Alloy 903，Incoloy 903 ，

British Specs:，American Specs:，German Specs:

Alloy 903 and Incoloy 903 Wire - Introduction with Composition, Properties, Applications and Product Forms

Alloy 903, commercially known as Incoloy 903, is a nickel-iron-cobalt based superalloy renowned for its exceptional combination of high strength, low thermal expansion, and excellent fabricability. This versatile material is available in a wide range of forms to suit diverse industrial needs, including Bar (Round bar, Flat bar), Ribbon, Wire, Rods, Tube, Pipe, Foil, Plate, Sheet, Strip, and Forging Stock. Among these, Incoloy 903 Wire stands out for its flexibility in intricate applications. Below is a comprehensive overview of its chemical composition, key properties, practical applications, and available product forms.

Chemical Composition

The carefully engineered chemical composition of Alloy 903 (Incoloy 903) is fundamental to its unique performance characteristics. The typical composition (by weight) is as follows:

Nickel (Ni): 38-42% (serves as the primary matrix element, contributing to corrosion resistance and structural stability)

Iron (Fe): 34-38% (balances the alloy and enhances mechanical strength at both ambient and elevated temperatures)

Cobalt (Co): 14-18% (improves high-temperature strength and creep resistance)

Niobium (Nb): 4.0-5.0% (a key strengthening element, forming intermetallic precipitates to boost strength)

Molybdenum (Mo): 2.5-3.5% (enhances creep resistance and high-temperature stability)

Titanium (Ti): 1.0-1.5% (aids in precipitation hardening, working with niobium to form strengthening phases)

Aluminum (Al): 0.5-1.0% (assists in grain refinement and contributes to high-temperature strength)

Carbon (C): 0.03-0.08% (controlled to promote grain boundary strength without excessive carbide formation)

Trace elements: Silicon (Si) ≤ 0.30%, Manganese (Mn) ≤ 0.30%, Phosphorus (P) ≤ 0.015%, Sulfur (S) ≤ 0.015% (optimize weldability and fabricability)

Key Properties

Alloy 903 and its various forms, including Incoloy 903 Wire, exhibit a remarkable set of properties that make them stand out in demanding environments:

Mechanical Properties (room temperature, heat-treated condition):

Tensile strength: 1030-1170 MPa (150,000-170,000 psi)

Yield strength (0.2% offset): 760-860 MPa (110,000-125,000 psi)

Elongation (in 50 mm): 15-20% (good ductility, enabling complex forming and welding across all product forms)

Hardness: 30-35 HRC (indicative of high strength and wear resistance)

High-Temperature Performance:

Thermal stability: Maintains significant strength up to 650°C (1200°F), with tensile strength remaining above 800 MPa at 500°C (932°F)

Creep resistance: Exhibits minimal deformation under sustained stress at 600-650°C (1112-1200°F), making it suitable for long-term high-temperature service in all forms

Low thermal expansion: Coefficient of thermal expansion is approximately 11.0 μm/(m·K) (20-650°C), significantly lower than many other superalloys, ensuring excellent dimensional stability during thermal cycling—critical for precision components like bars and tubes

Corrosion Resistance:

Good resistance to oxidation in air and combustion gases up to 700°C (1292°F)

Moderate resistance to aqueous corrosion, including freshwater and some industrial chemicals

Resists stress corrosion cracking in certain environments, particularly those with moderate chloride levels—beneficial for pipes and sheets in chemical processing

Physical Properties:

Density: 8.0 g/cm³ (0.289 lb/in³)

Thermal conductivity: 16 W/(m·K) at 20°C (68°F)

Melting point: 1360-1390°C (2480-2534°F)

Modulus of elasticity: 200 GPa (29,000 ksi) at room temperature

Product Forms

Alloy 903 is manufactured in a diverse range of forms to accommodate various industrial processes and applications:

Bar: Available as Round bar (diameters from 6 mm to 300 mm) and Flat bar (thickness 5 mm to 100 mm, width 20 mm to 500 mm), ideal for machining into precision components like fasteners and gears.

Ribbon: Thin, flat strips (thickness 0.1 mm to 2 mm, width 5 mm to 100 mm) used in electrical and thermal applications requiring flexibility and high-temperature resistance.

Wire: Incoloy 903 Wire (diameters 0.05 mm to 10 mm) offers exceptional ductility for forming springs, thermocouple sheaths, and welded mesh.

Rods: Solid cylindrical rods (diameters 3 mm to 50 mm) suitable for structural supports and small-scale machining.

Tube and Pipe: Seamless and welded options (outer diameter 6 mm to 200 mm, wall thickness 0.5 mm to 20 mm) for fluid transport in high-temperature systems.

Foil: Ultra-thin sheets (thickness 0.01 mm to 0.1 mm) used in lightweight thermal insulation and electronics.

Plate and Sheet: Flat forms (plate: thickness 5 mm to 100 mm; sheet: 0.3 mm to 5 mm) for fabricating large structural components like furnace liners and aircraft panels.

Strip: Narrow, flat strips (thickness 0.1 mm to 3 mm, width 10 mm to 200 mm) for precision manufacturing in aerospace and industrial machinery.

Forging Stock: Billets and ingots for hot forging into complex shapes such as turbine disks and heavy-duty industrial parts.

Applications

The versatility of Alloy 903 across its various forms makes it indispensable in industries requiring high performance under extreme conditions:

Aerospace and Defense:

Aircraft components: Round bars machined into fasteners; sheets and plates for structural panels; wire for springs in landing gear systems—all leveraging low thermal expansion for dimensional stability during flight.

Spacecraft systems: Forging stock shaped into rocket engine nozzles; tubes for coolant lines; ribbon for thermal management components, benefiting from high strength-to-weight ratio.

Missile systems: Flat bars for guidance system brackets; rods for structural supports; wire for sensor connectors, withstanding rapid temperature fluctuations.

Industrial Machinery:

High-precision tooling: Plates and flat bars for molds in high-temperature forming; foil for heat shields in precision machinery.

Heat treatment equipment: Tubes and pipes for heating element enclosures; bars for furnace rails; wire mesh (from wire form) for component baskets.

Cryogenic applications: Sheets and plates for low-temperature storage tanks; rods for structural supports, retaining toughness at sub-zero temperatures.

Power Generation:

Gas turbine components: Forging stock for turbine disks; tubes for fuel delivery; bars for valve stems, resisting creep at high operating temperatures.

Nuclear power systems: Pipes for coolant circulation; plates for reactor internals; wire for instrumentation, withstanding radiation and corrosion.

Specialized Applications by Form:

Wire: Thermocouple sheaths, high-temperature springs, and welded filters in chemical processing.

Tube/Pipe: Fluid transport in petrochemical refining and industrial heating systems.

Plate/Sheet: Heat exchanger panels in power plants and aerospace thermal control systems.

Bar/Rod: Machined parts like gears, shafts, and connectors in heavy machinery.

In summary, Alloy 903—available in forms ranging from Bar and Wire to Plate and Forging Stock—delivers a unique blend of high strength, low thermal expansion, and versatility. Its various product forms enable tailored solutions across aerospace, industrial, and power generation sectors, solidifying its role as a critical material in high-performance engineering.

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.