A short review on the role of alloying elements in duplex stainless steels

Duplex stainless steels consisting of ferrite and austenite are widely used due to their excellent mechanical properties and corrosion resistance. Compared with ferritic stainless steels, duplex stainless steels have better plasticity, toughness, and welding performance. They also possess higher strength and better resistance to stress, pitting, and crevice corrosion than austenitic stainless steels. In addition to the above-mentioned properties, there are cost-saving advantages in duplex stainless steels due to their lower nickel content. Today, the types of duplex stainless steel are mainly divided into four categories: lean duplex stainless steel, standard duplex stainless steel, super duplex stainless steel, and hyper duplex stainless steel. Alloying design of duplex stainless steel is an important strategy to achieve high performance. In the last two decades, significant progress has been made in both theoretical calculations and experiments. By adjusting alloying elements such as chromium, nickel, molybdenum, nitrogen, copper, tungsten and rare earth, etc., the mechanical properties and/or corrosion resistance of the duplex stainless steels can be further improved. Summarizing the comprehensive progress of alloying design of duplex stainless steel is of great significance in providing a data basis for establishing the corresponding relationship between chemical compositions and properties. Therefore, this paper reveals the specific roles of alloying elements in the duplex stainless steels and provides a reference for alloying design with different performance requirements.