Alloy 32760 (UNS S32760)

The grade known as ‘S32760’ was originally developed by Mather & Platt and marketed as Zeron 100. Mather & Platt was a UK-based company, hailing from Manchester, focused on the manufacture of large-scale centrifugal pumps. The use of super duplex stainless steels for such applications was obvious, given the potentially aggressive solutions being handled, requiring significant corrosion resistance, strength and wear resistance. Hence, the team at Mather & Platt sought to optimize ease of casting and long-term performance of their pump bodies for more demanding applications. The pump division of Mather & Platt was subsequently acquired by Weir Pumps, although the Manchester site and foundry closed. The Zeron 100 trademark is now held by Rolled Alloys Inc.

Alloy 32760 is a super duplex stainless steel supplied in the hot worked and solution annealed condition. As a super duplex stainless steel, it combines the desirable aspects of both austenitic and ferritic grades. The higher chromium, molybdenum and nitrogen contents result in a Pitting Resistance Equivalent number (PREN) of >40, providing pitting and crevice corrosion resistance superior to austenitic and duplex stainless steels in almost all corrosive media, and a Critical Pitting Temperature exceeding 50°C nb. versions of the PREN formula also include W as a positive influence on overall pitting resistance.

It provides higher strength than both austenitic and 22% Cr duplex stainless steels, and is listed in NACE MR 0175 for sour service and ASME for pressure vessel applications.