Super Duplex Steel Fasteners

Super Duplex Steel Fasteners, Material Overview & Form Factors

Super Duplex Steel is a high-performance alloy used wherever standard fasteners cannot meet the corrosion, temperature, or strength envelope. TorqBolt manufactures the full Super Duplex Steel 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 Excels

Super Duplex Steel 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 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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