Alloy 188,Haynes 188 Wire,UNS R30188

Alloy 188,Udimet 188 Wire,UNS R30188

Alloy 188 (Udimet 188 Wire, UNS R30188) - Introduction with Composition, Properties, Applications and Product Forms

Alloy 188, commercially known as Udimet 188 and designated by UNS R30188, is a cobalt-nickel-chromium-tungsten superalloy celebrated for its exceptional high-temperature strength, oxidation resistance, and thermal fatigue performance. This alloy is specifically engineered to thrive in extreme thermal environments—including cyclic heating and cooling—making it a critical material in aerospace, energy, and industrial applications where components face prolonged exposure to combustion gases, high stress, and harsh atmospheres. 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. Udimet 188 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 188 (Udimet 188 Wire, UNS R30188) is the foundation of its exceptional high-temperature performance and corrosion resistance. The typical composition (by weight) is as follows:

Cobalt (Co): 39-41% (the primary matrix element, delivering high-temperature stability and enhancing thermal fatigue resistance)

Nickel (Ni): 21-23% (improves ductility, corrosion resistance, and compatibility with high-temperature alloys in assemblies)

Chromium (Cr): 20-22% (forms a dense, protective chromium oxide layer, ensuring superior oxidation and sulfidation resistance at ultra-high temperatures)

Tungsten (W): 13-15% (strengthens the alloy through solid-solution hardening and forms stable carbides, boosting creep and rupture resistance)

Molybdenum (Mo): 1.5-2.5% (supplements high-temperature strength and enhances resistance to pitting corrosion in harsh chemical environments)

Iron (Fe): ≤ 3.0% (minimized to preserve high-temperature properties and oxidation resistance)

Carbon (C): 0.05-0.15% (forms carbides with tungsten and chromium, reinforcing grain boundaries and improving creep rupture strength)

Silicon (Si): 0.2-0.5% (aids in deoxidation during manufacturing and supports oxide layer formation for better oxidation resistance)

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

Aluminum (Al): ≤ 0.5% (controls oxide layer growth and extends long-term oxidation resistance)

Titanium (Ti): ≤ 0.5% (stabilizes carbides and refines microstructure for improved mechanical consistency)

Phosphorus (P): ≤ 0.03% (strictly limited to prevent grain boundary embrittlement)

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

This engineered blend—centered on cobalt, chromium, and refractory metals—delivers Alloy 188’s signature ultra-high-temperature performance, thermal fatigue resistance, and corrosion stability, critical for demanding thermal applications.

Key Properties

Alloy 188 (Udimet 188 Wire, UNS R30188) and its various forms exhibit extraordinary properties that make them indispensable in ultra-high-temperature, corrosive, and cyclic-stress environments:

Mechanical Properties (solution-annealed condition):

Tensile strength: 780-880 MPa (113,100-127,600 psi) at room temperature; retains ~320 MPa (46,400 psi) at 1000°C (1832°F)

Yield strength (0.2% offset): 350-420 MPa (50,800-60,900 psi) at room temperature; retains ~250 MPa (36,300 psi) at 1000°C (1832°F)

Elongation (in 50 mm): 30-40% at room temperature; 15-25% at 1000°C (1832°F) (excellent ductility for forming complex components like turbine seals)

Reduction of area: 45-55% (superior toughness, resisting fracture under high-temperature cyclic stress)

Hardness: 210-250 HB (Brinell hardness) at room temperature; maintains ~160 HB at 1000°C (1832°F)

High-Temperature Properties:

Continuous service temperature: Up to 1150°C (2102°F) (among the top performers for cobalt-based superalloys, with long-term stability)

Creep resistance: Exceptional resistance to creep deformation at ultra-high temperatures—1000-hour creep rupture strength of ~110 MPa (15,950 psi) at 1100°C (2012°F)

Thermal fatigue resistance: Withstands repeated thermal cycling (e.g., -60°C to 1100°C) without cracking, critical for components like gas turbine combustion liners

Oxidation resistance: Superior resistance to oxidation and scaling in air at temperatures up to 1200°C (2192°F), with minimal weight loss even after 10,000 hours at 1050°C (1922°F)

Corrosion Resistance:

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

Sulfidation resistance: Resists sulfidation in sulfur-containing environments (e.g., coal-fired power plants) up to 1000°C (1832°F)

Pitting/crevice corrosion: Good resistance to pitting in chloride-rich environments, suitable for marine and offshore high-temperature components

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

Physical Properties:

Density: 8.9-9.0 g/cm³ (0.322-0.325 lb/in³)

Thermal conductivity: 12-14 W/(m·K) at 20°C (68°F); increases to 29-32 W/(m·K) at 1000°C (1832°F) (efficient heat dissipation at high temperatures)

Coefficient of thermal expansion: 14.0-16.0 μm/(m·K) (20-1000°C) (controlled expansion to minimize thermal stress in assembled components)

Modulus of elasticity: 220-230 GPa (31,900-33,400 ksi) at room temperature; decreases to ~155 GPa (22,500 ksi) at 1000°C (1832°F)

Melting point: 1370-1420°C (2498-2588°F)

Product Forms

Alloy 188 (Udimet 188 Wire, UNS R30188) 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: Udimet 188 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.

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).

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, rocket engine coolant tubes).

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

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.

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

Applications

The exceptional ultra-high-temperature strength, oxidation resistance, and thermal fatigue resistance of Alloy 188 (Udimet 188 Wire, UNS R30188) across its various forms make it a critical material in industries requiring performance under extreme thermal conditions:

Aerospace and Aviation:

Gas turbine engines: Combustion liners, turbine vanes, and afterburner components (from plate, forging stock, and sheet) withstanding temperatures up to 1150°C (2102°F).

Rocket propulsion: Nozzle throats, fuel injector components, and heat shields (from forging stock, tube, and sheet) resisting extreme heat from rocket fuel combustion.

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

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.

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

Waste-to-energy plants: Combustion chamber liners and heat recovery components (from sheet and plate) withstanding corrosive flue gases at 1000°C+.

Industrial and High-Temperature Processing:

High-temperature furnaces: Furnace walls, heating elements, and thermocouple sheaths (from wire, plate, and tube) operating in air or inert atmospheres up to 1200°C (2192°F).

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

Metallurgical processing: Hot rolling mill components, heat treatment fixtures, and molten metal handling parts (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.

Hypersonic vehicles: Heat shields and structural components (from plate and forging stock) enduring aerodynamic heating up to 1150°C (2102°F).

Specialized Applications by Form:

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

Plate/Sheet: Combustion liners, furnace walls, and aerospace heat exchangers.

Tube/Pipe: High-temperature fluid transport (fuel lines, coolant tubes) and thermocouple protection sheaths.

Forging Stock: Complex turbine disks, rocket nozzles, and heavy-duty industrial furnace components.

In summary, Alloy 188 (Udimet 188 Wire, UNS R30188) — available in forms from Bar and Wire to Plate and Forging Stock — delivers exceptional ultra-high-temperature strength, oxidation resistance, and thermal fatigue 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 1272 gallon liquid totes Special package is available on request.