UNS N07718 | EN 2.4668 | ASTM B637 | AMS 5662 / 5663 / 5962 | AMS 5596
Inconel 718 bolts (UNS N07718) achieve a minimum tensile strength of 185 ksi (1275 MPa) per AMS 5662/5663, rising to 220 ksi in the cold-worked AMS 5962 condition — approximately 2.3x the tensile strength of A4-70 stainless steel fasteners at room temperature, and retaining usable strength down to -196°C. Unifit Fastener manufactures and stocks Inconel 718 bolts, stud bolts, hex nuts, and threaded rods from its Mumbai facility, with EN 10204 3.1 MTCs, NACE MR0175 compliance documentation, and same-week dispatch on standard sizes. Inconel 718 bolts, manufactured from the legendary UNS N07718 precipitation-hardened nickel-chromium superalloy, are the fastener of choice for engineers who simply cannot afford failure.
At Unifit Fastener, we manufacture and supply Inconel 718 bolts, stud bolts, hex nuts, socket head cap screws, and threaded rods that meet or exceed the world's most demanding specifications — including ASTM B637, AMS 5662, AMS 5663, AMS 5962, and DIN EN 2.4668. With tensile strengths reaching 220 ksi, outstanding resistance to chloride stress corrosion cracking, H₂S, and sour gas, and reliable performance from cryogenic temperatures to 700°C (1300°F), our Inconel 718 fasteners are certified, export-ready, and backed by full material test certificates (MTC).
Whether you're sourcing for an aerospace assembly, a subsea wellhead, or a chemical processing plant, Unifit Fastener delivers precision-engineered Inconel 718 fasteners on time, to specification, with complete traceability. Request a quote today and experience the Unifit quality difference.
Request a QuoteInconel 718 is a precipitation-hardened nickel-chromium-based superalloy recognized globally under the designations UNS N07718, EN 2.4668, Alloy 718, and Werkstoff 2.4668. It belongs to the Inconel family of high-performance nickel alloys developed for applications where standard stainless steels and carbon steels simply cannot perform.
The alloy's chemistry combines nickel (50-55%), chromium (17-21%), iron (balance), and key strengthening elements including niobium, tantalum, molybdenum, titanium, and aluminum. When subjected to a carefully controlled age-hardening heat treatment process, these elements precipitate as intermetallic phases within the nickel matrix — dramatically increasing hardness, tensile strength, and creep resistance without sacrificing corrosion resistance or ductility.
As fasteners, Inconel 718 bolts in the aged condition (AMS 5663, 185 ksi minimum) provide approximately 40-85% higher tensile strength than Inconel 625 bolts in the annealed condition (100-115 ksi typical), making them the preferred choice where both high mechanical load and corrosion resistance are simultaneously required.
The following chemical composition is per ASTM B637 / AMS 5662 / AMS 5663 for Inconel 718 bolts and fasteners. Strict adherence to these compositional limits is what gives Alloy 718 its unique combination of strength, corrosion resistance, and high-temperature stability.
| Element | Ni+Co | Fe | Cr | Nb+Ta | Mo | Ti | Al | Co | Mn | Si |
|---|---|---|---|---|---|---|---|---|---|---|
| Min % | 50 | Bal | 17.0 | 4.75 | 2.80 | 0.65 | – | 0.20 | – | – |
| Max % | 55 | Bal | 21.0 | 5.50 | 3.30 | 1.15 | 1.0 | 0.80 | 0.35 | 0.35 |
Note: Carbon max 0.08%, Phosphorus max 0.015%, Sulfur max 0.015%, Boron max 0.006%. The balance of iron provides structural matrix stabilization. Niobium and tantalum (Nb+Ta) are the primary precipitation-strengthening elements that form the γ″ (gamma double-prime) phase responsible for Inconel 718's outstanding room-temperature strength.
The mechanical performance of Inconel 718 bolts varies by heat treatment condition. The following table compares key properties across the primary specification states, allowing engineers to select the appropriate grade for their application requirements.
| Property | Value (Imperial) | Value (Metric) | Specification |
|---|---|---|---|
| Tensile Strength (min) | 185 ksi | 1275 MPa | AMS 5662/5663 |
| Tensile Strength (Cold Worked) | 220 ksi | 1517 MPa | AMS 5962 |
| Yield Strength (0.2% Offset) | 150 ksi | 1034 MPa | Aged Condition |
| Elongation | 22% min | 22% min | Room Temp |
| Density | 0.296 lb/in3 | 8.19 g/cm3 | – |
| Melting Point | 2300-2440 °F | 1260-1336 °C | – |
| Max Service Temperature | 1300 °F | 700 °C | Aged Condition |
| Temperature (°F) | Ultimate Tensile Strength (ksi) | Yield Strength (ksi) | Elongation (%) |
|---|---|---|---|
| Room Temperature | 210* | 175* | 22.0 |
| 400 | 198* | 163* | 20.0 |
| 800 | 191* | 156* | 19.0 |
| 1000 | 185* | 153* | 18.0 |
| 1200 | 168* | 148* | 19.0 |
| 1400 | 111* | 110* | 27.0 |
Unifit Fastener supplies Inconel 718 bolts against all major international material, dimensional, and quality standards. Understanding which specification is appropriate for your application is critical to ensuring performance, regulatory compliance, and interoperability.
| Standard / Spec | Description | Typical Use Case |
|---|---|---|
| ASTM B637 | Raw material specification for precipitation-hardened nickel alloys | Most widely used; covers hot & cold-worked bars |
| AMS 5662 | Solution annealed bar — softest, most machinable state | Used where formability is priority |
| AMS 5663 | Age hardened bar — high hardness & tensile strength | Preferred for critical fasteners |
| AMS 5962 | Cold worked — highest tensile (220 ksi min) | Extreme high-strength applications up to 900°F |
| AMS 5596 | Solution treated sheet/plate for strength & creep resistance | High-temp panels, flanges |
| ASME SFA 5.14 | Welding wire specification | Weld-compatible fastener applications |
| ASTM B670 | Precipitation-hardened sheet & plate | Aerospace panel & structural use |
| EN 2.4668 / UNS N07718 | European & US material designation | International procurement reference |
| DIN 17752 / 17754 | German specification for Ni alloy bars and bolts | EU/German projects |
| ASME B18.2.2 / B18.5 | Dimensional standards for bolts & screws | Ensures fitment compatibility |
The corrosion resistance of Inconel 718 is one of its most commercially valuable properties, enabled by the synergistic effects of its key alloying elements.
Nickel provides the foundational resistance to reducing environments and many inorganic acids. It offers excellent resistance to caustic soda (NaOH), neutral salt solutions, and most organic acids, making Inconel 718 bolts highly versatile across chemical processing plants.
Chromium forms a self-healing, dense oxide layer that provides resistance to oxidizing acids, sulfur-containing compounds, and mild to moderately oxidizing chloride environments. It is the primary element responsible for resistance to high-temperature oxidation.
Molybdenum dramatically improves resistance to pitting and crevice corrosion in chloride and halide-containing environments — the primary failure mode of conventional stainless steels. It is particularly effective in sour gas (H2S + CO2) and seawater conditions.
| Property | Metric | Imperial |
|---|---|---|
| Coefficient of Thermal Expansion (20°C) | 13 µm/m·°C | 7.22 µin/in·°F |
| Heat Capacity | 0.435 J/g·°C | 0.104 BTU/lb·°F |
| Thermal Conductivity | 11.4 W/m·K | 79.1 BTU·in/hr·ft2·°F |
| Melting Point (Solidus) | 1260 °C | 2300 °F |
| Melting Point (Liquidus) | 1336 °C | 2440 °F |
The following torque chart is calculated from a yield strength of 175 ksi. Use lubricated values when thread lubricant or anti-seize compound is applied. Dry torque applies to bare metal threads.
| Nominal Dia. | Threads/in | Torque ft-lb (Dry) | Torque ft-lb (Lubricated) |
|---|---|---|---|
| 1/4" | 20 | 16.2 | 12.0 |
| 5/16" | 18 | 33.1 | 24.9 |
| 3/8" | 16 | 58.8 | 44.1 |
| 7/16" | 14 | 94.0 | 70.6 |
| 1/2" | 13 | 143.4 | 107.5 |
| 5/8" | 11 | 285.5 | 214.2 |
| 3/4" | 10 | 508.0 | 380.0 |
| 7/8" | 9 | 816.0 | 613.0 |
| 1" | 8 | 1225.0 | 919.0 |
| 1-1/4" | 7 | 2132.0 | 1598.0 |
| 1-1/2" | 6 | 3709.0 | 2781.0 |
Inconel 718 bolts are specified across the most demanding industrial sectors on the planet. Their unique combination of strength, corrosion resistance, and temperature capability makes them irreplaceable in applications where failure is not an option.
Choosing the right alloy fastener requires understanding how Inconel 718 compares to alternative materials across the key performance parameters that matter most for your application.
| Material | Inconel 718 | Inconel 625 | 316L SS | Hastelloy C276 |
|---|---|---|---|---|
| Max Temp (°F) | 1300 | 1800 | 870 | 1900 |
| Tensile Strength (ksi) | 185-220 | 130-145 | 80-95 | 100-115 |
| Chloride SCC Resistance | Excellent | Excellent | Poor | Excellent |
| H2S Resistance | Excellent | Good | Moderate | Excellent |
| Machinability | Good | Moderate | Good | Difficult |
| Weldability | Outstanding | Excellent | Good | Good |
| Cryogenic Performance | Excellent | Good | Good | Moderate |
| Relative Cost | $$ | $$$ | $ | $$$ |
| Primary Advantage | Strength + Corrosion balance | Very high temp | Economy | Extreme corrosion |
When should you specify Inconel 718 over alternatives? Choose Inconel 718 when your application demands maximum tensile strength combined with corrosion resistance up to 700°C. For pure high-temperature oxidation resistance above 700°C, Inconel 625 or Inconel 601 may be preferable. For extreme corrosion environments where strength is secondary, Hastelloy C276 may be a better fit.
Inconel 718's exceptional strength comes from a two-step heat treatment process that precipitates strengthening phases within the nickel matrix:
Step 1 — Solution Annealing: Material is heated to 1700-1850°F (927-1010°C) and water quenched, dissolving alloying elements into a solid solution and producing a soft, machinable microstructure (AMS 5662 state).
Step 2 — Age Hardening: Material is heated to 1325°F (718°C) for 8 hours, then furnace-cooled to 1150°F (620°C), held for a further 8 hours, then air-cooled. This precipitates γ″ (Ni3Nb) and γ′ (Ni3(Al,Ti)) phases that dramatically increase hardness and tensile strength (AMS 5663 state).
Cold Working (AMS 5962): Additional cold working after solution annealing further increases dislocation density, achieving minimum tensile of 220 ksi at room temperature. Suitable up to 900°F.
Inconel 718 threads can be formed by rolling or cutting in the annealed condition, offering the optimal combination of quality and tool life. Once age-hardened, additional machining becomes significantly more difficult and requires specialized tooling. Thread rolling is the preferred method as it induces beneficial compressive residual stresses that improve fatigue life.
At Unifit Fastener, quality is not a department — it is embedded in every step of our manufacturing process. Every Inconel 718 fastener we supply is manufactured, tested, and certified to the highest international standards.
Inconel 718 (UNS N07718 / DIN 2.4668) is a precipitation-hardened nickel-chromium superalloy renowned for its exceptional tensile strength (up to 220 ksi), outstanding corrosion resistance, and reliable performance from cryogenic temperatures up to 1300°F (700°C).
Inconel 718 bolts provide a minimum tensile strength of 185 ksi (1275 MPa) per AMS 5662/5663 and ASTM B637. Cold-worked bolts manufactured to AMS 5962 specification achieve a minimum of 220 ksi (1517 MPa) at room temperature only — this value reduces significantly above 900°F (482°C). Specify AMS 5963 for standard high-strength bolts; specify AMS 5962 only when maximum room-temperature tensile is the primary requirement and service temperature does not exceed 900°F.
The primary standards include ASTM B637, AMS 5662, AMS 5663, AMS 5962, AMS 5596, ASME SFA 5.14, EN 2.4668, UNS N07718, and DIN 17752/17754. Dimensional standards include ASME B18.2.2 and DIN 931/933/934.
Inconel 718 bolts are rated for service up to 1300°F (700°C) in the aged condition. For applications above this temperature, Inconel 625 or Inconel 601 may be more suitable.
Their nickel-chromium base provides resistance to chloride stress corrosion cracking, H2S environments, CO2, sour gas, and both aqueous and oxidizing media. Molybdenum adds pitting resistance in halide-containing environments.
Yes. Inconel 718 has outstanding weldability in both annealed and aged conditions. It can be welded without post-weld hardening or cracking, though welding in the aged condition may create a softened heat-affected zone.
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