Type 329 (UNS S32900/1.4460)

● High corrosion resistance.
● Up to 28% chromium.
● Duplex steel (austenitic-ferritic).
● Inexpensive.
● Acid-resistant.

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The Stainless Steel Type 329 is duplex steel being a combination of austenitic and ferritic types. It can resist pitting as well as corrosion cracking under stress. This type of steel is better to use in forged valve pumps and their components.

Type 329 is also frequently used for centrifugal machines. This type of steel forges better at temperatures around 1250/1050C or 2280/1900F. The parts need to be air-cooled once they are forged. Duplex steel of such grade is very difficult to weld, and hence its machinability is very low.

Common Names: The other names of stainless steel 329 are AISI 329, and UNS S32900.

Executive Standards:

  • ASTM A240
  • ASME SA240
  • ASTM A268
  • ASME SA268
  • ASTM A789
  • ASME SA789
  • ASTM A790
  • ASME SA790
  • ASTM A511
  • ASME SA511
  • DIN 1.4460

Chemical Properties:


Mechanical Properties: 

Ultimate tensile strength725 MPa (105000 psi)
Tensile strength, yield (@0.2%)550 MPa (79800 psi)
Elastic modulus190 to 210 GPa (27557 to 30458 Ksi)
Poisson’s ratio0.27 – 0.30
Elongation (50 mm)25%
Hardness, Brinell (Knoop) (RB) (RC) (Vickers)230 (253) (96) (20) (242)

Physical Properties: The most notable physical property of SS Type 329 is its density which is 7.80 g/cm3 (0.282 lb/in3

Key Features:

  • The thermal expansion coefficient (TEC) at 20C to 815C (68F to 1500F) is 14.4µm/mC (8 µin/inF).
  • Slightly lower alloy content as compared to Grade 2205.
  • Parts and components must be solutions annealed at around 1020C to 1100C (1870F to 2010F) and then must be quenched in water.

Product Forms Available:

  • Plates
  • Pipes
  • Round Bar
  • Tube
  • Flanges
  • Wire
  • Fittings


  • Off-shore technology.
  • Paper industry.
  • Chemical tanks.
  • Heat exchangers.
  • Refineries.
  • Flanges, fittings, and pipes for the oil and gas industries.
  • Compressor parts.
  • Marine shafts for pressure vessel parts.
  • Desalination plants at seawater.

Possible Alternative Grades:

  • Type 2205
  • Type 316L
  • Type 904L

Frequently Asked Questions

  • What is the temperature for the full martensite transformation of SS 329?

The temperature for a full martensite transformation for Type 329 SS is 1038C (1090F) for 30 minutes and then cool it down below 16C (60F).

  • Is oxyacetylene welding recommended for SS329?

No, the recommended welding for SS 329 is standard fusion-resistance methods.

  • How to forge SS329?

Soak SS 329 at 1177C (2150F) for 60 minutes. Don’t work it below 1010C (1850F). Post-work treatment is mandatory before the steel hardens.

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