• Alloy 255 (Super Duplex 255)
  • 1.4507
  • X2CrNiMoCuN 25-6-3
  • Z3 CNDU 25-07 Az
  • Norsok MDS D51
  • ASTM A790
  • ASTM A815
View Data Tables For This Product

Ferralium 255 (Pipe & Tube) (UNS 32550)

Ferralium® 255 is a super duplex stainless steel supplied in the cold finished and annealed condition. As a 25% Chromium alloy, with significant additions of Copper, it offers excellent corrosion resistance in a wide variety of corrosive chemicals including sulphuric, nitric and phosphoric acid.  In seawater and other chloride containing environments it also provides outstanding resistance to pitting and crevice corrosion, with Critical Pitting Temperature exceeding 50°C. Excellent ductility and impact strength at both ambient and sub-zero temperatures combine with a high resistance to abrasion, erosion and cavitation erosion.


In its various product forms, Ferralium® 255 is listed in NACE MR 0175 for sour service and gained ASME Approval for Pressure Vessel applications. It has been tested to the highest degree using tests designed to guarantee that the trade-marked product possesses high integrity, a correct phase balance and the absence of sigma and other deleterious phases.

Ferralium 255 (pipe and tube)


  • Alloy 255 (Super Duplex 255)
  • 1.4507
  • X2CrNiMoCuN 25-6-3
  • Z3 CNDU 25-07 Az
  • Norsok MDS D51
  • ASTM A790
  • ASTM A815
View Data Tables For This Product

Data Tables

Chemical Composition:


Mechanical Properties:

0.2% Proof Stress550 N/mm280 ksi
Tensile Strength760 N/mm2110 ksi
Elongation, 5.65√S0 and 4D15%
Reduction of Area
Hardness (Rockwell C)28 HRC max.


  1. Testing shall be carried out in accordance with ASTM A370 or EN ISO 6892-1 (tensile), EN ISO 6506-1 (hardness)
  2. Minimum properties quoted (tested at room temperature, mid-wall, in a longitudinal direction)
  3. Testing performed on each melt of material per heat treatment batch
  4. Hardness shall be in accordance with NACE MR 1075 with a maximum HRC value of 28 (270HB)
  5. Additional tests routinely undertaken:

– Hydrostatic Pressure Test of ASTM A999/A999M

– Non-Destructive Test of ASTM E213 or ASTM E309

– Flattening Test requirements of ASTM A999/A999M

Physical Properties:

Density (Kg/m3)7810
Magnetic Permeability (20°C)33
Young’s Modulus (kN/mm2)199
Specific Electrical Resistance, 20°C (Ω-m)0.80 x 10-6
Mean coefficient of thermal expansion, 20-100°C (m/m/degC)11.1 x 10-6
Specific Heat, 20°C (J/kg.K)475
Thermal conductivity, 20°C (W/m.K)14.2

Product Features

Key Features:

  • Originally developed in 1960’s, pioneering the addition of nitrogen, to create the first super duplex stainless steel
  • Continuously developed through 1990’s to extend PREN > 40
  • Pitting Resistance Equivalent (PREN) >40, indicating outstanding resistance to pitting and crevice corrosion
  • Higher copper content provides self-healing effect at sites of pitting to inhibit further growth
  • Available as bars, plate, pipe and fittings with complementary weld wire


  • Oil & Gas industry equipment
  • Process industry equipment in sulphuric acid, nitric acid, phosphoric acid, PP / PVC/TiOx production, agrochemicals
  • Pulp and paper applications such as black liquor heater tubes
  • Water and sewage treatment, desalination, swimming pools
  • Grain and vegetable processing plant
Brochure Ferralium 255 SD50 detailed product information (rev2)
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