What is CD4MCuN?

ASTM A890 CD4MCuN or Grade 1B is the nearest equivalent grade to the wrought super duplex stainless steel Ferralium 255 or UNS S32550.

It is also designated as ASTM A995 and ASME SA351/995 grade CD4MCuN or 1B, also written as J93372 or X2 CrNiMoCuN 25-6-3

Langley Alloys carries a comprehensive stock of Ferralium 255 (1.4507, F61) as solid bar up to 16” in diameter and plate up to 3” thickness, as well as selected pipes and fittings. Machining components from solid bar or plate can help to reduce risk of rejection, as the wrought product form is much less likely to suffer from internal defects. As these defects become apparent on castings only after machining, considerable time and expense can be lost. However, castings can be an effective way to produce more complex geometries or reduce the cost for larger components or longer production runs. The mechanical properties of a wrought product (rolled, forged) is significantly better than a cast product.

Ferralium 255 key features:

  • Originally developed in 1960’s by Langley Alloys, Ferralium 255 pioneered the addition of nitrogen as the first super duplex stainless steel
  • Continuously developed through 1990’s to extend PREN > 40, and more recently to increase mechanical properties
  • First super duplex stainless steel to achieve 586N/mm2 as a minimum 0.2% Proof Stress, up to 12” (300mm) section sizes
  • Outstanding resistance to pitting and crevice corrosion
  • Very low levels of sulphur minimise the likelihood of inclusions as sites for potential pitting corrosion
  • Higher copper content provides self-healing effect at sites of pitting to inhibit further growth
  • Particularly suitable for larger components as the formation of sigma phase is much less likely than it is for other Super Duplex grades

Got any Questions? Get in Touch

For more information about super duplex stainless steel alloys, please don’t hesitate to contact us today. We would be happy to answer any questions that you may have regarding specifications and common applications.

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