- Grade / Alloy
- 317LMN
- EN / W.Nr.
- 1.4439X3CrNiMoN17-13-5
- AISI / SAE
- —
- UNS
- S31726
- 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 | ≤ 2 |
| PPhosphorus | ≤ 0.045 |
| SSulfur | ≤ 0.015 |
| NNitrogen | 0.12–0.22 |
| CrChromium | 16.5–18.5 |
| MoMolybdenum | 4–5 |
| NiNickel | 12.5–14.5 |
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.
Key characteristics of 317LMN
317LMN is an austenitic stainless steel for chloride-containing and more demanding corrosive environments. Molybdenum and nitrogen improve resistance to corrosion beginning as small pits or within narrow gaps. These characteristics matter in equipment exposed to chemical fluids. The grade is one of the more highly alloyed options beyond the common 316 family.
The significance of low carbon
The L denotes low carbon, while N identifies nitrogen alloying. Low carbon helps retain corrosion resistance in welded stainless equipment. Molybdenum and nitrogen support protection against localised corrosion. The combination gives tanks and piping the familiar characteristics of austenitic stainless together with enhanced resistance to more demanding environments.
Its place in process applications
Chemical-plant equipment bodies, process tanks and piping are among its applications. In these systems, the effect of the fluid on the metal surface matters to long-term equipment use. Contact with chloride-containing liquids is one setting where the grade is relevant. Temperature and chemical composition are major factors determining the level of protection required.
Distinct from 317L and 254 SMO
317LMN differs from standard 317L through its molybdenum and nitrogen contents. 254 SMO is another austenitic stainless with higher molybdenum, known for more demanding chloride conditions. The composition of 317LMN defines its own position among these corrosion-resistant options. The designations 1.4439 and S31726 identify this particular grade within the broader 317 naming family.
Typical application areas
Chemical equipment, process tanks and piping.
Product and cutting options
Relevant product forms for this material are listed below. Availability varies with grade and dimensions.