Hastelloy X
A Ni-Cr-Fe-Mo nickel alloy for high temperature
Typical values for the temper in the title
Hastelloy X contains about 22% chromium, about 18.5% iron and 9% molybdenum. It keeps strength and oxidation resistance at very high temperatures, and forms and welds well, so complex sheet parts can be made from it.
It is the classic material for combustors and hot sheet parts in gas turbines and jet engines, and is also used in industrial furnaces and petrochemical equipment.
Mechanical and physical properties
| Property | Value | Note |
|---|---|---|
| Tensile strength Rm | 785 MPa | |
| Yield strength Rp0.2 | 360 MPa | |
| Elongation A | 43% | |
| Hardness | 200 HB | |
| Modulus of elasticity E | 197 GPa | |
| Density ρ | 8.22 g/cm³ | |
| Machinability | 18% | relative rating in the site database |
Chemical composition (wt %)
| Element | Range | Role |
|---|---|---|
| Cr chromium | 20.5–23.0 | oxidation resistance |
| Fe iron | 17.0–20.0 | |
| Mo molybdenum | 8.0–10.0 | hot strength |
| Co cobalt | 0.5–2.5 | |
| W tungsten | 0.20–1.0 | |
| C carbon | 0.05–0.15 | hot strength |
| Mn / Si | max 1.0 each | |
| Ni nickel | balance |
Ranges per ASTM B619 (UNS N06002).
Conditions and heat treatment
A solid-solution alloy: it is not hardened by heat treatment, and is supplied annealed or cold worked.
| Condition | Properties | When to choose it |
|---|---|---|
| Solution annealed | ductile, formable and weldable | delivery condition |
Applications
- Gas turbine combustors
- Hot sheet parts in jet engines
- Furnace parts
- Hot petrochemical equipment
- Printed parts for heat
Fabrication
Welding
Welds well by TIG and MIG. Careful cleaning before welding is especially important: oil, paint or sulfur on the surface cause weld cracking.
Machining
Nickel alloys work harden, stay strong when hot, and wear tools. Use low speed, a steady feed that does not "rub", sharp rigid tools and plenty of coolant.
Forming
Forms well annealed, so it suits complex sheet parts.
Compared with similar materials
| Material | Rm / Rp0.2 | Welding | When it is the better choice |
|---|---|---|---|
| Inconel 600 | 550-690 / 170-345 MPa | Good | for milder heat, cheaper · material page |
| Inconel 625 | 827–1034 / 414–758 MPa | Excellent — ERNiCrMo-3 | stronger, more corrosion resistant · material page |
| 310 / 310S | 515–620 / 205–310 MPa | Good — ER310 | a heat-resistant stainless, much cheaper · material page |
Common mistakes
Using 310 instead, under heat and load
310 has much lower hot strength.
Machining with stainless parameters
The material is abrasive and work hardens.
Assuming it is heat-treatable
It is solid-solution strengthened.
Equivalents, standards and supply
| EN | 2.4665 |
|---|---|
| DIN | NiCr22Fe18Mo |
| Standards | ASTM B435 / AMS 5536 |
| Forms | plate · rod · pipe |
| Producers | Haynes Int. · Special Metals · VDM |
Learn more
Values are typical and for comparison only. For design, rely on the standard and the mill certificate. Sources: ASTM (B127, B164, B168, B443, B575, B619 and others), Special Metals and Haynes data sheets, and the METAL HUB materials database. Inconel and Monel are trademarks of Special Metals, and Hastelloy of Haynes International.
Updated: October 31, 2026