Super Duplex Stainless Steel UNS S39274 has become a material of choice across industries requiring exceptional strength, corrosion resistance, and performance under extreme conditions.
Developed to outperform standard duplex grades, UNS S39274 is a high-alloyed super duplex stainless steel combining chromium, molybdenum, and nitrogen in precise ratios.
With enhanced pitting resistance and high mechanical strength, this grade is extensively used in offshore, chemical processing, and desalination applications. If you’re exploring the ideal material for critical environments, understanding the key properties of Super Duplex Stainless Steel UNS S39274 is essential.
What is Super Duplex Stainless Steel?
Super duplex stainless steel is a type of stainless alloy that features a mixed microstructure of austenite and ferrite, typically in a 50:50 ratio. This dual-phase structure offers a unique combination of high tensile strength and superior resistance to stress corrosion cracking, outperforming standard austenitic and duplex stainless steels.
While conventional duplex grades are suitable for many uses, super duplex stainless steel grades like UNS S39274 and UNS S32760 provide even greater corrosion resistance and mechanical performance in aggressive media such as seawater, acidic slurries, and chloride-rich environments.
UNS S39274 Chemical Composition
UNS S39274 contains a high percentage of chromium (25–27%), molybdenum (3.5–4.5%), and nitrogen (0.3%) to improve its corrosion and pitting resistance. Below is the typical composition chart:
| Element | Content (%) |
|---|---|
| Chromium | 25.0 – 27.0 |
| Nickel | 6.0 – 8.0 |
| Molybdenum | 3.5 – 4.5 |
| Nitrogen | 0.3 max |
| Carbon | 0.03 max |
| Manganese | 1.0 max |
| Silicon | 0.8 max |
| Iron | Balance |
This precise blend delivers an excellent pitting resistance equivalent number (PREN) typically >40, which is considered very high for stainless steels.
Mechanical Properties of UNS S39274
| Property | Value |
|---|---|
| Tensile Strength | 750 MPa min |
| Yield Strength (0.2% offset) | 550 MPa min |
| Elongation | 25% min |
| Hardness (Brinell) | ≤ 290 HB |
| Impact Toughness | > 100 J at -50°C |
These mechanical properties ensure structural stability and toughness even in cryogenic and high-pressure applications.
Grades Comparable to UNS S39274
UNS S39274 is often compared with UNS S32760, another widely used super duplex stainless steel grade. While both are designed for high resistance to corrosion, S39274 typically offers slightly better mechanical performance and higher pitting resistance due to its precise alloy composition.
| Grade | PREN Value | Corrosion Resistance | Strength |
|---|---|---|---|
| S39274 | >42 | Very High | Very High |
| S32760 | 41–42 | High | High |
Key Features of Super Duplex UNS S39274
- High resistance to pitting and crevice corrosion in chloride-containing environments
- Excellent stress corrosion cracking resistance
- Outstanding mechanical strength, double that of standard austenitic stainless steels
- High resistance to erosion and fatigue
- Reliable performance in seawater, brine, and acidic conditions
- Long service life with minimal maintenance
Applications of UNS S39274
Because of its corrosion resistance and mechanical properties, super duplex stainless steel UNS S39274 is used in:
- Offshore oil & gas platforms
- Seawater desalination plants
- Heat exchangers and pressure vessels
- Pulp and paper digesters
- Marine and shipbuilding components
- Chemical processing pipelines
- Water injection and riser systems
Trusted Super Duplex Stainless Steel Suppliers
When sourcing super duplex stainless steel, it’s vital to choose suppliers who provide traceable material certification and consistent quality. Look for suppliers who offer:
- Mill test certificates (EN 10204 3.1 or 3.2)
- Stock in various forms – sheets, plates, pipes, bars, and flanges
- Fast delivery for critical projects
- Custom machining and fabrication services