Materials / Grade-critical stainless
Super duplex 2507
- UNS
- S32750
- W.Nr
- 1.4410
- EN
- X2CrNiMoN25-7-4
A 25-chromium super duplex stainless with roughly double the yield strength of 316L, which usually means thinner sections and less weight for the same duty.
Composition
| Element | Min | Max |
|---|---|---|
| Cr | 24.0 | 26.0 |
| Ni | 6.0 | 8.0 |
| Mo | 3.0 | 5.0 |
| N | 0.24 | 0.32 |
| Mn | — | 1.2 |
| Cu | — | 0.5 |
| C | — | 0.030 |
| S | — | 0.020 |
| Fe | — | bal |
Per cent by weight, to the governing standard.
- Fe64.0
- Cr25.0
- Ni7.0
- Mo4.0
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
- 800 MPa
- Yield strength (0.2%), min
- 550 MPa
- Elongation, min
- 15 %
- Ferrite content
- Typically 35–55 %
Standards by form
| Plate, sheet & strip | ASTM A240 | |
|---|---|---|
| Pipe & tube | ASTM A790 | |
| Forgings & fittings | ASTM A182 / A815 | |
| Bar | ASTM A276 / A479 |
Where it is specified
- Seawater systems, desalination, offshore process piping
- Chloride-bearing service where austenitic grades crack
- PREN typically 42 or above
Duplex fails on structure while the chemistry still reads clean
Duplex grades fail on structure, not chemistry. Incorrect solution annealing or an uncontrolled cool leaves intermetallic sigma phase and a ferrite balance outside 35–55 %, which destroys toughness and corrosion resistance while every element on the certificate still reads in range. Nitrogen at the low end also quietly drops the PREN below what was specified.
What we specify and check
- Ferrite content measured on the delivered material
- PREN calculated from measured values, not from the nominal grade
- Solution anneal and quench records demanded
- ASTM A923 testing for intermetallic phase where specified
- Impact testing where low-temperature service applies
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.
Request Super duplex 2507
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