1.4547 / UNS S31254 / F44 / 254 SMO: Product Introduction
1.4547, also known as UNS S31254, F44, or commonly referred to as 254 SMO, is a high-alloy austenitic stainless steel with excellent corrosion resistance. This article provides a detailed introduction to 1.4547/UNS S31254/F44/254 SMO, covering its chemical composition, mechanical properties, performance at different temperatures, industry applications, shapes and sizes, production standards, welding and processing capabilities, advantages and disadvantages, and a comparison with similar alloys.
Chemical Composition
1.4547/UNS S31254/F44/254 SMO has a specific chemical composition that contributes to its corrosion resistance and mechanical properties:
| Element | Composition (%) |
|---|---|
| Chromium (Cr) | 19.5 – 20.5 |
| Nickel (Ni) | 17.5 – 18.5 |
| Molybdenum (Mo) | 6.0 – 6.5 |
| Copper (Cu) | 0.5 – 1.0 |
| Nitrogen (N) | 0.18 – 0.22 |
| Carbon (C) | 0.020 max |
| Silicon (Si) | 0.80 max |
| Manganese (Mn) | 1.00 max |
| Phosphorus (P) | 0.030 max |
| Sulfur (S) | 0.010 max |
Mechanical Properties
1.4547/UNS S31254/F44/254 SMO exhibits excellent mechanical properties suitable for various applications:
| Property | Value |
|---|---|
| Tensile Strength, ksi (MPa) | 100 (690) min |
| Yield Strength (0.2% offset), ksi (MPa) | 50 (345) min |
| Elongation (% in 2 inches) | 35 min |
| Hardness, Rockwell B (HRB) | 55 max |
Performance Characteristics
1.4547/UNS S31254/F44/254 SMO offers outstanding performance across diverse conditions:
- Corrosion Resistance: Excellent resistance to both uniform corrosion and localized corrosion, including pitting and crevice corrosion, in chloride-containing environments.
- High Temperature Strength: Maintains strength and toughness at elevated temperatures, suitable for applications in marine and chemical processing industries.
- Weldability: Good weldability with conventional methods, such as TIG and MIG welding, ensuring ease of fabrication.
Industry Applications
1.4547/UNS S31254/F44/254 SMO is utilized in industries requiring robust corrosion resistance and high strength:
| Industry Sector | Applications |
|---|---|
| Chemical Processing | Heat exchangers, evaporators, and reactor tanks. |
| Oil and Gas | Offshore platforms, pipelines, and valves in harsh environments. |
| Marine | Seawater desalination, marine exhaust systems, and shipbuilding. |
Shapes and Sizes
1.4547/UNS S31254/F44/254 SMO is available in various forms and sizes to meet specific application needs:
- Forms: Sheets, plates, bars, tubes, pipes, fittings, and welding consumables.
- Sizes: Thickness ranging from 0.1 mm to 50 mm for plates, and diameter ranging from 6 mm to 300 mm for round bars.
Production Standards
1.4547/UNS S31254/F44/254 SMO adheres to international production standards ensuring quality and performance:
| Product Form | Shapes Available | Sizes Available | Production Standards |
|---|---|---|---|
| Plates/Sheets | Sheets, Plates | Thickness: 0.1 mm – 50 mm | ASTM A240, EN 10088 |
| Bars/Rods | Round bars, Square bars | Diameter: 6 mm – 300 mm | ASTM A276, EN 10088 |
| Pipes/Tubes | Seamless, Welded | OD: 6 mm – 300 mm | ASTM A312, ASTM A358 |
Welding and Processing
1.4547/UNS S31254/F44/254 SMO offers good weldability and processing characteristics:
- Welding: Can be welded using standard methods like TIG, MIG, and submerged arc welding, with post-weld heat treatment recommended to maintain corrosion resistance.
- Machinability: Machinable with appropriate tooling and cutting speeds due to its high work hardening rate.
Advantages and Disadvantages
| Aspect | Details |
|---|---|
| Advantages | Exceptional corrosion resistance, high strength, excellent weldability, and suitability for critical applications in aggressive environments. |
| Disadvantages | Higher initial cost compared to standard stainless steels, requires expertise in handling and fabrication due to its high alloy content. |
Similar Alloys
| Alloy Name | Comparison |
|---|---|
| 904L (UNS N08904) | Lower alloy content, slightly lower corrosion resistance compared to 1.4547/UNS S31254/F44/254 SMO, but more cost-effective. |
| Duplex Stainless Steels (e.g., UNS S31803) | Offers a balance of strength and corrosion resistance, suitable for similar applications in marine and chemical industries. |
Comparison of Similar Alloys
| Property/Feature | 1.4547/UNS S31254/F44/254 SMO | 904L (UNS N08904) | Duplex Stainless Steel (UNS S31803) |
|---|---|---|---|
| Chromium Content (%) | 19.5 – 20.5 | 20.0 – 25.0 | 21.0 – 23.0 |
| Nickel Content (%) | 17.5 – 18.5 | 23.0 – 28.0 | 4.5 – 6.5 |
| Molybdenum Content (%) | 6.0 – 6.5 | 4.0 – 5.0 | 2.5 – 3.5 |
| Corrosion Resistance | Excellent resistance to chloride-induced corrosion including pitting and crevice corrosion. | Good corrosion resistance, lower than 1.4547/UNS S31254/F44/254 SMO in chloride environments. | Balanced corrosion resistance, lower than 1.4547/UNS S31254/F44/254 SMO in extreme chloride environments. |
| Applications | Chemical processing, oil and gas, marine environments. | Chemical and pharmaceutical industries, paper production. | Oil and gas, chemical processing, marine environments. |
This comprehensive article introduces 1.4547/UNS S31254/F44/254 SMO, highlighting its chemical composition, mechanical properties, performance characteristics, industry applications, available forms and sizes, production standards, welding and processing capabilities, as well as advantages, disadvantages, and comparisons with similar alloys. Engineers and professionals seeking highly corrosion-resistant materials for critical applications will find this information valuable in selecting the appropriate alloy to meet specific operational requirements.