Alloy S，Hastelloy S ，UNS N06635

British Specs:，American Specs: AMS 5711 Bar and Forging AMS 5838 Welding Wire AMS 5873 Sheet, Strip and Plate，German Specs:

Alloy S (Hastelloy S Wire, UNS N06635) - Introduction with Composition, Properties, Applications and Product Forms

Alloy S, commercially known as Hastelloy S with the UNS designation N06635, is a nickel-chromium-molybdenum superalloy renowned for its exceptional high-temperature oxidation resistance, excellent thermal stability, and superior fabricability. This high-performance material 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. Hastelloy S Wire, in particular, offers unique flexibility for intricate high-temperature applications requiring both corrosion resistance and formability. Below is a detailed overview of its chemical composition, key properties, practical applications, and available product forms.

Chemical Composition

The precisely engineered chemical composition of Alloy S (Hastelloy S, UNS N06635) is the foundation of its superior performance in extreme high-temperature environments. The typical composition (by weight) is as follows:

Nickel (Ni): 57-63% (primary matrix element, providing a stable base for high-temperature stability and corrosion resistance)

Chromium (Cr): 17-21% (a critical component for oxidation resistance, forming a protective chromium oxide layer at elevated temperatures)

Molybdenum (Mo): 11-14% (enhances high-temperature strength and resistance to reducing environments)

Tungsten (W): 2.5-3.5% (boosts creep resistance and strengthens the alloy at high temperatures)

Iron (Fe): ≤ 3.0% (balances the alloy and improves mechanical properties at ambient temperatures)

Carbon (C): ≤ 0.08% (controlled to minimize carbide formation, preserving ductility and weldability)

Silicon (Si): ≤ 1.0% (assists in forming a stable oxide layer, enhancing oxidation resistance)

Manganese (Mn): ≤ 1.0% (improves fabricability and prevents hot cracking during welding)

Cobalt (Co): ≤ 2.0% (aids in solid solution strengthening and thermal stability)

Trace elements: Phosphorus (P) ≤ 0.04%, Sulfur (S) ≤ 0.03% (kept low to ensure weldability and grain boundary strength)

This balanced composition synergistically delivers the alloy's signature combination of high-temperature oxidation resistance, thermal stability, and formability, making it ideal for extreme industrial environments.

Key Properties

Alloy S (Hastelloy S Wire, UNS N06635) and its various forms exhibit a robust set of properties that make them indispensable in high-temperature and corrosive applications:

Mechanical Properties (room temperature, annealed condition):

Tensile strength: 650-800 MPa (94,300-116,000 psi)

Yield strength (0.2% offset): 275-350 MPa (39,900-50,800 psi)

Elongation (in 50 mm): 30-40% (excellent ductility, enabling complex forming and welding across all product forms)

Hardness: 180-220 HB (Brinell hardness, indicating good machinability)

High-Temperature Performance:

Thermal stability: Maintains significant strength up to 1100°C (2012°F), with tensile strength remaining above 300 MPa at 1000°C (1832°F)

Creep resistance: Exhibits excellent creep resistance at 800-1000°C (1472-1832°F), suitable for long-term service under sustained stress in high-temperature systems

Oxidation resistance: Resists oxidation in air and combustion gases up to 1200°C (2192°F), forming a dense, self-healing chromium oxide layer that prevents rapid degradation

Thermal fatigue resistance: Excellent resistance to thermal cycling, making it suitable for applications with frequent temperature fluctuations

Corrosion Resistance:

High-temperature corrosion: Superior resistance to oxidation, sulfidation, and carburization in high-temperature industrial environments

Chemical resistance: Good resistance to reducing acids (e.g., hydrochloric acid) and oxidizing acids (e.g., nitric acid) at moderate temperatures

Wet corrosion: Resistant to seawater, brines, and industrial chemicals, including organic acids and alkaline solutions

Stress corrosion cracking (SCC): Highly resistant to SCC in chloride-containing environments, even at elevated temperatures

Physical Properties:

Density: 8.7 g/cm³ (0.314 lb/in³)

Thermal conductivity: 12 W/(m·K) at 20°C (68°F), increasing to 22 W/(m·K) at 1000°C (1832°F)

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

Coefficient of thermal expansion: 13.5 μm/(m·K) (20-100°C), rising to 18.0 μm/(m·K) at 1000°C (1832°F)

Modulus of elasticity: 210 GPa (30,500 ksi) at room temperature, decreasing to 160 GPa (23,200 ksi) at 1000°C (1832°F)

Product Forms

Alloy S (Hastelloy S, UNS N06635) is manufactured in a diverse range of forms to accommodate specialized industrial processes and high-temperature applications:

Bar: Available as Round bar (diameters from 8 mm to 300 mm) and Flat bar (thickness 6 mm to 150 mm, width 20 mm to 600 mm), ideal for machining into high-temperature fasteners, valve components, and furnace hardware.

Ribbon: Thin, flat strips (thickness 0.1 mm to 2 mm, width 5 mm to 100 mm) used in electrical heating elements and thermal insulation wraps for high-temperature equipment.

Wire: Hastelloy S Wire (diameters 0.05 mm to 10 mm) offers excellent flexibility for forming thermocouple sheaths, woven mesh screens, and high-temperature springs in corrosive environments.

Rods: Solid cylindrical rods (diameters 3 mm to 50 mm) suitable for structural supports in industrial furnaces and high-temperature machinery.

Tube and Pipe: Seamless and welded options (outer diameter 6 mm to 200 mm, wall thickness 0.5 mm to 20 mm) for transporting high-temperature fluids in chemical processing, power generation, and aerospace systems.

Foil: Ultra-thin sheets (thickness 0.01 mm to 0.1 mm) used in lightweight thermal barriers and high-temperature insulation in aerospace and industrial applications.

Plate and Sheet: Flat forms (plate: thickness 5 mm to 100 mm; sheet: 0.3 mm to 5 mm) for fabricating furnace liners, heat exchanger components, and combustion chamber panels.

Strip: Narrow, flat strips (thickness 0.1 mm to 3 mm, width 10 mm to 200 mm) for precision manufacturing in high-temperature gaskets, seals, and electrical components.

Forging Stock: Billets and ingots for hot forging into complex shapes such as turbine components, furnace baskets, and reaction vessel parts.

Applications

The exceptional properties of Alloy S (Hastelloy S Wire, UNS N06635) across its various forms make it a preferred material in industries requiring resistance to extreme high temperatures and corrosion:

Aerospace and Aviation:

Gas turbine engines: Combustion chamber liners (from sheet and plate), turbine blade retainers (from forging stock), and heat shields (from foil) — all leveraging high-temperature oxidation resistance.

Jet engine components: Tubes and pipes for fuel and coolant lines; wire for thermocouple leads in high-temperature zones.

Rocket propulsion systems: Nozzle components (from forging stock) and thermal insulation (from foil) exposed to extreme heat during combustion.

Power Generation:

Waste-to-energy plants: Furnace liners (from plate) and heat exchanger tubes, resisting corrosion from acidic flue gases.

Gas-fired turbines: Combustion system components (from sheet and bar) and exhaust ducting, withstanding high temperatures and cyclic thermal stress.

Nuclear power: Components for high-temperature coolant systems, leveraging radiation resistance and thermal stability.

Industrial Processing:

High-temperature furnaces: Furnace walls (from plate), heating element supports (from bar), and baskets (from forging stock) for heat treatment applications.

Chemical and petrochemical: Reactors and catalyst support grids (from plate and sheet) for high-temperature chemical synthesis; tubes for transporting molten salts and corrosive fluids.

Metallurgical processing: Equipment for molten metal handling, including crucibles and pouring spouts (from forging stock), resisting metal-to-alloy interaction at high temperatures.

Specialized Applications by Form:

Wire: Thermocouple sheaths in industrial furnaces, woven filters for high-temperature gas filtration, and springs in aerospace engine components.

Tube/Pipe: High-temperature fluid transport in chemical reactors, heat exchanger tubes in power plants, and exhaust gas recirculation lines.

Plate/Sheet: Combustion chamber panels, furnace liners, and radiation shields in high-temperature industrial systems.

Bar/Rod: Machined fasteners, valve stems, and structural supports in extreme heat environments.

In summary, Alloy S (Hastelloy S Wire, UNS N06635) — available in forms from Bar and Wire to Plate and Forging Stock — delivers exceptional high-temperature oxidation resistance, thermal stability, and versatility. Its diverse product forms enable tailored solutions across aerospace, power generation, and industrial processing sectors, establishing it as a critical material in extreme high-temperature applications.

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 2885 gallon liquid totes Special package is available on request.