Hastelloy C22 at a glance
- Designation: UNS N06022, Werkstoff 2.4602, NiCr21Mo14W, commonly called Alloy C-22.
- Family: nickel-chromium-molybdenum (Ni-Cr-Mo alloy), nickel balance with ~22% Cr, ~13% Mo and ~3% W.
- Versatility signature: it resists oxidizing and reducing media alike, nitric, sulfuric, hydrochloric and mixed acids, plus wet chlorine and ferric/cupric chlorides.
- Corrosion: PREN ~70, among the highest of commercial corrosion-resistant alloys. It stands up to pitting, crevice corrosion and stress-corrosion cracking.
- Supply: all forms to ASTM B575/B574/B622. Ex-stock for immediate dispatch. Every order ships with an EN 10204 3.1/3.2 mill test certificate.
What is Hastelloy C22?
Hastelloy C22 belongs to the nickel-base family of corrosion-resistant alloys, specifically the Ni-Cr-Mo group, and gets its strength from molybdenum and tungsten in solid solution. What sets it apart is versatility. Most alloys get tuned for one job: high chromium for oxidizing media, high molybdenum for reducing media. C22 does both, thanks to a balanced chemistry of roughly 22% Cr, 13% Mo, and 3% W. That's why it's the C-family grade you reach for when a process shifts between oxidizing and reducing conditions, or when you simply don't know the exact chemistry you're dealing with.
A common misnomer is "Inconel C22", no such grade exists. The correct name is Hastelloy C22, also called Alloy C-22 (UNS N06022), a nickel-chromium-molybdenum alloy. Get the designation right on the purchase order and the MTC, and you'll avoid disputes at receiving inspection. Reach for C22 when chlorides, wet chlorine or mixed acids go beyond what austenitic and super-austenitic stainless (316L, 904L) can handle, even beyond what Incoloy 825 can take. It sits at the top of the nickel alloys corrosion ladder.
Chemical composition
High chromium, molybdenum, and tungsten work together in UNS N06022 to give it wide-ranging acid resistance and strong defense against localized corrosion. Carbon stays very low, at or below 0.015%, which holds back carbide precipitation. That's why the weld heat-affected zone doesn't sensitize.
| Element | Content (wt %) | Role |
|---|---|---|
| Nickel (Ni) | Balance | Base, chloride SCC resistance |
| Chromium (Cr) | 20.0 – 22.5 | Oxidizing-media & oxidation resistance |
| Molybdenum (Mo) | 12.5 – 14.5 | Reducing-acid, pitting & crevice resistance |
| Tungsten (W) | 2.5 – 3.5 | Reinforces localized-corrosion resistance |
| Iron (Fe) | 2.0 – 6.0 | Residual |
| Cobalt (Co) | ≤ 2.5 | Residual |
| Carbon (C) | ≤ 0.015 | Low, resists HAZ sensitization |
| Vanadium (V) | ≤ 0.35 | Residual |
| Manganese (Mn) | ≤ 0.50 | – |
| Silicon (Si) | ≤ 0.08 | – |
| Phosphorus (P) | ≤ 0.02 | – |
| Sulfur (S) | ≤ 0.02 | – |
Mechanical properties
Room-temperature minima for solution-annealed plate to ASTM B575. Solution annealing is the standard condition for corrosion service, since it dissolves carbides and intermetallics and gives maximum ductility and resistance.
| Property | Solution-annealed plate (ASTM B575) |
|---|---|
| Tensile strength | ≥ 690 MPa (100 ksi) |
| Yield strength (0.2% offset) | ≥ 310 MPa (45 ksi) |
| Elongation | ≥ 45% |
| Hardness (typical) | ≤ ~100 HRB (typ. 89 HRB) |
Physical properties
| Property | Value |
|---|---|
| Density | 8.69 g/cm³ |
| Melting range | 1357 – 1399 °C |
| Thermal conductivity (RT) | ~10.1 W/m·K |
| Mean coefficient of thermal expansion (RT–100 °C) | ~12.4 µm/m·°C |
| Elastic modulus | ~206 GPa |
| Magnetic response | Essentially non-magnetic |
Density of 8.69 g/cm³ drives plate and bar weight. To convert a cut size to mass for an RFQ, use the steel plate weight calculator or the guide on how to calculate steel plate weight.
Corrosion behavior & PREN: why C22 is specified
Engineers specify Hastelloy C22 for the toughest mixed-service environments. Chromium in the alloy handles oxidizing media like nitric and other oxidizing acids. Molybdenum and tungsten, meanwhile, take care of reducing media such as hydrochloric and sulfuric acids. That combination lets one grade cover a process that swings between the two extremes, something a chromium-rich or molybdenum-rich alloy on its own couldn't manage; each would fail once the chemistry crossed into the other's territory. Hastelloy also stands up to wet chlorine, ferric and cupric chlorides, and chlorine-contaminated organics. It resists pitting, crevice corrosion and chloride stress-corrosion cracking too.
Its PREN of about 70, on the tungsten-adjusted Cr + 3.3·(Mo + ½W) convention, places it at the top of the corrosion-resistant-alloy ladder, well above the super-duplex stainless steels:
| Grade | PREN (approx.) | Choose when |
|---|---|---|
| 316 / 316L | ~24 | Mild chlorides, general chemical duty |
| 904L | ~34 | Sulfuric acid, moderate chlorides |
| Duplex 2205 | ~35 | Chloride duty at higher strength |
| Super-Duplex 2507 | ~43 | Seawater, high-strength chloride duty |
| Hastelloy C22 | ~70 | Oxidizing + reducing extremes, wet chlorine, severe mixed acids |
For high-sulfuric-acid duty specifically, see sulfuric acid resistance. Where H2S shows up, C22 can be supplied to NACE MR0175 / ISO 15156 sour-service requirements.
Equivalent grades & designations
| System | Designation |
|---|---|
| UNS | N06022 |
| Werkstoff (W.-Nr.) | 2.4602 |
| DIN | NiCr21Mo14W |
| Trade / common names | Alloy C-22, Hastelloy C-22 |
| Common misnomer | "Inconel C22" (no such grade, it is Hastelloy/Alloy C-22) |
| ASME | SB-575 |
| JIS | No direct equivalent |
Cross-check the designations on the purchase order and the MTC against the UNS / W.-Nr. / JIS cross-reference. Doing so heads off disputes at receiving inspection.
Available forms & sizes
Hastelloy C22 (N06022) sits ex-stock in both flat and long forms, ready for immediate dispatch. Each form links through to its own product page, where you can check live stock and sizes.
| Form | Typical standard | Product page |
|---|---|---|
| Plate, sheet & strip | ASTM B575 / SB-575 | Hastelloy C22 plate & sheet (RFQ) |
| Round bar & rod | ASTM B574 / SB-574 | Hastelloy C22 round bar |
| Seamless pipe & tube | ASTM B622 / SB-622 | Hastelloy pipe |
| Flanges | ASTM B462 / SB-462 | Hastelloy flanges |
| Pipe fittings | ASTM B366 / SB-366 | Hastelloy pipe fittings |
| Forged fittings | ASTM B462 / B564 | Hastelloy forged fittings |
| Fasteners | Bolting per B574 / B462 | Hastelloy fasteners |
Standards & specifications complied
Hastelloy C22 is supplied against the applicable ASTM/ASME specifications by form:
| Form | ASTM | ASME |
|---|---|---|
| Plate, sheet & strip | ASTM B575 | ASME SB-575 |
| Rod & bar | ASTM B574 | ASME SB-574 |
| Seamless pipe & tube | ASTM B622 | ASME SB-622 |
| Welded pipe & tube | ASTM B619 / B626 | ASME SB-619 / SB-626 |
| Fittings | ASTM B366 | ASME SB-366 |
| Flanges & forgings | ASTM B462 | ASME SB-462 |
For sour hydrocarbon service the heat is supplied in the qualified condition to NACE MR0175 / ISO 15156.
How C22 compares: C276, C2000 & Inconel 625
All Ni-Cr-Mo alloys here. The choice comes down to what medium dominates and which acid you're dealing with.
- vs Hastelloy C276: C276 carries more molybdenum and is the classic choice for hot reducing acids, but C22's higher chromium makes it outperform C276 in oxidizing and highly oxidizing chloride environments. Choose C22 over C276 when the medium is oxidizing, mixed, or variable; stay with C276 for consistently reducing hydrochloric/sulfuric duty.
- vs Hastelloy C2000: C2000 adds copper for still-broader acid coverage; C22 remains the versatile all-rounder where tungsten-reinforced localized-corrosion resistance is the priority.
- vs Inconel 625: 625 (PREN ~51) is a lower-cost, higher-strength Ni-Cr-Mo alloy for chlorides and sour service. Step up to C22 (PREN ~70) when the acid or chloride severity exceeds 625's ceiling.
- vs Alloy 20: Alloy 20 is a lower-tier, copper-bearing option for sulfuric-acid duty; move to C22 when oxidizing extremes, wet chlorine or localized corrosion are in play.
Welding & fabrication
Hastelloy C22 is readily welded with matching filler ERNiCrMo-10 (FM C-22) by GTAW, GMAW and SMAW. Because the alloy is low-carbon, weldments resist sensitization and intergranular attack, and it is normally supplied and used in the solution-annealed condition. Keep heat input and interpass temperature controlled to preserve corrosion resistance; see welding stainless and nickel alloys and how to prevent sensitization. For the role of the anneal, see heat treatment & solution annealing.
Applications
Chemical and acid processing: reactors, columns, heat exchangers and piping that handle mixed oxidizing and reducing acids. See chemical / acid processing.
FGD and pollution control: flue-gas desulfurization scrubbers, ducts and stack liners face wet, acidic, chloride-laden gas. It's a classic C22 duty within pollution control & FGD service.
Pharmaceutical and waste treatment: hygienic reactors, pulp-and-paper bleaching equipment and waste-treatment hardware all get exposed to aggressive chlorinated and mixed media. See pharmaceutical and pulp & paper.
Ordering & certification
Every Hastelloy C22 order comes with an EN 10204 3.1/3.2 mill test certificate that ties heat and cast numbers back to the physical material. See EN 10204 3.1 mill test certificate for details. On request we can also provide positive material identification (PMI) confirming N06022, intergranular corrosion testing per ASTM G28/A262, and ultrasonic (UT) testing. The full inspection workflow is covered at testing, MTC, NDT & PMI. One thing worth pointing out: Nandini Steel's ISO 9001:2015 certified scope names Hastelloy plates as a declared specialty, a credential backed by third-party verification.
Buyers often slip up here: they order plain "Hastelloy C22" and leave out the governing standard, form, and condition. Spell out the form, size, ASTM/ASME standard, and the solution-annealed condition on the PO. Add NACE MR0175 when the service is sour. Do that and the heat gets supplied correctly the first time, MTC included.
Request a quote
Nandini Steel holds ISO 9001:2015 certification and works as a stockist and supplier of Hastelloy C22 (UNS N06022), covering plate, sheet, pipe, tube, round bar, flanges, fittings and fasteners. Everything sits ex-stock, ready to go out the door, and the material itself is genuine mill stock sourced from producers like Aperam, Outokumpu, Jindal, POSCO, Nippon Steel and JFE. Each order comes with an EN 10204 3.1/3.2 mill test certificate.
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RFQ for live pricing: share the form, size, standard and condition, and we'll get back to you with availability. For traceability details, check our certifications and quality assurance pages, or just contact us directly.