Difference Between Duplex and Super Duplex Stainless Steel

Check Advantages & Disadvantages Duplex Steel

Difference Between Duplex and Super Duplex Stainless Steel
DSS and super duplex grades are designed with a dual structure austenitic and ferritic grade. These steel products are nearly identical and can be distinguished by certain characteristics.

• A SDSS grade is designed with a chemical composition of 24 to 26% chromium with 6-8% nickel and 3-5% molybdenum. The Duplex steel, on the contrary, is designed with 21% chromium, 4.5% of nickel, and 2.5 content of molybdenum.
• The higher chemical content in the SDSS grade gives the steel superior resistance to corrosion, pitting, and chloride stress corrosion compared to the duplex grade.
• The DSS grade is however cheaper than SDSS.

Top 10 advantages of Duplex Steel

• The austenitic and ferritic microstructure gives the grade higher strength compared to standard grades.
• Excellent corrosion resistance properties.
• Enhanced toughness and ductility
• High resistance to harsh chloride corrosion cracking
• Resistance to pitting and crevice corrosion
• Good sulfide stress corrosion
• Outstanding workability.
• Superior welding capabilities
• The steel works well in temperatures up to 300 degrees c.
• Cost-effective

Top 10 benefits to using of Super Duplex Steel
A SDSS grade is designed with a dual microstructure and has superior performance in different applications. Some of the benefits of this grade are:

• High energy absorption
• Excellent thermal conductivity in the system
• Higher heat conductivity with low thermal expansion
• Outstanding workability and weldability
• Superior strength
• Enhanced resistance against corrosion induced by pitting by acids
• Good resistance to chloride stress corrosion cracking and crevice corrosion.
• Working temperatures up to 600 degrees F
• Enhanced resistance to erosion and fatigue
• Superb mechanical properties in different conditions

Disadvantages of DSS and SDSS
The dual microstructure grade has its set of disadvantages alongside its advantages. The major disadvantage of this component is that it has lower heat resistance in comparison to other austenitic stainless steel products. These steel grades are limited to work in temperatures between -50 to 300 degrees C, as there are chances that deleterious intermetallic phases are formed.

DSS And Super Duplex Stainless Steel Applications
The DSS and SDSS are versatile grades that are commonly seen in:

Why DSS material for marine segmentation?
Duplex material grades are designed with an excellent chemical composition which allows them to have good corrosion resistance coupled with enhanced tolerance to pitting that is seen in marine environments. The good durability and safety of this steel propels them to be a good choice for marine segmentation.

DSS in desalination plants
Desalination is a common method today to processes toxic affluents and corrosive media. The entire desalination process is very expensive and requires special expertise. The process requires a steel grade that has good strength coupled with higher corrosion resistance properties and is available at affordable rates. All these features match the DSS grade, which also showcases good reliability and offers a long service life.

Check the price comparison and list of Grades of Duplex Stainless Steel material