Materials / Superalloy
Hastelloy C-22
- UNS
- N06022
- W.Nr
- 2.4602
- EN
- NiCr21Mo14W
A higher-chromium alternative to C-276 with better resistance to oxidising media and localised attack, and better as-welded stability across a wider range of conditions.
Composition
| Element | Min | Max |
|---|---|---|
| Ni | — | bal |
| Cr | 20.0 | 22.5 |
| Mo | 12.5 | 14.5 |
| Fe | 2.0 | 6.0 |
| W | 2.5 | 3.5 |
| Co | — | 2.5 |
| V | — | 0.35 |
| C | — | 0.015 |
Per cent by weight, to the governing standard.
- Ni58.3
- Cr21.3
- Mo13.5
- Fe4.0
- W3.0
Per cent by weight, at the midpoint of each specified window. Elements given only as a maximum have no midpoint to take, so they sit inside the balance rather than being estimated; trace elements below 0.5 % are not shown. Indicative only; the composition table above and the governing standard are what define the limits.
Mechanical
- Tensile strength, min
- 690 MPa
- Yield strength (0.2%), min
- 310 MPa
- Elongation, min
- 45 %
- Condition
- Solution annealed
Standards by form
| Plate, sheet & strip | ASTM B575 | |
|---|---|---|
| Pipe & tube | ASTM B622 | |
| Bar & rod | ASTM B574 | |
| Fittings | ASTM B366 |
Where it is specified
- Oxidising and mixed acid service where C-276 is marginal
- Pharmaceutical and chemical process vessels, scrubbers, flue gas systems
- Outstanding resistance to pitting and crevice corrosion
C-22 and C-276 are cross-sold in both directions
C-22 and C-276 are easy to cross-sell in either direction: the two look identical in the crate, and their certificates read alike to anyone not checking the numbers. The alloys are not interchangeable: their chromium and molybdenum balance is different, and so is the service each one survives.
What we specify and check
- PMI distinguishing Cr 20.0–22.5 and Mo 12.5–14.5 from the C-276 windows
- Certificate matched to the heat number in the crate
- ASTM G28 testing where specified
- Confirmation the grade ordered is the grade quoted, in writing, before the PO
We commission an accredited independent laboratory to test the heat before the material leaves China. You will receive that report unedited, whether it passes or not.
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