Super duplex steel is a highly durable and corrosion-resistant type of duplex stainless steel that combines the properties of austenitic and ferritic stainless steels. It contains higher levels of chromium, molybdenum, and nitrogen compared to standard duplex steel, which enhances its resistance to pitting, crevice corrosion, and stress corrosion cracking. This makes it especially suitable for demanding environments, such as offshore oil and gas, marine, and chemical processing industries, where exposure to chlorides and other aggressive chemicals is common. Super duplex steel offers excellent mechanical strength and durability, often outperforming other stainless steels in extreme conditions.

The primary difference between duplex steel and super duplex steel lies in their composition, strength, and corrosion resistance. Duplex steel has a balanced microstructure of austenitic and ferritic stainless steels, offering good strength, weldability, and resistance to stress corrosion cracking. Commonly used grade is Duplex 2205, which is effective in moderately corrosive environments. Super duplex steel, on the other hand, has higher levels of chromium, molybdenum, and nitrogen than standard duplex steel, providing enhanced strength and superior corrosion resistance, particularly against pitting and crevice corrosion. Super duplex grades, like 2507, are specifically designed for extremely demanding environments, such as deep-sea, offshore, and chemical processing, where exposure to chlorides is high. Overall, super duplex steel performs better in harsh, chloride-rich environments, making it suitable for more extreme conditions than standard duplex steel.