ISO 9001:2015 · UNS S32205–S32304 · ASTM A182 F60

Duplex Steel Fasteners Manufacturer, Supplier & Exporter of Premium Fasteners

Duplex steel fasteners deliver twice the yield strength of standard austenitic stainless steel with superior resistance to stress corrosion cracking and pitting. We supply Duplex 2205 and 2304 fasteners for oil & gas, marine, and chemical industries.

2

Grades

12

Products

-50°C

Min Temp

300°C

Max Temp

620 MPa

Min tensile strength · Duplex 2205 per ASTM A182 F60

Very Good

PREN 35+ · pitting & crevice corrosion resistance

7.82 g/cm³

Density (avg) · dual austenite-ferrite microstructure

The high-strength dual-phase alloy explained

What is Duplex Steel Fasteners?

Duplex stainless steel is a two-phase ferritic-austenitic alloy family containing 21–23% chromium, 4.5–6.5% nickel and 3–3.5% molybdenum, giving it approximately twice the yield strength of standard austenitic grades and significantly higher resistance to chloride stress corrosion cracking. The dual microstructure — approximately 50% austenite and 50% ferrite — combines the best properties of both phases for demanding corrosion-fatigue and high-strength applications. Duplex steel fasteners are specified for offshore platforms, pulp and paper digesters, desalination plants and structural marine applications where SS 316L is inadequate due to chloride SCC risk or weight constraints. Grade 2205 (UNS S32205) is the most widely used duplex fastener grade, with PREN ≥ 35 and yield strength of 450 MPa.
PropertySpecification
Microstructure50% Austenite + 50% Ferrite
Cr Content21–23%
Ni Content3–7%
Max Service Temperature300°C
PREN≥ 35 (2205)
ASTM StandardsA182 F60, A276

Duplex Steel grades — which do you need?

Multiple fastener grades and material grades of Duplex Steel Fasteners exist for demanding industrial fasteners and engineering applications, each providing distinct mechanical properties, corrosion resistance, temperature capability, and strength. Compare the available grades below to support precise material selection aligned with operating environment, industry standards, and specific engineering requirements.

Grade UNS PREN Key property Max temp Best application
Duplex 2205 (Most popular) UNS S32205 ≥ 35 Chloride + strength 300°C Offshore, pulp & paper View grade
Duplex 2304 UNS S32304 ≥ 25 Moderate chloride 280°C Water treatment, tanks View grade

Duplex Steel Fasteners — International Standards & Material Certifications

Duplex Steel Fasteners from RealBolt Engineering Industries are manufactured to ASME SA-182 F60, SA-276, and SA-479 material standards. Every batch ships with EN 10204 MTC 3.1; NACE MR0175/ISO 15156 sour gas documentation, NORSOK M-630, and third-party 3.2 certification are available for offshore applications.

Duplex Steel Fasteners Applications — Industries & Use Cases

Duplex Steel Fasteners from RealBolt Engineering Industries are specified by engineers and procurement teams across demanding industries where twice the yield strength of austenitic stainless steel combined with excellent chloride stress corrosion cracking and pitting resistance is critical to fastener performance and service life. Primary end-use sectors for Duplex Steel Fasteners include oil and gas offshore platforms, pulp and paper, desalination plants, marine structural, and chemical processing with chloride media — click each industry below to see specific application details and recommended grades.
Duplex 2205 (UNS S32205) fasteners are specified for offshore platform structural connections, subsea pipeline flanges and top-side process piping where both high strength (450 MPa yield) and chloride SCC resistance are required.
Duplex 2205 resists chloride-containing bleach liquors and acidic washing stages that attack SS 316L. Used in digesters, bleach-plant pipework and pressure vessel bolting.
Duplex 2205 and 2304 fasteners are used in multi-stage flash (MSF) and reverse osmosis (RO) desalination plants for their combined resistance to seawater chlorides and biofouling environments.
Organic acid tanks, urea synthesis vessels, and chloride-bearing scrubber systems where 316L is susceptible to stress corrosion cracking specify Duplex 2205 for its higher critical pitting temperature.
Duplex 2205 fasteners are used in cable-stay bridge anchor assemblies and port/jetty structural connections for the combination of high yield strength (avoiding bolt relaxation) and chloride corrosion resistance.

Duplex Steel vs Super Duplex vs Stainless Steel

This comparison table supports offshore engineers, corrosion engineers, and procurement managers in evaluating Duplex Steel Fasteners, Super Duplex 2507 Fasteners, and SS 316L Fasteners based on PREN pitting resistance, yield strength, maximum service temperature, NACE MR0175 and NORSOK M-630 compliance, and relative cost — for chloride-bearing, offshore, and sour gas service applications. Use this data to make an informed alloy selection for your specific operating environment, design code, and budget — or contact RealBolt’s technical team for a project-specific recommendation.
Property Duplex 2205 Super Duplex 2507 SS 316L
PREN (pitting resistance) >=35 >=40 ~24
Max service temp 300°C 300°C 800°C
Yield strength (min) 450 MPa 550 MPa 170 MPa
Tensile strength (min) 620 MPa 795 MPa 485 MPa
Relative cost Medium-High High Medium
NACE MR0175 compliant Yes Yes Conditional

Verdict: Duplex 2205 covers most offshore and chloride applications. Super Duplex 2507 is required where PREN >=40 is specified for subsea NORSOK M-630 service. SS 316L is the entry-level option for mild chloride environments.

Need Duplex Steel fasteners? Get a competitive price today.

Partner with RealBolt Engineering Industries for certified Duplex Steel Fasteners backed by full EN 10204 material test reports, competitive pricing, and reliable global delivery from our Mumbai facility. Our technical team supports specification of Duplex 2205 (F60) and Duplex 2304 Duplex Steel Fasteners with NACE MR0175, NORSOK M-630, and EN 10204 3.1/3.2 certification, in sizes M12–M100 and custom-machined specials from certified UNS S32205 and S32304 bar stock. Request a quote today and receive a competitive price within 24 hours.

Duplex Steel Fasteners — Common Questions Answered by Our Technical Team

Browse the expert answers below to the most frequently asked questions about Duplex Steel Fasteners — covering Duplex 2205 vs 2304 selection, PREN calculation and pitting resistance, NACE MR0175 sour gas compliance, NORSOK M-630 qualification, sigma-phase embrittlement temperature limits, available sizes, and EN 10204 3.1/3.2 documentation. If your question is not answered here, contact the RealBolt technical team directly for grade-specific guidance, project support, and competitive pricing on Duplex Steel Fasteners.
Duplex 2205 offers approximately twice the yield strength of SS 316L (450 MPa vs 170 MPa) and significantly higher resistance to chloride stress corrosion cracking (SCC) and pitting. This allows thinner cross-sections (cost saving) with better performance in warm chloride environments above 50°C where 316L is at risk of SCC.
PREN (Pitting Resistance Equivalent Number) = %Cr + 3.3×%Mo + 16×%N. A higher PREN indicates better resistance to chloride pitting. Duplex 2205 has PREN ≥ 35, making it suitable for seawater splash zones. Super Duplex 2507 (PREN ≥ 40) is recommended for fully submerged or flowing seawater service.
Duplex 2205 meets NACE MR0175 / ISO 15156 requirements for sour service in the annealed condition with hardness ≤ 28 HRC. We supply Duplex fasteners with NACE-compliant documentation. For higher H₂S partial pressures, Super Duplex 2507 may be specified.
Duplex 2205 fasteners are limited to 300°C continuous service. Above 280–320°C, sigma-phase embrittlement can occur, reducing impact toughness. For applications above 300°C, consider Inconel 625 or Hastelloy C276 which retain ductility at higher temperatures.

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