Project Description

Alloy 31 (UNS N08031)

Alloy 31 (UNS N08031) is an iron-nickel-chromium-molybdenum alloy with nitrogen and copper additions which has hybridized properties of austenitic super stainless steels and regular nickel alloys. Alloy 31 has exceptional corrosion resistance to alkaline & halide-containing media, sulfuric acid, phosphoric acid, chlorine dioxide media, nitric acid as well as reducing & oxidizing medias. It is widely used in offshore & marine industries, chemical & petrochemical processing, pharmaceutical piping, oil and gas extraction, and ore digestion plants. Especially, Alloy 31 can be used for the fabrication of pressure vessels which may endure a wide temperature-range from cryogenic level to elevated temperatures(-196°C to 550 °C).

Equivalent Grades

Nicrofer 3127hMoNS1404Alloy 31N08031X1NiCrMoCu 32-28-71.4562X1NiCrMoCu 32-28-7

Product Forms

Wire, Bar, Strip, Sheet, Plate, Tube, Pipe, Pipe Fittings, Forgings

Chemical Composition, %


Typical Physical & Mechanical Properties (RT, Solution Annealed)

Density, g/cm3Melting Point, ℃Tensile Strength, MPaYield Strength, MPaElongation,%


Rod, Bar, Wire, ForgingsASTM B564, ASTM B581, ASTM B649, ASME SB581, ASME SB649
Plate, Sheet, StripASTM B625, ASME SB625, API 5LD
Pipe, TubeASTM B163, ASTM B423, ASTM B704, ASTM B705, ASTM B751, ASTM B775, ASTM B829, ASME SB163, ASME SB423, ASME SB704, ASME SB705, ASME SB751, ASME SB775, ASME SB829, ISO 6207, DIN 77751
OthersDIN 17744, ASTM B366, ASME SB366


  • Outstanding corrosion resistance in alkaline and acidic halide-containing media
  • Excellent resistance to sulfuric acid, even in highly concentrated form
  • Excellent resistance to corrosion and erosion in phosphoric acid media
  • Outstanding resistance to surface corrosion and local corrosion in chlorine dioxide bleaching plants in paper production
  • Excellent resistance in reducing and oxidizing media as well as in boiling azeotropic nitric acid
  • Good workability and weldability


  • Components for flue gas desulfurization (FGD) plants
  • Plants for the production of phosphoric acid via the wet digestion process
  • Pipes and heat exchangers for sulfuric acids contaminated with chlorides
  • Pipes containing ocean water and brackish water, condensers and chillers
  • Pickling plants for sulfuric acid as well as nitric-hydrofluoric acid
  • Treatment of sulfuric acids from waste
  • Evaporation and crystallization of salts
  • Components for the cellulose and paper industry
  • Digestion of ores, e.g. in HIPAL (high-pressure acid leach) plants for the digestion of laterite ores
  • Mineral oil production and refineries
  • Organic acids and ester synthesis
  • Fine chemicals
  • Strain-hardened transport and feed pipes as well as slicklines, wirelines and flowlines in the transport of oil and gas