High-Temperature Ni-Cr-Fe-Mo Alloy for Gas Turbine & Industrial Furnace Applications  |  AMS 5536  |  Special Alloys

What is Hastelloy X?

Hastelloy X (UNS N06002) is a nickel-base solid-solution alloy developed in the 1950s specifically for high-temperature structural service. Its nominal chemistry — balance Ni, 22% Cr, 18% Fe, 9% Mo, 0.6% Co, 0.6% W, and controlled carbon — was deliberately formulated to combine oxidation resistance with fabricability and moderate creep strength. The result is the only Hastelloy alloy whose primary design target is high-temperature oxidation, not aqueous corrosion.

The 20.5–23% chromium level is the highest in the Hastelloy family and is responsible for the protective Cr₂O₃ scale that gives Hastelloy X continuous oxidation resistance to 1100 °C and intermittent capability to 1200 °C. Molybdenum contributes solid-solution strengthening and improves resistance to mildly reducing atmospheres, while the substantial iron content lowers raw material cost and improves forgeability compared with fully nickel-base alloys. Because it is not precipitation-hardened, Hastelloy X remains ductile and weldable and does not require the complex aging schedules of alloys such as Inconel 718.

Typical uses include combustion chambers, afterburners, transition ducts, and turbine exhaust components in aerospace and industrial gas turbines, as well as radiant tubes, muffles, retorts, and reformer hardware in industrial furnaces and petrochemical plants. When specifying, remember: Hastelloy X is an oxidation alloy. For aggressive wet-corrosion environments, choose Hastelloy C-276 or C-22; for higher creep strength above 760 °C, consider age-hardenable Inconel 718 or oxide-dispersion-strengthened (ODS) alloys.

Chemical Composition

Per AMS 5536 / ASTM B435 / ASTM B572. Weight percent. Cr, Mo, and C are the defining elements for high-temperature oxidation and creep behavior.

⭐ Elements that define Hastelloy X's high-temperature oxidation and creep performance

Mechanical Properties

Hastelloy X is solid-solution strengthened. Properties are stable after solution annealing and remain ductile across a wide temperature range.

Physical Properties

Heat Treatment

Hastelloy X is normally used in the solution-annealed condition. The higher annealing temperature compared with corrosion Hastelloys ensures complete carbide dissolution and optimizes high-temperature ductility.

High-Temperature Corrosion Resistance

Important: Hastelloy X is an oxidation alloy, not a wet-corrosion alloy. Its corrosion performance should be evaluated in dry, high-temperature environments. For aggressive aqueous media, refer to Hastelloy C-276 or C-22.

Hastelloy X vs Competing High-Temperature Alloys

Rating guide: strength, oxidation resistance, creep resistance, fabricability, relative cost.

Applications

Hastelloy X is selected wherever components must resist oxidation, thermal cycling, and moderate creep simultaneously. Common applications include:

Applicable Standards

Hastelloy X is covered by aerospace (AMS) and industrial (ASTM, DIN) specifications. HT PIPE supplies material with mill test reports conforming to the standard requested.

HT PIPE Project Experience

HT PIPE supplied 2.1 tons of Hastelloy X sheet (AMS 5536, 2.0–6.0 mm thickness) for combustor liner repair on industrial gas turbines. The order required grain size ASTM 4–6, 815 °C stress-rupture testing per lot, and full EN 10204 3.1 certification with mill traceability. All lots met the 1000-hour stress-rupture criterion. Material was cut-to-size, edge-conditioned, and delivered within the customer's outage schedule.

For furnace and petrochemical projects, we regularly supply Hastelloy X sheet, plate, and welded tube in ASTM B435 / B572 or AMS specifications with high-temperature test reports. Contact our sales engineers to match certification and heat treatment to your service conditions.

Frequently Asked Questions