Outokumpu 254 SMO® High Performance Austenitic Stainless Steel Tube,Pipe

Outokumpu 254 SMO® High Performance Austenitic Stainless Steel Tube Product Information -:- For detailed product information, please contact sales. -: Outokumpu 254 SMO® High Performance Austenitic Stainless Steel Tube Synonyms -:- For detailed product information, please contact sales. -:

Outokumpu 254 SMO® High Performance Austenitic Stainless Steel Product Information -:- For detailed product information, please contact sales. -: ### **Product Name:** Outokumpu 254 SMO® (UNS S31254 / 1.4547) High-Performance Austenitic Stainless Steel **Classification:** Super Austenitic Stainless Steel with Extreme Chloride Resistance --- ### **1. Overview** Outokumpu 254 SMO® is a **premium super austenitic stainless steel** specifically engineered to deliver exceptional resistance to pitting, crevice corrosion, and stress corrosion cracking (SCC) in the most aggressive chloride-containing environments. It represents the pinnacle of stainless steel performance, bridging the gap between standard austenitic grades and nickel-based alloys. With an exceptionally high **Pitting Resistance Equivalent Number (PREN >43)**, 254 SMO® is the benchmark material for applications where conventional stainless steels fail, particularly in seawater, chemical processing, and pollution control. The trademark **SMO®** signifies its high Molybdenum content and superior performance. ### **2. Chemical Composition (Weight %, typical)** The composition is meticulously balanced to maximize chloride ion resistance while maintaining structural integrity. | Element | Minimum (%) | Typical (%) | Maximum (%) | Notes | |---------|------------|------------|------------|-------| | **Carbon (C)** | - | 0.010 | 0.020 | Extremely low carbon prevents sensitization, ensuring excellent weldability and intergranular corrosion resistance. | | **Chromium (Cr)** | 19.5 | 20.0 | 20.5 | Provides fundamental passivity and resistance to oxidizing media. | | **Nickel (Ni)** | 17.5 | 18.0 | 18.5 | Stabilizes the austenitic phase and provides essential resistance to stress corrosion cracking (SCC). | | **Molybdenum (Mo)** | 6.0 | 6.1 | 6.5 | **The defining element.** This very high molybdenum content is the primary contributor to its unparalleled resistance to localized corrosion in chlorides. | | **Copper (Cu)** | 0.50 | 0.70 | 1.00 | Enhances resistance to reducing acids, particularly sulfuric acid. | | **Nitrogen (N)** | 0.18 | 0.20 | 0.22 | **Critical additive.** Significantly increases pitting resistance and provides solid solution strengthening, elevating yield strength. | | **Manganese (Mn)** | - | 0.5 | 1.00 | Austenite stabilizer. | | **Silicon (Si)** | - | 0.30 | 0.40 | - | | **Phosphorus (P)** | - | 0.020 | 0.030 | - | | **Sulfur (S)** | - | 0.005 | 0.010 | Kept very low for optimal corrosion resistance. | | **Iron (Fe)** | Balance | Balance | Balance | - | **Key Metric:** **PREN (Cr + 3.3Mo + 16N) ≥ 43**, placing it among the highest of all stainless steels. ### **3. Physical & Mechanical Properties** *Properties are typical for solution annealed material (min 1150°C water quench).* **Mechanical Properties:** * **Tensile Strength (Rm):** 650 - 850 MPa (94 - 123 ksi) * **Yield Strength (Rp0.2):** 300 MPa min (44 ksi min) *[Note: Significantly higher than 316L or 904L due to N strengthening]* * **Elongation (A):** 35% min * **Hardness (typical):** 95 - 115 HRB (200 - 240 HV) * **Modulus of Elasticity:** 200 GPa (29 x 10⁶ psi) * **Charpy V-Notch Impact:** Excellent, typically >100 J at -196°C. **Physical Properties:** * **Density:** 8.0 g/cm³ (0.289 lb/in³) * **Melting Range:** 1320 - 1390 °C (2410 - 2535 °F) * **Thermal Conductivity:** 13.5 W/m·K (at 20°C) * **Coefficient of Thermal Expansion:** 16.0 x 10⁻⁶ /K (20-100°C) *[Higher than carbon steel]* * **Magnetic Permeability:** < 1.05 (fully austenitic and non-magnetic when annealed) **Corrosion Resistance Key Metrics:** * **Critical Pitting Temperature (CPT):** Typically > 75°C in ASTM G48 Method A (6% FeCl₃). * **Critical Crevice Temperature (CCT):** Typically > 50°C, far exceeding conventional grades. * **Stress Corrosion Cracking (SCC):** Exceptional resistance in hot chloride solutions. ### **4. Key Characteristics** * **Unrivaled Chloride Resistance:** The benchmark for resisting pitting and crevice corrosion in seawater, brackish water, and chloride-rich process streams, even under stagnant or low-flow conditions. * **High Strength:** The high nitrogen content provides significant solid solution strengthening, resulting in a yield strength approximately 50% higher than 316L, allowing for thinner, lighter sections. * **Excellent SCC Resistance:** The combined high levels of nickel, chromium, molybdenum, and nitrogen impart superb resistance to chloride-induced stress corrosion cracking. * **Good Weldability:** Can be welded using all standard methods, but requires care to preserve corrosion resistance. Must use over-alloyed filler metals (e.g., AWS A5.14 ERNiCrMo-3/4) and avoid excessive heat input to prevent secondary phase precipitation. * **Good Fabricability:** Can be cold formed and machined, but its high strength and work hardening rate require more power and specialized techniques compared to standard austenitics. ### **5. Product Applications** Outokumpu 254 SMO® is specified for the world's most demanding applications where chloride corrosion is the primary threat: * **Seawater & Offshore:** Seawater cooling piping, heat exchanger tubes, pump casings, shafts, ballast systems, and offshore platform components. * **Desalination Plants:** High-pressure RO membranes housings, heat exchanger tubes in multi-stage flash (MSF) and multi-effect distillation (MED) units, and brine heaters. * **Chemical & Petrochemical:** Process equipment handling wet chlorine gas, hypochlorite, chloride-contaminated organic acids, and severe oxidizing acids. * **Pollution Control (FGD):** Absorber towers, mist eliminators, ducting, and dampers in flue gas desulfurization systems. * **Pulp & Paper:** Equipment in bleaching plants (ClO₂ stages) and chemical recovery lines. * **Marine & Shipbuilding:** Propeller shafts, rudders, seawater valves, and exhaust scrubber systems. ### **6. International Standards & Specifications** 254 SMO® is covered by major international material standards. | Region/System | Standard & Designation | Form/Product Standard | |---------------|----------------------|----------------------| | **UNS / ASTM** | **UNS S31254** | Unified Numbering System | | **ASTM / ASME** | **ASTM A240 / ASME SA-240** | Plate, Sheet, and Strip | | **ASTM / ASME** | **ASTM A312 / ASME SA-312** | Seamless and Welded Pipe | | **ASTM / ASME** | **ASTM B688 / ASME SB-688** | Welded Pipe (Chromium-Nickel-Molybdenum-Iron) | | **European (EN)** | **1.4547** (X1CrNiMoCuN20-18-7) | EN 10088-2 (Sheet/Plate), EN 10216-5 (Seamless Pipe) | | **Germany (DIN)** | **DIN 1.4547** | - | | **Japan (JIS)** | **SUS 312L** | - | | **ISO** | **ISO 15510: X1CrNiMoCuN20-18-7** | - | ### **7. Available Forms & Processing** * **Standard Forms:** Sheet, plate, strip, bar, wire, seamless and welded pipe & tube, fittings, and forgings. * **Condition:** Supplied in the **solution annealed and quenched** condition to ensure all carbides and intermetallic phases are dissolved, guaranteeing optimal corrosion resistance. * **Fabrication:** * **Welding:** **Critical Procedure.** Use TIG/GTAW with matching or over-alloyed filler (ERNiCrMo-3/4, e.g., Outokumpu P12). Keep heat input low, use stringer beads, and ensure rapid cooling. Post-weld pickling is highly recommended. * **Machining:** Requires rigid tooling, positive rake angles, sharp tools, and adequate cooling/lubrication. Power requirements are higher than for 316. * **Forming:** Cold forming is possible but requires greater force. Intermediate annealing may be necessary for severe deformations. ### **8. Why Choose Outokumpu 254 SMO®?** Outokumpu is the original developer of this grade and offers unparalleled expertise: * **Original Developer & Quality Leader:** Guarantees the original, optimized composition and metallurgy. * **Superior Product Consistency:** Advanced melting and refining processes (AOD, VOD, ESR) ensure ultra-low impurity levels and homogeneity. * **Comprehensive Technical Support:** Provides extensive data and application engineering for the most challenging environments. * **Proven Long-Term Performance:** Decades of documented success in critical applications worldwide, offering a cost-effective alternative to nickel alloys. --- **Disclaimer:** This datasheet provides general information. For applications in aggressive environments, especially under tensile stress, specific corrosion testing is advised. The high thermal expansion coefficient must be considered in system design. Always consult Outokumpu's latest technical manuals and engage with their application specialists for design, fabrication, and qualification of welding procedures. 254 SMO® is a registered trademark of Outokumpu Oyj. -:- For detailed product information, please contact sales. -: Outokumpu 254 SMO® High Performance Austenitic Stainless Steel Specification Dimensions Size： Diameter 20-1000 mm Length <7400 mm Size:We can customized as required Standard： Per your request or drawing We can customized as required Properties（Theoretical） Chemical Composition -:- For detailed product information, please contact sales. -: Outokumpu 254 SMO® High Performance Austenitic Stainless Steel Properties -:- For detailed product information, please contact sales. -:

Applications of Outokumpu 254 SMO® High Performance Austenitic Stainless Steel Tube -:- For detailed product information, please contact sales. -: Chemical Identifiers Outokumpu 254 SMO® High Performance Austenitic Stainless Steel Tube -:- For detailed product information, please contact sales. -:

Packing of Outokumpu 254 SMO® High Performance Austenitic Stainless Steel Tube -:- For detailed product information, please contact sales. -: Standard Packing: -:- For detailed product information, please contact sales. -: Typical bulk packaging includes palletized plastic 5 gallon/25 kg. pails, fiber and Steel Tube drums to 1 ton super sacks in full container (FCL) or truck load (T/L) quantities. Research and sample quantities and hygroscopic, oxidizing or other air sensitive materials may be packaged under argon or vacuum. Solutions are packaged in polypropylene, plastic or glass jars up to palletized 3871 gallon liquid totes Special package is available on request. E FORUs’ is carefully handled to minimize damage during storage and transportation and to preserve the quality of our products in their original condition