Material: Duplex Stainless Steel – Strength Meets Corrosion Resistance
Overview:
Duplex Stainless Steel is a two-phase alloy combining both austenitic and ferritic microstructures, offering a rare balance of high strength, excellent corrosion resistance, and cost-efficiency. With nearly twice the strength of standard austenitic stainless steels and improved resistance to chloride-induced corrosion, Duplex steel is the ideal solution for critical industrial fasteners.
At SM Fasteners, we specialize in precision-machined Duplex grade fasteners that meet international standards and provide long-lasting performance in aggressive and high-pressure environments.
Why Choose Duplex Fasteners?
Duplex stainless steels (such as UNS S31803 / S32205) are used where ordinary stainless steels fall short, especially in marine, oil & gas, and chemical processing applications.
✅ Higher tensile and yield strength than SS 304/316
✅ Excellent pitting and crevice corrosion resistance
✅ Resistant to chloride stress corrosion cracking (CSCC)
✅ Superior weldability and fatigue strength
✅ Cost-effective alternative to nickel alloys
Chemical Composition (Duplex S31803 / S32205)
| Element | % Composition |
|---|---|
| Chromium (Cr) | 21.0 – 23.0 |
| Nickel (Ni) | 4.5 – 6.5 |
| Molybdenum (Mo) | 2.5 – 3.5 |
| Nitrogen (N) | 0.08 – 0.20 |
| Manganese (Mn) | ≤ 2.0 |
| Carbon (C) | ≤ 0.030 |
| Iron (Fe) | Balance |
Mechanical Properties
| Property | Value |
|---|---|
| Tensile Strength | ≥ 620 MPa |
| Yield Strength (0.2% Offset) | ≥ 450 MPa |
| Elongation | ≥ 25% |
| Hardness | ≤ 290 HBW |
| Impact Toughness | Excellent (Even at sub-zero) |
Applications of Duplex Fasteners
Duplex fasteners are engineered for highly corrosive, high-load environments where performance and durability are critical:
Offshore Platforms & Subsea Equipment
Chemical Processing Plants
Heat Exchangers & Condensers
Paper & Pulp Bleaching Systems
Desalination Plants
Water Treatment & Storage Tanks
Mining & Fertilizer Industries
Duplex Fastener Types Available
Hex Bolts & Heavy Hex Bolts
Studs (Full & Double-Ended)
Nuts (Hex, Dome, Lock)
Washers (Flat, Spring, Tapered)
U-Bolts, Eye Bolts, L-Bolts, Custom Forged Fasteners
Packaging & Delivery
Our Duplex fasteners are carefully packed and labeled for industrial use and export:
Packed in corrosion-resistant VCI bags
High-strength wooden or corrugated boxes
Clear labeling with grade, size, heat number, and batch
Ready for global shipping and urgent dispatch across India
Documentation & Certifications
We ensure traceability and compliance by offering:
Mill Test Certificate (EN 10204 3.1 / 3.2)
PMI (Positive Material Identification)
Hardness & Ultrasonic Testing (if required)
IGC & Ferrite Testing Reports
Third-party Inspection Certificates
RoHS & REACH Compliance Reports
Request a Quotation or Technical Assistance
Have a project that demands corrosion resistance and strength? We’re here to assist.
📧 susheel@smfastners.com
📱 +91 8968469570
💬 WhatsApp Chat
🔩 SM Fasteners – Trusted Supplier of Duplex Stainless Steel Fasteners Across Industries