254 SMO (UNS S31254 / W.Nr. 1.4547)
254 SMO (UNS S31254 / W.Nr. 1.4547) is a super austenitic stainless steel that is well known for its outstanding resistance to pitting, crevice corrosion, stress cracking, and fatigue corrosion.
Equivalent Grades
| Trademark | GB | GOST | ASTM | UNS | DIN | W.Nr. | NF | BS | JIS | SS |
254 SMO
F44 | – | – | – | S31254 | X1CrNiMoCuN20-18-7 | 1.4547 | Z1 CNDU 20.18.06AZ | X1CrNiMoCuN20-18-7 | – | – |
Chemical Composition, %
| Alloy | C | Si | Mn | P | S | Cr | Ni | Mo | Fe |
| 254 SMO | ≤0.02 | ≤0.80 | ≤1.0 | ≤0.03 | ≤0.02 | 19.5-20.5 | 17.5-18.5 | 6.0-6.5 | Bal |
Typical Physical and Mechanical Properties (RT, Annealed)
| Density, g/cm3 | Melting Point, ℃ | Tensile Strength, MPa | Yield Strength, MPa | ELongation, % | Hardness, HB |
| 8.0 | 1110-1210 | 675-850 | ≥310 | ≥35 | / |
Available Products and Specifications
| Rod, Bar, Wire and Forgings | ASTM A479, ASTM B276 |
| Plate, Sheet and Strip | ASTM A240, ASTM B480 |
| Pipe and Tube | ASTM A358, ASTM A312, ASTM A409, ASTM A813, ASTM A814, ASTM B690 |
| Welding Product | – |
| Others | ASTM B366 |
Features
- Excellent resistance to pitting and crevice corrosion, PRE = ≥42.5*
- High resistance to general corrosion
- High resistance to stress corrosion cracking
- Higher strength than conventional austenitic stainless steels
- Good weldability
Applications
254 SMO is used in the following applications:
- Equipment for handling of seawater, such as seawater cooling, cooling water pipes, ballast water systems, firefighting systems etc.
- Hydraulic and instrumentation tubing
- Equipment in pulp bleaching plants
- Components in gas cleaning systems
- Tanks and pipelines for chemicals with high halide contents
