Hastelloy® X

Hastelloy® X - Pyromet® 680 - UNS N06002 - W. Nr. 2.4665 - Nickel Alloy X - NiCrMo Alloy

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Table of Contents
Datasheet Chemistry
Inventory Applications
General Data Mechanical Properties
Specifications Physical Properties & Application Data
Machining, Welding, & Processing References

Alloy X is an alloy with high strength and oxidation resistance to 2200 °F as well as good carburization and nitriding resistance. It has also been found to have good resistance to stress-corrosion cracking in some petrochemical applications. It has an ASME Boiler and Pressure Vessel code case.

Alloy X has excellent forming and welding characteristics, resistance to oxidizing, reducing, and neutral atmospheres. It exhibits good ductility after prolonged service temperatures of 1200 °F through 16,000 hours.

Alloy X is also suitable for internal structural components in industrial furnaces such as rolls, retorts, baffles, flash drier components, and muffles. It is a good choice for material for heat treating components such as trays and fixtures due to its excellent resistance to oxidizing atmospheres.


View or download our alloy X datasheet here


Nominal Composition (Weight%)
Ni 47 Bal.
Cr 22
Fe 18
Mo 9
Co 1.5
W 0.6
C 0.1
Mn 1 Max.
Si 1 Max.
B 0.008 Max.
Nb 0.5 Max.
Al 0.5 Max.
Ti 0.15 Max.
*Composition information provided by Haynes' datasheet on Hastelloy® X, available here.

Typical Inventory

Round Bar, Plate, Strip


Alloy X is recommended especially for use in furnace applications because it has unusual resistance to oxidizing, reducing, and neutral atmospheres. Furnace rolls made of this alloy were still in good condition after operating for 8700 hours at 2150 °F. Furnace trays, used to support heavy loads, have been exposed to temperatures up to 2300 °F. in an oxidizing atmosphere without bending or warping. Alloy X is also used for retorts, muffles, catalyst support grids, furnace baffles, tubing for pyrolysis operations and flash drier components.

Alloy X has wide use in gas turbine engines for combustion zone components such as transition duct, combustor cans, spray bars, and flame holders, as well as in afterburners, tailpipes, and cabin heaters.

General Data

Alloy X is one of the most widely used nickel base superalloys for gas turbine engine components. This solid solution strengthened grade has good strength and excellent oxidation resistance to 2000 °F. Alloy X has excellent resistance to reducing and carburizing atmospheres making it suitable for furnace components. Due to its high molybdenum content, Alloy X may be subject to catastrophic oxidation at 2200 °F.

  • Good high temperature strength.
  • Oxidation resistance through 2000 °F.
  • Carburization resistant.

Mechanical Properties

The typical properties listed can usually be provided in rounds, sheet, strip, plate, & custom forgings. We have the equipment to produce small quantities in special sizes to meet our customers’ specific needs. The table below shows Haynes' Nominal Room-Temperature Mechanical Properties of Alloy X Plate and Sheet. For most common forms and exceptions, check out the datasheet linked underneath the table.

Form Temp. UTS ksi (MPa) YS ksi (MPa) Elong. in 2 in., % Rockwell Hardness
Plate 70°F (21°C) 110.2 (760) 49.3 (340) 48.9 87B
Sheet 70°F (21°C) 113.5 (783) 54.5 (376) 46.5 86B

UTS = Ultimate Tensile Strength, YS = Yield Strength

Link to Haynes' datasheet on Hastelloy® X

Common Specifications

Note that the specifications listed are common for this alloy but are for reference only and may be specific to a certain form. The specifications listed are not comprehensive nor indicative of any edition, revision, or similar such as an amendment. Please, reach out to our sales department to request the Material Test Report (MTR) or to confirm your required specifications.

Form Standard
Identification UNS N06002, DIN 17744, DIN 17750-17754, W. Nr. 2.4665
Bar AMS 5754, ASTM B572, ASME SB572
Sheet, Plate, or Strip AMS 5536, ASTM B435, ASME SB435
Pipe - Seamless ASTM B622, ASTM B829, ASME SB622, ASME SB829
Pipe - Welded ASTM B619, ASTM B775, ASME SB619, ASME SB775
Tube - Seamless AMS 5587, ASTM B622, ASTM B751, ASTM B829, ASME SB622, ASME SB751, ASME B829
Tube - Welded AMS 5588, ASTM B626, ASTM B751, ASME SB626, ASME SB751
Fitting ASTM B366, ASME SB366
Forging AMS 5754
Weld Wire AMS 5798/ AWS A5.14 ERNiCrMo-2/ ASME IX F-No.43
Weld Electrode AWS A5.11 ENiCrMo-2

Physical Properties

Density: 0.297 lb/in3
Melting Range: 2300-2470 °F
Temperature, °F Coefficient* of Thermal Expansion, in/in°F x 10-6 Thermal Conductivity, Btu by ft/ft2 by hr by °F Modulus of Elasticity Dynamic, psi x 106
70* 30
1000 8.4 11.3 26
1200 8.6 12.7 25
1400 8.8 13.9 23
1600 9.0 15.2 22
1800 9.2 16.4 20

* 70 °F to indicated temperature.


Nickel and cobalt based alloys can be difficult to machinine. However, it should be emphasized that these alloys can be machined using conventional production methods at satisfactory rates. These alloys harden rapidly, generate high heat during cutting, weld to the cutting tool surface and offer high resistance to metal removal because of their high shear strengths. The following are key points which should be considered during machining operations:

  • CAPACITY - Machine should be rigid and overpowered as much as possible.
  • RIGIDITY - Work piece and tool should be held rigid. Minimize tool overhang.
  • TOOL SHARPNESS - Make sure tools are sharp at all times. Change to sharpened tools at regular intervals rather than out of necessity. A 0.015 inch wear land is considered a dull tool.
  • TOOLS - Use positive rake angle tools for most machining operations. Negative rake angle tools can be considered for intermittent cuts and heavy stock removal. Carbide-tipped tools are suggested for most applications. High speed tools can be used, with lower production rates, and are often recommended for intermittent cuts.
  • POSITIVE CUTS - Use heavy, constant, feeds to maintain positive cutting action. If feed slows and the tool dwells in the cut, work hardening occurs, tool life deteriorates and close tolerances are impossible.
  • LUBRICATION - lubricants are desirable. Soluble oils are recommended especially when using carbide tooling.


Link to Haynes' datasheet on Hastelloy® X

Hastelloy® is a registered trademark of Haynes International Inc.

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