ZERON® 100

ZERON 100 High Pressure Piping in a Reverse Osmosis Desalination Plant

ZERON® 100 (F55 Duplex / 25Cr Duplex) is a super duplex stainless steel for use in aggressive environments.

Its properties include:

    • Resistant to pitting and crevice corrosion in warm seawater with a guaranteed corrosion performance (PREN > 40)
    • Lower more stable price compared to nickel based alloys
    • Excellent resistance to stress corrosion cracking in both chloride and sour environments
    • Superior resistance to sulfuric acid at most concentrations
    • Improved resistance over austenitic stainless to erosion corrosion and corrosion fatigue
    • High Strength (80,000 psi minimum Yield Strength) permitting designs to reduce weight versus other corrosion resistant alloys
    • Readily weldable using ZERON 100 filler metal

ZERON 100 Fire Protection Piping on an offshore oil platform

ZERON 100 complies with UNS S32760, however, Rolled Alloys tightly controls the chemistry and production of ZERON 100 in strict accordance with the requirements of our in-house 'MDS' specifications which are tighter than standard ASTM specifications. This ensures a consistent quality product is produced with optimal corrosion resistance and charpy impact toughness.

Performance Profile

ZERON 100 was developed as a seawater resistant material for pump applications in the North Sea as a cast material. Its excellent performance, led to demand for the alloy in a wider range of product forms and the development of wrought product forms. The corrosion resistance and strength properties of ZERON 100 have led to its widespread adoption in a range of industries. Oil and gas applications include process, seawater, firewater and subsea pipework systems, with associated risers, manifolds, pressure vessels, valves and heat exchangers. Applications of ZERON® 100 (UNS S32760) in other industries include pollution control equipment such as flue gas desulfurization equipment (FGD), pulp and paper, power generation, chemical, pharmaceutical, desalination, mining, metallurgical and marine industries.

Optimized versions of ZERON 100 are available for specific applications. These include:

  • ZERON 100 FG (fastener grade) which is a strain hardened bar product available up to 2-1/2 inch diameter for high strength fasteners. ZERON® 100 FG is made to ASTM A276 condition S and also meets the tensile properties for  ASTM A193 grade B7.  It meets charpy impact toughness of 40 Joules (29.5 ft.lbf.) minimum at -50°C (-58°F).
  • ZERON 100X overalloyed weld filler for welding of ZERON 100 to itself and other stainless steels.
  • ZERON 100M matching weld filler for welding ZERON 100 components that will be post weld annealed.
  • ZERON 100HS (high strength) wire for slick line applications in oil and gas.


MIN 24.0 6.0 3.0 0.5 0.5 -- 0.2 -- -- -- -- --
MAX 26.0 8.0 4.0 1.0 1.0 0.03 0.3 1.0 1.0 0.030 0.010 Balance

PREN = %Cr + 3.3x%Mo + 16x%N    ZERON 100 PREN > 40

For standards ISO 15156/NACE MR0175 and BS 4515-2 a different PREN formula including tungsten is used.  Using the formula PREN = %Cr 3.3(%Mo + 0.5x%W) + 16x%N, ZERON 100 has a  PREN > 41


ASTM A 182ASTM A 182 (Grade F55)ASTM A 240ASTM A 276
ASTM A 473
ASTM A 479ASTM A 790
ASTM A 815
NORSOK MDS 055UNS S32760W. Nr./EN 1.4501
Werkstoff 1.4501


ZERON® 100 Fittings, ZERON® 100 Pipe, ZERON® 100 Plate, ZERON® 100 Round Bar, ZERON® 100 Sheet, ZERON® 100 Weld Wire

Common Trade Names

Super Duplex Stainless, UNS S32760, F55 Duplex, EN 1.4501, 25Cr Duplex, Super Duplex


  • Desal - Arona
  • Cantarell
  • Murrim Vessel
  • Sparge Pipes
  • Damper

Mechanical Properties

Temperature, °F 68 212 302 392 482
Ultimate Tensile Strength, ksi 109 102 99 97 94
0.2% Offset Yield Strength, ksi 80 68 65 62 58

Design Stresses – Pressure Vessels (ASME)

ZERON 100 (UNS S32760) is covered for ASME Section VIII, Division 1 construction by code case 2245 and in Section III, Division 1 by Case N-564-2. It is also included in B16.5 (Pipe Flanges and Flanged Fittings), B16.34 (Valves - Flanged, Threaded, and Welding End), 16.47 (Large Diameter Steel Flanges: NPS 26 through NPS 60), B31.3 (process Piping).

Temp, °F100200300400500600
Zeron 1001 31.1 ksi 31.0 ksi 29.4 ksi 29.0 ksi 29.0 ksi 29.0 ksi
22051 25.7 ksi 25.7 ksi 24.8 ksi 23.9 ksi 23.3 ksi 23.1 ksi
AL-6XN®1 27.1 ksi 27.1 ksi 25.7 ksi 24.6 ksi 23.8 ksi 23.3 ksi
ZERON 1002 36.3 ksi 35.9 ksi 34.4 ksi 34.0 ksi 34.0 ksi 34.0 ksi

 1 ASME Section VIII, Division 1; 2ASME B31.3

Impact Strength

ZERON® 100 has good impact strength. There is no true ductile brittle transition, just a gradual decrease in impact energy as the temperature is lowered. The impact energy varies according to product type and production route.  The impact strength of welded ZERON® 100 is slightly less than that of parent metal.

Present data suggests that 40J (30ft.lbf) is a suitable acceptance criterion for duplex stainless steels and figure 1 shows that 40J is achievable with all product forms of ZERON® 100 (UNS S32760) down to very low temperatures.  To obtain good impact toughness after welding, it requires a higher level of impact toughness in the parent material.  ZERON® 100 super duplex stainless steel base metal typically has a Charpy toughness > 70J at -50°C.

Corrosion Resistance

ZERON 100 compares favorably in chloride pitting resistance to more expensive 6% molybdenum alloys and is superior to 2205 or 316L.

316L 2.1 < 28 68 24
2205 3.1 68 120 35
904L 4.4 75 130 36
ZERON 100 3.5 108 180 41
AL-6XN 6.2 110 172 44
625 9.0 113 - 51
C22 13 - - 64
C-276 15.5 130 > 217 67

* CCCT - 10% FeCl3 6H20, per ASTM G 48 Practice B, CPT - 1 M NaCl, per ASTM G 150, PREN = Cr + 3.3 Mo + 16N

The copper addition in ZERON 100 is responsible for its enhanced resistance to sulfuric acid. ZERON 100 super duplex is superior to the more expensive grades such as alloy 20 or alloy 825 and is superior to duplex 2205 and 2507 super duplex at most concentrations. ZERON 100 super duplex also compares favorably to high silicon austenitic stainless steels, such as ZeCor®, SX, and Saramet in hot concentrated sulfuric acid. The iso-corrosion curves below show the 0.1 mm/year (0.004 ipy) corrosion lines for ZERON 100 super duplex and other alloys in dilute sulfuric and concentrated sulfuric acid

Zeron 100 Boiling Point CurveZeron 100 Corrosion Curve Graph