1.4410 vs 316L: Super Duplex S32750 Compared with Austenitic 316L

Is 1.4410 the Same as 316L?

No. 1.4410, designated X2CrNiMoN25-7-4 and known as super duplex 2507 or UNS S32750, is a super duplex stainless steel with a balanced ferritic-austenitic microstructure, while 316L is a fully austenitic low-carbon grade. The two materials differ fundamentally in structure, strength, and corrosion resistance, and are not interchangeable.

Chemical Composition

1.4410 contains carbon 0.030 percent maximum, silicon 1.00 percent maximum, manganese 2.00 percent maximum, phosphorus 0.035 percent maximum, sulfur 0.015 percent maximum, chromium 24.0 to 26.0 percent, nickel 6.0 to 8.0 percent, molybdenum 3.0 to 4.5 percent, and nitrogen 0.24 to 0.35 percent. The ultra-low carbon with high chromium, molybdenum, and nitrogen gives a pitting resistance equivalent number of 40 to 42 or higher.

Mechanical Properties

In the solution-annealed condition 1.4410 has a minimum tensile strength of 800 MPa and a minimum yield strength of 550 MPa with elongation of 25 percent and maximum hardness of 290 HBW. Its yield strength is roughly twice that of 316L, enabling thinner-wall component design and lighter pressure equipment.

Corrosion Resistance

The PREN above 40 provides outstanding resistance to pitting corrosion, crevice corrosion, and chloride-induced stress corrosion cracking, delivering stable performance in aggressive environments such as seawater and concentrated brine, where 316L would pit and fail. For continuous immersion in seawater, 2507 performs well up to about 60 degrees C.

Limitations

1.4410 is not hardenable by heat treatment, and long-term exposure at 300 to 950 degrees C must be avoided to prevent sigma-phase embrittlement. The maximum long-term service temperature is generally about 280 degrees C. Welding requires strict control of heat input, interpass temperature, and shielding gas to maintain the 50-50 phase balance.

Applications

1.4410 serves subsea pipelines, manifolds, and risers; chemical reactors, heat exchangers, and columns; desalination and flue gas desulfurization plants; pulp and paper digesters; and oil and gas downhole and topside equipment in sour service. It is also used where erosion-corrosion resistance matters in high-velocity flow.

Frequently Asked Questions

Q: What is 1.4410?

A: X2CrNiMoN25-7-4, the EN designation of super duplex 2507, UNS S32750.

Q: How does 1.4410 differ from 2205?

A: Higher chromium, molybdenum, and nitrogen, with PREN above 40 versus about 34.

Q: How much stronger is 1.4410 than 316L?

A: Roughly twice the yield strength, 550 MPa versus about 205 MPa.

Q: What is the maximum service temperature?

A: About 280 degrees C to avoid sigma-phase embrittlement.

Q: What applications use 1.4410?

A: Offshore, chemical, desalination, pulp and paper, and sour oil and gas service.

Q: Why choose 1.4410 over 316L?

A: For chloride environments where 316L pitting and SCC resistance is insufficient.

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