Inconel Alloy 718 Fasteners

Nickel-Chromium-Iron-Molybdenum-Niobium – Most Widely Used Superalloy

Buy Inconel 718 (UNS N07718 / Werkstoff 2.4668 / ASTM B637 / AMS 5662) bolts, stud bolts, hex nuts, and precision CNC fasteners from Exotic Alloy. Inconel 718 is the world's most widely used high-temperature superalloy, accounting for over 50% of all nickel superalloy tonnage. It delivers an exceptional combination of high tensile, creep-rupture, and fatigue strength from -253°C cryogenic to 700°C service temperatures.

Exotic Alloy manufactures Inconel 718 fasteners per AMS 5662, AMS 5663, AMS 5664, ASTM B637, and NACE MR0175 for aerospace jet engines, rocket casings, nuclear reactor control rods, and cryogenic LNG plant bolting from M6 to M100 / ¼" to 4" diameter.

Request a Quote

Technical Data

Alloy 718 Specifications

Chemical Composition — Inconel Alloy 718 (wt. %)

Element	Ni+Co	Cr	Nb+Ta	Mo	Ti	Al	Fe	Co	Mn	Si	C	B
Min %	50.00	17.00	4.75	2.80	0.65	0.20	Balance	–	–	–	–	–
Max %	55.00	21.00	5.50	3.30	1.15	0.80	Balance	1.00	0.35	0.35	0.08	0.006

Mechanical Properties — Inconel Alloy 718

Condition	UTS (MPa)	YS 0.2% (MPa)	Elongation (%)	Hardness
AMS 5662 Annealed	1240	1035	12	36–43 HRC
AMS 5663 Direct Age (DA)	1310	1100	12	38–43 HRC
AMS 5664 Annealed + Aged	1275	1035	12	36–44 HRC
At 649°C (1200°F)	1100	965	10	–

Physical Properties

Density	8.19 g/cm³
Melting Range	1260–1336°C (2300–2437°F)
Specific Heat Capacity	435 J/kg·K at 21°C
Thermal Conductivity	11.4 W/m·K at 21°C
Thermal Expansion	13.0 µm/m·°C (21–538°C)
Electrical Resistivity	1.25 µΩ·m

Equivalent Grades & Standards

UNS	Werkstoff / DIN	EN / BS	AFNOR
N07718	2.4668	NiCr19Fe19Nb5Mo3	NC19FeNb

Key Specifications: ASTM B637 / AMS 5662 / AMS 5663 / AMS 5664 / ASME SB-637

Machinability: Inconel 718 is significantly harder to machine than 625. Use carbide inserts with positive geometry and TiAlN coating, very low SFM (20–40), high feeds to keep the insert cutting continuously. High-pressure coolant (1000–2000 psi) directed at the cutting zone prevents tool-tip thermal failure.

Welding: 718 is one of the most weldable precipitation-hardening Ni superalloys due to its slow aging response that minimizes strain-age cracking. GTAW, GMAW, EBW, and PAW using ERNiCrMo-3 or matching Alloy 718 wire. PWHT: solution 980°C + double-age 720°C / 8h + 621°C / 8h.

Forging: Hot forge between 955–1118°C (1750–2045°F). Isothermal forging at 985–1025°C gives the finest grain structure (ASTM 8–10). Avoid forging below 940°C (1725°F). Post-forge solution + double-age treatment is mandatory.

Heat Treatment: Standard AMS 5663 heat treat: Solution anneal at 1010°C (1850°F) / 1h / rapid cool, then age at 718°C (1325°F) / 8h / furnace cool to 621°C (1150°F), hold 8h total, air cool. This produces the peak combination of tensile, fatigue, and creep strength.

Inconel 718 offers moderate corrosion resistance (PREN ≈ 28) compared to 625 or C-276, sufficient for turbine service in combustion gases and mild chemical environments. Fully qualified per NACE MR0175/ISO 15156 for sour oil & gas service. Resistant to seawater at ambient temperatures.

Key Characteristics

Outstanding high-temperature strength and oxidation resistance.
Excellent resistance to pitting, crevice corrosion, and intergranular attack.
High fatigue and thermal-fatigue strength in cyclic temperature service.
Superb resistance to chloride-ion stress-corrosion cracking.
Maintains structural integrity from cryogenic to extreme high-temperature service.

Typical Applications

Aerospace engineering: jet engine turbine blades, discs, and casings.
Chemical processing: reactor vessels, pressure containment bolting.
Marine and subsea: offshore wellhead, Christmas tree, HPHT connectors.
Nuclear power: reactor core hardware, primary coolant system fasteners.
Power generation: steam turbine bolting, ultra-supercritical boiler components.

Alloy 718