An austenitic-ferritic stainless variant with a higher stress corrosion cracking resistance in comparison to regular austenitic 304 and 316 stainless, but with a lower toughness and impact strength. This category of material includes grades 2205, F51, F53, and F60. Duplex stainless has increased in popularity over the years due to its excellent chemical and mechanical properties versus their basic stainless counterparts, given especially that the cost differences are minimal now as the availability has increased.

Custom outlet flange in duplex 2205
Custom outlet flange in duplex 2205

The granular structure of duplex is a ferrite-austenite hybrid with a superior strength to weight ratio in comparison to 304 or 316. It balances the weldability of an austenitic with a pure ferritic and retains decent mechanical toughness in applications with exposure to colder ambient temperatures. Offshore/seawater applications are a common use for this type of steel due to its excellent stress corrosion cracking properties. Therefore, duplex is often found in desalination and pressure vessel equipment located in port cities.

Duplex’s premium mechanical and chemical properties are slightly offset by its difficulty in formability. These grades are excellent for fixed service simple flange connections, but slightly less so when forming a complex metallic shape. Fortunately, the workability of duplex into complex and rounded structures is less of an issue in structural steel given the wide preference for simple mild steel in non corrosive applications.

Texas Flange can provide you with an excellent cost and lead time option for duplex steels as we offer them in forged and plate variants. Duplex plate is becoming a very popular option for longer service fluid works applications, and rightfully so. Feel free to get in touch with us for a quote.


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