50-50Nb Cast UNS R20501 Heat Resistant Alloy,C1

### **Product Datasheet: 50Cr-50Ni-Nb Heat Resistant Alloy (UNS R20501)** **A High-Chromium Nickel-Based Casting Alloy for Extreme Temperature Service** --- #### **1. Overview** **50Cr-50Ni-Nb Alloy** (UNS R20501), commonly referred to as **50-50Nb Cast Alloy**, is a high-performance heat-resistant casting alloy designed for severe high-temperature applications. This alloy features a balanced composition of approximately 50% chromium and 50% nickel, with niobium addition for stabilization against sensitization. The alloy exhibits exceptional resistance to oxidation, carburization, and thermal cycling in temperatures up to 1200°C (2190°F). Its unique composition provides outstanding protection against sulfur-bearing atmospheres and cyclic oxidation, making it particularly suitable for reformer furnaces, heat treatment fixtures, and other demanding high-temperature industrial applications. --- #### **2. Chemical Composition (Typical Weight %)** | Element | Content (%) | Role in the Alloy | |---------|-------------|-------------------| | **Nickel (Ni)** | ~45.0-55.0 | Provides austenitic matrix and base corrosion resistance | | **Chromium (Cr)** | ~45.0-55.0 | Confers exceptional oxidation and sulfidation resistance | | **Niobium (Nb)** | ~0.5-2.0 | Stabilizes against sensitization and intergranular corrosion | | **Iron (Fe)** | ≤ 2.0 | Residual element | | **Silicon (Si)** | ≤ 2.0 | Enhances oxidation resistance | | **Manganese (Mn)** | ≤ 1.5 | Residual element | | **Carbon (C)** | ≤ 0.2 | Controlled for high-temperature strength | | **Other Elements** | ≤ 1.0 | Residual elements | --- #### **3. Physical Properties (Typical)** | Property | Value / Condition | |----------|-------------------| | **Density** | 7.8-8.0 g/cm³ (0.282-0.289 lb/in³) | | **Melting Range** | 1350-1400 °C (2460-2550 °F) | | **Thermal Expansion Coefficient** | 14.5-15.5 μm/m·°C (20-1000°C) | | **Thermal Conductivity** | 12-14 W/m·K (at 500°C) | | **Modulus of Elasticity** | 180-200 GPa (26-29×10⁶ psi) | | **Specific Heat Capacity** | 500-550 J/kg·K (at 20°C) | --- #### **4. Mechanical Properties (Cast Condition)** **Room Temperature Properties:** * **Tensile Strength**: 450-550 MPa (65-80 ksi) * **Yield Strength (0.2% Offset)**: 250-350 MPa (36-51 ksi) * **Elongation**: 10-25% * **Hardness**: 170-220 HB **High-Temperature Performance (1000°C/1830°F):** * **Tensile Strength**: ~60-80 MPa (9-12 ksi) * **Creep Strength**: Excellent long-term stability * **Thermal Fatigue Resistance**: Outstanding performance --- #### **5. Corrosion & Heat Resistance** **Exceptional Performance in:** * **Oxidation Resistance**: Superior protection up to 1200°C (2190°F) * **Carburizing Atmospheres**: Excellent resistance to carbon penetration * **Sulfidation**: Outstanding performance in sulfur-bearing environments * **Thermal Cycling**: Excellent resistance to thermal shock and fatigue * **Chlorine-containing atmospheres**: Good resistance to chlorine corrosion --- #### **6. Product Applications** **Petrochemical Industry:** * Steam methane reformer tubes and fittings * Ethylene cracking furnace components * Pyrolysis tube supports and hangers * Catalyst support grids **Heat Treatment Industry:** * Radiant tubes and furnace muffles * Heat treatment fixtures and baskets * Annealing furnace components * Sintering furnace parts **Power Generation:** * Burner nozzles and components * Heat exchanger parts * Combustion chamber elements **Other Applications:** * Ceramic kiln furniture * Glass processing equipment * Waste incineration components --- #### **7. International Standards** * **UNS**: R20501 (Cast Version) * **Common Designations**: * **50Cr-50Ni-Cb** (Cast Grade) * **IN657** (Wrought Equivalent Reference) * **Primary Specifications**: * **ASTM A560/A560M**: Standard Specification for Castings, Chromium-Nickel Alloy * **Additional References**: * ASME Boiler and Pressure Vessel Code * ISO 4991: Steel and cast iron castings for pressure purposes * Various national and international heat-resistant alloy standards --- **Technical Note:** This 50Cr-50Ni-Nb cast alloy represents one of the highest chromium-containing grades in the heat-resistant casting family. Its exceptional oxidation resistance makes it suitable for the most severe high-temperature applications. The niobium addition provides crucial stabilization against sensitization during high-temperature service. *Note: While IN657 is referenced as a wrought equivalent, this datasheet specifically addresses the cast version (UNS R20501) per ASTM A560 specifications. Actual properties may vary based on casting process, heat treatment, and specific foundry practices.*

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 3388 gallon liquid totes Special package is available on request.