Hastelloy C22: properties, composition, uses and standards
Hastelloy C22 is a nickel–chromium–molybdenum alloy with tungsten, chosen for mixed oxidising and reducing acids, and weld overlays. UNS N06022, W.Nr 2.4602, PREN ≈ 65, density 8.69 g/cm³.
What is Hastelloy C22?
Hastelloy C22 is a nickel–chromium–molybdenum alloy with tungsten. Engineers choose it for mixed oxidising and reducing acids, and weld overlays. It is also known as Alloy C-22, UNS N06022, W.Nr 2.4602, Nicrofer 5621.
- UNS
- N06022
- W.Nr
- 2.4602
- EN
- NiCr21Mo14W
- Trade names
- Hastelloy C-22 · Nicrofer 5621
- Density
- 8.69 g/cm³
- Melting range
- 1357 – 1399 °C
- Magnetic
- Non-magnetic
- PREN (approx.)
- ≈ 65
Chemical composition and what each element does
Under technical review for TDS.
| Element | Current requirement |
|---|---|
| Nickel | As specified |
| Chromium | As specified |
| Molybdenum | As specified |
| Iron | As specified |
| Tungsten | As specified |
| Cobalt | As specified |
| Carbon | As specified |
| Manganese | As specified |
| Vanadium | As specified |
| Silicon | As specified |
Numerical specification requirements are published only after the applicable current standard edition has been verified. Governing specification to be verified: ASTM B575 for UNS N06022.
Higher chromium than C276 gives better resistance to oxidising acids and ferric/cupric chlorides.
Molybdenum keeps strong resistance in reducing acids.
Tungsten improves pitting and crevice resistance.
C22 filler is widely used to weld and overlay other alloys.
Hastelloy C22 at a glance
See the Hastelloy C22 product page for every form we supply and its standard.
Mechanical properties
Under technical review for TDS.
| Property | Current requirement |
|---|---|
| Tensile strength | As specified |
| Yield strength 0.2% | As specified |
| Elongation | As specified |
Numerical specification requirements are published only after the applicable current standard edition has been verified. Governing specification and condition to be verified: ASTM B575 for UNS N06022 — Solution-annealed plate & sheet.
Where Hastelloy C22 is used
- Chemical processing. Equipment seeing both oxidising and reducing conditions. Industry →
- Pharmaceutical. Multi-purpose reactors. Industry →
- FGD & incineration. Scrubbers and waste incinerators. Industry →
- Weld overlay. Cladding of vessels and valves. Industry →
Welding C22
The matching filler is ERNiCrMo-10 (AWS A5.14). ENiCrMo-10 electrode.
Keep heat input moderate and interpass temperature low, clean joints thoroughly, and pickle or passivate after welding where the service is corrosive.
Hastelloy C22 compared with similar grades
| Grade | PREN | Choose it for |
|---|---|---|
| Hastelloy C22 | ≈ 65 | Mixed oxidising and reducing acids, and weld overlays |
| Hastelloy C276 | ≈ 68 | The most aggressive mixed acids, wet chlorine and hypochlorite |
| Inconel 625 | ≈ 51 | Seawater, high strength and high temperature in one alloy |
| Inconel 825 | ≈ 31 | Sulphuric and phosphoric acid service, chloride stress-corrosion cracking and sour gas |
Hastelloy C22 standards by product
| Product | Standard |
|---|---|
| Hastelloy C22 sheet | ASTM B575 |
| Hastelloy C22 plate | ASTM B575 |
| Hastelloy C22 coil | ASTM B575 |
| Hastelloy C22 pipe & tube | ASTM B622 · ASTM B619 |
| Hastelloy C22 fittings | ASTM B366 WPHC22 · ASTM B462 / B564 |
| Hastelloy C22 flanges | ASTM B462 / B564 |
| Hastelloy C22 fasteners | May be machined from ASTM B574 bar (UNS N06022), where applicable; finished fastener requirements are to the purchase specification or project drawing |
Buying Hastelloy C22: what to specify
- The product standard and the UNS or designation — for example ASTM B575 UNS N06022.
- Size, thickness or schedule, and quantity in pieces and kg or metres.
- Heat-treatment condition where the standard offers a choice.
- Certificate: EN 10204 3.1 or 3.2 available on request / as specified in the PO; ask for 3.2 if a third party must witness.
- NACE MR0175 / ISO 15156 compliance if the service contains H₂S.