Super duplex is ‘shorthand’ for a family of high-performance stainless steels designed around a 25% chromium content. As the duplex name suggests, this family of alloys have a microstructure made up from both austenitic and ferritic grains. This duplex nature provides their unique combination of physical and mechanical properties.
The original duplex stainless steel was developed in Sweden for use in the sulfite paper industry. They were developed to combat corrosion problems common in that industry as a result of chloride-bearing cooling waters
The original super duplex stainless steel, Ferralium 255, was developed by Langley Alloys in the 1960s. A number of other grades have subsequently been developed. Since then, there have been a number of developments in the material, including Super Duplex F61.
The term was first used in the 1980s to describe highly alloyed, high-performance Duplex steel with a pitting resistance equivalent of >40 (based on Cr% + 3.3Mo% + 16N%).
Owing to its high level of chromium, this new type of duplex stainless steel provides superb resistance to acids, acid chloride and caustic solutions, as well as other environmental-damaging chemicals in the chemical/petrochemical, pulp and paper industries. Super duplex stainless steels feature superior stress corrosion than traditional duplex alloys, as well as better cracking and mechanical resistance than any other type of steel – including duplex alloys.
Super duplex materials are typically used in applications such as pumps, valves, fasteners, pipework, connectors, plus oil and gas components in the petrochemical/chemical, pulp, and paper industries.
Langley Alloys stocks the most complete range of super duplex material, including solid bars up to 16” (406.2mm) diameter, plate up to 3” thickness, plus access to pipes, flanges and fittings through our supply chain.
As the creator of Super Duplex Stainless Steel, there is no better source of information about this family of alloys than Langley Alloys.
For more information about super duplex materials, please don’t hesitate to contact us today. We would be happy to answer any questions that you may have regarding specifications and common applications.