Duplex steel is made up of:
Duplex stainless steel is a combination of both ferritic and austenitic grains of stainless steel. The basic chemical composition of duplex stainless steel is an equal mix of ferrite and austenite. This combination creates some very beneficial properties for this family of stainless steels.
Martensitic steel and austenitic steel
Ferritic grain of stainless steel
Ferritic + austenitic grains of stainless steel
Ferritic + martensitic grains of stainless steel