What is alloy 32750 (UNS S32750) material?

Alloy 32750 (UNS S32750) is a super duplex stainless steel supplied in the 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 >41, 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.

It achieves yield strengths of 80ksi (550Mpa), greater than most austenitic and duplex stainless steel grades. It cannot be hardened by heat treatment but can be strengthened by cold working. It also exhibits a low coefficient of thermal expansion and higher heat conductivity than austenitic steels and is suitable for working temperatures up to 300°C. Alloy 32750 is listed in NACE MR 0175 for sour service and having gained ASME Approval for Pressure Vessel applications it can be used in a wide variety of applications.

UNS S32750 steel Alloy 32750 material

UNS S32750 steel Alloy 32750 material

Service in highly corrosive conditions. The grade is characterized by:

  • Excellent resistance to stress corrosion cracking (SCC) in chloride-bearing environments
  • Excellent resistance to pitting and crevice corrosion
  • High resistance to general corrosion
  • Very high mechanical strength
  • Physical properties that offer design advantages
  • High resistance to erosion corrosion and corrosion fatigue
  • Good weldability


  • UNS: S32750
  • EN Number: 1.4410
  • EN Name: X 2 CrNiMoN 25-7-4
  • SS: 2328

Product standards

  • Seamless tube and pipe: EN 10216-5
  • Seamless and welded tube and pipe: ASTM A789; A790
  • Flanges: ASTM A182
  • Fittings: ASTM A182; (ASTM A815 applied for)
  • Plate, sheet and strip: ASTM A240, EN 10088-2
  • Bar steel: ASTM A479, EN 10088-3
  • Forged billets: EN 10088-3


  • Approved by the American Society of Mechanical Engineers (ASME) for use in accordance with ASME Boiler and Pressure Vessel Code, Section VIII, div. 1. There is no approval for UNS S32750 in the form of plate. However, according to ASME paragraph UG-15, the design values for seamless tube according to ASME Section VIII, div. 1 are also allowed to be used for plate.
  • ASME B31.3 Chemical Plant and Petroleum Refinery piping
  • NACE MR0175/ISO 15156 (Petroleum and natural gas industries – Materials for use in H2S-containing Environments in oil and gas production – Part 3: Cracking-resistant CRAs (corrosion resistant alloys and other alloys) (Published:2015)