Alloy 903,Incoloy 903,，EFORU

### **Alloy 903 / INCOLOY® 903 (UNS N19903) - Technical Datasheet** --- #### **1. Overview** **INCOLOY® 903** is a nickel-iron-cobalt superalloy known for its unique combination of low thermal expansion characteristics and high strength over a wide temperature range. This precipitation-hardenable alloy maintains constant modulus properties and controlled thermal expansion from cryogenic temperatures up to 540°C (1000°F), making it particularly suitable for applications requiring dimensional stability under varying thermal conditions. --- #### **2. Chemical Composition (Weight %)** The composition is precisely balanced for controlled thermal expansion and precipitation hardening. | Element | Content (%) | Role & Benefit | |---------|-------------|----------------| | **Nickel (Ni)** | 37.0 - 40.0 | Controls thermal expansion coefficient | | **Iron (Fe)** | Balance | Base element providing matrix structure | | **Cobalt (Co)** | 14.0 - 16.0 | Enhances strength and thermal stability | | **Niobium (Nb)** | 2.8 - 3.3 | Primary precipitation hardening element | | **Titanium (Ti)** | 1.3 - 1.6 | Secondary precipitation hardening element | | **Aluminum (Al)** | 0.6 - 1.0 | Contributes to precipitation hardening | | **Manganese (Mn)** | 0.10 max | Controlled impurity | | **Silicon (Si)** | 0.10 max | Controlled impurity | | **Carbon (C)** | 0.03 max | Controlled for optimal properties | | **Sulfur (S)** | 0.015 max | Controlled impurity | | **Copper (Cu)** | 0.20 max | Controlled impurity | *Note: "INCOLOY" is a registered trademark of Special Metals Corporation* --- #### **3. Physical Properties** The physical properties highlight its unique thermal characteristics. | Property | Value | |----------|-------| | **Density** | 8.25 g/cm³ (0.298 lb/in³) | | **Melting Point** | 1380-1430°C (2515-2610°F) | | **Specific Heat (20°C)** | 450 J/kg·K | | **Thermal Conductivity** | 11.5 W/m·K (at 20°C) | | **Mean Coefficient of Thermal Expansion** | **7.5 × 10⁻⁶/°C (20-200°C)**
**8.5 × 10⁻⁶/°C (20-400°C)** | | **Electrical Resistivity** | 1.10 μΩ·m | | **Modulus of Elasticity** | 175 GPa (25.4 × 10⁶ psi) | | **Magnetic Permeability** | Essentially non-magnetic | --- #### **4. Mechanical Properties** Properties vary significantly with heat treatment condition. **Solution Annealed Condition:** | Property | Value | |----------|-------| | **Tensile Strength** | 860-1030 MPa (125-150 ksi) | | **Yield Strength (0.2% Offset)** | 515-690 MPa (75-100 ksi) | | **Elongation** | 20-30% | | **Hardness** | 28-35 HRC | **Aged Condition (720°C/1325°F for 8 hours):** | Property | Value | |----------|-------| | **Tensile Strength** | 1310-1520 MPa (190-220 ksi) | | **Yield Strength** | 1170-1380 MPa (170-200 ksi) | | **Elongation** | 10-15% | | **Hardness** | 38-44 HRC | **Low Temperature Properties (-196°C/-320°F):** | Property | Value | |----------|-------| | **Tensile Strength** | 1650 MPa (240 ksi) | | **Yield Strength** | 1380 MPa (200 ksi) | | **Elongation** | 12% | --- #### **5. Heat Treatment** **Solution Treatment:** 980°C (1800°F) for 1 hour, rapid cool **Aging Treatment:** 720°C (1325°F) for 8 hours, furnace cool to 620°C (1150°F) at 55°C (100°F) per hour, then air cool **Alternative Aging:** 760°C (1400°F) for 4 hours for specific applications --- #### **6. Product Applications** **INCOLOY 903** serves in applications requiring dimensional stability and high strength: - **Aerospace Industry:** - Gas turbine engine seals and rings - Compressor casings - Missile components - Spacecraft structural members - **Precision Instruments:** - Laser system components - Optical mounting systems - Precision measuring equipment - Instrumentation frames - **Power Generation:** - Steam turbine components - Gas turbine parts - Power transmission systems - Generator components - **Automotive Industry:** - Turbocharger components - High-performance engine parts - Racing engine components - **Specialized Applications:** - Cryogenic equipment - Thermal barrier systems - Dimensionally stable structures - High-precision mechanisms --- #### **7. International Standards** The material conforms to various international specifications: | Standard | Specification | |----------|---------------| | **ASTM** | ASTM B637 - Precipitation Hardening Nickel Alloy Bars, Forgings, and Forging Stock | | **UNS** | UNS N19903 | | **AMS** | AMS 5545 (Sheet, Strip, Plate)
AMS 5546 (Bar and Forgings) | | **Aerospace** | AMS 5545, AMS 5546 | | **Military** | MIL-N-8947 | --- #### **8. Special Characteristics** - **Low Thermal Expansion:** Controlled expansion coefficient over wide temperature range - **Constant Modulus:** Stable elastic modulus from cryogenic to elevated temperatures - **High Strength:** Excellent strength-to-weight ratio - **Cryogenic Performance:** Maintains properties at extremely low temperatures - **Thermal Stability:** Resistant to thermal fatigue and creep --- #### **9. Fabrication Characteristics** - **Machining:** Best machined in solution annealed condition - **Welding:** Good weldability using GTAW with matching filler metal - **Forming:** Good hot working characteristics - **Heat Treatment:** Requires precise control of aging parameters - **Grinding:** Suitable for precision grinding operations --- #### **10. Thermal Expansion Properties** The alloy exhibits remarkably consistent thermal expansion behavior: - **20°C to 200°C:** 7.5 × 10⁻⁶/°C - **20°C to 400°C:** 8.5 × 10⁻⁶/°C - **20°C to 540°C:** 9.5 × 10⁻⁶/°C This controlled expansion matches many glasses and ceramics, enabling reliable sealing applications. --- #### **11. Summary** **INCOLOY® 903 (UNS N19903)** represents a specialized class of superalloys engineered for applications requiring both high strength and controlled thermal expansion characteristics. Its unique combination of mechanical properties and dimensional stability over a wide temperature range makes it invaluable for precision components in aerospace, instrumentation, and power generation industries. The alloy's ability to maintain nearly constant dimensions while providing high strength from cryogenic temperatures up to 540°C establishes it as a critical material for applications where thermal mismatch cannot be tolerated. Governed by comprehensive standards including AMS 5545-5546 and ASTM specifications, INCOLOY 903 continues to enable advanced engineering designs where dimensional stability and reliability under thermal cycling are paramount requirements.

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 1729 gallon liquid totes Special package is available on request.