Duplex stainless steel is a steel that combines the advantages of austenitic and ferritic stainless steels. The composition of duplex stainless steels usually consists of chromium, nickel, molybdenum and nitrogen. The amount of each element in the composition may vary depending on the specific grade or alloy. However, in general, duplex stainless steels have a higher chromium content (about 22 percent ) than conventional austenitic stainless steels. This high content of chromium gives it excellent corrosion resistance. In addition to chromium, duplex stainless steels also contain about 5-8 percent nickel, which provides additional strength and toughness. Molybdenum is added to enhance pitting resistance, while nitrogen helps improve solderability. The combination of these elements increases strength and corrosion resistance compared to other types of stainless steel. It's worth noting that the different grades within the duplex family of stainless steels have different compositions - which allow them to be used in a variety of applications, such as chemical processing equipment or refineries where harsh environments are common.