& other
high strength


Freedom of form

A perfect solution for geometrically complex designs. Ideal for your heat exchanger challenges. Forta FDX 27 duplex.

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Fall in love with the world’s most formable duplex

Outokumpu's Forta FDX 27 grade provides a totally new stainless solution for applications where the formability of other duplex grades is not sufficient or limits design capabilities. Heat exchangers are just one example.

Forta FDX 27 exhibits a unique combination of high strength and substantially improved formability utilizing Transformation Induced Plasticity (TRIP).

Ferritic-austenitic stainless steels, also referred to as duplex stainless steels, combine many of the beneficial properties of ferritic and austenitic steels. Due to the relatively high content of chromium and nitrogen, these steels offer good resistance to localized and uniform corrosion.

Why Outokumpu?

Outokumpu is a global leader in stainless steel and has been involved in its continued development and innovation from its earliest history. A strong customer focus, sustainability and technical excellence are at the heart of everything we do. As a customer you benefit from our extensive R&D and technical support.

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Why switch to Forta FDX 27?

Increased formability

Forta FDX 27 has excellent formability in comparison to other duplex stainless steels and close to stainless steel types such as 316L. These remarkable mechanical properties enable components formed by deep drawing Forta FDX 27 to adopt similar designs to those made in standard austenitic stainless steels with good results. Test programs have verified that Forta FDX 27 is suitable for forming demanding components such as heat exchanger plates.

High mechanical strength

Tensile tests show that Forta FDX 27 has high mechanical strength, comparable to corresponding duplex grades. However, its elongation to fracture is much improved, exhibiting a superior combination of strength and formability compared to corresponding austenitic grades.

Resistant to uniform corrosion

Uniform corrosion is characterized by a uniform attack on a steel surface that comes into contact with a corrosive medium. The corrosion resistance is generally considered good if the corrosion rate is less than 0.1 mm/year. Due to its high chromium content, Forta FDX 27 offers excellent corrosion resistance in many environments.

Resistant to pitting and crevice corrosion

A steel’s resistance to pitting and crevice corrosion increases with its content of chromium, molybdenum and nitrogen. The content of these alloying elements determines the pitting resistance equivalent (PRE) for the material. Forta FDX 27 has a PRE value of 27, compared with 24 for type 316L stainless steel. A much more reliable way of ranking steels is according to their critical pitting temperature (CPT) – again Forta FDX 27 demonstrates superior performance.

High resistance to stress corrosion cracking and corrosion fatigue

Stainless steel can be affected by stress corrosion cracking (SCC) in chloride containing environments at elevated temperatures. Standard austenitic stainless steels are particularly vulnerable to SCC while duplex stainless steels, like Forta FDX 27, are less susceptible. The combination of high mechanical strength and very good resistance to corrosion also gives Forta FDX 27 a high resistance to corrosion fatigue that is considerably better than type 316L stainless steel.

Good abrasion and erosion resistance

When subjected to abrasion testing under ASTM G65, procedure B, Forta FDX 27 shows a volume loss that is 42% lower than 316L type stainless steels. Tests to GOST standards show similar results.

Good fatigue resistance

The high yield and tensile strength of Forta FDX 27 also results in high fatigue strength that corresponds approximately to its yield strength.

High energy absorption

When the energy absorption capabilities of Forta FDX 27 are compared with type 316L stainless steel the duplex steel offers an improvement of greater than 21%.

Low thermal expansion

Forta FDX 27 has a coefficient of thermal expansion of just 12.5 (10-6/K) at temperatures between 20 to 100 °C. This compares with 13 (10-6/K) for other duplex steels and 15 (10-6/K) for austenitic stainless steels.

Good weldability

A weldment created using Forta FDX 27 has good formability in line with standard duplex grades. However, the impact of the TRIP-effect can be reduced during welding operations due to the heating and cooling of the weldment and use of filler.

How can Forta FDX 27 boost heat exchanger performance?

Outokumpu’s newly developed Forta FDX 27 duplex concept exhibits a unique combination of high strength and high elongation. It also offers price stability due to the relatively low content of alloying elements such as nickel and molybdenum that can fluctuate considerably in price over time.

With Forta FDX 27 it is possible to manufacture high strength GPHE plates with the same (or close to the same) surface area as traditional austenitic stainless steel and it is often possible to use the existing stamping tools.

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Strength paired with excellent corrosion resistance

Forta FDX 27 has a PRE value of 27, compared with 24 for type 316L stainless steel. A much more reliable way of ranking steels is according to their critical pitting temperature (CPT) – again Forta FDX 27 demonstrates superior performance.

The combination of high mechanical strength and very good resistance to corrosion gives Forta FDX 27 a high corrosion fatigue performance that is considerably better than Supra 316L/4404.

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10 things your purchasing team might ask about switching to Forta FDX 27

You might want to tell your team, that Forta FDX 27 is based on a duplex stainless steel, so it has a relatively low level of the expensive alloying elements of nickel and molybdenum. This means that its cost will be largely unaffected by fluctuations in their price.

Get to know the facts

Outokumpu Forta FDX 27 datasheet

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Forming guidelines for Forta FDX 27

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Order your free samples of Forta FDX 27

To help you evaluate Forta FDX 27 for your own applications we are happy to provide free samples in limited quantities. Just tell us what thickness and sheet size you would like to try. Our samples are supplied with a 2E finish - cold rolled, heat treated and, mechanically descaled.

We have available:

1 mm, 1,5 mm and 2,5 mm samples from stock and 0,4-3,7 mm on request

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How Forta FDX 27 works – the TRIP effect explained

Before the development of Forta FDX 27, the TRIP effect had only been known to work effectively with austenitic steel grades and it had never been successfully realized in duplex grades.

Forta FDX 27 behaves as a duplex in terms of strength. But rather than starting to neck at 0.2% strain, the TRIP effect allows the strain to be increased up to 0.35% while maintaining its high strength.

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Contact our experts or order the product.

If you want to know more about Forta FDX 27 then please contact our engineering team, who will be happy to answer any technical questions such as:

  • What are the properties of duplex stainless steels?
  • How des Forta FDX 27 perform in corrosive environments?
  • What changes to forming processes are required when switching to Forta FDX 27?

If you want to go into even more detail then Outokumpu offers extensive consultancy services to support our customers in making a seamless, cost-effective transition to Forta FDX 27.

You can also contact our sales team here if you would like to request a quote, or find out more about how Forta FDX 27 can deliver tangible technical and economic benefits for your business.

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Thank you for your interest in Outokumpu.

We hope you find this information useful.

Best wishes,
Outokumpu team

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