Super Duplex Steel
Super duplex is specified where standard duplex isn't enough - typically in offshore platforms, subsea pipelines, seawater cooling systems, desalination plants, chemical processing and marine structures.
Super duplex stainless steel is the highest-performing grade family in the duplex range: a controlled austenitic–ferritic microstructure with elevated chromium, molybdenum and nitrogen delivering a Pitting Resistance Equivalent Number (PREN) above 40.
Steel Dynamics UK stocks super duplex 1.4501 (UNS S32760) and 1.4410 (UNS S32750, also known as SAF 2507) in plate and sheet from leading European mills - cut to size and supplied with full 3.1 certification under ISO 9001 and ISO 19443.
Super Duplex Steel
Super Duplex Stainless Steel is a type of corrosion-resistant alloy that is highly resistant to chloride-induced stress corrosion cracking and pitting. It is often used as a substitute for 300 series Stainless Steel, high nickel super-austenitic steels and nickel-based alloys.
Its dual-phase austenitic–ferritic microstructure provides a unique combination of properties: very high yield strength, excellent toughness, and superior resistance to pitting, crevice corrosion and stress corrosion cracking, especially in chloride-rich or acidic environments.
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UNS 32750 - 1.4410
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UNS 32760 - 1.4501
Super Duplex Applications
The superior properties of Super Duplex sheet and plate make it highly suitable for critical and aggressive environments across a wide range of industries. Common applications include offshore platforms, subsea pipelines, heat exchangers, pressure vessels, chemical and petrochemical processing equipment, desalination plants, and marine structures.
Due to its exceptional mechanical strength, Super Duplex allows for thinner wall sections and reduced overall weight while maintaining structural integrity and corrosion performance. This not only reduces fabrication and installation costs but also delivers excellent lifecycle value.
Why Super Duplex
While austenitic grades such as 304L or 316L may be suitable for general corrosion resistance, they cannot match the strength or chloride stress corrosion cracking resistance of Super Duplex. The enhanced alloy composition of UNS S32750 / 1.4410 and UNS S32760 / 1.4501 provides the best possible balance of performance, durability and cost for the most demanding applications.
Compared with standard Duplex (1.4462) or Lean Duplex grades, Super Duplex offers superior corrosion resistance, higher mechanical strength, and outstanding resistance to pitting and crevice corrosion in chloride-containing environments such as seawater, brine and chemical process systems.
Frequently Asked Questions
What is super duplex stainless steel?
Super duplex is a family of dual-phase (austenitic-ferritic) stainless steels with a Pitting Resistance Equivalent Number (PREN) above 40. It offers roughly 2.5× the yield strength of 316L austenitic stainless and outstanding resistance to chloride pitting, crevice corrosion and stress corrosion cracking. The most common grades are 1.4501 (UNS S32760, Zeron 100) and 1.4410 (UNS S32750, SAF 2507).
What's the difference between 1.4501 and 1.4410 super duplex?
Both have PREN >40 and similar mechanical properties. 1.4501 (S32760, Zeron 100) has slightly higher tungsten and copper, giving it edge advantages in specific acidic environments. 1.4410 (S32750, SAF 2507) is the more widely stocked grade globally. In most specifications the two are interchangeable.
When should I use super duplex instead of duplex?
When PREN >40 is specified, when chloride content is very high (subsea, seawater), when service temperatures are elevated in chloride environments, or when the design cannot tolerate any pitting or stress corrosion cracking risk over a long service life.
Can super duplex be waterjet cut?
Yes, and it should be. Super duplex depends on a precise phase balance between austenite and ferrite. Thermal cutting processes (laser, plasma) can shift that balance in the heat-affected zone, degrading corrosion resistance. Waterjet cutting is cold, preserving the specification.
Do you stock super duplex in the UK?
Yes. Plate and sheet in 1.4501 and 1.4410, held in our facility in Lancashire, cut to size and shipped nationwide.
Its dual-phase microstructure delivers very high yield strength (roughly 2.5× that of 316L), excellent toughness even at sub-zero service temperatures, and superior resistance to chloride pitting, crevice corrosion and stress corrosion cracking.
Working super duplex demands care. Welding, forming and cutting must preserve the phase balance; introduce too much heat and the material's performance advantage disappears.
