Alloy 2205 (UNS S32205 (UNS31803))


Alloy 2205 is a 22% Cr duplex stainless steel, supplied in the solution annealed condition. As a duplex stainless steel, it combines the desirable aspect of properties of both austenitic and ferritic grades. The high chromium, molybdenum and nitrogen contents results in a Pitting Resistance Equivalent number (PREN) of 33-34, providing pitting and crevice corrosion resistance superior to Alloy 316L or Alloy 317L austenitic stainless steels in almost all corrosive media. Due to its excellent corrosion properties, it is well-suited to environments containing chlorides and hydrogen sulphide, for use in oil & gas extraction from sour wells, in refineries and in process solutions contaminated with chlorides.

It also has good erosion fatigue properties as well as lower thermal expansion and higher thermal conductivity than austenitic steels. The yield strength is about twice that of austenitic stainless steels, allowing a designer to save weight and make the alloy more cost competitive when compared to Alloy 316L or Alloy 317L.

Key Features:

  • Higher strength than standard stainless steels
  • Higher corrosion resistance than Alloy 316L stainless steel in a wide variety of corrosive chemicals including sulphuric, phosphoric and nitric acids
  • Good resistance to pitting and crevice corrosion in seawater
  • High stress corrosion resistance
  • Lower thermal expansion than austenitic stainless steels
  • Higher thermal conductivity than austenitic stainless steels


  • Process industry components in sulphuric acid, nitric acid, phosphoric acid, ethylene oxide, polypropylene & PVC production
  • Equipment handling organic & fatty acids, chemical storage, tankers, heat exchangers
  • Marine industry and shipbuilding propellers, shafts, rudders, shaft seals, pumps, bolts, fasteners, valves, instrumentation
  • Oil and chemical tankers
  • Oil & Gas industry pumps, valves, pipe, vessels, wellhead equipment, subsea equipment, separators, heat exchangers
  • Pollution control systems, effluent scrubbing, flue gas desulphurisation (FGD)
  • Waste water treatment, sour water purification
  • Pulp & paper industry applications such as pulp liquor heaters, bleach tower linings, digesters, brownstock washers
  • Food industry applications including brewery piping, evaporators, hot liquor tanks, presses

Chemical Composition:

Cr Ni Mo Co Nb (+Ta) Ti V W Cu C Mn N Si P S Fe Al
Min 22.00 4.50 3.00 0.14 0.20
Max 23.00 6.50 3.50 0.03 0.20 0.70 0.03 0.02 Bal

Mechanical Properties:

0.2% Proof Stress 450 N/mm2 91.4ksi
Tensile Strength 655 N/mm2 123.3ksi
Elongation, 5.65√S0 25%
Reduction of area 45%
Hardness (Brinell) <270
Impact Strength (Room Temp) 80J (av)
Impact Strength (-46°C) : Longitudinal <100mm 80J
100-260mm 45J (35J min)
>260mm For info only
Impact Strength (-46oC) : Transverse 50-260mm 45J (35J min)
>260mm For info only


  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 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
  5. ASTM G48A corrosion test (at 25°C) No pitting and < 3.0g/m2 weight loss
  6. Ferrite content 40-55%
  7. Microstructure certified free from grain boundary carbides, sigma, chi and laves phases

Physical Properties:

Density (Kg/m3) 7810
Magnetic Permeability (20°C) <50
Young’s Modulus (kN/mm2) 190
Specific Electrical Resistance, 20°C (µΩ.m) 0.85
Mean coefficient of thermal expansion, 20-300°C (m/m/oC) 11 x 10-6
Specific Heat, 20°C (J/kg.K) 400
Thermal conductivity, 20°C (W/m.K) 15


Datasheet - DS-Alloy 2205 (rev2)

Datasheet - DS-Alloy 2205 (rev2)