochemical Industry:** - Catalytic cracking units - Alkylation processes - Catalyst regeneration systems - **Energy Generation:** - Feedwater heaters - Condenser tubes in alkaline environments - Boiler components - **Industrial Applications:** - Heat exchangers in caustic service - Transfer lines for alkaline solutions - Reaction vessels for organic chemicals --- #### **6. International Standards** The material meets various international specifications: | Standard | Specification | |----------|---------------| | **ASTM** | ASTM B163 - Seamless Condenser and Heat-Exchanger Tubes
ASTM B164 - Nickel-Copper Alloy Rod, Bar, and Wire
ASTM B165 - Nickel-Copper Alloy Pipe | | **UNS** | UNS N03260 | | **ASME** | SB-163, SB-164, SB-165 | | **DIN** | DIN 17740 - NiCr260 | | **EN** | EN 10095 - NW4401 | | **ISO** | ISO 6208 - NiCr260 | --- #### **7. Corrosion Resistance** - **Excellent** resistance to hot concentrated caustic solutions - **Outstanding** performance in molten caustic environments - **Good** resistance to neutral and alkaline salts - **Moderate** resistance to dilute acids - **Poor** resistance to oxidizing acids and sulfur compounds --- #### **8. Fabrication Characteristics** - **Machining:** Similar to nickel 200/201 with proper tool geometry - **Welding:** Excellent weldability using GTAW and GMAW processes - **Forming:** Good cold and hot working characteristics - **Heat Treatment:** Stress relief at 425-540°C (800-1000°F) - **Annealing:** 650-870°C (1200-1600°F) in controlled atmosphere --- #### **9. Special Considerations** - **Caustic Service:** Superior to standard nickel alloys in hot concentrated caustic - **Temperature Limits:** Suitable for continuous service up to 600°C (1110°F) - **Environmental Limits:** Avoid strongly oxidizing conditions - **Microstructural Stability:** Resistant to sensitization in welded condition --- #### **10. Summary** **Alloy 260 (UNS N03260)** represents a specialized nickel alloy optimized for severe caustic and alkaline environments. Its calcium-modified composition provides enhanced resistance to stress corrosion cracking and general corrosion in applications involving hot concentrated caustic solutions and molten salts. The alloy maintains excellent mechanical properties at elevated temperatures while offering good fabricability and weldability. Governed by comprehensive international standards including ASTM B163-165, Alloy 260 remains the material of choice for critical components in chemical processing, pulp and paper manufacturing, and other industries where caustic corrosion resistance is paramount.

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 1713 gallon liquid totes Special package is available on request.