ASTM A890 CD4MCuN (Grade 1B) is the cast grade nearest to the wrought super duplex stainless steel Ferralium® 255, or UNS S32550.
It is also designated ASTM A995 and ASME SA351/995 grade CD4MCuN or 1B, and written as J93372 or X2 CrNiMoCuN 25-6-3.
Wrought versus cast
We carry a comprehensive stock of Ferralium® 255 (1.4507, F61) as solid bar up to 16" diameter and plate up to 3" thickness, plus selected pipes and fittings.
Machining components from solid bar or plate reduces the risk of rejection, because the wrought product form is far less likely to contain internal defects. On castings, such defects often only appear after machining, losing considerable time and expense. Castings can still be effective for complex geometries, or for reducing cost on larger components and longer production runs, but the mechanical properties of a wrought product (rolled or forged) are significantly better than a cast one.
Ferralium® 255 key features
- Patented by Langley Alloys in 1968, Ferralium® 255 pioneered the addition of nitrogen as the first super duplex stainless steel
- Continuously developed through the 1990s to extend PREN > 40, and more recently to raise 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 sulphur levels minimise inclusions that can act as sites for pitting corrosion
- Higher copper content gives a self-healing effect at pitting sites, inhibiting further growth
- Particularly suitable for larger components, as sigma phase is much less likely to form than in other super duplex grades