Hastelloy X (UNS N06002): A Super Alloy Stable at High Temperatures
Alloy Definition and Chemical Composition
Hastelloy X is known for its excellent oxidation resistance, high temperature strength and weldability properties. It is a nickel based super alloy. This material has been developed particularly in line with the demands of the aerospace, energy and petrochemical sectors.
Its chemical composition is approximately as follows:
- Nickel (Ni): 47.5 – 61%
- Iron (Fe): 17 – 20%
- Chromium (Cr): 20.5 – 23%
- Molybdenum (Mo): 8 – 10%
- Cobalt (Co): Max. 1.0%
- Manganese, Silicon, Carbon, Aluminium, Titanium: In trace amounts
Thanks to this composition, at high temperatures up to 1100 °C it can preserve its resistance to oxidation and fracture. In terms of microstructure it is austenitic, and grain boundary precipitation is at a minimum level. This in turn makes the alloy suitable for post-weld operations.
Hastelloy X ASTM, AMS and International Standards
The Hastelloy X alloy is made available commercially and industrially within the scope of the following specifications:
- ASTM B435 – Plate, sheet and strip
- ASTM B619 / B622 – Seamless and welded pipes
- ASTM B366 – Pipe fittings
- AMS 5536 – Aerospace grade sheet and plate
- AMS 5754 – Bar, forged and cast parts
- AMS 5587 – Pipes and piping systems
- UNS N06002 – Chemical composition designation
- Werkstoff Nr. 2.4665 – German DIN standard equivalent
Compliance with these standards is of importance especially in regulation-heavy sectors such as aerospace and nuclear energy applications.
Hastelloy X Trade Names and Equivalent Materials
- Hastelloy® X – Registered by Haynes International
- Alloy X, Inconel HX, ATI HX – Equivalent terms used in the technical literature
- UNS N06002, W.Nr. 2.4665 – International codings
- NiCr22Fe18Mo – European EN chemical symbol
Among its equivalents there are also commercial variants such as Udimet Alloy 500, Haynes HX and Nicrofer 4722 Co. All these materials, however, must be consistent with Hastelloy X at the level of the standards.
Areas of Use and Industrial Applications
Hastelloy X is preferred especially in applications where high temperature, mechanical load and oxidative environments are present together:
1.Aerospace Industry
*Jet engine combustion chambers
*Exhaust systems and combustion tubes
*Heat resistant fittings
2.Gas Turbines and Power Generation
*Gas turbine components
*Heat exchangers and recuperators
*High temperature burner systems
3.Petrochemical and Refinery Plants
*Reforming reactors
*Oxidising gas lines
*High temperature process pipes
4.Nuclear Power Plant Components
*Internal components exposed to high radiation and temperature
*Heat transfer lines with a controlled atmosphere
5.Heat Treatment Furnaces
*In-furnace parts, transport pallets, baskets
*Thermocouple protection tubes
Thanks to its mechanical and chemical stability under high temperature, process efficiency and safety are directly increased in these applications.
Advantages
- Excellent Oxidation Resistance: It remains stable in oxidising atmospheres up to 1200 °C. The high chromium and iron content contributes to this performance.
- Mechanical Stability at High Temperature: It is strong in terms of creep strength and elongation at break. With this property it is ideal for parts operating under high temperature.
- Weldability: It can be joined easily by the TIG, MIG and plasma arc welding methods. The risk of cracking after welding is low.
- Good Machinability: It offers better chip removal capability compared with other nickel-based alloys.
- High Metallurgical Homogeneity: The internal structure of the alloy has been developed so as to be durable against thermal cycles.
Disadvantages
- Corrosion Resistance in Limited Environments: Compared with alloys with a high molybdenum ratio such as C-22 or C-276, it may show lower performance in some acids (especially in reducing environments containing chloride).
- Cost: It is costly because of the high nickel and molybdenum content. It is not economical for general structural applications.
- Carbide Precipitation in Welded Zones: In cases of long-term exposure to high temperature, carbide precipitation may form at the grain boundaries. This situation may affect performance in some applications.
Conclusion and Engineering Evaluation
Hastelloy X is a reliable super alloy for components operating at very high temperatures and at the same time exposed to oxidising and mechanical loading. It stands out especially in the field of aerospace engines, gas turbines and high temperature process equipment with its metallurgical stability and weldability.
Low maintenance costs and a long service life reduce the total cost of ownership and, despite the initial investment cost, make it a sustainable choice. For precision engineering applications, industrial projects requiring certification and high safety processes, Hastelloy X is a technically superior selection.
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We supply this material
We supply Hastelloy X (2.4665) — to the AMS 5536 standard, in the dimensions and forms required. Contact us for stock availability and pricing.
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