The work experience of CISRI (China) in the field of duplex stainless steels (DSS) is of 25 years. In this period a series of DSS including 6 grades have been industrially developed.

All these duplex grades contain nitrogen up to 0.20% together with 18, 22 and 25% Cr and 2–3% Mo respectively. In addition, they are characterized by a microstructure with about 50% ferrite and 50% austenite.

The combination of high strength, improved resistance to various types of localized corrosion as well as good weldability has led to a wide application of DSS in China. In oil refining, chemical and petrochemical processing industries, and chemical fertilizer industry etc. the duplex grades have substituted for austenitic stainless steels in many equipment, valve and pump parts.