Alloy 903,Incoloy 903 ,,E FORU

British Specs:，American Specs:，German Specs:

### **Product Introduction: Alloy 903 / Incoloy 903 (UNS N19903)** **Overview** Alloy 903, commercially known as **Incoloy 903**, is a nickel-iron-cobalt **low thermal expansion superalloy**. Its defining characteristic is its controlled, low coefficient of thermal expansion (CTE) combined with high strength over a wide temperature range, typically from cryogenic temperatures up to about 500°C (930°F). This unique property is achieved through a specific composition balanced to create a stable austenitic matrix. Unlike many high-temperature alloys designed for oxidation resistance, Incoloy 903 is primarily engineered for applications where dimensional stability under thermal cycling is critical. It is strengthened by age-hardening (precipitation hardening) which develops high yield strength while maintaining its low expansion characteristics. This makes it an indispensable material for precision components in aerospace and gas turbine engines. **Key Characteristics** * **Controlled Low Thermal Expansion:** Maintains nearly constant dimensions over a wide temperature range. * **High Strength-to-Weight Ratio:** Excellent mechanical properties achieved through age-hardening. * **Good Fatigue Strength:** Resists cracking under cyclic loading conditions. * **Age-Hardenable:** Gains its high strength from a specific heat treatment process. * **Useful Cryogenic Properties:** Maintains good toughness and strength at low temperatures. --- ### **Chemical Composition (Weight %)** The precise chemical composition is critical for achieving the desired low expansion properties and strength. | Element | Content (%) | | :--- | :--- | | **Nickel (Ni)** | 36.0 - 39.0 | | **Iron (Fe)** | Balance | | **Cobalt (Co)** | 14.0 - 17.0 | | **Niobium (Nb) + Tantalum (Ta)** | 2.90 - 3.50 | | **Titanium (Ti)** | 1.35 - 1.75 | | **Aluminum (Al)** | 0.70 - 1.15 | | **Silicon (Si)** | ≤ 0.30 | | **Manganese (Mn)** | ≤ 0.20 | | **Carbon (C)** | ≤ 0.05 | | **Sulfur (S)** | ≤ 0.015 | | **Boron (B)** | ≤ 0.012 | *Note: The balance is Iron (Fe). The combination of Ni, Co, and Fe is carefully controlled to achieve the low expansion characteristic.* --- ### **Physical Properties** The physical properties, especially the thermal expansion, are the key differentiators for this alloy. | Property | Value / Condition | | :--- | :--- | | **Density** | 8.25 g/cm³ (0.298 lb/in³) | | **Melting Range** | ~1370 °C (~2500 °F) | | **Mean Coefficient of Thermal Expansion** | **8.5 x 10⁻⁶ /°C** | | *Temperature Range* | *20 - 400°C (68 - 750°F)* | | **Thermal Conductivity** | 11.5 W/m·K (at 100°C) | | **Specific Heat** | 440 J/kg·K (at 20°C) | | **Electrical Resistivity** | 1.05 μΩ·m | | **Modulus of Elasticity** | 148 GPa (21.5 x 10⁶ psi) | --- ### **Mechanical Properties (Typical for Age-Hardened Condition)** Properties are developed through a solution anneal and a multi-step age-hardening treatment. | Property | Value at Room Temperature | | :--- | :--- | | **Tensile Strength** | 1240 - 1380 MPa (180 - 200 ksi) | | **Yield Strength (0.2% Offset)** | 1030 - 1170 MPa (150 - 170 ksi) | | **Elongation** | 12 - 18% | | **Reduction of Area** | 18 - 28% | | **Hardness** | 36 - 42 HRC | --- ### **Product Applications** Incoloy 903 is used in high-precision applications where components must not expand or contract significantly under temperature changes, thereby maintaining tight clearances. * **Aerospace Gas Turbine Engines:** * **Turbine Shrouds and Rings:** Maintains tight blade tip clearances for improved engine efficiency. * **Seals and Casings:** Critical for controlling airflow and pressure within the engine. * **Spacers and Support Rings.** * **Precision Instruments and Optical Systems:** Components that require dimensional stability despite temperature fluctuations. * **Cryogenic Equipment:** Components for liquid fuel systems and other low-temperature applications. --- ### **International Standards** Incoloy 903 is covered by several key aerospace and industrial standards. | Standard Type | Standard Number | Title / Specification | | :--- | :--- | :--- | | **Material Standard (ASTM)** | **ASTM B625** | Standard Specification for UNS N08904, N08354, and N09904 Plate, Sheet, and Strip | | | **ASTM B637** | Standard Specification for Precipitation-Hardening Nickel Alloy Bars, Forgings, and Forging Stock for High-Temperature Service | | **Aerospace Material (AMS)** | **AMS 5916** | Ring, Sealing, Low Thermal Expansion, 38Ni-15Co-3Cb-1.7Ti-1.4Al, Vacuum Melted, Solution and Precipitation Heat Treated | | **UNS Designation** | **N19903** | Unified Numbering System | **Important Note:** Incoloy 903 is a controlled expansion superalloy and is **not** designed for high-temperature oxidizing environments. Its maximum service temperature is limited by its oxidation resistance, not its strength. For applications requiring both low expansion and better oxidation resistance, successors like **Incoloy 907** and **Incoloy 909** were developed. --- **Disclaimer:** The information provided here is for reference purposes. The properties of Incoloy 903 are highly dependent on the specific heat treatment (solution annealing and aging cycle). For design and critical applications, always consult the official material data sheets from the manufacturer and the complete, latest version of the relevant standards.

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 3015 gallon liquid totes Special package is available on request.