Data completeness: partial. Last verified 19 August 2026.
Designations
| Common name | 6XN |
| UNS | N08367 |
| EN number | 1.4562 |
| Class | Super-austenitic stainless steel |
| Specified by | ASTM A240/A240M, EN 10088-2 |
6XN carries a UNS number beginning with N, so it is formally a nickel alloy rather than a stainless steel, and at roughly 25% nickel that classification is honest. It is the six-and-a-half-molybdenum answer to 254 SMO, two points higher on the pitting ranking, and it is a plate alloy: the datasheet consulted lists a Quarto plate row and nothing else.
Properties, with what each one rests on
| Property | Value | Unit | Condition | Evidence | Source | Retrieved |
|---|---|---|---|---|---|---|
| Proof strength Rp0.2, minimum (EN) | 300 | MPa | Quarto plate, 20 °C | E3 | EN 10088-2 via Outokumpu Ultra range datasheet — high-alloy austenitic stainless steels | 2026-08-20 |
| Tensile strength Rm, minimum | 650 | MPa | Quarto plate; datasheet gives a 650–850 range | E3 | EN 10088-2 via Outokumpu Ultra range datasheet — high-alloy austenitic stainless steels | 2026-08-20 |
| Elongation A, minimum | 40 | % | Quarto plate; A and A80 both 40 | E3 | EN 10088-2 via Outokumpu Ultra range datasheet — high-alloy austenitic stainless steels | 2026-08-20 |
| PREN | 45 | — | from typical composition, not from a heat | E3 | Outokumpu Ultra range datasheet — high-alloy austenitic stainless steels | 2026-08-20 |
| Density | 8.1 | g/cm³ | 20 °C | E3 | Outokumpu Ultra range datasheet — high-alloy austenitic stainless steels | 2026-08-20 |
| Modulus of elasticity | 195 | GPa | 20 °C | E3 | Outokumpu Ultra range datasheet — high-alloy austenitic stainless steels | 2026-08-20 |
| Thermal conductivity | 12 | W/(m·K) | 20 °C | E3 | Outokumpu Ultra range datasheet — high-alloy austenitic stainless steels | 2026-08-20 |
| Cold rolled and hot rolled minima | not established | — | — | — | the datasheet consulted lists only Quarto plate for this grade | — |
| Critical pitting and crevice temperatures | not established | — | — | — | not in the datasheet consulted; at this alloy level they are the selection criteria | — |
| Composition limits | not established | — | — | — | ASTM A240 is paywalled; the datasheet gives typical values, which are not limits | — |
7 sourced values, 3 gaps named. Publishing the gaps is more useful than filling them from an aggregator that does not say where its numbers came from. The routes to filling them are the standard itself, a mill datasheet, or a mill certificate for your actual heat — which supersedes both at E5.
Where the numbers come from
Proof strength Rp0.2, minimum (EN). Plate. The 254 SMO plate row in the same table is also 300 MPa; its cold rolled row is 320 MPa. Comparing this page’s figure with a cold rolled figure elsewhere changes the product form as well as the alloy.
PREN. 20.5% Cr, 6.5% Mo and 0.20% N give 45.2 in the datasheet’s own formula. Two points above 254 SMO and two above 2507, which in practice means the three are selected on service record and price rather than on this number.
Density. The heaviest alloy in the datasheet consulted, which is what a quarter of nickel does to a steel.
Why we do not just copy an aggregator. Because then this page would be a worse copy of MatWeb with no way for you to tell which rows to trust, and the one thing we have that MatWeb does not is the evidence column. Our coverage and its limits.
What 6XN is usually chosen for
Seawater and brine handling in plate form — condenser and heat exchanger shells, desalination vessels, offshore process equipment. Its high nickel gives it better resistance to chloride stress corrosion cracking than the standard austenitics, and being single phase it has no phase balance to hold during welding, unlike the super duplex alternatives.
And what it is usually rejected for
Price, weight and heat transfer. It is one of the most expensive stainless alloys per tonne, it is the densest in its family so a plate structure is heavier, and its thermal conductivity is among the lowest, which costs area in a heat exchanger. Where a duplex can be used, it usually is.
The number to be more careful with than any of the above is the difference between a specified minimum and a typical value — a floor the standard guarantees, versus what a supplier’s production usually does. The full version, and the most expensive routine mistake in material data.
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What this page does not cover
- Only plate minima are established here.
- Critical pitting and crevice temperatures, which decide seawater selection.
- Weld metal properties, which for a segregating super-austenitic are the weak point.
- Elevated temperature strength, fatigue and fracture toughness.
- Composition limits, not established.
Generated from data/materials/6xn.yaml. Regenerate rather than editing this file by hand — edits here are lost on the next build.