Data completeness: partial. Last verified 19 August 2026.
Designations
| Common name | 4565 |
| UNS | S34565 |
| EN number | 1.4565 |
| Class | Super-austenitic stainless steel |
| Specified by | ASTM A240/A240M, EN 10088-2 |
4565 is the high-nitrogen super-austenitic: about 0.45% nitrogen against 0.20% in 254 SMO, with manganese in the composition to hold that nitrogen in solution. The result is a proof strength minimum of 420 MPa in a single-phase austenitic — higher than 2205 duplex on the equivalent row, and with 30% elongation rather than 20%. That combination is the whole argument for the grade.
Properties, with what each one rests on
| Property | Value | Unit | Condition | Evidence | Source | Retrieved |
|---|---|---|---|---|---|---|
| Proof strength Rp0.2, minimum (EN) | 420 | MPa | cold rolled coil and sheet, 20 °C | E3 | EN 10088-2 via Outokumpu Ultra range datasheet — high-alloy austenitic stainless steels | 2026-08-20 |
| Tensile strength Rm, minimum | 800 | MPa | cold rolled; datasheet gives an 800–950 range | E3 | EN 10088-2 via Outokumpu Ultra range datasheet — high-alloy austenitic stainless steels | 2026-08-20 |
| Elongation A, minimum | 30 | % | cold rolled; A and A80 both 30 | E3 | EN 10088-2 via Outokumpu Ultra range datasheet — high-alloy austenitic stainless steels | 2026-08-20 |
| PREN | 46 | — | from typical composition, not from a heat | E3 | Outokumpu Ultra range datasheet — high-alloy austenitic stainless steels | 2026-08-20 |
| Density | 8.0 | g/cm³ | 20 °C | E3 | Outokumpu Ultra range datasheet — high-alloy austenitic stainless steels | 2026-08-20 |
| Modulus of elasticity | 190 | 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 |
| 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 | — |
| Work hardening rate and forming limits | not established | — | — | — | high-nitrogen austenitics work harden severely and the datasheet consulted does not quantify it | — |
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). Unusually, the Quarto plate row for this grade is the same 420 MPa rather than lower. Nitrogen strengthening does not depend on cold work, so the product form penalty that applies to most grades in these tables does not apply here.
PREN. 24% Cr, 4.5% Mo and 0.45% N give 46.1 in the datasheet’s own formula. Note where it comes from: nitrogen contributes 7.2 points of that total, more than the molybdenum contributes in 316L altogether. It is also the reason to be careful with the number, since the nitrogen coefficient of 16 is the least settled part of the formula.
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 4565 is usually chosen for
Pressure-bearing seawater and brine equipment where a duplex would be the obvious answer but cannot be used — because the part runs too hot for a duplex, because it must stay austenitic for toughness at low temperature, or because non-magnetic behaviour is required. Umbilicals, seawater pumps and high-pressure process vessels.
And what it is usually rejected for
Cost and formability. It is among the most expensive alloys in the range, and the same nitrogen that gives it strength makes it work harden hard, so forming and machining need more power, more tool wear and more intermediate annealing than an ordinary austenitic. It is also a specialist product with long lead times.
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.
Compare
What this page does not cover
- Critical pitting and crevice temperatures are not established here.
- Work hardening and forming behaviour, which is where the grade costs money in the shop.
- Weld metal properties and filler selection.
- Elevated temperature strength, fatigue and fracture toughness.
- Composition limits, not established.
Generated from data/materials/4565.yaml. Regenerate rather than editing this file by hand — edits here are lost on the next build.