
ASTM A928 Grade 2205 2304 255 2507 329 Duplex Stainless Steel Pipe EFW Steel Tube For Chemical Transportation
Duplex stainless steels are a family of stainless steels that have a mixed microstructure of austenite and ferrite. They are known for their high strength, excellent corrosion resistance, and good weldability. ASTM A928 is a standard specification for duplex stainless steel pipes, particularly for use in chemical transportation.
Material
Duplex stainless steels are primarily composed of iron, chromium, and nickel, with varying amounts of molybdenum, nitrogen, and other alloying elements. The specific grades covered under ASTM A928 include:
- Grade 2205
- Grade 2304
- Grade 255
- Grade 2507
- Grade 329
Specification
ASTM A928 outlines the requirements for duplex stainless steel pipes used in various applications, particularly in environments that require resistance to pitting and crevice corrosion.
Key Features
- High Strength: Duplex stainless steels have a higher yield strength compared to austenitic stainless steels.
- Corrosion Resistance: Excellent resistance to pitting and stress corrosion cracking.
- Weldability: Good weldability with proper techniques.
- Cost-Effective: Offers a balance of performance and cost compared to other high-alloy materials.
Chemical Composition
The following table presents the chemical composition of the various duplex stainless steel grades:
Grade | C (%) | Cr (%) | Ni (%) | Mo (%) | N (%) | Fe (%) |
2205 | ≤0.03 | 22.0-23.0 | 4.5-6.5 | 3.0-5.0 | 0.08-0.2 | Balance |
2304 | ≤0.03 | 19.0-21.0 | 3.0-5.0 | 0.0-0.5 | 0.0-0.2 | Balance |
255 | ≤0.03 | 24.0-26.0 | 4.5-6.5 | 5.0-7.0 | 0.0-0.2 | Balance |
2507 | ≤0.03 | 24.0-26.0 | 6.0-8.0 | 3.5-5.0 | 0.0-0.2 | Balance |
329 | ≤0.03 | 24.0-26.0 | 4.0-6.0 | 0.0-0.5 | 0.0-0.2 | Balance |
Mechanical Properties
The following table outlines the mechanical properties of the duplex stainless steel grades:
Grade | Yield Strength (MPa) | Tensile Strength (MPa) | Elongation (%) | Hardness (HB) |
2205 | ≥ 450 | ≥ 620 | ≥ 25 | ≤ 290 |
2304 | ≥ 450 | ≥ 600 | ≥ 30 | ≤ 290 |
255 | ≥ 500 | ≥ 700 | ≥ 20 | ≤ 300 |
2507 | ≥ 550 | ≥ 800 | ≥ 25 | ≤ 300 |
329 | ≥ 450 | ≥ 650 | ≥ 25 | ≤ 290 |
Steel Grade
The steel grades mentioned above are specifically designed to meet the requirements of various applications in the chemical industry, oil and gas, and marine environments.
Application
Duplex stainless steel pipes are widely used in:
- Chemical processing
- Oil and gas exploration
- Marine applications
- Wastewater treatment
- Power generation
Possible Alternative Grades
While ASTM A928 grades are suitable for many applications, alternative grades may also be considered based on specific requirements:
- Austenitic Stainless Steels: Such as 304 and 316 for less aggressive environments.
- Super Duplex Stainless Steels: Such as S32750 and S32760 for more demanding applications.
- Nickel Alloys: Such as Inconel and Monel for extreme corrosion resistance.





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