AISI 254 SMO Stainless Steel Plate | 254SMO China steel mill-Direct Supply
What is AISI 254 SMO Stainless Steel?
As a professional China steel mill-Direct Supply and stainless steel plate supplier, SHH STEEL is pleased to present AISI 254 SMO Stainless Steel Plate.
254 SMO is widely known and searched under many different names and designations, including 254 SMO, 254SMO, UNS S31254, 1.4547, X1CrNiMoCuN20-18-7, Alloy 254, SMO 254, 6Mo stainless steel, and super austenitic 254 SMO. All these refer to the same high-performance 6% molybdenum super austenitic stainless steel grade.
254 SMO contains high levels of chromium (19.5–20.5%), nickel (17.5–18.5%), molybdenum (6.0–6.5%) and nitrogen (0.18–0.22%), with a small copper addition. This composition delivers a very high Pitting Resistance Equivalent Number (PREN typically > 40–42), providing outstanding resistance to pitting, crevice corrosion and stress corrosion cracking in chloride environments, particularly seawater, brackish water and aggressive chemical process streams.
The grade is non-magnetic in the annealed condition and is widely used in offshore, desalination, chemical processing, pulp and paper, and flue gas cleaning systems where conventional 316L, 317L or even 904L is insufficient.
SHH STEEL supplies 254 SMO as true China steel mill-Direct Supply, sourcing directly from major Chinese stainless steel mills. This model delivers competitive mill pricing, consistent quality, complete heat traceability and reliable delivery. SHH STEEL offers 254 SMO in plate and sheet form across a practical range of thicknesses and surface finishes.
254 SMO is frequently compared with a240 316l, a240 317l, a240 904l, a240 2205 and a240 2507 when selecting materials for highly corrosive chloride service. SHH STEEL provides technical support to help customers choose the most appropriate grade.
Material Specification
| Specification Element | Requirement | SHH STEEL Compliance |
|---|---|---|
| Grade | 254 SMO / UNS S31254 / 1.4547 | Confirmed |
| Related Standards | ASTM A240, ASME SA240, EN 10088, related | Available |
| Product Form | Plate, Sheet | Available |
| Delivery Condition | Solution Annealed | Standard |
| Thickness Range | 0.5 mm – 50 mm (thicker available on request) | Custom sizes supported |
| Width | Up to 1500–2000 mm | Available |
| Length | Up to 6000–12000 mm or cut-to-length | Available |
| Surface Finish | 2B, No.1, and others on request | Available |
| Certification | EN 10204 3.1 / Mill Test Certificate | Available |
SHH STEEL can supply 254 SMO dual-certified to ASTM A240 / ASME SA240 when required by the project.
Chemical Composition
Typical Chemical Composition of 254 SMO (UNS S31254):
| Element | Content (%) |
|---|---|
| Carbon (C) | ≤ 0.020 |
| Silicon (Si) | ≤ 0.80 |
| Manganese (Mn) | ≤ 1.00 |
| Phosphorus (P) | ≤ 0.030 |
| Sulfur (S) | ≤ 0.010 |
| Chromium (Cr) | 19.50 – 20.50 |
| Nickel (Ni) | 17.50 – 18.50 |
| Molybdenum (Mo) | 6.00 – 6.50 |
| Nitrogen (N) | 0.18 – 0.22 |
| Copper (Cu) | 0.50 – 1.00 |
| Iron (Fe) | Balance |
The high molybdenum (6%) and nitrogen contents are the key features that give 254 SMO its outstanding pitting and crevice corrosion resistance (high PREN). The extra-low carbon content ensures excellent weldability and resistance to intergranular corrosion. SHH STEEL carefully controls composition to ensure consistent high-performance results.
Mechanical Properties
Annealed Condition (typical values)
| Property | Value |
|---|---|
| Tensile Strength | ≥ 650 MPa |
| Yield Strength (0.2%) | ≥ 300 MPa |
| Elongation (in 50 mm) | ≥ 35% |
| Hardness | ≤ 250 HB |
254 SMO offers higher strength than conventional austenitic grades such as 316L or 904L while retaining good ductility and toughness. SHH STEEL supplies material with consistent mechanical properties suitable for fabrication and welding in highly corrosive chloride service.
Physical Properties Density is approximately 8.00 g/cm³. The grade is non-magnetic in the annealed condition. Melting range is approximately 1325–1400°C.
Material Comparison
Material Comparison
| Grade | Mo (%) | N (%) | PREN (approx.) | Pitting/Crevice Resistance | Strength Level | Typical Preference |
|---|---|---|---|---|---|---|
| AISI 316L | 2.0–3.0 | Low | ~24–28 | Better | Standard | Standard welded chloride service |
| AISI 317L | 3.0–4.0 | Low | ~30–34 | Superior | Standard | Aggressive chloride service |
| AISI 904L | 4.0–5.0 | Low | ~35–38 | Excellent | Standard | Aggressive chloride & acid |
| 254 SMO | 6.0–6.5 | 0.18–0.22 | >40–42 | Outstanding | Higher | Seawater & severe chloride service |
| AISI 2205 | 3.0–3.5 | 0.14–0.20 | ~35–38 | Excellent | High | High strength + chloride resistance |
| AISI 2507 | 3.0–5.0 | 0.24–0.32 | >40 | Outstanding | Very High | Super duplex severe service |
254 SMO (also known as UNS S31254, 1.4547, Alloy 254 and 6Mo stainless steel) provides a significant upgrade in pitting and crevice corrosion resistance over a240 316l, a240 317l and a240 904l. When both very high strength and high corrosion resistance are required, SHH STEEL also recommends evaluating super duplex grades such as a240 2507.
Corrosion Resistance
254 SMO offers outstanding resistance to pitting and crevice corrosion in chloride environments, including seawater, brackish water and high-chloride process streams. Its high PREN makes it one of the best austenitic choices for severe chloride service. It also provides good resistance to stress corrosion cracking and many chemical media.
It is widely used where 316L, 317L and even 904L suffer from localized corrosion. In the most extreme conditions involving very high temperatures and chlorides, super duplex or nickel alloys may still be required. SHH STEEL can assist in material selection based on the specific service environment.
Weldability
254 SMO has good weldability. Matching or higher-alloy filler metals (such as 254 SMO or nickel-based fillers) are recommended. The extra-low carbon and balanced composition provide good resistance to intergranular corrosion in the as-welded condition. Post-weld annealing is generally not required for most applications.
SHH STEEL recommends controlled heat input and proper post-weld cleaning to achieve optimum corrosion performance in severe chloride service.
Heat Treatment
254 SMO is normally supplied in the solution-annealed condition by SHH STEEL.
Recommended solution annealing temperature range is 1150–1200°C, followed by rapid cooling. Proper annealing optimizes corrosion resistance and mechanical properties. SHH STEEL controls heat treatment to ensure consistent high-performance results.
Surface Finishes
| Finish | Description | Typical Use / Keywords |
|---|---|---|
| 2B | Cold-rolled, annealed, pickled, skin-passed | 254 SMO 2B – most common for general fabrication |
| No.1 | Hot-rolled, annealed and pickled | 254 SMO No.1 – industrial plate |
| Special | Ground or custom finishes | 254 SMO Special – on request |
SHH STEEL regularly supplies 254 SMO in 2B and No.1 finishes, and can provide other finishes according to project requirements.
Tolerances
Dimensional tolerances for 254 SMO Stainless Steel Plate supplied by SHH STEEL generally conform to ASTM A480 practices.
Typical available size range is thickness 0.5 mm – 50 mm, width up to 1500–2000 mm, and length up to 6000–12000 mm or cut-to-length. SHH STEEL provides precise dimensional control and can support tighter tolerances when required.
Equivalent Material Grades
| Grade / Designation | Standard / Region | Notes |
|---|---|---|
| 254 SMO / 254SMO | — | — |
| UNS S31254 | Unified Numbering System | Most common UNS designation |
| 1.4547 / X1CrNiMoCuN20-18-7 | EN (Europe) | European equivalent |
| Alloy 254 / SMO 254 | Commercial | Common trade names |
| 6Mo stainless steel | Commercial | Descriptive name |
| Related high-Mo grades | JIS / GB | Approximate national equivalents |
Related grades for comparison include a240 316l, a240 317l, a240 904l, a240 2205 and a240 2507.
Applications
254 SMO (also searched as UNS S31254, 1.4547, Alloy 254, SMO 254 and 6Mo stainless steel) is selected for severe chloride environments where conventional austenitic grades are insufficient. Typical applications of 254 SMO include:
| Industry / Sector | Typical Components / Equipment (with keywords) |
|---|---|
| Offshore & Marine | 254 SMO seawater systems, piping, heat exchangers and components |
| Desalination | 254 SMO desalination plant equipment and piping |
| Chemical & Process Industry | 254 SMO tanks, vessels, reactors and process equipment |
| Pulp & Paper | 254 SMO process equipment in aggressive chloride environments |
| Flue Gas Cleaning / FGD | 254 SMO scrubbers, ducts and components |
| Oil & Gas | 254 SMO equipment in chloride-containing process streams |
| General Severe Chloride Service | 254 SMO heat exchangers, pumps and welded structures |
SHH STEEL supplies 254 SMO for these highly demanding corrosive applications with consistent quality. For related industry solutions, see our marine industry, petrochemical industry and equipment manufacturing pages. Supporting services include steel cutting services and steel welding services.
Why Choose SHH STEEL
SHH STEEL is a China steel mill-Direct Supply specializing in stainless steel plate and sheet. By working directly with major Chinese stainless steel mills, SHH STEEL supplies 254 SMO with the following advantages:
- Genuine China steel mill-Direct Supply pricing
- Consistent quality and complete heat traceability
- Full Mill Test Certificates (EN 10204 3.1)
- High-molybdenum super austenitic material optimized for seawater and severe chloride service
- Flexible dimensions and surface finishes (including 254 SMO 2B and 254 SMO No.1)
- Technical support for selection among 316L, 317L, 904L, 254 SMO, 2205 and 2507
- Value-added services including steel cutting services, steel welding services and worldwide shipping service
For more information about our company and full product range, please visit China steel Mill Agent-SHH STEEL.
FAQ
- What are the other common names for 254 SMO?254 SMO is also widely known as 254SMO, UNS S31254, 1.4547, X1CrNiMoCuN20-18-7, Alloy 254, SMO 254 and 6Mo stainless steel. SHH STEEL can supply material certified to the required designation.
- What is the main advantage of 254 SMO over 316L, 317L or 904L?254 SMO has much higher molybdenum (6%) and nitrogen, giving it a significantly higher PREN and outstanding resistance to pitting and crevice corrosion in seawater and aggressive chlorides. SHH STEEL recommends 254 SMO when conventional austenitic grades are insufficient.
- Is 254 SMO better than duplex stainless steels?254 SMO offers excellent corrosion resistance in many chloride environments with good fabricability. Duplex and super duplex grades (2205, 2507) provide higher strength. SHH STEEL can help evaluate the best balance of corrosion resistance, strength and cost for your project.
- Is 254 SMO magnetic?Non-magnetic in the annealed condition. SHH STEEL supplies fully annealed material as standard.
- What is the density of 254 SMO?Approximately 8.00 g/cm³. SHH STEEL provides material certificates confirming physical and mechanical properties.
- Can 254 SMO be welded easily?Yes. It has good weldability. Matching or appropriate high-alloy filler metals are recommended. SHH STEEL advises proper procedures for critical chloride service.
- Does SHH STEEL supply dual-certified ASTM A240 / 254 SMO material?Yes, SHH STEEL commonly supplies dual-certified material upon request.
Conclusion
254 SMO Stainless Steel Plate (also known as UNS S31254, 1.4547, Alloy 254, SMO 254 and 6Mo stainless steel) is a high-molybdenum super austenitic grade that offers outstanding resistance to pitting, crevice corrosion and stress corrosion cracking in chloride environments. It is the preferred material for offshore, desalination, chemical processing, pulp and paper and flue gas cleaning applications where conventional austenitic stainless steels are insufficient.
As a professional China steel mill-Direct Supply, SHH STEEL provides high-quality 254 SMO Stainless Steel Plate with competitive pricing, full certification and complete technical support.
Contact SHH STEEL today for stock availability, surface finish options (including 254 SMO 2B and 254 SMO No.1), or a competitive quotation.
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