Hastelloy C-22
Nickel-chromium-molybdenum for mixed chemical environments
Typical values for the temper in the title
Hastelloy C-22 is a nickel alloy with about 21% chromium, about 13.5% molybdenum and about 3% tungsten. Compared with C-276 it has more chromium and less molybdenum, so it resists oxidizing environments better, while still resisting reducing environments and localized chloride corrosion very well.
It is chosen when the process includes both oxidizers and reducers, or when the environment varies: chemical and pharmaceutical equipment, waste and flue gas treatment systems, and heat exchangers. It is also common as a filler wire for joining dissimilar alloys.
Mechanical and physical properties
| Property | Value | Note |
|---|---|---|
| Tensile strength Rm | ≈690 MPa (annealed) | |
| Yield strength Rp0.2 | ≈310 MPa (annealed) | |
| Elongation A | ≈45% | |
| Modulus of elasticity E | 206 GPa | |
| Density ρ | 8.69 g/cm³ | |
| Machinability | 35% | relative rating in the site database |
Chemical composition (wt %)
| Element | Range | Role |
|---|---|---|
| Cr chromium | 20.0–22.5 | oxidizing environments |
| Mo molybdenum | 12.5–14.5 | reducing environments, pitting |
| W tungsten | 2.5–3.5 | localized corrosion |
| Fe iron | 2.0–6.0 | |
| Co cobalt | max 2.5 | |
| C carbon | max 0.015 | low: welding without sensitization |
| Ni nickel | balance |
Ranges per the Saky Steel table for N06022.
Conditions and heat treatment
The alloy is usually supplied annealed, which is its service condition. It is not hardened by heat treatment.
| Condition | Properties | When to choose it |
|---|---|---|
| Solution annealed | ductile, maximum resistance | all uses |
Applications
- Chemical equipment in mixed environments
- Pharmaceutical equipment
- Waste and flue gas treatment
- Heat exchangers
- Filler wire for dissimilar alloys
Fabrication
Welding
Welds well with matching filler (ERNiCrMo-10). Low carbon prevents sensitization in the heat-affected zone.
Machining
Work hardens and wears tools. Sharp carbide tools, continuous feed and low speed, without letting the tool rub in place.
Choosing vs C-276
In a purely reducing environment C-276 is slightly better. In oxidizing or mixed environments, C-22.
Compared with similar materials
| Material | Rm / Rp0.2 | Welding | When it is the better choice |
|---|---|---|---|
| Hastelloy C-276 | 690–1000 / 350–460 MPa | Good — ERNiCrMo-4 | Hastelloy C-276: more molybdenum, for reducing environments · material page |
| Inconel 625 | 827–1034 / 414–758 MPa | Excellent — ERNiCrMo-3 | Inconel 625: nickel-chromium-molybdenum, stronger · material page |
| Incoloy 825 | ≥586 MPa (annealed) / ≥241 MPa (annealed) | Good — matching filler | Incoloy 825: cheaper, less resistant · material page |
Common mistakes
Choosing C-276 for an oxidizing environment
C-22 is more resistant there.
Welding with non-matching filler
The weld becomes the weak link in corrosion.
Using it for high-temperature load
It is meant for corrosion, not creep.
Equivalents, standards and supply
| UNS | N06022 |
|---|---|
| Standards | ASTM B574 / ASTM B575 |
| Forms | bar · plate · sheet · tube |
| Producers | Haynes International · 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