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| Grade | Code | UNS | Austenitic Stainless Steel |
| 254 SMO/ 1.4547 | X1CrNiMoCuN20-18-7 | S31254 |
254 SMO/ 1.4547 is a highly alloyed super-austenitic stainless steel grade. Compared with conventional austenitic stainless steels, it offers much higher resistance to pitting, crevice corrosion, general corrosion and stress corrosion cracking. This grade combines high mechanical strength with good ductility, formability and weldability, providing a long service life under aggressive operating conditions.
| C % | Si % | Mn % | P % | S % | Cr % | Ni % | Mo % | N % | Cu % | Fe % |
| ≤0.020 | ≤0.70 | ≤1.00 | ≤0.030 | ≤0.010 | 19.50–20.50 | 17.50–18.50 | 6.00–7.00 | 0.18–0.25 | 0.50–1.00 | Bal. |
| Product form | Rp0.2 [MPa] | Rm [MPa] | Elongation [%] | Hardness [HB] | Density [g/cm³] |
| Bar | ≥300 | 650–850 | ≥35 | ≤250 | 8.00 |
| Plate – quarto | ≥310 | 655–850 | ≥40 | ≤223 | 8.00 |
| Sheet – cold rolled | ≥320 | 690–850 | ≥35 | ≤223 | 8.00 |
| Industry | Common Products |
| Marine and shipbuilding | Seawater piping, ballast water treatment UV chambers, marine exhaust gas scrubbers |
| Offshore oil and gas | Hydraulic and instrumentation tubing, manifolds, valve bodies |
| Chemical and petrochemical | Process piping, chemical storage tanks, heat exchangers |
| Pulp and paper | Bleaching towers, bleaching chemical piping, tall oil distillation columns |
| Flue gas cleaning | Scrubber and absorber bodies, spray pipes and nozzles, flue gas ducts |
| Desalination and water treatment | High-pressure seawater piping, evaporators and brine heaters, heat exchangers |
| Power generation | Condenser tubes, seawater cooling lines, flue gas desulfurization equipment |
| Food and beverage | Process tanks, hygienic piping, plate heat exchangers |
| Pharmaceutical and bioprocess | Reactor vessels, high-purity process piping, CIP cleaning system equipment |
| Mining and hydrometallurgy | Leach tanks, corrosive slurry pipelines, pump and valve components |
254 SMO/ 1.4547 is a grade that requires somewhat tighter control during fabrication than standard austenitic stainless steels. During machining, low cutting speeds and suitable cutting tools are preferred due to work hardening, while welding operations require controlled heat input and suitable nickel-based filler metals. When necessary, solution annealing is performed at 1150–1200 °C followed by rapid cooling. Since intermetallic phases may form, it is not suitable for long-term use in the 600–1000 °C range; however, thanks to its austenitic structure, it can exhibit very good impact strength down to –196 °C. Therefore, 254 SMO/ 1.4547 is a special stainless steel grade that retains its reliability at low temperatures but is not preferred for continuous high-temperature service.
254 SMO®, EN 1.4547, DIN/W.Nr. 1.4547, X1CrNiMoCuN20-18-7, UNS S31254, ASTM A182 F44
| Product form | ASTM specification |
| Bar | ASTM A276/A276M, ASTM A479/A479M |
| Plate | ASTM A240/A240M – UNS S31254 |
| Sheet | ASTM A240/A240M – UNS S31254 |
| Pipe – seamless | ASTM A312/A312M, ASTM A213/A213M, ASTM A269/A269M |
| Pipe – welded | ASTM A312/A312M, ASTM A249/A249M, ASTM A269/A269M, ASTM A358/A358M, ASTM A409/A409M |
Alloy 926 – EN 1.4529 / UNS N08926
Super Duplex 2507 – EN 1.4410 / UNS S32750 / F53
AISI 904L – EN 1.4539 / UNS N08904
Note: The information contained in this datasheet is for informational purposes only; no liability is accepted.
