Duplex stainless steels are called “duplex” because they have a two-phase microstructure consisting of grains of ferritic and austenitic stainless steel. Strength: Duplex stainless steels are about twice as strong as regular austenitic or ferritic stainless steels.

We are the biggest producers of bigger diameter bolts and nuts in India, as our name suggests we are manufacturing big bolts and nuts in Duplex steel grades under the mentioned table.. We manufacture duplex steel bolts as per grade Alloy 2205, DUPLEX steel is a mix of Austenite and Ferritic steel microstructure, which is why they are also known as Duplex steel. They also have great resistance to corrosion and have higher strength as compared to stainless steel grades like 316 or 304.

Duplex stainless steels are usually divided into three groups based on their pitting corrosion resistance, characterised by the pitting resistance equivalence number, PREN = %Cr + 3.3 %Mo + 16 %N.

Standard duplex (PREN range: 28–38)

Typically Grade EN 1.4462 (also called 2205). It is typical of the mid-range of properties and is perhaps the most used today

Super-duplex (PREN range: 38-45)

Typically grade EN 1.4410 up to so-called hyper duplex grades (PREN: >45) developed later to meet specific demands of the oil and gas as well as those of the chemical industries. They offer superior corrosion resistance and strength but are more difficult to process because the higher contents of Cr, Ni, Mo, N and even W promote the formation of intermetallic phases, which reduce drastically the impact resistance of the steel. Faulty processing will result in poor performance and users are advised to deal with reputable suppliers/processors. Applications include deepwater offshore oil production.

Lean duplex grades (PREN range: 22–27)

Typically grade EN 1.4362, have been developed more recently for less demanding applications, particularly in the building and construction industry. Their corrosion resistance is closer to that of the standard austenitic grade EN 1.4401 (with a plus on resistance to stress corrosion cracking) and their mechanical properties are higher. This can be a great advantage when strength is important. This is the case in bridges, pressure vessels or tie bars.