Super Duplex 2507 Pipe ASTM A790 UNS S32750 Super Duplex Stainless Steel Pipe

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The nitrogen content (0.24–0.32%) in S32750 plays a crucial role:

Enhances strength and corrosion resistance.

Stabilizes the austenitic phase, improving weldability and toughness.

Nitrogen also helps prevent the formation of harmful intermetallic phases (e.g., sigma phase) during welding or prolonged exposure to high temperatures.

While S32750 is weldable, it requires careful control of heat input and interpass temperatures to avoid:

Formation of sigma phase or chromium carbides, which can degrade corrosion resistance and toughness.

Excessive ferrite content in the weld zone.

Recommended filler metals: ER2594 or ER2553 for matching properties.

Post-weld heat treatment is generally not required but may be used in specific cases to restore corrosion resistance.

S32750 has good thermal stability up to 300°C (572°F). Beyond this temperature, prolonged exposure can lead to:

Embrittlement due to the formation of intermetallic phases.

Reduced corrosion resistance.

This limits its use in high-temperature applications compared to nickel-based alloys.

Despite being a premium material, S32750 is often more cost-effective than high-nickel alloys like Inconel or Hastelloy for applications requiring high strength and corrosion resistance.

Its lower nickel content (6–8%) compared to austenitic stainless steels (e.g., 316L with 10–14% Ni) makes it more economical.