Unifit Fastener is a leading manufacturer, supplier, and exporter of Inconel 718 Fasteners in India, offering ASTM B637 / ASME SB637 grade bolts, nuts, stud bolts, washers, and screws in UNS N07718 (Werkstoff Nr. 2.4668). Inconel 718 fasteners maintain minimum tensile strength of 1275 MPa (185 ksi) in the precipitation-hardened condition per AMS 5663 and can achieve up to 1517 MPa (220 ksi) in the cold-worked AMS 5962 condition. The alloy also provides excellent creep-rupture performance at temperatures up to 700°C (1300°F), making it suitable for applications where carbon steel fasteners lose strength above 400°C and austenitic stainless steel fasteners become unsuitable above 500°C.
Unifit manufactures Inconel 718 bolts, stud bolts, nuts, washers, and custom-engineered fastening components in metric sizes from M3 to M100 and imperial sizes from 3/8" to 4", conforming to DIN, ISO, JIS, BS, and ASME standards. Products are supplied with full EN 10204 3.1 material certification, complete material traceability, and NACE MR0175 documentation for sour gas service when specified. Standard and custom dimensions are available for aerospace, oil and gas, petrochemical, power generation, nuclear, and high-temperature industrial applications, with ex-stock availability and global dispatch from our Mumbai facility.
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What Are Inconel 718 Fasteners?
Inconel 718, also designated UNS N07718, Werkstoff Nr. 2.4668, Nicrofer 5219, and Superimphy 718, is a precipitation-hardenable nickel-chromium superalloy that provides an outstanding balance of mechanical properties at both cryogenic and elevated temperatures. Unlike austenitic stainless steels, Inconel 718 fasteners retain more than 80% of their room-temperature tensile strength even at 650°C, making them indispensable in high-stress, thermally demanding assemblies.
The alloy derives its strength from a dual precipitation-hardening mechanism involving gamma-prime (Ni3Al/Ti) and gamma-double-prime (Ni3Nb) phases dispersed within the nickel matrix. This microstructural design delivers superior fatigue resistance, low thermal creep, and dimensional stability - qualities that are critical in rotating machinery, pressure vessel flanges, and subsea wellhead components.
Key Characteristics at a Glance
- Tensile strength up to 1,379 MPa (200 ksi) at room temperature
- 0.2% yield strength of approximately 1,172 MPa (170 ksi)
- Elongation at break: 12% (aged condition)
- Outstanding creep-rupture strength at temperatures up to 700°C
- Excellent resistance to oxidizing and reducing atmospheres
- Superior resistance to hydrogen embrittlement versus most superalloys
- Low magnetic permeability in solution-annealed condition
Inconel 718 Fasteners Specifications
| Specification Parameter | Details / Range |
| Material Grade | Inconel 718 / Alloy 718 |
| UNS Number | N07718 |
| Werkstoff Nr. | 2.4668 |
| Trade Names | Nicrofer 5219, Superimphy 718, Pyromet 718 |
| Standard | ASTM B637 / ASME SB637 |
| Dimensions Standard | DIN 931, 933, 934, 7991, 976, 125 / ASME B18.2.1, B18.3 |
| Bolt Metric Sizes | M3 to M100 |
| Bolt Imperial Sizes | 3/8" to 4" |
| Length Range | 3 mm to 200 mm (custom sizes available) |
| Nut Size Range | M3 to M56 / 3/6" to 2" |
| Washer Size Range | M3 to M56 / 3/6" to 2" |
| Threads Available | UNF, BSW, BSF, METRIC, UNC, or as required |
| Thread Configuration | ASME B1.2A/3A - 2B/3B Inch Unified & B1.13M 6h-6G Metric Coarse |
| Head Form | Hex, Square, Round, Hex flange, Flat, T-head, Triangular |
| Neck Type | Hex, Oval, Square, Triangular, Knurled |
| Surface Treatment | Passivation, Plain, Chrome Plating, Teflon Coating, Zinc Plating |
| Surface Coating | Black Oxide, Cadmium, Galvanized, Xylan, Dacromet, Anodizing |
| Manufacturing Process | Hot Forging, Cold Forging, CNC Machining, Threading |
| Test Certificate | EN 10204 / 3.1 MTC, PED 97/23/EC, Merkblatt AD 2000 W2 |
| Delivery Time (Standard) | 7-15 working days |
| Delivery Time (Custom) | 2-4 weeks |
| Place of Origin | India (Mumbai) |
Inconel 718 Chemical Composition
The chemical composition of Inconel Alloy 718 fasteners is precisely controlled to ensure consistent precipitation hardening response, corrosion resistance, and mechanical performance across all product forms:
| Element | Symbol | Min % | Max % |
| Nickel + Cobalt | Ni + Co | 50.00 | 55.00 |
| Chromium | Cr | 17.00 | 21.00 |
| Iron | Fe | Balance | Balance |
| Niobium + Tantalum | Nb + Ta | 4.75 | 5.50 |
| Molybdenum | Mo | 2.80 | 3.30 |
| Titanium | Ti | 0.65 | 1.15 |
| Aluminum | Al | 0.20 | 0.80 |
| Cobalt | Co | - | 1.00 max |
| Carbon | C | - | 0.08 max |
| Manganese | Mn | - | 0.35 max |
| Silicon | Si | - | 0.35 max |
| Phosphorus | P | - | 0.015 max |
| Sulfur | S | - | 0.015 max |
| Boron | B | - | 0.006 max |
| Copper | Cu | - | 0.30 max |
Inconel 718 Fastener Mechanical Properties
| Property | Value (Imperial) | Value (Metric) |
| Ultimate Tensile Strength | 185 ksi (min) | 1,275 MPa (min) |
| 0.2% Yield Strength | 150 ksi (min) | 1,034 MPa (min) |
| Elongation in 2 in (50 mm) | 12% (min) | 12% (min) |
| Density | 0.297 lb/in³ | 8.22 g/cm³ |
| Melting Range | 2300-2435°F | 1260-1335°C |
| Modulus of Elasticity | 29 x 106 psi | 200 GPa |
| Thermal Conductivity | 79 Btu·in/h·ft²·°F | 11.4 W/m·°C |
| Specific Heat | 0.104 Btu/lb·°F | 435 J/kg·°C |
Physical Properties of Inconel 718 (2.4668) - Temperature Dependant
| Property | RT | 100°C | 200°C | 300°C | 400°C |
| Electrical Resistivity (µOhm·cm) | 121 | 122 | 125 | 127 | 129 |
| Thermal Conductivity (W/m·°C) | 11.4 | 12.6 | 14.3 | 15.9 | 17.5 |
| Mean Thermal Expansion (µm/m·°C) | - | 12.8 | 13.5 | 13.8 | 14.1 |
| Dynamic Modulus of Elasticity (GPa) | 200 | 195 | 191 | 185 | 179 |
Creep and Stress-Rupture Strengths of Inconel 718 Fasteners
The table below shows the approximate initial stress required to produce specified creep in Inconel 718 fasteners at elevated temperatures - a critical design parameter for high-temperature bolted assemblies:
| Temp °C | Temp °F | Creep % | 10h ksi | 10h MPa | 100h ksi | 100h MPa | 1000h ksi | 1000h MPa |
| 538 | 1000 | 0.5 | 157 | 1083 | 146 | 1007 | 132 | 910 |
| 538 | 1000 | 1.0 | 160 | 1103 | 150 | 1034 | 138 | 952 |
| 593 | 1100 | 0.5 | 140 | 965 | 126 | 869 | 108 | 745 |
| 593 | 1100 | 1.0 | 143 | 986 | 130 | 896 | 112 | 772 |
| 649 | 1200 | 0.5 | 121 | 834 | 101 | 696 | 75 | 517 |
| 649 | 1200 | 1.0 | 124 | 855 | 103 | 710 | 78 | 538 |
| 704 | 1300 | 0.5 | 95 | 655 | 64 | 441 | 35 | 241 |
| 704 | 1300 | 1.0 | 98 | 676 | 67 | 462 | 41 | 283 |
Equivalent Grade Chart - Inconel 718 Fasteners
| Grade Name | UNS Number | Werkstoff Nr. | EN Standard | DIN Standard |
| Inconel 718 | N07718 | 2.4668 | 2.4668 | 2.4668 |
| Superimphy 718 | N07718 | 2.4668 | - | - |
| Nicrofer 5219 | N07718 | 2.4668 | - | - |
| Pyromet 718 | N07718 | 2.4668 | - | - |
Inconel 718 Fasteners Available at Unifit Fastener
Different Types Of Bolts
- Inconel 718 Structural Bolts
- Inconel 718 Heavy Hex Bolts
- Inconel 718 Hex Bolts
- Inconel 718 Hexagon Head Bolts
- Inconel 718 Machine Bolts
- Inconel 718 T Bolts
- Inconel 718 Eye Bolt
- Inconel 718 Foundation Bolts
- Inconel Alloy 718 J Bolts
- Inconel 718 Flange Bolts
Different Types Of Nuts
- Inconel 718 Hex Nuts
- Inconel 718 Heavy Hex Nuts
- Inconel 718 Wing Nuts
- Inconel 718 Cap Nuts
- Inconel 718 Square Nuts
- Inconel 718 Coupling Nuts
- Inconel 718 Hex Jam Nuts
- Inconel 718 Nylock Nuts
- Inconel 718 Slotted Nuts
Different Types Of Washers
- Inconel 718 Plain Washers
- Inconel 718 Spring Washers
- Inconel 718 Locking Washer
- Inconel 718 Split Washer
- Inconel Alloy 718 Flat Washers
- Inconel 718 Fender Washer
- Inconel 718 Conical Washers
- Inconel 718 Square Washers
Different Types Of Screw
- Inconel 718 Socket Set Screw
- Inconel 718 Self Drilling Screw
- Inconel 718 Socket Head Cap Screw
- Inconel 718 Hex Head Screws
- Inconel 718 Eye Screw
- Alloy 718 Self Tapping Screws
- Inconel 718 Machine Screw
- Alloy 718 Thread Rolling Screw
Dimensions Chart - Inconel Alloy 718 Stud Bolts (Nominal Diameter)
| Diameter (in) | Plain UNC | Plain 8UN |
| 1/2 | 19568 | - |
| 5/8 | 19569 | - |
| 3/4 | 19570 | - |
| 7/8 | 19571 | - |
| 1 | 19572 | - |
| 11/8 | 19573 | 13979 |
| 11/4 | 19574 | 13980 |
| 11/2 | 19657 | 13982 |
| 13/8 | 19656 | 13981 |
| 13/4 | 19658 | 13983 |
| 2 | 19659 | 13984 |
Torque Chart - 2.4668 Inconel 718 Studs
| Diameter (in) | Threads/in | Torque ft-lb (Dry) | Torque ft-lb (Lubricated) |
| 1/4" | 20 | 3.4 | 2.5 |
| 1/4" | 28 | 3.9 | 2.9 |
| 5/16" | 18 | 7.0 | 5.3 |
| 3/8" | 16 | 12.4 | 9.3 |
| 7/16" | 14 | 19.9 | 14.9 |
| 1/2" | 13 | 30.3 | 22.7 |
| 9/16" | 12 | 43.7 | 32.8 |
| 5/8" | 11 | 60.4 | 45.3 |
| 3/4" | 10 | 107 | 80 |
| 7/8" | 9 | 173 | 130 |
| 1" | 8 | 259 | 194 |
| 1-1/4" | 7 | 451 | 338 |
| 1-1/2" | 6 | 784 | 588 |
Indicative Price List - Inconel 718 Fasteners (ASTM B166 / UNS N07718)
Note: Prices are indicative and subject to change based on material cost, order quantity, surface treatment, and delivery terms. Contact Unifit Fastener for a formal quotation.
| Product | Thread Size | USD (approx.) | INR (approx.) | AED (approx.) |
| Inconel 718 Hex Bolt | M1.6 | $0.30 | ₹22.50 | 1.10 |
| Alloy 718 Threaded Rod (ASTM B166) | M10-M16 | $0.06 | ₹4.50 | 0.22 |
| Werkstoff 2.4668 Nuts | M20 | $2.50 | ₹187.50-1350 | 9.17-66 |
| Inconel 718 Stud Bolt | M10 | $0.03 | ₹2.25 | 0.11 |
| Nickel Alloy 718 Head Screw | M6-M10 | $1.19 | ₹89.25 | 4.37 |
| UNS N07718 Eye Bolt | M24 | $0.15 | ₹11.25 | 0.55 |
| 2.4668 Inconel Hex Screw | M10 | $0.05 | ₹3.75 | 0.18 |
| Nickel 718 Stud Screw | M3.5 | $2.00 | ₹150.00 | 7.34 |
| ASME SB166 Flat Washer | M2.6 | $0.30 | ₹22.50 | 1.10 |
| EN 2.4668 Spring Washer | M1.6 | $0.30 | ₹22.50 | 1.10 |
Applications & Industries - Inconel 718 Fasteners
The extraordinary property profile of Inconel 718 makes its fasteners irreplaceable in sectors that operate under the harshest conditions known to engineering:
| Industry | Specific Applications |
| Aerospace & Aviation | Gas turbine engine casings, compressor discs, airframe structural joints, jet engine exhaust systems, aircraft landing gear, rocket motor components |
| Oil & Gas | Wellhead equipment, subsea Christmas trees, down-hole completion tools, offshore platform structural bolting, natural gas processing flanges |
| Nuclear Power | Reactor pressure vessel studs, steam generator tube sheet bolting, nuclear fuel assembly fixtures |
| Petrochemical & Refining | High-pressure heat exchangers, catalytic cracker vessels, ethylene cracking furnaces, sour gas process equipment |
| Power Generation | Steam turbine casings, land-based gas turbine hot-section hardware, supercritical boiler studs |
| Chemical Processing | Pumps, valves, and reactors handling sulfuric acid, hydrochloric acid, and chloride-bearing media |
| Cryogenic / LNG | Liquefied natural gas storage tank flanges, cryogenic transfer line bolting, low-temperature pressure vessels |
| Defence & Marine | Naval vessel propulsion systems, submarine pressure hull fasteners, defence equipment structural joints |
| Automotive Racing | High-performance engine head studs, turbocharger bolts, exhaust manifold fasteners |
Key Features & Benefits of Unifit Fastener's Inconel 718 Fasteners
| Feature | Benefit to You |
| Precipitation-Hardened Microstructure | Consistently high strength without risk of sigma phase embrittlement |
| Wide Temperature Service Range (-253°C to +700°C) | Single fastener grade for cryogenic through high-temperature service |
| Superior Creep-Rupture Strength | Maintains clamping load in long-term elevated-temperature service |
| Excellent Pitting & Crevice Corrosion Resistance | Longer maintenance intervals in chloride-rich environments |
| Weldable & Formable | Supports complex custom fastener geometries with full mechanical property retention post-weld |
| Dual Certified ASTM / ASME | Simplifies procurement for pressure vessel and piping code compliance |
| Custom Sizes on Request | Eliminates off-the-shelf compromise for critical design geometries |
| Third-Party Inspection Available | Full TPIA, PMI, and hardness testing from accredited labs |
Inconel 718 vs Inconel 625 vs Hastelloy C276 - Fastener Comparison
| Property | Inconel 718 | Inconel 625 | Hastelloy C276 |
| UNS Number | N07718 | N06625 | N10276 |
| Tensile Strength (MPa) | 1,379 (aged) | 827 (annealed) | 790 |
| Yield Strength (MPa) | 1,172 (aged) | 517 (annealed) | 355 |
| Maximum Service Temperature (°C) | 700 | 980 | 1,040 |
| Creep Resistance | Excellent | Good | Good |
| Pitting Resistance | Good | Excellent | Excellent |
| Crevice Corrosion Resistance | Good | Excellent | Excellent |
| Weldability | Good - weld in annealed condition; post-weld aging restores full strength. Heat-affected zone may soften if welded in the aged condition. | Excellent | Excellent |
| Strengthening Mechanism | Precipitation Hardening | Solid Solution Strengthening | Solid Solution Strengthening |
| Primary Use Case | High-Strength Structural Fasteners | Corrosion-Critical Fasteners | Severe Wet Chemical Service |
| Relative Cost | $$ | $$$ | $$$$ |
Manufacturing Process & Quality Control at Unifit Fastener
Production Process
- Raw Material Procurement: Mill-certified Inconel 718 bar / wire stock from approved vendors
- Hot Forging: Performed at 980–1120°C to achieve controlled grain flow and optimal microstructure
- Cold Forging / Cold Heading: Applied for smaller diameter precision fasteners
- Heat Treatment: Solution annealing at 980°C / 1 hour + double aging at 720°C (8h) then 620°C (8h)
- Thread Rolling / Machining: CNC precision threading to ASME B1.1 / B1.13M specification
- Surface Finishing: Passivation, Teflon coating, Zinc plating, Dacromet per customer requirements
- Inspection & Testing: 100% dimensional inspection; destructive/non-destructive testing
- Documentation: Dual certified MTCs, EN 10204 3.1, PMI test reports
Quality Tests Performed
- Mechanical Testing: Tensile, yield, elongation, hardness (Rockwell / Brinell)
- PMI (Positive Material Identification): XRF-based elemental verification
- Micro & Macro Examination: Grain size assessment per ASTM E112
- Pitting Resistance Testing: ASTM G48 immersion test
- Flattening Test & Flaring Test for tubular fasteners
- Ultrasonic Testing (UT) and Liquid Penetrant Testing (LPT) on request
- Spectro Analysis for full chemical composition verification
Certifications & Standards Compliance
| Standard / Certification | Scope |
| ASTM B637 | Rod, bar, and forgings for high-temperature service |
| ASME SB637 | ASME Boiler & Pressure Vessel Code (Section II) equivalent |
| EN 10204 Type 3.1 | Inspection certificate with independent verification |
| PED 97/23/EC | European Pressure Equipment Directive compliance |
| Merkblatt AD 2000 W2 | German pressure vessel materials code |
| ISO 9001:2015 | Quality management system certification |
| NACE MR0175 / ISO 15156 | Sour service hydrogen sulfide environment suitability |
Global Export Delivery Schedule - Inconel 718 Fasteners
| Destination Country | Estimated Delivery Time |
| UAE / Dubai | 5-7 working days |
| Saudi Arabia | 7 working days |
| Singapore | 8 working days |
| Indonesia | 9 working days |
| Egypt | 18 working days |
| Jordan | 21 working days |
| South Africa | 25-30 working days |
| Brazil | 45-60 working days |
| Australia | 60 working days |
| Thailand | 7 working days |
| USA / Canada | 10-14 working days (air freight) |
| UK / Europe | 10-12 working days (air freight) |
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