Super Duplex UNS S32550 Fasteners

Super Duplex Steel S32550 Fasteners — Material Overview & Form Factors

Super Duplex Steel S32550 is a high-performance alloy used wherever standard fasteners cannot meet the corrosion, temperature, or strength envelope. TorqBolt manufactures the full Super Duplex Steel S32550 fastener range — bolts, nuts, screws, washers, studs, and custom forgings — under one ISO 9001:2015 quality system, with PED 2014/68/EU module-H qualification for pressure-equipment service.

Where Super Duplex Steel S32550 Excels

Super Duplex Steel S32550 is specified in oil & gas wellhead components, refinery heat exchangers, petrochemical reactors, power-generation turbines, marine offshore platforms, and pharmaceutical / food-grade processing. Its corrosion resistance, high-temperature strength, and weldability make it the default for service conditions outside the carbon and standard-stainless envelope.

Form Factors Available

Standards & Certification

Super Duplex Steel S32550 fasteners are supplied with EN 10204 3.1 (mill cert) or 3.2 (third-party witnessed) material test reports as standard. Additional certification packages: NACE MR0175 / ISO 15156, NORSOK M-650, API 6A (wellhead), API 20E (subsea bolting), PED 2014/68/EU. Third-party inspection by TUV, Lloyd's, BV, DNV, SGS, and Intertek arrangeable on order.

Duplex & Super Duplex Stainless Steels

Duplex stainless steels have ~50/50 ferrite-austenite microstructure, doubling yield strength of 304/316 grades while improving chloride pitting resistance.

Duplex 2205 (UNS S32205) is standard with PREN ~35. Super Duplex 2507 (S32750) and Zeron 100 (S32760) push PREN to 41-42. SA-182 F51 / F53 / F55 / F60 are the ASME forged-flange equivalents.

Phase balance is critical: ferrite must stay 35-65% in weld + HAZ (ASTM A923 testing). Solution anneal at 1040-1100°C followed by water quench. Fasteners ship per ASTM A276 / A479 with EN 10204 3.1 / 3.2 certs including ferrite count and Charpy at -46°C.

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