C 800AT Nickel-Iron-Chromium Alloy,UNS N08811,,E FORU

### **Product Introduction: C-800AT Nickel-Iron-Chromium Alloy (UNS N08811)** **C-800AT Nickel-Iron-Chromium Alloy (UNS N08811)** is an advanced thermomechanically processed version of the C-800H alloy, specifically engineered to deliver superior microstructural stability and enhanced high-temperature performance. This nickel-iron-chromium superalloy features optimized aluminum and titanium content ratios that promote the formation of a highly stable gamma prime phase, providing exceptional creep resistance and long-term structural integrity in temperatures ranging from 540°C to 980°C (1000°F to 1800°F). The "AT" designation highlights the precisely controlled Aluminum and Titanium chemistry, which enables the alloy to maintain excellent mechanical properties under prolonged exposure to aggressive high-temperature environments, including carburizing and oxidizing atmospheres. --- #### **1. Chemical Composition (Weight %)** The chemical composition of C-800AT Nickel-Iron-Chromium Alloy per UNS N08811 is as follows: | Element | Content (%) | Element | Content (%) | |---------|-------------|---------|-------------| | **Nickel (Ni)** | 30.0 - 34.0 | **Chromium (Cr)** | 19.0 - 22.0 | | **Iron (Fe)** | 39.5 min | **Aluminum (Al)** | 0.25 - 0.45 | | **Titanium (Ti)** | 0.25 - 0.45 | **Carbon (C)** | 0.05 - 0.08 | | **Manganese (Mn)** | 1.00 max | **Silicon (Si)** | 0.75 max | | **Copper (Cu)** | 0.50 max | **Sulfur (S)** | 0.010 max | | **Al + Ti** | 0.50 - 0.90 | | | --- #### **2. Physical & Mechanical Properties** **Physical Properties:** | Property | Metric Units | Imperial Units | |----------|-----------------|------| | **Density** | 8.03 g/cm³ | 0.290 lb/in³ | | **Melting Range** | 1355 - 1390 °C | 2470 - 2535 °F | | **Thermal Conductivity** | 12.1 W/m·K | 83.9 Btu·in/hr·ft²·°F | | **Coefficient of Thermal Expansion** | 14.5 μm/m·°C | 8.1 μin/in·°F | | **Specific Heat** | 455 J/kg·K | 0.109 Btu/lb·°F | | **Electrical Resistivity** | 0.98 μΩ·m | - | | **Modulus of Elasticity** | 195 GPa | 28.3 x 10⁶ psi | **Mechanical Properties (Solution Annealed Condition):** | Property | Value | |----------|-----------------| | **Tensile Strength** | 620 - 760 MPa | 90 - 110 ksi | | **Yield Strength (0.2% Offset)** | 280 - 450 MPa | 41 - 65 ksi | | **Elongation** | 35 - 45% | | **Hardness (Rockwell B)** | 78 - 88 HRB | **Elevated Temperature Properties (at 815°C/1500°F):** | **Tensile Strength** | 180 MPa | 26 ksi | | **Yield Strength** | 125 MPa | 18 ksi | | **Creep Rupture Strength (1000h)** | 45 MPa | 6.5 ksi | --- #### **3. Key Characteristics & Product Applications** **Key Characteristics:** - **Enhanced Microstructural Stability**: Optimized Al/Ti ratio for superior long-term high-temperature performance - **Exceptional Creep Resistance**: Superior stress rupture properties under sustained loading at elevated temperatures - **Advanced Oxidation Resistance**: Enhanced protection against high-temperature scaling and degradation - **Carburization Resistance**: Excellent performance in carburizing atmospheres up to 980°C (1800°F) - **Thermal Fatigue Resistance**: Superior performance under thermal cycling conditions - **Controlled Precipitation**: Optimized gamma prime formation for consistent high-temperature strength **Product Applications:** C-800AT Nickel-Iron-Chromium Alloy serves in the most demanding high-temperature applications: - **Petrochemical Processing**: - Ethylene cracking furnace tubes and components - Steam hydrocarbon reformer assemblies - Pyrolysis heater tubing systems - High-temperature process reactors - **Heat Treatment Industry**: - High-temperature radiant tube systems - Carburizing and annealing retorts - Heat treatment fixture components - Continuous furnace roller systems - **Power Generation**: - Advanced heat recovery systems - High-efficiency superheater tubing - Gas turbine exhaust components - Nuclear power plant heat exchangers - **Industrial Processing**: - Calciner and roaster components - High-temperature heat exchanger tubing - Process furnace radiant sections - Thermal oxidizer systems --- #### **4. International Standards & Specifications** C-800AT Nickel-Iron-Chromium Alloy complies with the following international standards: **Primary Specifications:** - **UNS N08811**: Unified Numbering System - **ASTM B515**: UNS N08811 Seamless Tubes for Service Above 540°C (1000°F) - **ASTM B564**: Nickel Alloy Forgings - **ASME SB-515**: Code-qualified for pressure vessel applications **International Equivalents:** - **EN**: 1.4877 (X5NiCrAlTi31-20+AT) - **DIN**: 1.4877 - **ISO**: 6207 (Special Quality Requirements) - **TÜV**: Certified for high-temperature pressure equipment --- #### **Summary of Key Advantages** - **Optimized High-Temperature Performance**: Enhanced creep and stress rupture properties through controlled Al/Ti chemistry - **Superior Microstructural Stability**: Excellent long-term performance under sustained high-temperature exposure - **Enhanced Environmental Resistance**: Superior oxidation and carburization resistance in aggressive atmospheres - **Proven Reliability**: Demonstrated performance in critical petrochemical and power applications - **Advanced Manufacturing Quality**: Consistent properties through specialized thermomechanical processing - **Comprehensive Certification**: Meets international standards for high-temperature pressure equipment **Technical Note**: C-800AT requires specialized heat treatment including solution annealing at 1120-1170°C (2050-2140°F) followed by controlled cooling to achieve optimal microstructural characteristics. The precise Al/Ti ratio (typically maintained near 1:1) enables the formation of a stable, fine-scale gamma prime precipitation that provides exceptional creep resistance while maintaining good ductility. The alloy demonstrates excellent weldability using matching filler metals, though post-weld heat treatment is recommended for critical applications. For maximum high-temperature performance, thermal stabilization treatments at 760-870°C (1400-1600°F) are often employed to optimize the precipitation structure. The material exhibits superior resistance to thermal fatigue and maintains excellent dimensional stability under cyclic temperature conditions.

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 3193 gallon liquid totes Special package is available on request.