Nickel-based super alloy: Hastelloy S (UNS N06635)

What is Hastelloy S?

Hastelloy S (also known as alloy s), named UNS N06635, is a nickel based superalloy with excellent thermal stability, low thermal expansion, and oxidation resistance at 1095 ° C [2000 ° F]. It retains strength and ductility after aging at 425 to 870 ° C [800 to 1600 ° F]. Hastelloy S is mainly used in applications involving severe cyclic heating conditions where components must be able to maintain strength, ductility and metallurgical integrity after prolonged exposure, and are widely used as seals for gas turbine engines, and their low coefficient of thermal expansion is also important.
Hastelloy S is a nickel base superalloy composed of nickel, molybdenum, chromium, cobalt and other elements. The nickel content of Hastelloy S alloy is about 62%. Hastelloy S is a high heat, nickel based alloy with excellent thermal stability and high thermomechanical properties, oxidation resistance and up to 2000 ° f (1093 ° C). Simple heat treatment, Hastelloy S will exhibit high heat and thermal fatigue strength.

hastelloy s ring gakset - Nickel-based super alloy: Hastelloy S (UNS N06635)

ASME B16.20 Hastelloy S Octagonal Ring Joint Gasket R24.

Types of Hastelloy

  • Hastelloy B-3 nickel molybdenum alloy has excellent corrosion resistance in reducing environment
  • The upgraded version of Hastelloy B-3: B-3 has excellent corrosion resistance to hydrochloric acid at any temperature and concentration
  • Hastelloy C-4: good thermal stability, good toughness and corrosion resistance at 650-1040 ℃
  • Hastelloy C-22: has better uniform corrosion resistance than C-4 and C-276 in oxidizing medium and excellent local corrosion resistance
  • Hastelloy C-276: good resistance to oxidizing and moderate reducing corrosion, excellent resistance to stress corrosion
  • Hastelloy C-2000: the most comprehensive corrosion resistant alloy with excellent uniform corrosion resistance in oxidation and reduction environments
  • Hastelloy G-35: the upgraded product of G-30 has better corrosion resistance and thermal stability, and has excellent performance in phosphoric acid and other strong oxidizing mixed acid media with high chromium content
  • Hastelloy X: combined with the characteristics of high strength, oxidation resistance and easy processing, each of the above grades has its own specific chemical composition, mechanical properties and strong points, so we can’t generalize the characteristics of Hastelloy.

Hastelloy alloy is mainly divided into three series B, C and G. it is mainly used in iron-based Cr Ni or Cr Ni Mo stainless steel, non-metallic materials and other occasions with strong corrosive medium.
In order to improve the corrosion resistance and cold and hot working properties of Hastelloy, three major improvements have been made to Hastelloy:

  • Series B: B → B-3 (00ni70mo28) → B-3
  • Series C: C → C-276 (00cr16mo16w4) → C-4 (00cr16mo16) → C-22 (00cr22mo13w3) → C-2000 (00cr20mo16)
  • G Series: G → G-3 (00cr22ni48mo7cu) → G-30 (00cr30ni48mo7cu)
  • The most widely used materials are N06635 (B-3), N10276 (C-276), N06635 (C-22), N06455 (C-4) and N06985 (G-3)

Chemical Composition of Hastelloy S (UNS N06635)

Ni Mo Cr Fe W Co Mn C V P S Si
Remainder 15.0-17.0 14.5-16.5 4.0-7.0 3.0-4.5 2.5 max 1.0 max .01 max .35 max .04 max .03 max .08 max

Physical Properties of Hastelloy S (UNS N06635)

Density Melting Range Specific Heat Electrical Resistivity
g/cm3 °C °F J/kg. k Btu/lb.°F µΩ·m
8.75 1335-1380 2435-2516 398 0.095 1280

Mechanical Properties of Hastelloy S (UNS N06635)

Tensile Strength, min. Yield Strength, min Elongation, min. Hardness, min
Mpa ksi Mpa ksi % HRA
835 121 445 64.5 49 52

Annealing of Hastelloy S (UNS N06635)

Solution annealed at 1950 F followed by air cool.

Forging of Hastelloy S (UNS N06635)

Forging is done in t he temperature range of 2100 F to 1600 F. Final forging reduction should be confined to the temperature range of 1900 F to 1500 F.

Welding of Hastelloy S (UNS N06635)

The alloy may be welded by manual and automatic methods including gas-metal-arc and gas-tungsten- arc. May be welded in the as supplied condition by manual or automatic methods including TIG and MIG welding. Matching filler metal should be used and pre or post heating are not required.

Heat treatment of Hastelloy S (UNS N06635)

The alloy is solution treated at 1950ºF (1065ºC) and subsequently aged at temperatures from 800 through to 1600ºF (425 through 870ºC), where a whole range of tensile and impact properties may be obtained.

Aging of Hastelloy S (UNS N06635)

Aging has very little effect on the mechanical properties. The alloy retains strength and ductility even after prolonged exposure at temperatures from 1000 F to 1600 F.

ASTM Specifications

Pipe Smls Pipe Welded Tube Smls Tube Welded Sheet/Plate Bar Forging Fitting Wire
B622 B619 B622 B626 B575 B574 B564 B366

Application areas of nickel-based alloy Hastelloy S (UNS N06635):

This alloy was developed for conditions involving severely cyclical heating conditions where components must be capable of retaining their strength and ductility after long exposure. The alloy is used extensively in seal rings in gas turbine engines where its low coefficient of thermal expansion is also important. Some of the more common uses of Hastelloy S include:

  • Wire wound resistors.
  • Bimetal contacts.
  • Electric and electronic applications.
  • Marine engineering.
  • Chemical and hydrocarbon processing equipment.
  • Gasoline and freshwater tanks.
  • Crude petroleum stills.
  • De-aerating heaters.
  • Boiler feed water heaters and other heat exchangers.
  • Pumps, shafts and fasteners.
  • Industrial heat exchangers.
  • Chlorinated solvents.
  • Crude oil distillation towers.
  • Meter and valve parts.
  • Screw machine products.
  • Oil refinery piping.
  • Heat exchangers.
  • Nuclear fuel production.
  • Generator tubing.
  • High temperature heating coils.
  • Crude oil transfer piping.
  • Propeller and pump shafts.
  • Piping system.
  • Heat exchange tubes.
  • Pipe fittings.
  • Flanges.
  • Valves.

Variety specifications and supply status of Nickel-based super alloy: Hastelloy S (UNS N06635):

Variety classification:

Yaang Pipe Industry can produce various specifications of Hastelloy S seamless pipeHastelloy S steel plateHastelloy S round bar, Hastelloy S forgings, Hastelloy S flangeHastelloy S pipe fittings, Hastelloy S welded pipe, Hastelloy S steel strip, Hastelloy S wire and supporting welding materials. 

Delivery status:

  • Seamless pipe: solid solution + acid white, length can be set;
  • Plate: solid solution, pickling, trimming;
  • Welded pipe: solid solution acid white + RT% flaw detection;
  • Forging: annealing + car polish; Bars are forged and rolled, surface polished or car polished;
  • Strips are delivered after cold rolling, solid solution soft state, and deoxidized;
  • Wire rods are finely ground in solid solution pickled disk or straight strips, solid solution straight strips Delivery in light state.

Source: China Hastelloy S Flanges Manufcturer – Yaang Pipe Industry (

(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)

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Nickel-based super alloy: Hastelloy S (UNS N06635)
Hastelloy S (also known as alloy s), named UNS N06635, is a nickel based superalloy with excellent thermal stability, low thermal expansion, and oxidation resistance at 1095 ° C [2000 ° F].
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