S32550 and S32760 are both super duplex stainless steels based on a 25% chromium addition. S32550 is supplied with a higher yield strength than S32760 in solid bar form, and its 2% copper addition gives superior resistance to sulphuric acid.
S32550 (Ferralium® 255)
Ferralium® 255 was the first commercially produced super duplex stainless steel. Langley Alloys patented it in 1967 and brought it to market under the Ferralium® trademark in 1969, giving it more than 50 years of track record in the most demanding environments. Its generic composition was later defined as UNS S32550 (DIN 1.4507).
S32760 (Zeron 100)
S32760 was originally developed by Mather & Platt, the Manchester-based UK pump maker, and marketed as Zeron 100. Super duplex was an obvious choice for pump bodies handling aggressive solutions. The Mather & Platt pump division was later acquired by Weir Pumps, though the Manchester site and foundry closed, and the Zeron 100 trademark is now held by Rolled Alloys Inc. Alloy 32760 (UNS S32760, 1.4501, F55) includes a deliberate addition of tungsten, claimed to selectively improve corrosion resistance.
Key differences
S32550 contains up to 2% copper to support increased resistance to sulphuric acid. It is also the only super duplex stainless steel to achieve a minimum yield strength of 85ksi (586N/mm2) as solid bar, where S32760 has a minimum of 80ksi (550N/mm2).
Availability
Ferralium® 255 (S32550) is available only from Langley Alloys, as round bar from 1/2"-14" (12.7-355.6mm), plate up to 3" (76.2mm), pipe, flanges and fittings. We also stock S32760 as round bars from 5/8"-20" diameter (15.87-508mm), plate up to 3" (76.2mm) thickness, plus pipes in scheduled sizes, flanges and fittings.