Inconel 718 is a high-strength, corrosion-resistant nickel-based superalloy specifically designed for
demanding applications that require exceptional performance under extreme conditions. It is widely used in
the aerospace, marine, nuclear, and oil & gas industries for manufacturing bolts, nuts, washers, studs, and
other fasteners that must withstand high stress, heat, and corrosion.
One of the most significant properties of Inconel 718 is its remarkable tensile, yield, and creep-rupture strength at elevated temperatures—up to 700°C (1290°F). This makes it the material of choice for jet engines, turbines, exhaust systems, and high-temperature pressure vessels. Unlike many alloys, Inconel 718 maintains its strength and structural stability even after long-term exposure to heat.
Inconel 718 also provides excellent resistance to oxidation, pitting, and stress-corrosion cracking in both acidic and high-salinity environments. This makes Inconel 718 fasteners particularly valuable in subsea equipment, chemical plants, and other aggressive operating conditions.
The alloy is precipitation-hardenable, which means it gains strength through a heat treatment process without compromising ductility or toughness. It also offers good weldability and machinability compared to other nickel alloys.
With a balanced composition of nickel, chromium, iron, niobium, molybdenum, and titanium, Inconel 718 delivers reliable, long-term performance in critical applications where failure is not an option.
Our Inconel 718 fasteners are manufactured to stringent quality standards to meet the highest industrial requirements. Contact us to learn more about our full range of Inconel 718 bolts, nuts, and custom fastener solutions.
| Element | Minimum (%) | Maximum (%) | Notes |
|---|---|---|---|
| Nickel (Ni) | 50.00 | 55.00 | Base alloying element |
| Chromium (Cr) | 17.00 | 21.00 | Enhances oxidation resistance |
| Iron (Fe) | — | — | Balance |
| Niobium + Tantalum (Nb+Ta) | 4.75 | 5.50 | Provides strengthening through precipitation |
| Molybdenum (Mo) | 2.80 | 3.30 | Increases strength and corrosion resistance |
| Titanium (Ti) | 0.65 | 1.15 | Strengthening agent |
| Aluminum (Al) | 0.20 | 0.80 | Aids in age-hardening |
| Cobalt (Co) | — | ≤ 1.00 (if specified) | Optional addition |
| Carbon (C) | — | ≤ 0.08 | Kept low to avoid carbide precipitation |
| Manganese (Mn) | — | ≤ 0.35 | Controlled for weldability |
| Silicon (Si) | — | ≤ 0.35 | Controlled for ductility |
| Phosphorus (P) | — | ≤ 0.015 | Impurity — should be minimized |
| Sulfur (S) | — | ≤ 0.015 | Impurity — should be minimized |
| Boron (B) | — | ≤ 0.006 | Minor Element, improves grain boundary Strength |
Standard Reference: ASTM A1014 – Standard Specification for Precipitation-Hardening Bolting (UNS N07718) for High Temperature Service.
According to ASTM A1014 (Solution-Annealed + Aged Condition) Here is a detailed chart of the mechanical properties of Inconel 718 as per ASTM A1014:
| Property | Value | Condition |
|---|---|---|
| Tensile Strength, min | 1380 MPa (200 ksi) | Room Temperature |
| Yield Strength (0.2% offset, min) | 1035 MPa (150 ksi) | Room Temperature |
| Elongation (min) | 12% | In 4D gauge Length |
| Reduction of Area, min | 15% | Tensile specimen |
| Hardness | ≤ 40 HRC (typical) | After age-hardening |
| Modulus of Elasticity | ~207 GPa (30 x 10³ ksi) | Room temperature |
| Density | 8.19 g/cm³ (0.296 lb/in³) | — |
| Operating Temperature Range | Up to 700°C (1290°F) | Long-term service |
| Impact Toughness | Excellent | Maintained at cryogenic temps |
• Solution Treated: 980°C (1800°F) for 1 hour, air cooled.
• Aged: 720°C (1325°F) for 8 hours, furnace cooled to 620°C (1150°F), held for 8 hours, then air cooled.
| Standard / Organization | Designation / Grade | Notes |
|---|---|---|
| UNS (Unified Numbering System) | N07718 | Most Commonly used alloy code |
| ASTM | ASTM B637 / ASTM A1014 | For bars, forgings, and solution-annealed forms |
| AMS (Aerospace Material Spec.) | AMS 5662 / AMS 5663 / AMS 5664 | Used in aerospace and turbine components |
| API (American Petroleum Institute) | API 6A CRA (718) | For downhole and wellhead equipment |
| ISO | ISO 15156-3 / ISO 6208 | For sour service and medical implants |
| DIN (Germany) | 2.4668 | Common Werkstoffnummer designation |
| EN (Europe) | EN 10269, EN 10204 | For mechanical and pressure applications |
| AFNOR (France) | NC19FeNb | French designation |
| BS (British Standard) | BS HR 505 | Legacy British code |
| JIS (Japan) | NCF 718 | Japanese designation |
| Trade Name | Inconel® 718 (Special Metals) | Registered trademark by Special Metals Corp |
Note :
• Inconel® is a registered trademark of Special Metals Corporation.
• Inconel 718 is covered under API 6A CRA (Corrosion Resistant Alloy) requirements, particularly for wellhead
and Christmas tree equipment, valves, and connectors in sour environments (NACE MR0175 compliant).
• Always check the specification version (e.g., AMS 5662 vs 5664) depending on heat treatment and form.
• The alloy is widely used in aerospace, marine, nuclear, and petrochemical sectors.
Inconel 718 offers exceptional heat resistance due to its nickel-chromium matrix combined with niobium, molybdenum, titanium, and aluminum additions. It maintains high tensile and creep-rupture strength up to 700°C (1290°F), making it ideal for long-term exposure in hot environments. The alloy exhibits excellent oxidation and scaling resistance, even under cyclic heating and cooling conditions. Unlike many other superalloys, Inconel 718 resists thermal fatigue and retains structural integrity without significant degradation over time. This performance makes it suitable for jet engines, gas turbines, nuclear reactors, and other high-temperature industrial applications.
Inconel 718 is known for being difficult to machine due to its high strength, work hardening rate, and toughness, especially after heat treatment. The alloy tends to harden rapidly under cutting conditions, causing tool wear and heat buildup. However, with the use of carbide tooling, low cutting speeds, high-pressure coolant, and rigid setups, good machinability can be achieved. Solution-annealed material is easier to machine than aged material. CNC machining, EDM, and grinding are commonly used. Despite challenges, its superior performance in extreme environments justifies the effort required in machining it.
