Stainless Steel Grade Duplex 2304 (UNS S32304)

Topics Covered

Chemical Composition
Mechanical Properties
Other Designations
Manufacturing Process


Stainless steel grade Duplex 2304 is a duplex stainless steel type with a structure that is a balance of ferritic and austenitic. It has high strength and toughness, resistance to stress corrosion cracking, high thermal conductivity, low thermal expansion, and easy fabrication. It is recommended that this steel is not used in areas where the steel would be exposes to temperatures over 1058°C (570°F) for prolonged periods.

The following datasheet provides an overview of stainless steel grade Duplex 2304.

Chemical Composition

The chemical composition of stainless steel grade Duplex 2304 is outlined in the following table.

Element Content (%)
Iron, Fe 72.679
Chromium, Cr 23
Nickel, Ni 4
Molybdenum, Mo 0.20
Nitrogen, N 0.1
Carbon, C 0.02
Sulfur, S 0.001

Mechanical Properties

The mechanical properties of stainless steel grade Duplex 2304 are displayed in the following table.

Properties Metric Imperial
Tensile strength ≥ 600 MPa ≥ 87000 psi
Yield strength (@strain 0.200 %) ≥ 400 MPa ≥ 58000 psi
Modulus of elasticity 200 GPa 29000 ksi
Shear modulus (@temperature 20°C/ 68°F) 75.0 GPa 10900 ksi
Poisson’s ratio 0.333 0.333
Elongation at break ≥ 25 % ≥ 25 %
Hardness, Rockwell C ≤ 20.0 ≤ 20.0
Hardness, Brinell 180 - 230 180 - 230

Other Designations

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Equivalent materials to stainless steel grade Duplex 2304 are given below:

  • ASTM A240
  • ASTM A276
  • ASTM A480
  • ASTM A789
  • ASTM A790
  • DIN 1.4362

Manufacturing Process

Machining of stainless steel grade Duplex 2304 is performed at low speeds, and constant feeds help to reduce its tendency to work harden. This material is tougher than grade 304 and 316 stainless steels due to its long stringy chip. Chip breakers are recommended. Unlike the 300 series stainless steel, Duplex 2304 steel requires more pressure while performing forming due to its higher yield strength. Its low ductility characteristic tends to make it difficult to perform forming operations.

Welding can be performed using most of the traditional methods such as gas–tungsten arc welding (GTAW), submerged arc welding (SAW), and gas–metal arc welding (GMAW). The filler metal should be a balanced of ferrite/ austenite type like 2205 or 2304.

Hot working can be done after heating the material to 954-1093°C (1750-2000°F), which is followed rapid cooling. Annealing after working is recommended. For annealing, the material is heated to 930-1050°C (1710-1920°F) and then rapidly quenched.


Stainless steel grade Duplex 2304 is used by various industries including pulp and paper, coal handling, potash, food and beverage, and waste water.

The specific applications are as follows:

  • Bridges
  • Storage tanks
  • Water heaters
  • Heat exchangers
  • Pressure vessels
  • Feedwater tubes
  • Heat exchangers
  • Flue-gas cleaning
  • Seawater systems
  • Desalination plants
  • Parts for structural design
  • Rotors, impellers and shafts
  • Firewalls and blast walls on offshore platforms
  • Cargo tanks and pipe systems in chemical tankers
  • Piping and instrumentation tubing for general service

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