254SMo Stainless Steel
254SMo is a super austenitic stainless steel containing 19.5% to 20.5% chromium, 17.5% to 18.5% nickel, 6.0% to 6.5% molybdenum, and smaller amounts of nitrogen and copper. The molybdenum and nitrogen content supports resistance to pitting, crevice corrosion, and stress corrosion in chlorides, sulfuric acid, hydrochloric acid, and seawater. Carbon is limited to ≤0.02%. The source also describes higher mechanical strength than conventional austenitic stainless steel, together with toughness, weldability, and stable high temperature performance for severe corrosive service.
Product details
Chemical composition
| 254SMo | C | Si | Mn | P | S | Ni | Cr | Cu | Mo | N |
|---|---|---|---|---|---|---|---|---|---|---|
| min | – | – | – | – | – | 17.5 | 19.5 | 0.5 | 6.0 | 0.18 |
| max | 0.02 | 0.8 | 1.0 | 0.03 | 0.01 | 18.5 | 20.5 | 1.0 | 6.5 | 0.22 |
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Grade equivalents
| English Item | UNS | W.Nr. | JIS | GB/T | Other Grades |
|---|---|---|---|---|---|
| 254SMo | S31254 | 1.4547 | – | F44 015Cr20Ni18Mo6CuN 00Cr20Ni18Mo6CuN | X1CrNiMoCuN20-18-7 |
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Physical properties
| Density g/cm³ | 8.24 |
|---|---|
| Melting range ℃ | 1320-1390 |
| Thermal conductivity (100℃) λ/(W/m•℃) | 14.5 |
| Specific heat J/kg•℃ | 500 |
| Elastic modulus GPa | 195 |
| Electrical resistivity μΩ•m | 0.85 |
| Linear expansion coefficient a/10-6℃-1 | 16.5 |
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Mechanical properties
| Tensile strength Rm N/mm | ≥650 |
|---|---|
| Yield strength RP0.2 N/mm | ≥310 |
| Elongation % | ≥35 |
| Hardness HB | 182-223 |
| *After solution heat treatment | |
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Applications
- Marine engineering: seawater-desalination equipment, offshore-platform piping, and seawater heat exchangers exposed to chlorides
- Chemical processing: sulfuric or hydrochloric acid equipment, reactors, and tanks for corrosive media such as halide solutions
- Environmental protection: flue gas desulfurization absorbers and spray systems, plus wastewater equipment handling acidic effluent
- Oil and gas: sulfur-bearing production equipment and refinery piping exposed to hydrogen sulfide and chlorides
- Food processing: salt-production equipment and soy-sauce brewing systems exposed to high-salt and acidic conditions
- Pulp and paper: pulp-bleaching equipment and digesters exposed to oxidizing acids and chlorides
- Energy: corrosion-resistant nuclear-power piping and coal-fired power-plant condensers exposed to high-temperature, high-pressure corrosive media
Available product forms
- Round Bar
- Wire
- Forgings
- Plate
- Strip
- Seamless Pipe
- Welded Pipe
- Capillary Tube
- Flanges
- Pipe Fittings
- Non-standard Custom Parts
Values follow the Milike materials catalogue and are provided for preliminary review. Confirm the applicable purchase specification, heat treatment condition, and inspection requirements before final material selection.
- Heat and batch traceability
- PMI testing available
- Cut-to-size processing
- Material certificates on request
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