Understanding Duplex Stainless Steel

To the executive or business owner who just needs something made of stainless steel, the choices can be confusing. One of the first choices one often needs to make on a project is to choose between austenitic, ferritic and duplex stainless steel, which is half austenitic and half ferritic. Here is an explanation of what goes into duplex stainless steel and some of its preferred applications.

Duplex Stainless Steel - Storage Tank

Why Duplex?

Duplex stainless steel is designed to provide the benefits of austenitic and ferritic steels but without their drawbacks. Austenitic stainless steel is classified as a low-strength stainless steel. In addition, it is not resistant enough to stress corrosion cracking in many applications. Austenitic steel also has a high nickel content, making it more volatile in pricing. Ferritic stainless steel is also low strength and has weldability issues, especially in thick sheets. Ferritic steel also doesn’t resist low temperatures very well.

Duplex stainless steel, by virtue of its “50-50” composition, seems to retain the benefits of both steels while avoiding the pitfalls. It is twice as strong as either of its components, thus allowing a much wider range of applications. In situations where austenitic or ferritic steel is strong enough, duplex can be used in thinner sheets and provide the same performance with reduced weight. This makes it great for storage tanks, pressure vessels and structural applications, including bridges.

Duplex stainless has high weldability, even in thick sections. This is ironic, because those thick sections aren’t as necessary with duplex stainless as they are with austenitic or ferritic. Duplex is also tougher and can be used for applications with temperatures as low as -80 degrees C. Duplex stainless is highly resistant to corrosion cracking, which makes it great for swimming pools, brewing tanks, hot water tanks and processing plants.

Contraindications for Duplex Stainless

The main reason to not use duplex stainless is that its strength makes it less formable and less machineable than ferritic or austenitic steel. This makes it inappropriate for uses such as sinks, where a high degree of formability is needed. While it is highly resistant to cold, it can decompose in heat. Consequently, it is not recommended for use in temperatures higher than 300 degrees C.

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About Paul

Paul Bartlett is the owner and director of Western Stainless Solutions. He has a passionate commitment to personally seeing each project through from conception to completion. Mr Bartlett has owned Western Stainless Solutions since 2005. He had prior experience as a foreman for Caterlink, where he learned to fit out numerous restaurants with stainless steel equipment.

With Western Stainless Solutions, Mr Bartlett has overseen numerous large projects, always getting them finished on time and on budget. His favourite projects include:

  • Fiona Stanley Hospital
  • Joondalup Health Campus
  • Coles Inglewood
  • Woolworths Yanchep
  • Mt Barker Chicken
  • The Merrywell Bar
  • Perth Children's Hospital
  • St John of God Subiaco refurb and development

Mr Bartlett has extensive experience in completing large projects, but is always around to add a personal touch to projects such as restaurants and pubs.

Mr Bartlett also has experience in the sports world. He currently serves as a volunteer coach for School Sports WA and spent two years as the General Manager of the Stirling Senators in the State Basketball League.

The bottom line: Mr Bartlett specialises in getting things done. He has a “hands-on” approach that is rare for owners of businesses the size of Western Stainless Solutions.