Alloy 901,Nimonic 901 Forgings,UNS N09901

Alloy 901,Incoloy 901 Wire,UNS N,09901

Alloy 901 (Incoloy 901 Wire, UNS N09901) - Introduction with Composition, Properties, Applications and Product Forms

Alloy 901, commercially known as Incoloy 901 and designated by UNS N09901, is a precipitation-hardening nickel-iron-chromium superalloy engineered for exceptional strength and stability at moderate to high temperatures (up to 650°C/1200°F). Unlike ultra-high-temperature nickel alloys, it balances high mechanical performance with excellent fabricability—making it a cost-effective choice for aerospace, power generation, and industrial applications where components face cyclic thermal stress and mechanical loads. It is available in a comprehensive range of forms to meet diverse industrial needs, including Bar (Round bar, Flat bar), Ribbon, Wire, Rods, Tube, Pipe, Foil, Plate, Sheet, Strip, and Forging Stock. Incoloy 901 Wire, in particular, stands out for its uniform strength and weldability, making it ideal for welding filler metal, spring manufacturing, and precision components in gas turbine engines. Below is a detailed overview of its chemical composition, key properties, practical applications, and available product forms.

Chemical Composition

The precisely balanced chemical composition of Alloy 901 (Incoloy 901, UNS N09901) is the foundation of its high-temperature strength, fabricability, and thermal stability. The typical composition (by weight) is as follows:

Nickel (Ni): 40-45% (the primary matrix element, enabling precipitation of strengthening phases; enhances ductility and low-temperature toughness while resisting thermal fatigue)

Iron (Fe): 30-35% (balances the alloy’s density and cost; improves hot workability for forging, rolling, and wire drawing—critical for producing thin forms like foil and strip)

Chromium (Cr): 11-14% (forms a dense, protective chromium oxide layer, ensuring resistance to oxidation and sulfidation in high-temperature air and industrial gases)

Molybdenum (Mo): 5.0-6.5% (strengthens the alloy matrix through solid-solution hardening; enhances creep resistance and resistance to pitting corrosion in mild chloride environments)

Titanium (Ti): 2.5-3.5% (the key precipitation-hardening element—forms gamma-prime (γ’) intermetallic precipitates during aging, delivering exceptional high-temperature strength)

Aluminum (Al): 0.7-1.3% (works with titanium to refine γ’ precipitates, boosting strength at elevated temperatures without compromising ductility)

Carbon (C): 0.03-0.08% (forms fine carbides with chromium and molybdenum, reinforcing grain boundaries and improving creep rupture strength)

Silicon (Si): ≤ 0.5% (aids in deoxidation during manufacturing and supports oxide layer formation for oxidation resistance)

Manganese (Mn): ≤ 0.5% (enhances hot workability, reducing cracking during forging and rolling of thick plates and bars)

Phosphorus (P): ≤ 0.015% (strictly limited to avoid grain boundary embrittlement, critical for components under cyclic thermal stress)

Sulfur (S): ≤ 0.01% (minimized to ensure good ductility and resistance to stress corrosion cracking in high-temperature steam)

Boron (B): 0.001-0.005% (strengthens grain boundaries, improving creep resistance and thermal fatigue performance without altering fabricability)

This engineered blend—combining nickel-chromium-molybdenum for corrosion/strength and titanium-aluminum for precipitation hardening—delivers Alloy 901’s signature balance of performance and ease of manufacturing.

Key Properties

Alloy 901 (Incoloy 901 Wire, UNS N09901) and its various forms exhibit exceptional properties tailored for moderate-to-high-temperature, cyclic-stress environments:

Mechanical Properties (Aged Condition, 705°C/1300°F for 4 hours + 620°C/1150°F for 4 hours)

Tensile Strength: 1100-1300 MPa (159,500-188,500 psi) at room temperature; retains ~700 MPa (101,500 psi) at 600°C (1112°F)

Yield Strength (0.2% offset): 850-1050 MPa (123,300-152,300 psi) at room temperature; retains ~600 MPa (87,000 psi) at 600°C (1112°F)

Elongation (in 50 mm): 15-25% (excellent ductility for cold forming—e.g., bending wire into springs, shaping tube into engine coolant lines)

Reduction of Area: 30-40% (superior toughness, resisting fracture under thermal cycling and mechanical impact)

Hardness: 35-41 HRC (Rockwell hardness) at room temperature; maintains ~28 HRC at 600°C (1112°F)

High-Temperature Properties

Continuous Service Temperature: Up to 650°C (1200°F) (optimal performance range; short-term exposure up to 760°C/1400°F)

Creep Resistance: Excellent for moderate temperatures—1000-hour creep rupture strength of ~350 MPa (50,800 psi) at 600°C (1112°F) and ~180 MPa (26,100 psi) at 650°C (1200°F) (outperforms stainless steels and low-alloy steels)

Thermal Fatigue Resistance: Withstands 5000+ thermal cycles (e.g., 200°C/392°F to 600°C/1112°F) without cracking, critical for gas turbine and power generation components

Corrosion & Oxidation Resistance

Oxidation Resistance: Forms a stable chromium oxide layer, resisting scaling in air at temperatures up to 815°C (1500°F) for extended periods (suitable for engine exhaust and furnace environments)

General Corrosion: Good resistance to high-temperature steam, industrial gases (e.g., natural gas combustion products), and mild acids (e.g., dilute sulfuric acid)

Pitting/Crevice Corrosion: Moderate resistance to chloride-induced pitting (suitable for dry, low-humidity industrial environments; supplementary coatings used for marine or high-chloride applications)

Physical Properties

Density: 7.9 g/cm³ (0.285 lb/in³) (lower than pure nickel alloys, reducing weight in structural applications like aircraft engine parts)

Thermal Conductivity: 13.0 W/(m·K) at 20°C (68°F); increases to 20.0 W/(m·K) at 600°C (1112°F) (efficient heat transfer for heat exchanger and cooling system components)

Coefficient of Thermal Expansion: 12.5 μm/(m·K) (20-300°C/68-572°F); 14.8 μm/(m·K) (20-600°C/68-1112°F) (controlled expansion to minimize thermal stress in assembled systems like turbine casings)

Modulus of Elasticity: 205 GPa (29,700 ksi) at room temperature; decreases to ~175 GPa (25,400 ksi) at 600°C (1112°F)

Melting Point: 1330-1380°C (2426-2516°F)

Product Forms

Alloy 901 (Incoloy 901, UNS N09901) is manufactured in a diverse range of forms to accommodate specialized moderate-to-high-temperature applications:

Bar: Round bar (diameters 6-200 mm) and Flat bar (thickness 5-100 mm, width 20-500 mm) — ideal for machining into gas turbine compressor blades, valve stems, and high-strength fasteners for aircraft engines.

Ribbon: Thin, flat strips (thickness 0.07-0.8 mm, width 3-80 mm) — used in thermal spray coatings for corrosion/oxidation protection on steel substrates and flexible seals for high-temperature furnaces.

Wire: Incoloy 901 Wire (diameters 0.3-6 mm) — serves as welding filler metal (TIG/MIG) for joining 901 components, as precision springs in engine control systems, and as sensor wires in high-temperature instrumentation.

Rods: Solid cylindrical rods (diameters 2-50 mm) — used for GTAW filler metal and manufacturing small components like pump shafts and instrument probes in power plants.

Tube and Pipe: Seamless tube (outer diameter 4-150 mm, wall thickness 0.5-10 mm) and pipe (NPS ½-12) — critical for engine coolant lines, heat exchanger tubes, and industrial furnace fuel lines.

Foil: Ultra-thin sheets (thickness 0.012-0.1 mm) — used as thermal barriers in electronic components and thin gaskets in precision instruments exposed to moderate heat.

Plate and Sheet: Plate (thickness 3-50 mm) and Sheet (thickness 0.2-3 mm) — fabricated into gas turbine combustion liners, boiler components, and industrial furnace walls.

Strip: Narrow, flat strips (thickness 0.07-2 mm, width 2-50 mm) — used for precision components like heat exchanger fins, electrical contacts, and seal rings in high-temperature machinery.

Forging Stock: Billets and ingots (sizes up to 500×500 mm) — hot-forged into complex shapes (e.g., turbine disks, engine casings) requiring high strength and thermal stability.

Applications

The exceptional balance of high-temperature strength, fabricability, and cost-effectiveness of Alloy 901 (Incoloy 901 Wire, UNS N09901) makes it a staple in industries requiring reliable performance at moderate-to-high temperatures:

Aerospace & Aviation

Gas Turbine Engines: Compressor blades (bar/forging stock), combustion liners (plate/sheet), and coolant tubes (tube) — withstands 500-650°C temperatures and cyclic stress from engine start-stop cycles.

Aircraft Structural Components: High-strength fasteners (bar/wire) and engine mounts (forging stock) — balances strength and weight for airframe and engine integration.

Auxiliary Power Units (APUs): Heat exchanger plates (sheet) and fuel lines (tube) — resists high-temperature steam and fuel combustion byproducts.

Power Generation

Gas/Steam Turbines: Hot-section components (plate/forging stock) and heat exchanger tubes (tube) — endures moderate temperatures (500-600°C) and cyclic loading in power plants.

Waste-to-Energy Plants: Furnace walls (plate) and flue gas heat recovery components (sheet) — resists oxidation and mild corrosion from flue gases.

Geothermal Power: Wellhead tubing (tube) — withstands high-temperature (up to 200°C) geothermal fluids and mild scaling.

Industrial & Manufacturing

High-Temperature Furnaces: Furnace liners (plate), heating element supports (rod), and thermocouple sheaths (tube) — operates reliably in 500-650°C furnace atmospheres.

Chemical Processing: Reactor internals (bar/plate) and heat exchanger tubes (tube) — resists high-temperature steam and mild organic chemicals.

Metallurgical Processing: Heat treatment fixtures (forging stock/bar) — retains shape and strength during metal annealing cycles (up to 600°C).

Specialized Applications by Form

Wire: Welding filler metal for gas turbine components; precision springs in engine control systems.

Tube/Plate: Engine coolant lines and gas turbine combustion liners.

Bar/Forging Stock: Compressor blades and turbine disks for aerospace and power generation.

Strip/Sheet: Heat exchanger fins and industrial furnace wall panels.

In summary, Alloy 901 (Incoloy 901 Wire, UNS N09901) — available in forms from Bar and Wire to Plate and Forging Stock — fills a critical niche for moderate-to-high-temperature applications where strength, fabricability, and cost-effectiveness are equally important. Its diverse product forms and balanced properties make it a trusted material in aerospace, power generation, and industrial sectors, enabling reliable performance in components that face cyclic thermal stress and mechanical loads.

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 975 gallon liquid totes Special package is available on request.