Austenitic-ferritic stainless steels, usually referred to as duplex
steels, combine many of the good properties of ferritic and
austenitic stainless steels.
The high chromium content in combination with
nitrogen, and often also molybdenum, gives duplex
steels their superior resistance to both pitting and crevice
corrosion. The duplex structure gives very good
strength and, allied with the high corrosion resistance,
very good resistance to stress corrosion.

Austenitic-ferritic stainless steels, usually referred to as duplex
steels, combine many of the good properties of ferritic and
austenitic stainless steels.
The high chromium content in combination with
nitrogen, and often also molybdenum, gives duplex
steels their superior resistance to both pitting and crevice
corrosion. The duplex structure gives very good
strength and, allied with the high corrosion resistance,
very good resistance to stress corrosion.
Thanks to this exceptional combination of strength
and corrosion resistance, duplex steels are widely
used in everything from tanks for corrosive media to
structural components, chemical tankers and offshore
applications.
Duplex steels are primarily intended for applications
where the working temperature is from –40 to +250°C.
The weldability of duplex steels is good and all common
welding methods can be used.