Super Duplex Stainless Steels
Super Duplex Stainless Steels are improved Duplex (Austenitic-Ferritic) St/St, typically:
• Chrome (Cr) 25%
• Nickel (Ni) 7%
• Molybdenum (Mo) 3%
• Sometimes Copper (Cu) 1% or Tungsten (W) 1%
Also known as:
• Zeron 100 (UNS 32760), SAF 2507 UNS S32570, UNS J93380 (Cast Zeron
Other similar materials
• UNS S32550 (Ferralium 255)
o Cr26 Ni5 Mo3.5 Cu2 N
• CD-4MCu
o Cr25.5 Ni5.5 Mo2 Cu3 N
• Several under brand names
Typical Properties
• Tensile 700 min N/mm2
• Yield 450 min N/mm2
• Elongation 25%
• Hardness 180-200 HB typ
• Density 7.8 g/cm3
Corrosion Properties
• Good for seawater service
• Especially good for:
o General corrosion
o Erosion /corrosion
o Chloride and Sulphide Stress corrosion cracking
o NACE
o Corrosion fatigue
• Poor fouling resistance
Additional Uses & Comments
• Very high strength
• Good high temperature rating but limited to 400 oC
• P/T class 300=750 psi CWP
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