Our Super Duplex bolts (Grade S32750) offer exceptional performance in harsh environments. They resist chloride-induced stress corrosion cracking up to three times better than standard 316 stainless steel. A nitrogen-enhanced formula achieves a tensile strength of 1000 MPa. Independent testing (ASTM G48) confirms zero pitting corrosion.
Each batch is precision cold-forged and strain-hardened to ensure consistent thread strength. We offer two key surface finishes:
Passivation (per ASTM A967)
Electrolytic polishing minimizes friction during installation while improving chloride resistance.
Magnetic particle inspection (per ASTM E709) detects surface defects before shipment.
Our Henan factory features an automated cold-forming line with an annual production capacity of 800 million duplex fasteners. Real-time process control ensures:
Hardness consistency: 30-35 HRC across all batches
Zero σ phase: Intermetallic content <0.5%
Full traceability: Laser-marked heat number and material certificate
We have over 2,000 pallets for M12-M64 bolts and guarantee shipping within 48 hours for standard orders.
Order 5+ tons and get:
Free salt-spray testing reports (ISO 9227) with your shipment
Dedicated technical support for installation torque calculations
Performance guarantee: If any bolt shows corrosion below PREN 40 value in chloride service, we'll replace the entire batch + cover lab analysis costs.
Plus: Container-load orders receive 6-month corrosion warranty extension.
Super Duplex Stainless Steel S32750 (UNS S32750; equivalent to 2507, DIN 1.4410)
Chemical Composition
Cr: 24.0-26.0%, Ni: 6.0-8.0%, Mo: 3.0-5.0%, N: 0.24-0.32%, C: ≤0.03%, Mn: ≤1.0%, Si: ≤0.8%, P: ≤0.03%, S: ≤0.02%, Cu: ≤0.5%
Mechanical Properties
Tensile Strength: ≥800 MPa
Yield Strength: ≥550 MPa
Hardness: ≤310 HB (Brinell); ≤32 HRC
Elongation: ≥15%
Corrosion Resistance
Exceptional resistance to pitting, crevice corrosion, and stress corrosion cracking (SCC) in extreme chloride environments (e.g., high-salinity seawater, acidic brines). Pitting Resistance Equivalent (PREN) ≥40 (superior to 2205 and 316).
Temperature Range
Service temperature: -50°C to 300°C (suitable for high-pressure, high-chloride industrial and offshore applications).
Magnetic Property
Magnetic (duplex microstructure: ~50% ferrite + ~50% austenite)
Thread Type
Full Threaded (continuous threading along the entire length)
Thread Standards
Metric Coarse (ISO), UNC (Unified National Coarse), UNF (Unified National Fine)
Metric Sizes (M)
M8 to M64 (common: M10, M12, M16, M20, M24, M30)
Imperial Sizes
3/8" to 2-1/2" (common: 1/2", 5/8", 3/4", 1", 1-1/4")
Length Range
50 mm to 6000 mm (metric); 2" to 240" (imperial)
Standards Compliance
ASTM A193 B8S Class 2, ASME SA193, ISO 898-6, DIN 976
Key Applications
Offshore oil/gas: subsea manifolds, wellhead connectors, riser systems
Chemical processing: high-pressure reactors, chloride-based solvent lines
Desalination: high-salinity brine handling
Marine: offshore platforms, seawater cooling systems
Surface Finish
Pickled, passivated, or polished (to enhance corrosion resistance and reduce contamination risk)
Frequently Asked Questions
Q: What is the minimum order quantity (MOQ) for custom products?
A: The MOQ for custom products depends on specifications, but generally starts from 1 pieces. For special cases, we can discuss further.
Q: Can you print our company logo on the products?
A: Yes, we can print your logo via laser engraving or stamping, as long as you provide the design file.
Q: Do you accept small quantity orders?
A: Yes, we accept small quantity orders. Even for trial orders, we'll provide the same quality and service as bulk orders.
