AMS 5786
AMS 5786 is the SAE Aerospace Material Specification for Hastelloy N (UNS N10003) nickel-molybdenum-chromium alloy in bar, forging, and tubing product forms. Hastelloy N (71% Ni, 16% Mo, 7% Cr, 5% Fe) is the only commercial alloy with demonstrated resistance to corrosion by molten fluoride salt mixtures at temperatures up to 1300°F (704°C) — the operating condition required for molten salt reactor (MSR) and thorium fuel cycle systems. Originally developed at Oak Ridge National Laboratory as INOR-8 for the Molten Salt Reactor Experiment, it has remained the reference material for advanced nuclear energy systems and high-temperature fluoride chemical processing for over six decades.
Beyond its unique fluoride salt resistance, Hastelloy N provides excellent high-temperature strength to 1300°F, good resistance to mineral acids, and outstanding oxidation resistance to 1800°F in air. AMS 5786 sets aerospace and high-performance chemical processing quality requirements for composition, cleanliness, and mechanical properties in machined component forms.
AMS 5786 Hastelloy N bar in the solution annealed condition develops minimum 100,000 psi UTS with minimum 40% elongation at room temperature. At 1200°F (649°C), tensile strength is approximately 70,000 psi with adequate ductility for pressure-bearing applications. The molybdenum content (16%) is the primary contributor to both the fluoride salt resistance (by forming stable Mo₂F₅ protective species) and the high-temperature solid-solution strength. For applications requiring maximum creep resistance at 1200–1300°F, an aging treatment at 1250°F (677°C) develops a M₆C carbide dispersion that improves stress rupture life.
- Molten salt reactor primary circuit pump and heat exchanger components
- Uranium hexafluoride (UF₆) processing equipment and valves
- Fluorine and hydrogen fluoride chemical reactor internals
- High-temperature fluoride salt transfer piping and fittings
- Advanced nuclear fuel cycle processing components
- Aerospace systems exposed to fluoride-containing atmospheres at elevated temperature
AMS 5878 — Alloy 230 Bar
Haynes Alloy 230 Ni-Cr-W-Mo for gas turbine combustion hardware to 2100°F — outstanding high-temperature strength and oxidation resistance.
AMS 5838 — Hastelloy S Sheet
Ni-Cr-Mo alloy with low thermal expansion for gas turbine combustion zone liners and afterburner components.
Certified Material for Critical Service
AMS 5786 certifications include chemical composition per heat (with molybdenum content documented at 15.0–18.0%), mechanical properties per lot at room and elevated temperatures, grain size, solution anneal condition, and inclusion rating per AMS 2301. For nuclear applications, additional requirements including ultrasonic inspection per ASTM E428, Charpy impact testing at low temperature, and irradiation data review from ORNL reports may be required by the applicable nuclear safety authority. Full heat-lot traceability to the specific VIM melt is maintained.