UNS S32205 is an improved version of the 2205-type duplex stainless steel. Compared to the earlier UNS S31803, it features more stringent chemical composition control, enhancing its corrosion resistance.

1. Overview of UNS S32205

Composition: S32205 = 22% Chromium + 5-6% Nickel + 3% Molybdenum + 0.14-0.20% Nitrogen, making it a stainless steel material with high strength and superior corrosion resistance.

2. Key Applications

• Marine environments: Desalination, ship components, offshore engineering

• Oil & gas industry: Transmission pipelines, pressure vessels

• Chemical & pulp industry: Heat exchangers, storage tanks, reactors

• Food processing & pharmaceutical industry: Piping, valves, pumps

• Bridges & construction: Structural components in highly corrosive environments

3. Chemical Composition of S32205

S32205 complies with ASTM A240 and ASTM A182 standards:

• Chromium (Cr)：22.0 – 23.0%

• Nickel (Ni)：4.50 – 6.50%

• Molybdenum (Mo)：3.00 – 3.50%

• Nitrogen (N)：0.14 – 0.20%

• Carbon (C)：≤ 0.03%

• Silicon (Si)：≤ 1.00%

• Manganese (Mn)：≤ 2.00%

• Phosphorus (P)：≤ 0.03%

• Sulfur (S)：≤ 0.02%

Difference from S31803: S32205 has stricter minimum Cr, Mo, and N limits, providing enhanced corrosion resistance, particularly against pitting and crevice corrosion.

4. Microstructure of S32205

S32205 consists of approximately 50% austenite + 50% ferrite, offering key advantages:

• Superior resistance to chloride-induced stress corrosion cracking (better than 304/316)

• Twice the yield strength of 304/316, reducing material usage

• Better toughness and ductility than ferritic stainless steel, though slightly lower than austenitic grades

• Excellent pitting and crevice corrosion resistance, suitable for high-chloride environments

5. Mechanical Properties

S32205’s mechanical properties (ASTM A240 standard):

• Density：7.8 g/cm³

• Tensile Strength：≥ 620 MPa

• Yield Strength：≥ 450 MPa

• Elongation：≥ 25%

• Hardness (Brinell)：≤ 290 HB

Comparison with 316L (Austenitic Stainless Steel):

• 316L has a yield strength of only 170 MPa, while S32205 offers 2.6 times more, allowing for reduced wall thickness and cost savings.

• Higher hardness, making it more wear-resistant and suitable for high-strength applications.

6. Corrosion Resistance of S32205

S32205 offers significantly superior corrosion resistance compared to 304 and 316L, particularly in chloride-containing environments.

（1）Corrosion resistance is measured using PREN (Pitting Resistance Equivalent Number):

PREN = Cr + 3.3 × Mo + 16 × N

• 304：

Chromium (Cr)：18%

Molybdenum (Mo)：0%

Nitrogen (N)：0%

PREN：18

• 316L：

Chromium (Cr)：17%

Molybdenum (Mo)：2.2%

Nitrogen (N)：0%

PREN：25

• S32205：

Chromium (Cr)：22%

Molybdenum (Mo)：3.2%

Nitrogen (N)：0.18%

PREN：35-38

PREN values above 32 indicate suitability for seawater environments. S32205 is clearly more corrosion-resistant than 316L, making it an ideal choice for marine, chemical, and other aggressive environments.

（2）Comparison of Corrosion Resistance:

7. Weldability of S32205

S32205 has good weldability, but controlling the heat input is crucial to maintaining its duplex structure.

（1）Recommended welding methods: 

• TIG (GTAW)

• MIG (GMAW)

• SMAW (Manual Arc Welding)

（2）Recommended filler metals:

• Welding wire: ER2209 (contains 22% Cr, 9% Ni, 3% Mo)

• Welding electrode: E2209-16

Avoid embrittlement in the heat-affected zone (HAZ). Post-weld heat treatment is generally not required, but controlled cooling is necessary.

8. Conclusion

• S32205 is an upgraded version of 2205 duplex stainless steel with superior corrosion resistance.

• Mechanical properties far exceed those of 304/316L, making it ideal for high-strength applications.

• Excellent resistance to pitting and chloride-induced stress corrosion cracking, making it suitable for marine, chemical, and oil & gas industries.

• Good weldability, provided heat input is controlled.

In summary, UNS S32205 Duplex Stainless Steel is an irreplaceable material in industries demanding high performance, such as marine, chemical, and oil & gas sectors. As material science continues to evolve, S32205 is expected to undergo further optimizations, expanding its applications and contributing to industry advancements by creating a more competitive material ecosystem.

We can process this alloy into round bars, plates, round pipes/square pipes, and coils according to your requirements. If you have any inquiries, please feel free to contact us. Our email address is: sale@bolaibao1.com. We look forward to your inquiry!