Duplex 2205

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UNS - S32205 / S31803

Duplex 2205 are nitrogen improved duplex stainless steel that was created to combat normal corrosion issues experienced with the 300 series stainless steels. "Duplex" define a family of stainless steels that are neither completely austenitic, like 304 stainless, nor absolutely Ferritic, like 430 stainless. The structure of 2205 duplex stainless steel comprises of austenite pools encompassed by a persistent ferrite phase.

In the annealed condition, 2205 consist around 40-50% ferrite. Frequently referred to as the workhorse grade, Duplex 2205 are the most generally utilized grades in the duplex family of stainless steels. One of the benefits of a duplex architecture is that it consolidates the great characteristics of a Ferritic alloy (stress corrosion cracking resistance and high strength) with those of an austenitic alloy (ease of fabrication and corrosion resistance). Use of 2205 Duplex stainless steel should be restricted to temperatures below 600° F. Extended high temperature exposure can embrittled 2205 stainless steel.

  • High resistance to chloride stress corrosion cracking
  • Resistance to chloride pitting and crevice corrosion
  • Good general corrosion resistance
  • Good sulphide stress corrosion resistance
  • High Strength
  • Good weldability and workability

  • Chemical process vessels, piping and heat exchangers
  • Pulp mill digesters, bleach washers, chip pre-steaming vessels
  • Food processing equipment
  • Oil field piping and heat exchangers
  • Flue gas desulfurization equipment

Corrosion Resistance

2205 duplex stainless steel is a profitable solution for many applications where the 300 series stainless steels are helpless to chloride stress corrosion splitting. Stress corrosion cracking developed when stainless steels are subjected to tensile stress; while in contact with solutions includes chlorides. Increasing temperatures additionally build the weakness of stainless steels to stress corrosion cracking. The mix of chromium, molybdenum and nitrogen convey the very good resistance of 2205 to chloride pitting and crevice corrosion. This resistance is critical for services, for example, marine environments, brackish water, bleaching operations, closed loop water systems and some food processing applications. The high chromium, molybdenum and nitrogen substance of 2205 give corrosion resistance better than basic stainless steels, for example, 316L and 317L in many situations.


Slow speeds, positive feeds, sharp tooling and rigid mounts are essential. It can be machinable with either high speed or carbide tooling, with speeds for carbide decreased by around 20 %.


Because of its naturally high strength and work hardening rate, 2205 is hard to form. It will take a lower range than 316 stainless and a higher allowance must be made for spring back.


Most standard welding techniques suit this grade, except welding without filler metals, which results in excess ferrite. AS 1554.6 pre-qualify welding for 2205 with 2209 rods or electrodes so that the saved metal has the right adjusted duplex structure. Adding nitrogen to the shielding gas guarantees that sufficient austenite is added to the structure. The heat input must be maintained at a low level, and the utilization of pre or post heat must be stayed away from. The co-proficient of thermal expansion for this grade is low; hence the distortion and stresses are lesser than that in austenite grades.

Hot Working

Hot work should be done within the scope of 1750-2100 F, although room temperature forming is recommended whenever possible. When any hot forming is executed, a full anneal with rapid quench is required to reattain maximum stability and properties.


Anneal at 1868-1958 F(1020-1070 C), water quench.

Chemical Composition %

S318030.03 Max0.08 - 0.201.0 max0.03 max0.02 max21.0 - 23.02.0 max4.5 - 6.52.5 - 3.5
S322050.03 Max0.14 - 0.201.0 max0.03 max0.02 max22.0 - 23.02.0 Max4.5 - 6.53.0 - 3.5

Mechanical Properties

Tensile Strength (ksi)0.2% Yield Strength (ksi)Elongation% in 2 inches

Physical Properties

UnitsTemperature in °C
Density7.88 g/cm³Room
Specific Heat0.11 Kcal/kg.C 20°
Melting Range1385 - 1444 °C-
Modulus of Elasticity 190 KN/mm²20°
Electrical Resistivity80 µΩ.cm20°
Coefficient of Expansion13.7 µm/m °C20 - 100°
Thermal Conductivity19.0 W/m -°K20°

ASTM Specifications

Pipe SMLS / Pipe WeldedTube SMLS / Tube WeldedSheet / Plate / StripBarFitting
A 790A 789A 240 A 276 A 182


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