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Material Specification

Alloy 254SMo

Alloy 254SMo Fasteners
6% Molybdenum Super Austenitic Stainless Steel (UNS S31254 / 1.4547 / F44)

High Moly Stainless Steel Alloy 254SMo Fasteners

Buy Alloy 254SMo (UNS S31254 / DIN EN 1.4547 / 254 SMO® / ASTM A182 F44) bolts, studs, nuts, and severe-service fasteners from Exotic Alloy, conforming to ASTM A182 F44, ASTM A276, ASTM A479, NORSOK M-630 (MDS R17/R18), and NACE MR0175. 254SMo is the world's standard 6-moly super austenitic stainless steel, containing 6.0%–7.0% molybdenum and high nitrogen, achieving an exceptional Pitting Resistance Equivalent Number (PREN) ≥ 43.

Exotic Alloy manufactures Alloy 254SMo heavy hex bolts, socket cap screws, all-thread stud bolts, and custom CNC machined components in metric (M4 to M100) and imperial (1/4" to 4") sizes. It provides extreme resistance to chloride pitting, crevice corrosion in stagnant seawater, and high mechanical fatigue resistance.

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Alloy 254SMo Bolting Products

Alloy 254SMo Specifications & Standards

  • ASTM A182 F44 / A276 / A479
  • UNS S31254 / 254 SMO®
  • NACE MR0175 / ISO 15156
  • DIN EN ISO 10088-3 (1.4547)
  • X1CrNiMoCuN20-18-7
  • NORSOK M-630 (MDS R17/R18)
Alloy 254SMo Material Datasheet

Alloy 254SMo Properties

Chemical Composition (Alloy 254SMo)
Elements C Mn P S Si Cr Ni Mo Cu N Fe
Min % - - - - - 19.50 17.50 6.00 0.50 0.18 Balance
Max % 0.020 1.00 0.030 0.010 0.80 20.50 18.50 7.00 1.00 0.25 Balance
Mechanical Properties (Alloy 254SMo)
Condition / Heat Treatment Tensile Strength (MPa) Yield Strength (MPa) Elongation (%) Hardness
Solution Annealed (Bar / Fasteners) 650 - 850 300 35 % 210 - 250 HB

Alloy 254SMo Characteristics

  • 6.0%–7.0% molybdenum and nitrogen provide extreme localized corrosion resistance (PREN ≥ 43).
  • Outstanding resistance to crevice corrosion in chlorinated seawater and saline environments.
  • High mechanical yield strength (approx. 50% higher than standard 300 series austenitics).
  • Exceptional impact toughness and ductility preserved down to cryogenic temperatures (-196°C).
  • Full compliance with strict NORSOK and subsea oil & gas qualification standards.

Applications

  • Subsea manifolds, flowlines, and marine riser bolting systems.
  • Offshore seawater cooling, firewater mains, and ballast systems.
  • Pulp mill chlorination bleaching stages, filter washers, and vats.
  • Seawater reverse-osmosis desalination high-pressure pumps and headers.
  • Marine scrubbers, flue-gas cleaning, and coastal infrastructure.