Austenitic-ferritic stainless steel also referred to as duplex stainless steels, combine many of the beneficial properties of ferritic and austenitic steels. Due to the high content of chromium and nitrogen, and often also molybdenum, these steels offer good resistance to localised and uniform corrosion. The duplex microstructure contributes to the high strength and high resistance to stress corrosion cracking. Duplex steels have good weldability.

Outokumpu produces a whole range of duplex grades from the lean alloyed LDX 2101® up to the super duplex grades 2507 and 4501. The publication presents the properties of LDX 2101®, 2304, LDX 2404™, 2205 and 2507. The properties of 4501 is in general terms very similar to those of 2507. Grade 4501 is delivered if specified.