UNS S32750 and UNS S32760 are both super duplex stainless steels, known for their high strength and excellent corrosion resistance, particularly in harsh environments such as offshore oil and gas operations. They’re very similar, but there are some nuanced differences worth knowing.
Chemical Composition (Main Elements)
Element |
S32750 (%) |
S32760 (%) |
| Chromium | 24.0 – 26.0 | 24.0 – 26.0 |
| Nickel | 6.0 – 8.0 | 6.0 – 8.0 |
| Molybdenum | 3.0 – 5.0 | 3.0 – 4.0 |
| Nitrogen | 0.24 – 0.32 | 0.2 – 0.3 |
| Copper | ≤ 0.5 | 0.5 – 1.0 |
Key Difference: S32760 includes copper (0.5–1.0%), which improves its resistance to certain acids (especially sulfuric) and helps prevent localised corrosion.
Mechanical Properties
Property |
S32750 |
S32760 |
| Tensile Strength (min) | 800 MPa | 750 MPa |
| Yield Strength (0.2% offset) | 550 MPa | 550 MPa |
| Elongation | ≥15% | ≥25% |
| Hardness (max) | 32 HRC | 28 HRC |
S32750 is generally a bit stronger in terms of tensile strength.
S32760 tends to be more ductile (higher elongation), which can be advantageous in certain forming or fatigue-prone applications.
Corrosion Resistance
Both grades offer excellent resistance to:
Chloride stress corrosion cracking
Pitting and crevice corrosion
General corrosion in aggressive environments
However:
S32760’s copper content gives it a slight edge in resistance to sulfuric acid and other reducing agents.
S32750 is more commonly used in general-purpose offshore and chemical plant environments.
Applications
UNS S32750 – Oil & gas platforms, pressure vessels, chemical processing, desalination
UNS S32760 – Subsea equipment, pumps, valves, heat exchangers, flue gas scrubbers (esp. where acidic environments exist)
Summary
Feature |
S32750 |
S32760 |
| Strength | Higher tensile | Slightly lower |
| Ductility | Lower | Higher |
| Acid Resistance | Good | Better (Cu helps) |
| Common Use | Offshore, desalination | Acids, pumps, mining |
| Cost & Availability | Slightly cheaper | Slightly more expensive |
If you’re picking between the two, the choice often comes down to specific environmental requirements. If you’re dealing with acidic or reducing environments, S32760 might be worth the extra cost. Otherwise, S32750 is an excellent, slightly stronger alternative.
For more information about UNS S32750 and UNS S32760 – Get in touch today!
Alternatively, more information about Super Duplex steels can be found here – What is Super Duplex?