Duplex Stainless Steels

We are a famous exporter and supplier of Duplex Stainless Steels based in Mumbai, Maharashtra. These steels have a high strength and a greater resistance to corrosion particularly stress corrosion and cracking. We offer this product in different qualities or grades. These steels are used in various processing plants, hot water tanks and much more. Our wholesale prices on this product are unbeatable.

Details :Duplex stainless steels are becoming more common. They are being offered by all the major stainless steel mills for a number of reasons

• Higher strength leading to weight saving
• Greater corrosion resistance particularly stress corrosion cracking
• Better price stability
• Lower price
• There is a conference on the subject of duplex every 2-3 years where dozens of highly technical papers are presented. There is a lot of marketing activity surrounding these grades. New grades are being announced frequently.
• Yet, even with all this interest, the best estimates for global market share for duplex are between 1 and 3%.The purpose of this article is to provide a straightforward guide to this steel type.

Grades :

• Duplex Grades
• Duplex 31803
• Super duplex s32750
• Super duplex s32760
• Lean duplex s32304
• 6 molu s31254
• Zeron 100.

Principle of Duplex Stainless Steels :

• The idea of duplex stainless steels dates back to the 1920s with the first cast being made at Avesta in Sweden in 1930. However, it is only in the last 30 years that duplex steels have begun to “take off” in a significant way.
• This is mainly due to advances in steelmaking techniques particularly with respect to control of nitrogen content.
• The standard austenitic steels like 304 (1.4301) and ferritic steels like 430 are relatively easy to make and to fabricate. As their names imply, they consist mainly of one phase, austenite or ferrite.
• Although these types are fine for a wide range of application.

Technical Weaknesses

• Austenitic – low strength (200 MPa 0.2% PS in solution annealed condition), low resistance to stress corrosion cracking
• Ferritic – low strength (a bit higher than austenitic, 250 MPa 0.2% PS), poor weldability in thick sections, poor low temperature toughness
• In addition, the high nickel content of the austenitic types leads to price volatility which is unwelcome to many end users.
• The basic idea of duplex is to produce a chemical composition that leads to an approximately equal mixture of ferrite and austenite. This balance of phases provides the following:

• Higher strength – The range of 0.2% PS for the current duplex grades is from 400 – 550 MPa. This can lead to reduced section thicknesses and therefore to reduced weight. This advantage is particularly significant for applications such as
  
  • Pressure Vessels and Storage Tanks
  • Structural Applications e.g. bridges

• Good weldability in thick sections – Not as straightforward as austenitics but much better than ferritics.
• Good toughness – Much better than ferritics particularly at low temperature, typically down to minus 50 deg C, stretching to minus 80 deg C.
• Resistance to stress corrosion cracking – Standard austenitic steels are particularly prone to this type of corrosion. The kind of applications where this advantage is important include
  
  • Hot water tanks
  • Brewing tanks
  • Process plant
  • Swimming pool structures

Characteristics

• Twice design strength of austenitic and ferritic stainless steels
• Wide range of corrosion resistance to match application
• Good toughness down to minus 80 deg C but not genuine cryogenic applications
• Particular resistance to stress corrosion cracking
• Weldable with care in thick sections
• More difficult to form and machine than austenitics
• Restricted to 300 deg C maximum .