When your application demands absolute reliability in extreme heat, aggressive chemicals, or harsh marine environments, standard fasteners simply won’t do. Unifit Fastener’s Inconel 625 fasteners (UNS N06625 / WNR 2.4856) are engineered for exactly those conditions. As an ISO 9001:2015 certified manufacturer and global exporter based in India, Unifit Fastener produces a comprehensive range of Alloy 625 bolts, nuts, studs, washers, and screws conforming to ASTM B564, ASME SB564, DIN 2.4856, and all major international standards.
Inconel 625 is a nickel–chromium–molybdenum superalloy celebrated for its outstanding corrosion resistance across a spectrum of media including sulfuric acid, hydrochloric acid, seawater, and caustic solutions, combined with exceptional tensile strength up to 930 MPa and a usable temperature range stretching from cryogenic conditions all the way to 1000°C.
Whether you’re operating in offshore oil & gas, chemical processing, aerospace, nuclear power, or marine engineering, Unifit Fastener delivers precision-engineered Inconel 625 fasteners with full MTC documentation, third-party inspection, and competitive lead times — so your critical assemblies never compromise on performance.
Unifit Fastener is a leading ISO 9001:2015 certified manufacturer, stockist, and global exporter of Inconel 625 Fasteners in India. Our Alloy 625 fasteners are produced under strict quality controls and are available in a complete range of forms: hex bolts, stud bolts, heavy hex nuts, socket cap screws, washers, threaded rods, and custom configurations.
As a manufacturer with deep metallurgical expertise, we guarantee dimensional accuracy to ±0.03 mm, full material traceability, and compliance with all major international standards — giving procurement engineers and project managers the confidence they need for mission-critical installations.
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Inconel 625 Fasteners Specifications
| International Standards | ASTM B564, ASME SB564, ASTM F468, ASTM F467, DIN, ISO, JIS, BS, AFNOR, GOST |
|---|---|
| Size (Bolts) | M3 to M100 / 3/16" to 4" / Custom |
| Nuts Size | M3 to M56 / 3/16" to 2" / Custom |
| Washer Size | M3 to M56 / 3/16" to 2" / Custom |
| Fasteners Length | 3 mm to 500 mm / Custom |
| Threads Available | UNF, UNC, BSW, BSF, METRIC, NPT, UNS, or as required |
| Thread Configuration | ASME B1.1, B1.13M - 2A/3A, 2B/3B, 6h-6G Metric Coarse |
| Form / Shape | Hex, Square, Round, Threading as per customer requirement |
| Head Types | Hex, Square, Round, Hex Flange, Flat, T-Head, Triangular |
| Neck Type | Hex, Square, Triangular, Oval, Knurled |
| Manufacturing Process | Hot Forging, Cold Forging, CNC Machining, Wire Drawing |
| Surface Treatment | Mill Finish, Polished, Brushed, Passivated, Phosphating, HDG |
| Dimensional Standards | DIN 931, 933, 934, 976, 125, ASME B18.2.1, B18.3 |
| Test Certificate | EN 10204 3.1 / 3.2, PED 97/23/EC, Merkblatt AD 2000 W2 |
| Certification | Dual Certified as per ASTM and ASME Codes |
| Packing | Wooden Cases, Wooden Pallets, Carton Boxes - Bulk or per request |
| Tolerance | +/-0.03 mm OEM/ODM |
Types Of Inconel 625 Fasteners
Unifit Fastener supplies Alloy 625 bolts, nuts, washers, screws, threaded rods, and studs for critical assemblies in offshore, marine, chemical, aerospace, and power generation environments.
Inconel 625 Bolts
Inconel 625 Nuts
Inconel 625 Washers
Inconel 625 Screws
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Alloy 625 Fasteners Chemical Composition
| Element | Symbol | Content (%) |
|---|---|---|
| Carbon | C | 0.10 max |
| Chromium | Cr | 20.0 - 23.0 |
| Molybdenum | Mo | 8.0 - 10.0 |
| Niobium + Tantalum | Nb + Ta | 3.15 - 4.15 |
| Nickel | Ni | 58.0 min |
| Iron | Fe | 5.0 max |
| Manganese | Mn | 0.50 max |
| Silicon | Si | 0.50 max |
| Sulfur | S | 0.015 max |
| Aluminum | Al | 0.40 max |
| Titanium | Ti | 0.40 max |
| Cobalt | Co | 1.00 max |
The high nickel (58% min) and chromium (20-23%) content provide a formidable barrier against oxidizing and reducing acids, while molybdenum (8-10%) and niobium (3.15-4.15%) deliver exceptional resistance to pitting, crevice corrosion, and intergranular attack even in sensitized conditions.
Mechanical Properties of Inconel 625 Fasteners
| Property | Value (Imperial) | Value (Metric) |
|---|---|---|
| Tensile Strength | 135,000 PSI | 930 MPa |
| Yield Strength (0.2% Offset) | 75,000 PSI | 517 MPa |
| Elongation | 42.5% | 42.5% |
| Hardness (Rockwell) | 145-220 HRB | - |
| Reduction of Area | 40% | 40% |
Physical Properties of Inconel 625 LCF Screws
| Property | Unit | Value |
|---|---|---|
| Density | g/cm³ | 8.44 |
| Density | lb/in³ | 0.305 |
| Melting Range | °F | 2350 - 2460 |
| Melting Range | °C | 1290 - 1350 |
| Curie Temperature | °C | -196 |
| Permeability | kA/m | 1.0006 at 15.9 |
| Modulus of Elasticity | GPa | 207 |
Inconel 625 Fasteners International Equivalent Standards
| Standard Body | Designation |
|---|---|
| UNS (American) | N06625 |
| Werkstoff Nr. (German/European) | 2.4856 |
| AFNOR (French) | NC22DNB4M |
| JIS (Japanese) | NCF 625 |
| BS (English) | NA 21 |
| GOST (Russian) | XH75MBTIO |
| EN | NiCr22Mo9Nb |
| Trade Names | Altemp 625, Chronin 625, Nickelvac 625 |
Types of Inconel 625 Fasteners
Inconel 625 Bolts
| Type | Size Range |
|---|---|
| Inconel 625 Hex Bolts (ASTM B564) | M4 to M100 / 1/4" to 4" |
| Heavy Hex Bolts | M12 to M72 |
| Carriage Bolts (DIN 2.4856) | M6 to M48 |
| Eye Bolts (ASTM F468 UNS N06625) | M8 to M64 |
| U-Bolts | M8 to M48 |
| Stud Bolts (ASTM F468) | M12 to M72 |
| 12-Point Flange Bolts | M10 to M56 |
| Anchor Bolts | M12 to M100 |
| J Bolts / Hook Bolts | M8 to M48 |
| Forged Hook Bolts | M10 to M64 |
| Allen / Hex Socket Bolts | M5 to M48 |
| Countersunk Bolts | M5 to M48 |
| Flange Head Bolts | M6 to M56 |
| Elevator Bolts | M6 to M36 |
| Lag Bolts | M6 to M36 |
Inconel 625 Nuts
| Type | Size Range |
|---|---|
| Hex Nuts (ASTM B564) | M3 to M56 |
| Heavy Hex Nuts | M12 to M72 |
| Square Nuts | M4 to M36 |
| Nylock / Nyloc Nuts | M6 to M56 |
| Castle Nuts | M8 to M48 |
| Flange Nuts | M6 to M48 |
| Acorn / Dome Nuts | M4 to M36 |
| Jam Nuts (DIN 2.4856) | M4 to M36 |
| Wing Nuts (Inconel 2.4856) | M4 to M36 |
| T-Nuts | M4 to M20 |
| Rivet Nuts (UNS N06625) | M3 to M16 |
| Insert Nuts | M3 to M16 |
| 12-Point Nuts | M6 to M48 |
| Coupling / Sleeve Nuts | M6 to M56 |
| Lock Nuts | M3 to M36 |
Inconel 625 Washers
| Type | Size Range |
|---|---|
| Plain / Flat Washers (ASTM B564) | M3 to M56 |
| Spring Lock Washers (DIN 2.4856) | M3 to M56 |
| Square Washers (UNS N06625) | M6 to M48 |
| Ogee Washers | M10 to M48 |
| Star Washers | M3 to M36 |
| Fender Washers (Inconel 2.4856) | M4 to M48 |
| Sealing Washers | M4 to M36 |
| Structural Washers (Chornin 625) | M10 to M48 |
| Tab Washers (ASME SB564) | M6 to M48 |
Inconel 625 Screws and Threaded Rods
| Type | Size Range |
|---|---|
| Socket Cap Screws (UNS N06626) | M3 to M48 |
| Button Head Screws | M3 to M24 |
| Torx Screws (ASTM B564) | M3 to M24 |
| Self-Drilling Screws | M4 to M14 |
| Self-Tapping Screws | M4 to M14 |
| Wood Screws (F468 UNS N06625) | M4 to M14 |
| Grub / Set Screws (DIN 2.4856) | M3 to M24 |
| Countersunk Screws | M3 to M24 |
| Machine Screws (Alloy 625) | M3 to M20 |
| Threaded Rods / Studs | M4 to M45 |
| Double-End Studs (N06625) | M6 to M56 |
| Tap-End Studs (ASTM F468) | M6 to M56 |
Inconel 625 Bolt Torque Chart
Proper torque application is critical for joint integrity. The values below are guidelines for clean, dry-threaded and lubricated Inconel 625 bolts at ambient temperature.
| Diameter | Threads/inch | Torque (ft-lb) Dry | Torque (ft-lb) Lubricated |
|---|---|---|---|
| 1/4" | 20 to 28 | 7.8 - 8.9 | 5.8 - 6.6 |
| 5/16" | 18 to 24 | 15.9 - 17.6 | 12.0 - 13.2 |
| 3/8" | 16 to 24 | 28.2 - 32.0 | 21.2 - 23.9 |
| 7/16" | 14 to 20 | 45.1 - 50.4 | 33.9 - 37.8 |
| 1/2" | 13 to 20 | 68.8 - 77.6 | 51.6 - 58.2 |
| 9/16" | 12 to 18 | 99.2 - 110.8 | 74.5 - 83.1 |
| 5/8" | 11 to 18 | 137.0 - 155.2 | 102.8 - 116.4 |
| 3/4" | 10 to 16 | 244 - 271 | 183 - 204 |
| 7/8" | 9 to 14 | 392 - 433 | 294 - 324 |
| 1" | 8 to 14 | 588 - 659 | 441 - 495 |
| 1-1/4" | 7 to 12 | 1024 - 1133 | 767 - 849 |
| 1-1/2" | 6 to 12 | 1780 - 2003 | 1335 - 1502 |
Key Advantages of Inconel 625 Fasteners
| Advantage | Why It Matters |
|---|---|
| Outstanding Corrosion Resistance | Resists sulfuric, hydrochloric, phosphoric acids and seawater, ideal for chemical plants, offshore platforms, and desalination units |
| High Tensile and Yield Strength | 930 MPa tensile / 517 MPa yield enables use in high-pressure systems without over-dimensioning |
| Wide Operating Temperature | Performs reliably from cryogenic (-196°C) to high heat (1000°C) |
| Non-Magnetic Properties | Critical for applications near sensitive electronics, MRI, and downhole instrumentation |
| Excellent Fatigue Resistance | Withstands cyclic loading in turbines, pumps, compressors, and subsea connectors |
| Low Thermal Expansion | Maintains dimensional stability across temperature swings, preventing joint loosening |
| Weldability without PWHT | Can be welded without post-weld heat treatment, reducing fabrication cost and time |
| Crevice and Pitting Resistance | High Mo and Nb content prevent localized corrosion in tight joints and threaded interfaces |
| Seawater Compatibility | Fully resistant to biofouling environments and chloride stress-corrosion cracking |
| Versatile Formability | Available across standard fastener forms and custom geometries |
Where Are Inconel 625 Fasteners Used?
Inconel 625 fasteners are the material of choice across demanding industrial sectors where standard stainless steel or carbon steel fasteners fail.
| Industry | Specific Application |
|---|---|
| Offshore Oil and Gas | Wellhead assemblies, subsea manifolds, riser clamps, BOP systems |
| Chemical Processing | Reactor vessels, heat exchanger flanges, acid-handling pipelines |
| Aerospace and Defense | Engine exhaust mounts, airframe structural fasteners, nacelle hardware |
| Marine and Naval | Propeller shaft bolting, seawater intake systems, hull penetrations |
| Nuclear Power | Reactor coolant system bolts, control rod mechanisms, containment structures |
| Power Generation | Gas turbine combustion liners, steam generator connections, boiler hardware |
| Desalination Plants | Evaporator vessel closures, pump casing fasteners, brine heater connections |
| Pharmaceutical / Food | Sanitary fittings in CIP/SIP systems requiring full corrosion resistance |
| Cryogenic Applications | LNG plant bolting, cold box connections, cryogenic valve assemblies |
| Pulp and Paper | Digester bolting, bleach plant equipment, recovery boiler attachments |
Comparative Analysis: Alloy 625 vs. Alloy 718 vs. SS 316L Fasteners
| Property | Inconel 625 | Inconel 718 | SS 316L |
|---|---|---|---|
| UNS No. | N06625 | N07718 | S31603 |
| Tensile Strength | 930 MPa | 1240 MPa | 485 MPa |
| Yield Strength | 517 MPa | 1034 MPa | 170 MPa |
| Max Service Temp. | 1000°C | 700°C | 870°C (oxidizing) |
| Seawater Resistance | Excellent | Good | Moderate |
| Acid Resistance | Excellent | Good | Good |
| Weldability | Excellent | Good (PWHT req.) | Excellent |
| Magnetic | Non-magnetic | Non-magnetic | Non-magnetic |
| Cost (Relative) | High | Higher | Low |
| Best For | Corrosive + high-temp | High-strength aerospace | General corrosion service |
Inconel 625 is preferred when broad corrosion resistance is the primary design criterion, especially in marine and chemical environments. Alloy 718 offers higher strength for aerospace applications but requires post-weld heat treatment. SS 316L remains an economical option for mild corrosion service.
Manufacturing Process
Step 1: Raw Material Sourcing
We source bar stock, wire, and forgings from approved mills with documented heat and chemical analysis. Material is dual-certified to ASTM and ASME codes with EN 10204 3.1 mill test certificates.
Step 2: Forming / Forging
Fasteners are produced via hot forging (M24-M100), cold forging (M3-M24), or CNC precision machining depending on geometry and size.
Step 3: Threading
Threads are precision-rolled or cut to ASME B1.1 / B1.13M tolerances. Rolling is preferred for smaller sizes because it improves fatigue resistance through compressive residual stresses.
Step 4: Surface Treatment
Finished fasteners undergo passivation, polishing, or customer-specified surface coating such as phosphating, HDG, black oxide, Xylan, or PTFE. Final surface is inspected under magnification.
Step 5: Testing and Inspection
- Dimensional inspection: CMM / calibrated go-no-go gauges
- Hardness testing per Rockwell / Brinell
- Tensile and yield testing per ASTM / ISO standards
- Intergranular Corrosion (IGC) test
- PMI (Positive Material Identification) - 100% of batches
- Ultrasonic / Radiographic testing on request
- Third-party inspection from SGS, TUV, BV, and Lloyds
Step 6: Marking and Packing
All fasteners are stamped or marked with grade, standard, heat number, and manufacturer code. Packing is provided in wooden cases, pallets, or carton boxes with moisture barriers for export.
Certifications and Quality Standards
| Certification / Standard | Scope |
|---|---|
| ISO 9001:2015 | Quality Management System for Manufacturing and Supply |
| EN 10204 3.1 / 3.2 | Material Test Certificate with chemical and mechanical data |
| PED 97/23/EC | Pressure Equipment Directive - EU market compliance |
| NACE MR0175 / ISO 15156 | Sour-service (H2S environment) fastener qualification |
| ASME Boiler and Pressure Vessel Code | Section II and VIII compliant material and fabrication |
| AD 2000 Merkblatt W2 | German pressure vessel standard compliance |
| AMS 5666 | Aerospace Material Specification for Inconel 625 bar and forgings |
| Third Party Inspection | SGS, TUV SUD, Bureau Veritas, Lloyds Register |
Surface Finishes for Inconel 625 Fasteners
| Surface Finish | Typical Application Industry |
|---|---|
| Mill Finish (as-machined) | General mechanical and industrial |
| Polished Finish (Ra 0.8-3.2 micrometre) | Pharmaceutical, food processing, architectural |
| Brushed Finish | Architectural, marine |
| Passivated Finish | Medical, food, chemical processing |
| Phosphating | Automotive, general industrial |
| HDG (Hot Dip Galvanizing) | Construction, structural |
| Black Oxide | Tooling, optical equipment |
| Xylan / PTFE Coating | Anti-galling, low-friction assemblies |
Machining of UNS N06625 Threaded Studs
| Parameter | Ipr (lpr) | Mm/rev | fpm | m/min |
|---|---|---|---|---|
| Surface Speed / Feed | 0.005-0.020 | 0.13-0.51 | 13-35 | 4.0-10.7 |
Inconel 625 work-hardens rapidly during machining. Use sharp, coated carbide or CBN tooling, high coolant flow, and avoid dwelling or rubbing to prevent surface hardening that impairs subsequent operations.
Test Methods for Alloy 625 Studs
| Alloy / Product | Test Methods |
|---|---|
| Inconel 625 Fasteners | E38 (Chemical Analysis), E76 (Nickel Alloys), E354 |
| Additional Mechanical Tests | ASTM E8 Tensile, E10 Brinell, E18 Rockwell, E92 Vickers |
| Corrosion Tests | ASTM G28 IGC, G46 Pitting, G61 Crevice Corrosion |
| Non-Destructive Tests | ASME Section V - UT, RT, MT, PT as applicable |
Full Inspection Capabilities at Unifit Fastener
- Hardness Test (Rockwell HRB/HRC, Brinell)
- Flattening Test
- Pitting Resistance Test
- Chemical Analysis via Spectroscopy (OES/XRF)
- Intergranular Corrosion (IGC) Test
- Positive Material Identification (PMI) - 100% per heat
- Flaring Test
- Micro and Macro Structural Analysis
- Stress Rupture Testing
- Microstructure Testing
Inconel Round Bar Weight Calculator
Estimate the weight of Inconel round bars for procurement, inventory planning, and shipping calculations. Enter the bar diameter and length to calculate the approximate weight in kilograms based on the material density.
Formula: Weight (kg) = (pi / 4) x Diameter^2 x Length x Density
Typical Density Values: Inconel 601: 8.11 g/cm³; Inconel 625: 8.44 g/cm³. Calculated values are approximate and should be verified against actual material specifications and mill test certificates.
Inconel 625 Fasteners DIN Standards
For Nuts: DIN 1587, DIN 315, ISO 5448, DIN 439, ISO 4035, DIN 6923, ISO 4161, DIN 917, DIN 934, ISO 4032, DIN 935, ISO 7035, DIN 936, ISO 8675, DIN 985, ISO 7040
For Bolts: DIN 529, DIN 580, DIN 444, DIN 6921, DIN 931, ISO 4014, ISO 7379, DIN 478, DIN 3570, DIN 603, DIN 976, DIN 975, DIN 931 Hex Head Bolts, ISO 4014 Hex Head Bolts, DIN 931/ISO 4014 Hex Bolts
For Washers: DIN 125, DIN 126, DIN 127, DIN 128, DIN 1440, DIN 433, DIN 436, DIN 6797, DIN 6916, DIN 7349, DIN 7980, DIN 7989, DIN 9021, ISO 7089, ISO 7090, ISO 7092, ISO 7093
For Screws: DIN 479, DIN 7504, DIN 7984, DIN 908, DIN 912, DIN 913, DIN 914, DIN 915, DIN 916, DIN 933, ISO 4017, ISO 4029, ISO 4762
Export Capability
Unifit Fastener supplies Inconel fasteners, washers, and round bars to customers across more than 50 countries worldwide. Our products have been exported to major industrial markets including the UAE, Saudi Arabia, Germany, the USA, Singapore, Australia, South Africa, and other regions. We provide complete export documentation, material test certificates (MTC), and third-party inspection reports upon request.
Packing and Delivery Information
All Inconel 601 and Inconel 625 washers, fasteners, and round bars are packed using industry-standard export packaging procedures to ensure safe transit and product integrity. Materials are packed in VCI-coated polyethylene bags, securely bundled, and placed in fumigated wooden crates or pallets with moisture-absorbing desiccants for sea and air freight shipments. Each consignment is heat-number marked and labelled for complete material traceability and compliance with customer specifications.
Lead Time and Delivery Schedule
We maintain ready stock of standard Inconel fasteners, washers, and round bars to support urgent project requirements.
- Standard stock items: typically dispatched within 2-5 business days.
- Custom sizes and non-standard specifications: generally supplied within 2-4 weeks, depending on manufacturing requirements.
- Export documentation, inspection certificates, and shipping documents: available within 48 hours of order confirmation.
Actual delivery schedules may vary depending on quantity, product specification, testing requirements, and destination country.
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FAQ's About Inconel 625 Fasteners
What industries use Inconel 625 fasteners?
They are widely used in aerospace, marine, offshore platforms, chemical processing, nuclear, and high-temperature applications.
Are Inconel 625 fasteners resistant to corrosion?
Yes, they resist pitting, crevice corrosion, and chloride-induced stress corrosion cracking, making them ideal for marine and chemical environments.
What is the melting range of Inconel 625?
Inconel 625 has a melting range of 1290-1350°C, making it suitable for extreme-temperature industrial applications.
Are custom thread pitches available for Inconel 625 fasteners?
Yes, custom threads can be manufactured to meet specific industrial requirements, including metric and imperial standards.