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.

CD4MCuN is a cast version of super duplex stainless steel, combining the most desirable features of both austenitic and ferritic stainless steels.

CD4MCuN duplex stainless steel is known for its excellent corrosion resistance, especially in aggressive environments containing chlorides. It is commonly used in applications where a combination of high strength and corrosion resistance is required, such as chemical processing, petrochemical industries and marine engineering.

Key Features of Ferralium 255

In addition, it has the following key features:

  • Originally developed in 1960s by Langley Alloys, Ferralium 255 pioneered the addition of nitrogen as the first super duplex stainless steel
  • Continuously developed through 1990s to extend PREN > 40, and more recently to increase mechanical properties
  • First super duplex stainless steel to achieve 586 N/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 sulfur minimize the likelihood of inclusions as sites for potential pitting corrosion
  • Higher copper content provides a 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

Get in Touch with Langley Alloys

At Langley Alloys, we carry a comprehensive stock of Ferralium 255 (1.4507, F61, S32550) as solid bars up to 16” in diameter and plates up to 3” in thickness, as well as selected pipes and fittings.

For more information about Ferralium 255 or other 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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