DUPLEX & SUPER DUPLEX
Duplex & Super Duplex Stainless Steel for Critical Applications
MillsForge supplies duplex and super duplex stainless steels for corrosive, high-strength, and demanding industrial applications, with material sourcing, manufacturing coordination, machining, inspection, testing, documentation, and international delivery managed according to project requirements.
UNS S31803 · S32205 · S32750 · S32760
DUPLEX STAINLESS STEEL GRADES
Duplex & Super Duplex Grades We Supply
Nickel alloys are selected for applications where corrosion resistance, elevated-temperature performance, mechanical strength, or resistance to aggressive process environments is required.
UNS S31803
Duplex Stainless Steel
A widely specified duplex stainless steel combining useful mechanical strength with resistance to chloride stress corrosion cracking and general corrosion.
UNS S32205 / 2205
Duplex 2205
A commonly used duplex stainless steel grade with tighter composition requirements than S31803, widely selected for chemical processing, oil and gas, marine, and industrial applications.
UNS S32750 / 2507
Super Duplex 2507
A high-alloy super duplex stainless steel combining high mechanical strength with strong resistance to pitting, crevice corrosion, and chloride-containing environments.
UNS S32760
Super Duplex Stainless Steel
A highly alloyed super duplex stainless steel designed for demanding corrosive environments requiring high strength and resistance to localized corrosion.
GRADE COMPARISON
Duplex vs Super Duplex Stainless Steel
| Grade | Common Name | Type | PREN* | Typical Positioning |
| S31803 | Duplex | Duplex | ~35 | General duplex applications |
| S32205 | 2205 | Duplex | ~35 | Widely used industrial duplex |
| S32750 | 2507 | Super Duplex | ≥40 | Severe chloride environments |
| S32760 | Super Duplex | Super Duplex | ≥40 | Severe corrosion + high-strength applications |
*PREN is commonly used as an indicator of resistance to localized pitting corrosion. Actual values depend on chemical composition and the calculation method used.
PRODUCT FORMS
Duplex & Super Duplex in the Forms Your Project Requires
Rings · Discs · Blocks · Shafts · Custom Shapes
WN · Blind · SO · LJ · Threaded · Custom
BW · SW · Threaded · Custom Fittings
Round Bars · Hollow Bars · Flat Bars
Stud Bolts · Bolts · Nuts · Custom Fasteners
Drawing-Based · Machined · Made-to-Order
MATERIAL PERFORMANCE
Why Duplex & Super Duplex Stainless Steel?
Corrosion Resistance
Duplex and super duplex grades provide resistance to a range of corrosive environments, including chloride-containing service where appropriate material selection is critical.
High Mechanical Strength
Duplex stainless steels generally provide higher strength than conventional austenitic stainless steels, allowing their use in demanding pressure and structural applications.
Resistance to Localized Corrosion
Super duplex grades are selected for applications requiring enhanced resistance to pitting and crevice corrosion in aggressive environments.
Chloride SCC Resistance
Duplex microstructures provide improved resistance to chloride stress corrosion cracking compared with many conventional austenitic stainless steels.
STANDARDS & SPECIFICATIONS
Duplex Stainless Steel to Applicable Standards
Bars & Rods
ASTM A276 / A276M
Stainless steel bars and shapes in applicable duplex and super duplex grades.
Forgings & Flanges
ASTM A182 / A182M
Typical grades:
F51 — S31803
F60 — S32205
F53 — S32750
F55 — S32760
Fittings
ASTM A815 / A815M
Wrought ferritic, ferritic/austenitic, and martensitic stainless steel piping fittings.
Plate / Sheet / Strip
ASTM A240 / A240M
Chromium and chromium-nickel stainless steel plate, sheet, and strip, including applicable duplex and super duplex grades.
Additional Specifications
ASME · EN · NORSOK · Customer Specifications
Applicable material standards depend on grade, product form, dimensions, supply condition, and project requirements.
PROJECT SPECIFICATIONS
NORSOK & Project-Specific Requirements
Duplex and super duplex materials used in offshore, oil and gas, and other critical applications may be subject to additional project-specific requirements covering manufacturing route, heat treatment, corrosion testing, microstructure, mechanical properties, inspection, and documentation.
NORSOK M-630 · NORSOK M-650 · Project MDS · Customer Specifications
Compliance is reviewed against the applicable material data sheet, qualification requirements, product form, and project specification.
INSPECTION & TESTING
Testing for Duplex & Super Duplex Materials
PMI
Positive Material Identification
Material chemistry can be verified according to project and inspection requirements.
Microstructure & Ferrite
Micrographic Examination · Ferrite Evaluation
Microstructure and ferrite content can be evaluated where required by the applicable material or project specification.
Corrosion Testing
ASTM G48 & Project-Specified Corrosion Testing
Corrosion testing can be coordinated according to applicable grade, product form, test method, temperature, and acceptance criteria.
Mechanical Testing
Tensile · Impact · Hardness · Proof Load Where Applicable
Mechanical testing can be performed according to applicable product standards and project requirements.
QUALITY & COMPLIANCE
Material Traceability & Documentation
Heat Traceability: Heat number and material identification maintained according to order requirements.
Inspection Reports: Dimensional, PMI, NDT, mechanical, corrosion, and other applicable inspection records.
Material Certification: EN 10204 3.1 / 3.2
Third-Party Inspection: Independent inspection by recognized third-party organizations can be coordinated when required.
APPLICATIONS
Duplex & Super Duplex for Corrosive Environments
- Oil & Gas: Piping, valves, flanges, fasteners, and components for demanding production and processing environments.
- Offshore & Marine: Components exposed to seawater, chlorides, and demanding offshore service conditions.
- Chemical Processing: Equipment and piping components for corrosive process environments.
- Petrochemical: Pressure-containing and process components requiring corrosion resistance and mechanical strength.
- Desalination & Water Treatment: Materials selected for chloride-containing water and process environments.
- Industrial Equipment: Custom components for pumps, valves, pressure equipment, and engineered systems.
MATERIAL KNOWLEDGE
Compare Duplex & Super Duplex Grades
S31803 vs S32205
Understand the relationship and key differences between the two widely specified duplex stainless steel grades.
Duplex 2205 vs Super Duplex 2507
Compare corrosion resistance, strength, alloy composition, and typical applications.
S32750 vs S32760
Compare two widely used super duplex stainless steel grades for demanding corrosive service.
DUPLEX & SUPER DUPLEX REQUIREMENTS
Looking for a Specific Duplex or Super Duplex Grade?
Send us the material grade, product form, dimensions, quantity, applicable specification, inspection and testing requirements, and delivery destination. We will review your requirement and coordinate a suitable supply solution.
What to include in your RFQ:
Grade · Product Form · Size · Quantity · Standard · Testing · Inspection