Hastelloy X / UNS N06002 / 2.4665 Round Bar: Hot Rolled and Forged Bars Diameter 5 - 350mm

1. Introduction and Overview

Hastelloy® X (UNS N06002, Werkstoff Nr. 2.4665) is a nickel-chromium-iron-molybdenum alloy renowned for its exceptional strength and oxidation resistance at high temperatures. It is one of the most widely used nickel-based superalloys for service in severely demanding thermal environments. This product information sheet details the specifications, properties, and applications of our high-quality Hastelloy X round bars, available in hot-rolled and forged conditions, with diameters ranging from 5mm to 350mm.

The primary reason for selecting Hastelloy X is its outstanding combination of fabrication characteristics and high-temperature performance. Unlike many other high-temperature alloys that can be challenging to weld and form, Hastelloy X offers good manufacturability while delivering reliable service in temperatures ranging from cryogenic levels up to 1200°C (2200°F). Our production process for these round bars—utilizing hot rolling for smaller diameters and precision forging for larger sections—ensures a homogeneous microstructure, minimal segregation, and optimal mechanical properties throughout the cross-section.

2. Key Characteristics and Advantages

The superior performance of Hastelloy X stems from its carefully balanced chemical composition. The key characteristics that make it a material of choice for critical applications include:

• Excellent Oxidation Resistance: The high chromium content (approx. 22%) forms a dense, adherent chromium oxide (Cr₂O₃) scale that protects the underlying metal from further degradation in oxidizing atmospheres up to 1175°C (2150°F).

• High-Temperature Strength: Solid solution strengthening from molybdenum and tungsten provides remarkable creep rupture strength and tensile strength at elevated temperatures, where many stainless steels begin to soften significantly.

• Good Fabricability: Despite its high strength, Hastelloy X can be readily formed, machined, and welded using standard techniques, making it suitable for complex component fabrication.

• Resistance to Reducing Atmospheres: The significant molybdenum content (approx. 9%) confers excellent resistance to sulfidizing environments and other reducing gases.

3. Chemical Composition (Typical % Weight)

The following table outlines the standard chemical composition of Hastelloy X as per ASTM/ASME and other common specifications.

Table 1: Standard Chemical Composition of Hastelloy X (UNS N06002)

Note: "Balance" for Nickel is typically around 47%.

4. Mechanical Properties

The mechanical properties of Hastelloy X are exceptional, particularly at elevated temperatures. The following tables provide typical room temperature and high-temperature properties for hot-rolled and forged bars in the solution-annealed condition.

Table 2: Typical Room Temperature Mechanical Properties (Solution Annealed)

Table 3: Typical Short-Time Elevated Temperature Properties

5. Product Specifications and Available Forms

Our Hastelloy X round bars are supplied in the solution-annealed condition to ensure optimal corrosion resistance and mechanical properties. They are available in a wide range of diameters to suit various manufacturing needs.

Table 4: Hastelloy X Round Bar Product Specifications

6. Manufacturing Process: Hot Rolling vs. Forging

• Hot-Rolled Bars (5mm - 100mm): This process involves heating the alloy billets above its recrystallization temperature and passing them through a series of rollers to achieve the desired diameter. Hot rolling is a cost-effective and efficient method for producing smaller diameter bars with a fine, uniform grain structure. It is ideal for applications where the bar will be subsequently machined into components like bolts, fasteners, and shafts.

• Forged Bars (80mm - 350mm): For larger diameters, we employ open-die or closed-die forging. Forging involves applying compressive forces to the heated billet, which results in a superior, directional grain flow that follows the contour of the bar. This process enhances the mechanical properties, particularly toughness, fatigue resistance, and creep strength in the longitudinal direction. Forged bars are preferred for the most critical applications, such as turbine shafts, large valves, and components subject to high cyclic stresses.

7. Applications

Hastelloy X round bars are specified across a wide range of high-temperature industries due to their reliability. Key application areas include:

• Aerospace & Gas Turbines: Combustion cans, transition ducts, burner liners, afterburner parts, turbine shafts, and spray bars.

• Industrial Furnaces: Radiant tubes, muffles, retorts, furnace rollers, and heat treatment baskets.

• Power Generation: Heat exchangers, combustor components, and hot gas path parts in land-based gas turbines.

• Chemical Processing: Components for high-temperature catalytic systems, pyrolysis reactors, and furnace hardware.

• Pollution Control: Thermal oxidizer internals and flare tips.

8. Machining and Welding

• Machining: Hastelloy X is machinable using methods similar to those for austenitic stainless steels but requires more power due to its high work-hardening rate. Positive rake angles, rigid setups, sharp carbide tools, and constant feed rates are recommended. Use heavy-duty cutting fluids for cooling and lubrication.

• Welding: The alloy is readily weldable using common techniques like Gas Tungsten Arc Welding (GTAW/TIG) and Gas Metal Arc Welding (GMAW/MIG). Matching filler metals such as ERNiCrMo-2 or ENiCrMo-2 are typically used. Post-weld heat treatment is not usually required for stress-relief but may be performed for optimal properties in specific applications.

9. Conclusion

Our supply of Hastelloy X round bars, produced via controlled hot-rolling and forging processes, guarantees a product with consistent chemistry, superior mechanical integrity, and proven performance in the world's most challenging high-temperature environments. With a diameter range from 5mm to 350mm, we provide a reliable solution for everything from precision-machined fasteners to massive, high-stress forged shafts.