ThePipingMart Blog Grades Hastelloy S (UNS N06635) – Composition, Properties and Uses

Hastelloy S (UNS N06635) – Composition, Properties and Uses

Hastelloy S

Hastelloy S is a nickel-based alloy known for its exceptional strength and resistance to various forms of corrosion. It was created to tackle the limitations of its predecessor, Hastelloy C, and has since become a popular material in multiple industries. This blog post will deeply investigate Hastelloy S and cover its composition, mechanical and physical properties, uses, corrosion resistance, heat treatment, machining, and welding.

Hastelloy S Composition

Hastelloy S primarily comprises nickel, chromium, and molybdenum. Its chemical composition also includes tungsten, silicon, carbon, manganese, and iron. The specific amounts of each element vary depending on the alloy’s grade and purpose.

Elements Content (%)
Nickel, Ni 67
Chromium, Cr 14.5 – 17
Molybdenum, Mo 14 – 16.5
Iron, Fe 3
Cobalt, Co 2
Tungsten, W 1
Copper, Cu 0.35
Manganese, Mn 0.30 – 1.0
Silicon, Si 0.20 – 0.75
Aluminum, Al 0.10 – 0.50
Carbon, C 0.020
Phosphorous, P 0.020
Boron, B 0.015
Sulfur, S 0.015
Lanthanum, La 0.010 – 0.10

Hastelloy S Mechanical Properties

Hastelloy S boasts excellent mechanical properties, including high strength, toughness, and ductility. It has a minimum yield strength of 330 MPa and a minimum tensile strength of 760 MPa. It can also withstand high temperatures, making it suitable for extreme environments.

Properties Metric Imperial
Tensile strength (@ 1093°C/1999°F, thickness 1.10-1.60 mm/0.0433-0.0630 in.) 110 MPa 16000 psi
Yield strength (@ 1093°C/1999°F, thickness 1.10-1.60 mm/0.0433-0.0630 in., 0.2% offset) 52 MPa 7540 psi
Elastic modulus 212 GPa 30700 ksi
Elongation at break (@ 982°C/1800°F, thickness 1.10-1.60 mm/0.0433-0.0630 in., in 50.8 mm) 46% 46%
Charpy Impact (V Notch; solution heat-treated, not aged) 190 J 140 ft-lb

Hastelloy S Physical Properties

Hastelloy S has a density of 8.36 g/cm3 and a melting point of 1350-1400°C. It has a coefficient of thermal expansion of 13.2 µm/m-K and a thermal conductivity of 8.9 W/m-K.

Properties Metric Imperial
Density 8.75 g/cm³ 0.316 lb/in³
Melting point 1360°C 2480°F

Hastelloy Equivalent

  • AMS 5711
  • AMS 5838
  • AMS 5873

Hastelloy S Uses

Hastelloy S is used in various applications, including chemical processing, aerospace, nuclear power, and marine industries. Its high strength, and corrosion resistance make it ideal for components and equipment exposed to aggressive and corrosive media.

Hastelloy S Corrosion Resistance

Hastelloy S is highly resistant to various corrosive environments, including sulfuric acid, hydrochloric acid, phosphoric acid, and organic acids. It is also resistant to corrosive gases, such as hydrogen sulfide, chlorine, and chlorine dioxide.

Hastelloy S Heat Treatment

Hastelloy S can be heat-treated to improve strength and toughness. The recommended heat treatment is a solution anneal at 1175°C for one hour, followed by air cooling. This process enhances the alloy’s corrosion resistance while maintaining its mechanical properties.

Hastelloy S Machining

Hastelloy S can be challenging due to its high strength and toughness. Carbide tools are recommended, and machining should be performed at low speeds to avoid work hardening. Coolants must also be used to prevent overheating and reduce tool wear.

Hastelloy S Welding

Hastelloy S can be welded using various welding processes, including TIG, MIG, and SMAW. However, carefully following the recommended welding procedures is essential to avoid cracking and other issues. The alloy should also be preheated before welding to minimize thermal stresses.


Hastelloy S is an excellent material for applications that require high strength, toughness, and corrosion resistance. Its mechanical and physical properties and resistance to aggressive environments make it a popular choice in various industries. The alloy can be challenging to machine and weld, but following the recommended procedures carefully is essential to avoid issues. If you’re considering using Hastelloy S for your next project, consult experts to ensure you get the most out of this remarkable material.

Related Post