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UNS S32550 - FERRALIUM 255 -F61

Ferralium 255 is a duplex alloy with excellent abrasion and cavitation resistance. SCC, pitting, and crevice corrosion resistance to chlorideIn marine applications, high ductility with high fatigue strength Doubling the yield strength of Alloy 20 and Duplex 2205 A critical pitting temperature of 40 °C (ASTM G48-Method A) is excellent.

The chemical, marine, metallurgical, municipal sanitation, plastics, oil and gas, petrochemical, pollution control, wet phosphoric acid, paper making, and metalworking industries all use FERRALIUM 255.

FERRALIUM 255 is used in areas where conventional stainless steels are inadequate or marginal. In the paper industry, for example, environmental laws forced the recycling of process liquids, causing an epidemic of corrosion. Closed systems can accumulate highly corrosive chemicals like chlorides. Paper makers discovered that previously reliable stainless steel equipment was no longer adequate for many applications.


  • F61 / UNS 32550
  • ASTM A276
  • ASTM A479
  • ASME SA479
  • W.1.4507
  • EN 10088-3
  • NACE MR0175 / ISO 15156-3
  • NACE MR0103 / ISO 17945

Fluid Flow Applications :

Process Temperature Corrodant Prior Material
Caffeine Production 95 °C Cholrides 316
Waste Odor Removal Ambient Cholrides -
Wet Process Phos Acid 180 °F H 2 SO 4 Solids 317L/316L
Sour Gas Downhole Instruments Up to 350 °F H 2 S Chlorides 316, 410,Nitronic 50
Waste Water Treatment 150-300 °F Mixed Acids Chlorides 316 FRP
Polycarbonate Production 250-300 °F Ambient 2205
Demineralize Water Ambient Chlorides PVC, Carbon Steel, Stainless
Gold Mine Oxygen Lance and Vent 217 °F H 2 SO 4 Chlorides 316, C-276 600, TI

Chemistry :

FERRALIUM 255's high critical pitting temperature and high critical crevice temperature provide more resistance to pitting and crevice corrosion than lesser alloyed materials. The alloy's very high yield strength combined with good ductility allows lower wall thicknesses in process equipment.

Chemical Requirements

Ni Cr Mo Mn C Si Fe
Max 6.5 27.0 3.9 1.50 0.04 1.00 Bal
Min 4.5 24.0 2.9

Tensile Data :

Mechanical Property Requirements

Ultimate Tensile Yield Strength (0.2% OS) Elong R/A Hardness Brinell
Min 110 KSi 80 KSi 15%9
Max 297
Min 760 MPa 550 MPa


FERRALIUM 255 is a cost effective alternative to materials such as the nickel alloys, 20 type alloys, brass and bronze. Marine environments have long been the domain of admiralty bronze. Alloy 255 is replacing admiralty bronze, and the nickel alloys, in offshore platforms, deck hardware, rudders and shafting.
Alloy 255 is also making inroads in "borderline" corrosion applications where the nickel alloys and high performance alloys have been used but may not have been absolutely necessary. In some instances, it has even been used to replace high performance Ni-Cr-Mo-F-Cu alloys in the phosphoric acid industry. Valves, pumps, shafts, marine environments, Applications in down-hole, waste water, polycarbonate production, and demineralized water production.

Work Process

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