Marine & Defence


S31803 (COLDUPLEX) is a standard grade of duplex stainless steel based on 22% chromium and 5% nickel. Often referred to as Alloy 2205, this material is the most widely used duplex grade due to its combination of very good general corrosion resistance and high strength.

S31803 has a superior corrosion resistance to austenitic grades such as 316 in most environments including seawater. The grade offers excellent resistance to intergranular corrosion, pitting and crevice corrosion combined with its resistance to chloride stress corrosion cracking at temperatures up to ~150ºC.

However, it is not generally suitable for use at temperatures above 300°C due to precipitation of brittle micro-constituents, nor below -50°C because of a ductile-to-brittle-transition.

Related Specifications of S31803

  • F51
  • NACE MR 0175
  • ASTM A182
  • ASTM A276
  • ASTM A473
  • 1.4462
  • X2CrNiMoN22-5-3

Nominal Composition of S31803

Fe rem, Cr 22.0%, Ni 5.0%, Mo 3.0%, N 0.17%

Mechanical Properties of S31803

Ultimate Tensile Strength (N/mm²) Proof Stress (N/mm²) Elongation (%) Hardness (HB)
620 448 25 280 max

Key Features of S31803

  • High strength levels
  • Very good resistance to pitting and crevice corrosion
  • High resistance to stress corrosion cracking, fatigue and erosion
  • Excellent resistance to chloride stress corrosion cracking
  • Good workability and weldability

Applications of S31803

Offshore & marine | Offshore pipework, components for gas, oil and process cooling plants; wellhead and subsea wellhead fittings; desalination plant, seawater cooled heat exchangers and high strength fasteners

Chemical processing | Chemical tanks, flue gas filters, acetic acid distillation parts and heat exchangers

Columbia Metals – a leading supplier of S31803

With decades of experience and a huge range of stock, Columbia Metals is an industry leader in the supply of S31803 and other high quality specialist engineering alloys.

To buy or learn more about S31803 contact us now, or fill in the enquiry form on the right hand side and we will be in touch shortly.

  Related Specifications Mechanical Properties
Alloy Name BS UNS BS EN Others Ultimate Tensile Strength N/mm² Minimum Yield Strength N/mm² Elongation % Hardness HB  
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