F55 SUPER DUPLEX Stainless Steel W. Nr. 1.4501 – UNS S32760 ASTM A182

F55 SUPER DUPLEX

F55 SUPER DUPLEX UNS S32760 Wr.1.4501 is an alloy with a microstructure balanced at 50% between austenite and ferrite, which guarantees very high mechanical strength (up to 600 MPa yield strength) and superior corrosion resistance, particularly in marine environments and in the Oil & Gas industry.

Thanks to its PREN (Pitting Resistance Equivalent) ≥40, the steel guarantees excellent resistance to pitting, crevice corrosion and chloride stress corrosion cracking, making it a valid choice to replace 300 series stainless steels (e.g. AISI 316), standard duplex steels (S31803) and even nickel and titanium alloys in some applications.

Reference standards:

  • ASTM A182 F55 (flanges and forgings)
  • ASTM A276, A479 (bars)
  • ASTM A240 (plates and strips)
  • EN 10088-3 1.4501 (X2CrNiMoCuWN25-7-4)
  • NORSOK MDS D51-D55, D57, D58
  • NACE MR01-75 / ISO 15156 (applications in sour environments)

Chemical composition (%)

Element Min (%) Max (%)
Chromium (Cr) 24.0 26.0
Nickel (Ni) 6.0 8.0
Molybdenum (Mo) 3.0 4.0
Copper (Cu) 0.50 1.00
Nitrogen (N) 0.20 0.30
Tungsten (W) 0.50 1.00
Carbon (C) – 0.03
Manganese (Mn) – 1.00
Silicon (Si) – 1.00
Sulfur (S) – 0.015
Phosphorus (P) – 0.035

Pitting Resistance Equivalent Number (PREN):
PREN = Cr % + (3.3 x Mo%) + (16 x N%)
Typical value: ≥40


Mechanical Properties (at room temperature)

Property Value
Tensile Strength (UTS) 730 – 930 MPa (106 – 135 ksi)
Yield Strength (0.2% Proof Strength) ≥530 MPa (77 ksi)
Elongation ≥25%
Hardness (Max) 290 HB
Impact Resistance (Charpy V-Notch, 20°C) 100 J (74 ft.lb)

Physical properties

Property Value
Density 7.8 g/cm³
Specific Heat Capacity (20°C) 500 J/kg·K
Thermal Expansion Coefficient (20 – 100°C) 13.0 x 10⁻⁶ K⁻¹
Thermal Conductivity (20°C) 15 W/m·K
Electrical Resistivity (20°C) 0.80 Ω·mm²/m
Modulus of Elasticity (20°C) 200 GPa

Heat treatments

  • Solution annealing: 1020 – 1100°C with rapid water quenching to preserve the duplex microstructure.
  • Hot forming: Optimum temperature between 950 and 1200°C.
  • Cold forming: Greater force required compared to austenitic stainless steels; may require intermediate annealing.

Available forms

F55 SUPER DUPLEX stainless steel S32760 is available in the following forms:


Industrial applications

Thanks to its exceptional mechanical strength and corrosion resistance, F55 SUPER DUPLEX S32760 is used in the following sectors:

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