- Grade / Alloy
- 1.4565
- EN / W.Nr.
- 1.4565X2CrNiMnMoN25-18-6-5
- AISI / SAE
- —
- UNS
- S34565
- Family
- Austenitic
Chemical composition
Chemical composition
Composition limitsComposition limits for long products within EN 10088-3.
| Element | Content (% by mass) |
|---|---|
| CCarbon | ≤ 0.03 |
| SiSilicon | ≤ 1 |
| MnManganese | 5–7 |
| PPhosphorus | ≤ 0.03 |
| SSulfur | ≤ 0.015 |
| NNitrogen | 0.3–0.6 |
| CrChromium | 24–26 |
| MoMolybdenum | 4–5 |
| NiNickel | 16–19 |
| NbNiobium | ≤ 0.15 |
Values describe the grade, not the analysis of a specific batch. The applicable product specification and material certificate determine acceptance. A dash does not mean zero.
Characteristics of 1.4565 stainless steel
1.4565 is a highly alloyed austenitic stainless steel containing chromium, nickel, molybdenum, manganese and nitrogen. Super-austenitic describes a family with compositions developed for corrosion resistance. High nitrogen is a distinctive part of this grade, contributing to both corrosion behaviour and mechanical strength. It retains a tough, ductile structure and is used in equipment that contacts corrosive fluids. UNS S34565 is one of its international designations.
Seawater and gas-cleaning applications
Seawater equipment and flue-gas scrubbers are recognised applications of 1.4565. Chlorides are present in seawater, while salts and different chemical species can meet the metal surface in a scrubber. These environments demand more than resistance to ordinary weather. 1.4565 serves contact surfaces where high corrosion resistance is valuable alongside mechanical strength. Chemical and petrochemical equipment also fall within this range of applications.
Nitrogen matters alongside molybdenum
Stainless steels are sometimes described through molybdenum content alone. 1.4565 illustrates why that is incomplete. The balance of chromium, molybdenum and nitrogen influences resistance to localised corrosion. Localised corrosion means metal loss concentrated at particular sites rather than an even reduction across the whole surface. The characteristics of the grade arise from this combined composition. The amount of one element cannot establish a universal ranking against other stainless steels.
Differences from 254 SMO and duplex grades
254 SMO is also super-austenitic, but its composition is different from that of 1.4565. High nitrogen and a different chromium–molybdenum balance give 1.4565 a distinct material identity. Duplex stainless steels contain both ferritic and austenitic structures. This affects strength and physical properties as well as corrosion behaviour. Materials that appear in discussions of similar equipment are therefore not simply different labels for the same product.
Typical application areas
Chemical equipment, seawater systems and gas scrubbers.
Product and cutting options
Relevant product forms for this material are listed below. Availability varies with grade and dimensions.