254 SMO
Data verified254 SMO is a 6% molybdenum super-austenitic stainless with nitrogen and copper, giving a PREN above 42. It was developed for seawater and hot chloride service where 316L pits and even 904L runs out of margin.
Chemical composition
| Element | Content (%) |
|---|---|
| C | ≤0.020 |
| Si | ≤0.80 |
| Mn | ≤1.00 |
| P | ≤0.030 |
| S | ≤0.010 |
| Cr | 19.50–20.50 |
| Ni | 17.50–18.50 |
| Mo | 6.00–6.50 |
| Cu | 0.50–1.00 |
| N | 0.18–0.22 |
Weight percent, per the governing standard ranges. Actual values per heat are on the mill certificate.
Properties
| Delivery condition | Solution annealed |
| Hardness | ≤220 HB (annealed) |
| Tensile strength | ≥690 MPa |
| Yield strength | ≥310 MPa |
| Density | 8.00 g/cm³ |
| PREN | ≥42 |
Heat treatment
Solution anneal 1150–1200 °C, water quench. Avoid holding in the 600–1000 °C range where intermetallic phases precipitate.
Equivalent grades
| Standard | Designation |
|---|---|
| din | 1.4547 |
| aisi | UNS S31254 (254 SMO) |
| gb | 015Cr20Ni18Mo6CuN |
Compare side by side: 254 SMO vs 904L
Equivalents overlap in chemistry and use but are not always identical — see our equivalents guide before substituting in certified designs.
Applications & Processing
Applications: Seawater handling and desalination, offshore piping, flue-gas desulfurization, pulp bleach plants, chemical processing with hot chlorides.
Processing: Welds with matching 254 SMO or nickel-base (625-type) fillers; fully austenitic structure means good formability but strong work hardening — machining needs rigid setups and sharp tooling.
FAQ
- 254 SMO or super duplex 2507 for seawater?
- Both reach PREN ≈42+. 2507 is stronger and cheaper per unit of strength; 254 SMO is fully austenitic, easier to form into complex shapes and immune to the duplex welding phase-balance problem.
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Ask for a quotationVisit NasteelSource: ASTM A240 published ranges (UNS S31254) · Last updated 2026-11-03. Data is indicative — verify critical values against the governing standard and mill certificate before use.