Duplex stainless steels are two-phase microstructure alloys having both ferrite and austenite grains in their microstructure. The austenite in the grain form is surrounded by the ferrite phase in about equal proportions.
The result is a grade with higher overall strength, better corrosion resistance, and a value for money in regard to the properties provided. Duplex stainless steels are used in applications where thinner sections are required. The Duplex grades use a combination of ferritic steel and austenitic steel properties like high strength and ease of fabrication respectively.
Their common applications include oil and gas industry, marine applications, and applications involving aggressive chemical environments.