Why Inconel 718 for Aerospace Fasteners
Aerospace fasteners must maintain bolt preload and resist fatigue failure under vibration, thermal cycling, and corrosive environments throughout the aircraft's service life. Inconel 718 is specified for fastener applications where conventional steel or titanium fasteners cannot meet the temperature or corrosion requirements. With tensile strength exceeding 180 ksi in the aged condition, Inconel 718 provides bolt strength comparable to high-strength steel while maintaining corrosion resistance and mechanical properties at temperatures up to 1,300°F—far above the capability of steel fasteners that require cadmium plating for corrosion protection.
Manufacturing Process
CastAlloy produces Inconel 718 fasteners through hot heading (forging) of bar stock followed by precision CNC machining of threads, shanks, and drive features. The forging process cold-works the head, improving its strength and fatigue resistance. Thread rolling (rather than cutting) produces stronger threads with compressive residual stresses at the root that resist fatigue crack initiation. Heat treatment per AMS 5663 achieves the full aged strength of the alloy. We manufacture hex bolts, twelve-point bolts, socket head cap screws, studs, nuts, and custom fastener configurations to NAS, AN, MS, and customer-specific standards.
Applications and Specifications
Inconel 718 fasteners from CastAlloy serve applications in gas turbine engine casings and flanges (where they maintain clamp load at elevated operating temperatures), exhaust system joints, high-temperature structural connections in engine pylons and thrust reversers, nuclear reactor vessel bolting (where the alloy's radiation resistance and relaxation properties are critical), and petrochemical equipment operating at elevated temperatures in corrosive environments. We produce fasteners to AMS 5662, 5663, 5664, ASTM B637, and customer-specified requirements with full certifications and material test reports.