- Grade / Alloy
- 1.4659
- EN / W.Nr.
- 1.4659X1CrNiMoCuNW24-22-6
- AISI / SAE
- —
- UNS
- S31266
- Family
- Austenitic
Chemical composition
Chemical composition
Composition limitsComposition limits for long products within EN 10088-3.
| Element | Content (% by mass) |
|---|---|
| CCarbon | ≤ 0.02 |
| SiSilicon | ≤ 0.7 |
| MnManganese | 2–4 |
| PPhosphorus | ≤ 0.03 |
| SSulfur | ≤ 0.01 |
| NNitrogen | 0.35–0.5 |
| CrChromium | 23–25 |
| CuCopper | 1–2 |
| MoMolybdenum | 5.5–6.5 |
| NiNickel | 21–23 |
| WTungsten | 1.5–2.5 |
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.
Understanding 1.4659 stainless steel
1.4659 is a super-austenitic stainless steel associated with high corrosion resistance. Tungsten, copper and nitrogen accompany its chromium, nickel and molybdenum content. This multi-element composition helps explain its role in demanding industrial environments. It is also identified as UNS S31266. An austenitic structure provides toughness and ductility, while the alloying elements contribute to resistance where corrosive fluids contact the metal surface.
The distinction of a tungsten-bearing composition
Molybdenum and nitrogen are familiar elements in highly corrosion-resistant stainless steels. 1.4659 adds tungsten to that combination. It therefore cannot be identified as another super-austenitic grade simply from an approximate molybdenum content. Resistance to attack concentrated at particular locations depends on the combined balance of elements. That complete composition underlies its separate grade designation; one element or a commercial name does not describe the whole material.
Where is it used?
Seawater systems, flue-gas treatment units and marine scrubbers are recognised applications. Certain equipment in chemical plants and the pulp and paper industry also falls within this range. A service fluid may contain several substances rather than a single chemical: salts, acids and other constituents can contact the same surface. 1.4659 is among the material options associated with these complex environments. Forms ranging from plate bodies to cut components allow a grade to serve different parts of such equipment.
Its relationship to 254 SMO and Alloy 625
254 SMO is a super-austenitic stainless steel, whereas Alloy 625 is nickel-based. Although 1.4659 can appear alongside them in discussions of some applications, it is not another name for either. Tungsten and high nitrogen distinguish its composition from other stainless grades; its iron-based structure also distinguishes it from nickel alloys. One laboratory result cannot rank corrosion resistance for every environment. The value of these materials lies in their properties under different fluid and temperature conditions.
Typical application areas
Seawater, gas-cleaning, chemical and pulp equipment.
Product and cutting options
Relevant product forms for this material are listed below. Availability varies with grade and dimensions.