Alloy PK33,Nimonic PK33 Pipe,

Alloy PK33,Nimonic PK33 Wire,

Alloy PK33 (Nimonic PK33 Wire) - Introduction with Composition, Properties, Applications and Product Forms

Alloy PK33, commercially known as Nimonic PK33 and part of the renowned Nimonic superalloy family, is a nickel-chromium-aluminum-titanium alloy celebrated for its exceptional high-temperature strength, creep resistance, and oxidation stability. This alloy is specifically engineered to perform reliably in extreme thermal environments—including prolonged exposure to elevated temperatures and cyclic stress—making it a critical material in aerospace, energy, and industrial applications where components face combustion gases, thermal cycling, and high 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. Nimonic PK33 Wire, in particular, stands out for its uniform high-temperature properties, flexibility, and precision, making it ideal for welding, thermal spray coatings, and intricate components in gas turbine engines and high-heat industrial systems. 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 PK33 (Nimonic PK33 Wire) is the foundation of its exceptional high-temperature performance and corrosion resistance. The typical composition (by weight) is as follows:

Nickel (Ni): 70-73% (the primary matrix element, delivering high-temperature stability, structural integrity, and supporting precipitate formation for strength)

Chromium (Cr): 19-21% (forms a dense, protective chromium oxide layer, ensuring superior oxidation and sulfidation resistance at ultra-high temperatures)

Aluminum (Al): 1.8-2.2% (works with titanium to form gamma-prime (γ’) intermetallic precipitates, the key to the alloy’s high-temperature strength)

Titanium (Ti): 2.8-3.2% (combines with aluminum to form gamma-prime precipitates, enhancing creep resistance and tensile strength at elevated temperatures)

Carbon (C): 0.05-0.10% (forms carbides with chromium, reinforcing grain boundaries and improving creep rupture strength)

Iron (Fe): ≤ 1.0% (minimized to preserve high-temperature properties and oxidation resistance)

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

Manganese (Mn): ≤ 0.5% (enhances hot workability, enabling fabrication into diverse product forms like wire and foil)

Boron (B): 0.003-0.010% (aids in grain boundary strengthening, reducing creep rupture and improving ductility at high temperatures)

Zirconium (Zr): 0.05-0.15% (stabilizes carbides and refines microstructure, further boosting creep resistance and thermal fatigue performance)

Phosphorus (P): ≤ 0.02% (strictly limited to prevent grain boundary embrittlement under high stress)

Sulfur (S): ≤ 0.01% (minimized to ensure good ductility and resistance to stress corrosion cracking)

This engineered blend—centered on nickel, chromium, and precipitate-forming elements—delivers Alloy PK33’s signature ultra-high-temperature strength, creep resistance, and oxidation stability, critical for demanding thermal applications.

Key Properties

Alloy PK33 (Nimonic PK33 Wire) and its various forms exhibit extraordinary properties that make them indispensable in ultra-high-temperature, corrosive, and cyclic-stress environments:

Mechanical Properties (solution-annealed and aged condition):

Tensile strength: 1100-1250 MPa (159,500-181,300 psi) at room temperature; retains ~450 MPa (65,300 psi) at 850°C (1562°F)

Yield strength (0.2% offset): 750-850 MPa (108,800-123,300 psi) at room temperature; retains ~380 MPa (55,100 psi) at 850°C (1562°F)

Elongation (in 50 mm): 15-25% at room temperature; 10-18% at 850°C (1562°F) (excellent ductility for forming complex components like turbine blades and seals)

Reduction of area: 25-35% (superior toughness, resisting fracture under high-temperature cyclic stress)

Hardness: 35-40 HRC (Rockwell hardness) at room temperature; maintains ~25 HRC at 850°C (1562°F)

High-Temperature Properties:

Continuous service temperature: Up to 950°C (1742°F) (a top performer for precipitation-strengthened nickel alloys, with long-term stability in air)

Creep resistance: Exceptional resistance to creep deformation—1000-hour creep rupture strength of ~220 MPa (31,900 psi) at 850°C (1562°F) and ~100 MPa (14,500 psi) at 950°C (1742°F)

Thermal fatigue resistance: Withstands repeated thermal cycling (e.g., 200°C to 900°C) without cracking, critical for components like gas turbine combustion liners and exhaust parts

Oxidation resistance: Superior resistance to oxidation and scaling in air at temperatures up to 1050°C (1922°F), with minimal weight gain even after 5000 hours at 950°C (1742°F)

Corrosion Resistance:

General corrosion: Excellent resistance to high-temperature combustion gases, industrial chemicals, and steam

Sulfidation resistance: Resists sulfidation in sulfur-containing environments (e.g., coal-fired power plants) up to 850°C (1562°F)

Pitting/crevice corrosion: Good resistance to pitting in mild chloride environments (e.g., aerospace components exposed to humidity)

Carburization resistance: Maintains integrity in mild carburizing atmospheres (e.g., industrial furnaces) by limiting carbon absorption and preventing carbide overgrowth

Physical Properties:

Density: 8.1-8.3 g/cm³ (0.293-0.299 lb/in³)

Thermal conductivity: 11-13 W/(m·K) at 20°C (68°F); increases to 22-25 W/(m·K) at 900°C (1652°F) (efficient heat dissipation at high temperatures, reducing thermal stress)

Coefficient of thermal expansion: 13.0-15.0 μm/(m·K) (20-900°C) (controlled expansion to minimize thermal stress in assembled components like turbine casings)

Modulus of elasticity: 205-215 GPa (29,700-31,200 ksi) at room temperature; decreases to ~140 GPa (20,300 ksi) at 900°C (1652°F)

Melting point: 1360-1410°C (2480-2570°F)

Product Forms

Alloy PK33 (Nimonic PK33 Wire) is manufactured in a diverse range of forms to accommodate specialized ultra-high-temperature and corrosion-resistant applications:

Bar: Available as Round bar (diameters from 10 mm to 200 mm) and Flat bar (thickness 5 mm to 100 mm, width 20 mm to 500 mm), ideal for machining into turbine components, valve stems, and high-temperature fasteners.

Ribbon: Thin, flat strips (thickness 0.1 mm to 1 mm, width 5 mm to 100 mm) used in thermal spray coatings, electrical heating elements, and flexible seals for high-temperature furnaces.

Wire: Nimonic PK33 Wire (diameters 0.5 mm to 6 mm) offers uniform high-temperature properties, suitable for welding (TIG/MIG), thermal spray applications, and precision heating coils in industrial furnaces.

Rods: Solid cylindrical rods (diameters 3 mm to 50 mm) used for gas tungsten arc welding (GTAW) filler metal and manufacturing small high-temperature components (e.g., sensor supports, valve pins).

Tube and Pipe: Hollow forms (outer diameter 6 mm to 100 mm, wall thickness 0.5 mm to 10 mm) for high-temperature fluid transport (e.g., furnace fuel lines, heat exchanger tubes in power plants).

Foil: Ultra-thin sheets (thickness 0.02 mm to 0.1 mm) used in high-temperature gaskets, heat shields for electronics, and thin-film thermal barriers.

Plate and Sheet: Flat forms (plate: thickness 3 mm to 50 mm; sheet: 0.3 mm to 3 mm) for fabricating combustion liners, furnace walls, and aerospace heat exchangers.

Strip: Narrow, flat strips (thickness 0.1 mm to 2 mm, width 3 mm to 50 mm) for precision components like turbine seals, heat exchanger fins, and electrical contacts in high-heat environments.

Forging Stock: Billets and ingots for hot forging into complex shapes (e.g., gas turbine disks, compressor blades, industrial furnace doors) requiring ultra-high-temperature strength.

Applications

The exceptional ultra-high-temperature strength, creep resistance, and oxidation stability of Alloy PK33 (Nimonic PK33 Wire) across its various forms make it a critical material in industries requiring performance under extreme thermal conditions:

Aerospace and Aviation:

Gas turbine engines: Compressor blades, turbine vanes, combustion liners, and afterburner components (from plate, forging stock, and sheet) withstanding temperatures up to 950°C (1742°F).

Aerospace fasteners: High-temperature bolts, studs, and rivets (from bar and rod) securing engine components exposed to cyclic thermal stress and vibration.

Auxiliary power units (APUs): Heat exchanger tubes and structural parts (from tube and sheet) resisting high temperatures in aircraft auxiliary systems.

Energy and Power Generation:

Gas/steam turbines: Hot-section components (from plate, forging stock, and bar) for industrial power turbines, enduring high temperatures and cyclic loading.

Waste-to-energy plants: Combustion chamber liners and heat recovery components (from sheet and plate) withstanding corrosive flue gases and temperatures above 850°C.

Nuclear power: Heat exchanger tubes and structural components (from tube and plate) resisting radiation and high-temperature coolants.

Industrial and High-Temperature Processing:

High-temperature furnaces: Furnace walls, heating elements, thermocouple sheaths, and hearth plates (from wire, plate, and tube) operating in air or inert atmospheres up to 1050°C (1922°F).

Chemical processing: Reactor liners, catalyst support grids, and heat exchangers (from plate, tube, and bar) withstanding aggressive chemicals (e.g., acids, organic solvents) at elevated temperatures.

Metallurgical processing: Heat treatment fixtures, molten metal handling parts, and annealing furnace components (from bar, forging stock, and plate) resisting wear and high heat.

Defense and Specialized Engineering:

Military aircraft engines: Critical hot-section components (from forging stock and plate) requiring ultra-high-temperature durability in combat environments.

Missile propulsion systems: Combustion chamber liners and exhaust components (from sheet and forging stock) resisting extreme heat from propellant combustion.

Naval systems: Marine gas turbine components (from plate, tube, and bar) resisting seawater corrosion and high temperatures.

Specialized Applications by Form:

Wire: Welding filler metal for joining high-temperature components, thermal spray coatings for wear protection, and precision heating coils.

Plate/Sheet: Combustion liners, furnace walls, and aerospace heat exchangers requiring large, flat high-temperature surfaces.

Tube/Pipe: High-temperature fluid transport (fuel lines, heat exchanger tubes) and thermocouple protection sheaths in corrosive environments.

Forging Stock: Complex turbine disks, compressor blades, and heavy-duty industrial furnace components requiring custom shapes and high strength.

In summary, Alloy PK33 (Nimonic PK33 Wire) — available in forms from Bar and Wire to Plate and Forging Stock — delivers exceptional ultra-high-temperature strength, creep resistance, and oxidation stability. Its diverse product forms enable tailored solutions across aerospace, energy, industrial, and defense sectors, establishing it as a critical material in applications requiring reliable performance under extreme thermal 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 1221 gallon liquid totes Special package is available on request.