GRADE PROFILE
C-276 — N10276
C-276 carries roughly 57% nickel, 16% chromium, 16% molybdenum and 4% tungsten, with carbon capped at 0.01%. It is the alloy for media nothing else will hold: hydrochloric acid, wet chlorine, hypochlorites. Its tungsten calls for the PREW formula, not PREN.
- Nickel alloy
- PREW 75
- Cost index 465
When to choose it
In hydrochloric acid, sulphuric acid, formic and acetic acids, wet chlorine, hypochlorites and chlorinated solutions. On reactors, heat exchangers and columns in the chemical industry, in pollution control and flue gas scrubbing. And in sour oilfield environments, against sulphide stress cracking.
The common criterion is the reducing character of the medium: that is where molybdenum and tungsten work, and where chromium alone is not enough.
When not to choose it
By default. It is one of the most expensive alloys in the catalogue, and in most chlorinated media a 2507 or a 254 SMO is more than sufficient.
In hot concentrated nitric acid, where corrosion rates become high — of the order of 22 mm per year at 65% boiling. C-276 is a reducing-medium alloy, not an oxidising one, and forgetting that leads to rapid failure.
In cold forming beyond 7% outer fibre elongation without re-annealing, since stress corrosion performance suffers.
In hot working outside the 954–1232 °C range, which is narrow and more sensitive to strain rate than that of an austenitic.
Composition
| Element | % | Note |
|---|---|---|
| Ni | 57 | balance |
| Cr | 16 | — |
| Mo | 16 | — |
| Fe | 5 | — |
| W | 4 | — |
| Co | ≤ 2.5 | — |
| Mn | ≤ 1 | — |
| V | ≤ 0.35 | — |
| Cu | ≤ 0.5 | — |
| Si | ≤ 0.08 | — |
| C | ≤ 0.01 | — |
Mechanical properties
We only publish mechanical properties tied to a specific standard and product form — welded tube, seamless tube and bar do not share the same values, and the gap routinely exceeds 30%. The figures that apply to your specification appear on the material certificate; ask us at enquiry stage.
Designations and standards
| Reference | Designation |
|---|---|
| EN (numeric) | 2.4819 |
| EN (symbolic) | — |
| ASTM / AISI | C-276 |
| UNS | N10276 |
| JIS | — |
| AFNOR | — |
Tube product standards :
- ASTM B622
- ASTM B983
- ASME SB622
Availability
Available in welded and seamless tube to ASTM B622 and B983. Structured dimensional data for this grade is not yet documented in our reference set: send us your sizes. EN 10204 3.1 material certificates supplied with the goods.
Related grades
- Alloy 625 (2.4856) — more chromium, less molybdenum, better in oxidising media and at temperature.
- Alloy 825 (N08825) — the step below for sulphuric and phosphoric acid.
- Titanium grade 7 (R52400) — the titanium route for reducing acids where chloride is present.
My grade isn't listed → · PREN calculator → · Compare grades →
Frequently asked questions
- Why PREW rather than PREN?
- Because the classic formula ignores tungsten, which contributes significantly here. PREW counts it at half the weight of molybdenum. A PREW of 75 does not compare with a PREN of 44: they are two different scales.
- C-276 or titanium grade 7 in hydrochloric acid?
- It depends on concentration, temperature and aeration. Titanium grade 7 excels in aerated chlorinated media; C-276 holds high concentrations better in reducing conditions. This is a case where testing in the real medium is worth the trouble.
- Is it weldable without heat treatment?
- Yes, its carbon at 0.01% maximum allows it. The filler metal must be of equivalent composition so as not to create a molybdenum-depleted zone.