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SUPER DUPLEX STAINLESS STEEL | HIGH-STRENGTH CORROSION-RESISTANT FASTENERS

Super Duplex UNS S32750 Bolts, Nuts, Studs & Washers | 2507 / ASTM A182 F53

Super Duplex UNS S32750 Fasteners combine very high mechanical strength with excellent resistance to chloride pitting, crevice corrosion and stress-corrosion cracking. Aanuraj supplies 2507 bolts, studs, nuts, washers and custom threaded fasteners for demanding industrial and export applications.

UNS S32750Super Duplex 2507EN 1.4410ASTM A182 F53ASTM A1082 TB32750X2CrNiMoN25-7-4SAF 2507
Technical Contents - Jump Directly to a Section OverviewGrade NamesKey FeaturesChemistryMechanicalPRENSolution AnnealingStandardsDimensionsFastener TypesEngineer GuideApplicationsWhy AanurajExport KeywordsBUY / TECH EXPERT

1. Super Duplex UNS S32750 Fasteners - Technical Overview

UNS S32750 is a high-alloy super duplex stainless steel with a ferritic-austenitic microstructure, designed for highly corrosive service and high mechanical strength.

Common names include UNS S32750, Super Duplex 2507, EN 1.4410, X2CrNiMoN25-7-4 and SAF 2507. ASTM A182 Grade F53 is a forged-product designation, while ASTM A1082/A1082M provides a high-strength stainless bolting specification and lists S32750 with grade-specific requirements.

~25CrHigh chromium family
800 MPaMin. tensile, A1082 up to 2 in.
550 MPaMin. yield, A1082 up to 2 in.
PREN >40Typical 2507 region
Engineering note: Specify the exact fastener standard, product form, size, heat treatment and inspection requirements. A182 F53 and A1082 are not interchangeable descriptions for every finished fastener.

2. Super Duplex 2507 - Different Names & Grade Designations

Designation / NameIdentificationUse
Super Duplex 2507Commercial nameGeneral engineering/procurement term.
UNS S32750UNS designationPrimary material identification.
EN 1.4410European material numberEuropean documents.
X2CrNiMoN25-7-4EN chemical designationEuropean grade designation.
SAF 2507Commercial nameWell-known 2507 name.
ASTM A182 F53Forged product gradeForged stainless pressure-component reference.
ASTM A1082 / TB32750High-strength boltingDedicated special-purpose stainless bolting reference.

3. Key Features of Super Duplex UNS S32750 Fasteners

Very High Strength
High proof and tensile strength for demanding bolted-joint designs.
Chloride SCC Resistance
Strong resistance to chloride stress-corrosion cracking in appropriate service.
High Pitting Resistance
Cr, Mo and N support strong pitting and crevice-corrosion resistance.
Seawater & Offshore
Selected for aggressive chloride environments and offshore equipment.
General Corrosion Resistance
Suitable for many aggressive chemical and petrochemical environments.
Erosion-Corrosion Resistance
Useful where flow and corrosive media challenge conventional stainless grades.

4. Super Duplex UNS S32750 Chemical Composition - Principal Elements

ElementASTM A182 F53 reference, wt.%Engineering role
Carbon (C)0.030 max.Low carbon limits carbide precipitation.
Silicon (Si)0.80 max.Process/deoxidation control.
Manganese (Mn)1.20 max.Process/alloy control.
Phosphorus (P)0.035 max.Controlled residual.
Sulfur (S)0.020 max.Controlled residual.
Chromium (Cr)24.0 - 26.0Passive-film and pitting resistance.
Nickel (Ni)6.0 - 8.0Austenite stabilization and toughness.
Molybdenum (Mo)3.0 - 5.0Localized-corrosion resistance.
Nitrogen (N)0.24 - 0.32Strength, austenite balance and pitting resistance.
Copper (Cu)0.50 max.Controlled minor element.
Iron (Fe)BalancePrincipal matrix element.

This is an ASTM A182 F53 material reference. The governing fastener specification and certified MTC control finished bolting.

5. Super Duplex S32750 Mechanical & Physical Properties

PropertyUp to 2 in. / 50 mmOver 2 in. / 50 mmBasis
Tensile Strength800 MPa / 116 ksi min.760 MPa / 110 ksi min.ASTM A1082 S32750
Yield Strength, 0.2%550 MPa / 80 ksi min.515 MPa / 75 ksi min.ASTM A1082 S32750
Elongation15% min.15% min.ASTM A1082
Hardness33 HRC / 310 HB max.33 HRC / 310 HB max.ASTM A1082
DensityApprox. 7.8 g/cm3Approx. 7.8 g/cm3Typical 2507 data
Elastic ModulusApprox. 200 GPaApprox. 200 GPaTypical 2507 data
Thermal ConductivityApprox. 15 W/m.KApprox. 15 W/m.KTypical 2507 data
Size matters: A1082 lists lower S32750 tensile/yield minimums above 2 in. Designers should state the actual size category.

6. PREN of Super Duplex 2507 - Pitting Resistance Equivalent Number

PREN = %Cr + 3.3 x %Mo + 16 x %N.

Typical 2507 PREN
Representative 25Cr-7Ni-4Mo-0.3N chemistry gives a PREN in the low-40s.
Why It Matters
Higher PREN generally indicates stronger pitting resistance, but it is not a complete corrosion qualification.
Service Conditions
Temperature, chloride, pH, surface condition, crevices and stress must also be evaluated.

7. Super Duplex S32750 Solution Annealing & Quenching

01Controlled Heating
Uniform heating
02Solution Anneal
1025-1125 C
03Complete Soak
Full section temperature
04Water Quench
Rapid cooling
05Inspection
Hardness + MTC
Heat-treatment reference: ASTM A1082 lists S32750 solution treatment at 1880-2060 F [1025-1125 C] with water quenching. Alleima SAF 2507 data recommends solution annealing around 1050-1120 C followed by water quenching for the applicable product form. The governing specification and qualified furnace procedure control the final cycle.

Super duplex heat treatment is intended to preserve the balanced ferritic-austenitic structure and corrosion performance. Avoid uncontrolled exposure in temperature ranges where undesirable intermetallic phases can form.

8. Super Duplex S32750 Fasteners - Standards & Specifications

RequirementReferencePurpose
Special-purpose boltingASTM A1082/A1082M + ASTM A962/A962MHigh-strength stainless bolting, testing, finish, threads, marking and certification requirements.
Forged pressure componentsASTM A182 F53 / ASME SA-182Forged S32750 pressure-component reference.
Bar / round stockASTM A276 / ASTM A479Stainless bar product forms.
Metric hex boltsISO 4014 / ISO 4017; DIN 931 / DIN 933Dimensional references.
Inch hex boltsASME B18.2.1Inch hex-bolt dimensions.
Metric nutsISO 4032 / DIN 934Metric hex-nut dimensions.
Inch nutsASME B18.2.2Inch nut dimensions.
ThreadsASME B1.1 / ISO metric thread standardsUNC/UNF and metric thread geometry/tolerances.
WashersISO 7089 / DIN 125 / ASME B18.21.1Plain washer dimensions.
Sour service where applicableNACE MR0175 / ISO 15156Service-environment qualification; project limits apply.

9. Super Duplex 2507 Fastener Dimensions - Metric & Inch

Metric Hex Bolts
M6 to M64 and larger project-specific sizes subject to the selected dimensional standard.
Inch Hex Bolts
Common 1/4 in to 2 in and larger special sizes to ASME dimensional requirements.
Full Threaded Studs
M8-M48 and inch configurations in full-thread or drawing-specific form.
Stud Bolts
Double-end, full-thread and special-length configurations.
Hex & Heavy Hex Nuts
Matching nuts to DIN, ISO or ASME dimensional requirements.
Plain Washers
Metric and USS/SAE-style inch washers to project specification.
Designer instruction: State nominal diameter, length, thread form, pitch/TPI, tolerance class, nut style, washer standard and governing material/fastener specification.

10. Types of Super Duplex UNS S32750 Fasteners

Hex Bolts
Heavy-duty bolting for flanges, equipment and process assemblies.
Hex Nuts
Matching high-strength nuts for S32750 bolting systems.
Full Threaded Studs
Studs for flanges, valves, pressure equipment and critical joints.
Stud Bolts
Double-end and full-thread configurations.
Washers
Plain washers for load distribution and corrosion-resistant assemblies.
U-Bolts & Special Fasteners
Custom pipe-support and drawing-controlled components.

11. Important Pointwise Guide for Designers & Engineers

1. Specify UNS S32750
Use the exact UNS grade instead of only writing "2507".
2. Specify the governing standard
Evaluate ASTM A1082/A1082M for special-purpose bolting and A182 F53 where a forged product specification is applicable.
3. Define size category
A1082 S32750 properties change above 2 in.
4. Control heat treatment
Solution annealing and rapid water quenching are critical.
5. Define threads
State metric pitch or UNC/UNF thread, tolerance and fit.
6. Define environment
Check chloride, seawater, H2S, temperature, pH and stress.
7. Require traceability
Specify heat number, MTC, PMI and inspection documents.
8. Check hardness
Confirm project/NACE limits before manufacture.
9. Check assembly compatibility
Evaluate mating metals, coating and service environment.

12. Super Duplex 2507 Bolts, Nuts, Studs & Washers - Applications

Oil & Gas
Offshore equipment, piping, valves and critical bolted joints.
Petrochemical
Process equipment, flanges, pumps and valves.
Marine & Offshore
Seawater systems and chloride-rich environments.
Desalination
High-chloride water systems and desalination equipment.
Power & Chemical
High-strength corrosion-resistant process bolting.
Heat Exchangers & Pumps
Equipment requiring high strength and localized-corrosion resistance.
Pulp & Paper
Corrosive process systems and equipment.
Water Treatment
Chloride-bearing water and process equipment.
Infrastructure
High-strength stainless mechanical assemblies.

13. Why Aanuraj for Super Duplex UNS S32750 Fasteners?

Hot Forging Expertise
The orange/yellow element of the Aanuraj identity represents the hot-forging process used for demanding fastener components.
Super Duplex Knowledge
Technical experience with duplex, super duplex, stainless and high-nickel fastener grades.
Material Traceability
Heat-wise identification, PMI and MTC documentation as required.
Forging + CNC + Thread Rolling
Integrated manufacturing capability supports dimensional control.
Custom Dimensions
Metric, inch, long-length studs, special bolts, nuts and washers.
Technical Support
Support for grade selection, standards, dimensions, heat treatment and documentation.

14. Super Duplex 2507 vs Duplex 2205 - Designer Reference

ConsiderationDuplex 2205Super Duplex 2507
UNSS31803 / S32205S32750
EN Number1.44621.4410
ChromiumApprox. 22%24-26%
MolybdenumApprox. 3%3-5%
NitrogenLower than 25070.24-0.32%
Typical PRENMid-30sLow-40s
StrengthHighVery high
Service selectionStrong general duplex optionMore aggressive chloride/corrosion and higher-strength requirements

15. European & Export SEO Keywords - Super Duplex UNS S32750 Fasteners

European countries: Germany, United Kingdom, France, Italy, Spain, Netherlands, Belgium, Poland, Sweden, Norway, Denmark, Finland, Austria, Switzerland, Czech Republic, Portugal, Greece, Ireland, Romania, Hungary and European Union markets.

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Technical note: This page is an engineering reference. The current applicable ASTM/ASME/EN/DIN standard, project specification, purchase order and certified MTC govern. ASTM A182 F53 is a forged product-form designation; ASTM A1082/A1082M is a high-strength bolting specification.