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Super Duplex Stainless Steel S32750 is a duplex alloy composed of approximately equal proportions of austenite and ferrite phases. This balanced microstructure provides a combination of high mechanical strength and exceptional corrosion resistance.
Because of its high chromium, molybdenum, and nitrogen content, S32750 forms a stable passive oxide layer, which significantly improves resistance to chloride-rich environments.
Therefore, it is widely used in marine, offshore, and chemical processing industries where both strength and corrosion resistance are critical.
The equivalents of S32750 is as follows:
Standard | UNS S32750 | DIN/EN 1.4410 | ASTM A240/SA240M |
Super Duplex Stainless Steel S32750 is a high-performance duplex alloy designed for extreme corrosion and high-strength applications.
UNS Number: S32750.
PREN Value: ≥ 40.
Yield Strength: ≥ 550 MPa.
Tensile Strength: 800–1000 MPa.
Main Advantage: Excellent resistance to chloride stress corrosion cracking (SCC), pitting, and crevice corrosion.
Typical Service Environments: Offshore, seawater, chemical processing, desalination systems.
Grade | C≤ | Mn≤ | P≤ | S≤ | Si≤ | Ni | Cr | Mo | N | Cu≤ |
S32750 | 0.03 | 1.20 | 0.035 | 0.02 | 0.80 | 6.0-8.0 | 24.0-26.0 | 3.0-5.0 | 0.24-0.32 | 0.5 |
S32750 provides significantly higher strength compared to standard austenitic stainless steels.
High yield strength enables thinner and lighter structural designs
Excellent fatigue resistance under cyclic loading
Stable performance in both low and high-temperature environments
Because of its duplex microstructure, it maintains strength without sacrificing corrosion resistance.
Grade | Tensile, min, ksi[MPa] | Yield, min, ksi[MPa] | Elongation, %(min) | Hardness, HB（max） |
S32750 | 116 [795] | 80 [550] | 15 | 310 |
Corrosion resistance: The high chromium and molybdenum content in S32750 makes it have strong overall corrosion resistance to organic acids such as formic acid and acetic acid. Compared with 904L, SAF2507 has stronger corrosion resistance.
Heat treatment ability: S32750 should be solution annealed and quenched after hot or cold forming. The temperature of solution annealing should not be lower than 1052°C, and air or water cooling quenching should be performed immediately afterwards.
Welding performance: S32750 has good weldability and can be welded by the following methods: SMAW, GTAW, PAW, FCW, SAW.
Density (Kg/m3) | 7810 |
Magnetic Permeability (20°C) | 33 |
Young’s Modulus (kN/mm2) | 199 |
Specific Electrical Resistance, 20°C (µΩ.m) | 0.8 |
Mean coefficient of thermal expansion, 20-300°C (m/m/oC) | 11.1 x 10-6 |
Specific Heat, 20°C (J/kg.K) | 475 |
Thermal conductivity, 20°C (W/m.K) | 14.2 |
STANDARD | WERKSTOFF NR. | UNS | EN |
Super Duplex S32750 | 1.4410 | S32750 | X2CrNiMoN25-7-4 |
Product | Standard | Show |
Pipe SMLS & Welded | ASTM A790/A928 |  |
Tube SMLS & Welded | ASTM A789 |  |
Sheet / Plate | ASTM A240 |  |
Bar / Rod | ASTM A276/A479 |  |
Forging / Flange | ASTM A182 |  |
BW Fittings | ASTM A815 |  |
Oil and Gas Industry Equipment
Super Duplex S32750 is widely used in oil and gas equipment because it provides excellent resistance to chloride stress corrosion cracking (SCC), high mechanical strength, and strong resistance to pitting and crevice corrosion. These properties make it suitable for harsh offshore and sour service environments where high pressure, seawater exposure, and corrosive gases are present.
Offshore Platforms, Heat Exchangers, Underwater Equipment, Fire-Fighting Systems
S32750 is ideal for offshore and marine applications because it maintains structural integrity in high-chloride seawater conditions and resists localized corrosion such as pitting and crevice corrosion. Its high strength also allows for weight reduction in offshore structures, while its excellent fatigue resistance ensures long-term performance under dynamic wave and pressure loading.
Chemical Processing Industry and Pipelines
In chemical processing environments, S32750 is used due to its outstanding resistance to a wide range of corrosive media, including acids, chlorides, and oxidizing agents. Its duplex microstructure provides a strong balance of mechanical strength and corrosion resistance, making it suitable for high-pressure chemical pipelines and aggressive processing systems.
Desalination Plants, High-Pressure Reverse Osmosis Systems, and Subsea Pipelines
S32750 is widely applied in desalination and reverse osmosis systems because it exhibits exceptional resistance to seawater corrosion and chloride-induced pitting. Its high PREN value (>40) ensures long service life in high-salinity environments, while its strength allows it to withstand high-pressure operation in RO membranes and subsea pipeline systems.
Mechanical Parts (High-Strength, Corrosion-Resistant Components)
Super Duplex S32750 is used for mechanical components because it offers a combination of very high yield strength and excellent corrosion resistance. This allows engineers to design lighter yet stronger parts that can operate reliably in aggressive environments without deformation or premature failure.
Energy Industry: FGD Systems, Industrial Washing Systems, and Absorption Towers
In power generation and energy processing systems, S32750 is selected due to its superior resistance to sulfur-containing gases, acidic condensates, and chloride-rich wash solutions. In flue gas desulfurization (FGD) and absorption towers, it prevents corrosion damage while maintaining long-term mechanical stability under continuous wet and acidic operating conditions.
Super Duplex S32750 is selected when standard stainless steels such as 316L or duplex 2205 are no longer sufficient.
Compared with 316L, it offers significantly higher resistance to chloride corrosion
Compared with 2205, it provides improved strength and higher PREN value
Compared with nickel alloys, it offers a more cost-effective solution while maintaining high performance
Therefore, it is widely used in critical engineering systems where failure is not acceptable.
