UNS S31803 F51

Duplex F51 / UNS S31803 is a corrosion resistant, high strength steel that is typically used for pipes, valves and bolting connectors in severe environments such as the oil and gas industry.

  • UNS S31803
  • Werkstoff number 1.4462
  • EN10088-3
  • X2CrNiMoN22-5-3
  • ASTM A182 F51
  • NORSOK D41 to D45

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The word duplex is based upon the concept that the material has a two-phase microstructure consisting of grains of ferritic and austenitic stainless steel formulated in the same material. The term “Super-Duplex” denotes high-performance Duplex steel based on elevated contents of chromium, nickel and molybdenum. These elements improve pitting corrosion resistance, while additions of nitrogen promoted structural hardening, raising the yield strength and ultimate strength values without impairing toughness.

Duplex stainless steels are about twice as strong as regular austenitic or ferritic stainless steels, have significantly better toughness and ductility than ferritic grades (although they do not reach the values of austenitic grades), have a range of corrosion resistance comparable to the range for austenitic stainless steels, have very good stress corrosion cracking resistance.

Chemical Analysis


Mechanical Properties

Tensile Strength (MPa /N/mm2 )655-880
0.2% Proof Stress (MPa /N/mm2 ) minimum485
Elongation (A5 & 4D) minimum 25.00%
Reduction of Area minimum 45.00%
Hardness (HB) maximum270
Charpy V-notch Impact at ambient Temp (J)100 minimum
Charpy V-notch Impact at -46 deg C (J)45 minimum
Ultrasonic TestingAt customers; request
Ferrite Content 35%-55%
Corrosion Test to ASTM G48 Method A25 deg C for 24 hours
Microstructure Microstructure certified free from grain boundary carbides, sigma, chi and laves phases

For more technical information download our F51 information sheet here


F51 is used within the chemical processing, aerospace, oil and gas, power generation and heat treating industy.

Typical applications include

  • pumps
  • valves
  • pipework / flanges
  • bolting connectors & manifolds
  • rings
  • shafts
  • forgings
  • pressure systems

“We are not the biggest steel distributor around, but have differentiated ourselves by focusing on service, reliability and trying to find ways of helping customers rather than by just supplying metal – conversion, holding specific stock for quick delivery and consignment stock”

Mike Andrews


Proud Associates

Broder Metals Group Certified To AS9120
Broder Metals Group Certified To AS9120