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)
    • Cr26 Ni5 Mo3.5 Cu2 N
  • CD-4MCu
    • 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:
    • General corrosion
    • Erosion /corrosion
    • Chloride and Sulphide Stress corrosion cracking
    • NACE <HRC34
    • 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