AMS 5838
AMS 5838 is the SAE Aerospace Material Specification for Hastelloy S (UNS N06635) nickel-chromium-molybdenum alloy in sheet, strip, and plate product forms. Hastelloy S (67% Ni, 15.5% Cr, 14.5% Mo, with Al, La, and Fe additions) was specifically engineered for gas turbine combustion zone hardware requiring the combination of good high-temperature oxidation resistance, adequate high-temperature strength, and a controlled low coefficient of thermal expansion. The lower thermal expansion coefficient of Hastelloy S compared to conventional nickel alloys reduces thermally induced stresses during combustor start-up and shut-down cycling, extending the thermal fatigue life of combustion liner panels and flame holder components.
Sheet and strip to AMS 5838 is the primary aerospace product form, used for formed and welded combustion liner panels, outer combustor bodies, transition liner sections, and afterburner flameholder assemblies. The sheet is supplied solution annealed for optimal forming and welding, with TIG (GTAW) welding using matching or ERNiCrMo-10 filler metal as the standard joining process.
AMS 5838 Hastelloy S sheet in the solution annealed condition develops minimum 115,000 psi UTS with minimum 40% elongation. At 1800°F (982°C), the alloy retains approximately 10,000–15,000 psi UTS — adequate for the stresses in thin-gauge combustion liner panels. The thermal expansion coefficient of Hastelloy S at 1000°F (538°C) is approximately 8.1 × 10⁻⁶ in/in/°F, compared to 9.0–10.0 × 10⁻⁶ for most nickel alloys and 10.0–12.0 × 10⁻⁶ for austenitic stainless steels. This 10–20% reduction in expansion rate directly reduces thermal fatigue damage accumulation per cycle in combustion liner applications.
- Gas turbine combustion liner inner and outer panels
- Combustor transition duct liner sections
- Afterburner flameholder assemblies in military turbofan engines
- Industrial gas turbine combustion basket panels
- Aerospace thermal management structures subject to repeated thermal cycling
- Gas turbine exhaust mixing devices and nozzle liner panels
AMS 5878 — Alloy 230 Bar
Haynes Alloy 230 bar and forgings for gas turbine combustion hardware at 2100°F — outstanding oxidation resistance and high-temperature strength.
AMS 5786 — Hastelloy N Bar
Ni-Mo alloy for molten fluoride salt environments — the unique specification for advanced nuclear and fluoride chemical applications.
Certified Material for Critical Service
AMS 5838 sheet certifications include chemical composition per heat (with Mo and Al content documented), mechanical properties per lot at room and elevated temperatures, solution anneal condition, grain size where specified, and dimensional inspection (thickness, width, flatness). Oxidation resistance testing per ASTM B76 (cyclic oxidation testing) may be specified for engine qualification programs. For gas turbine combustion liner applications, the applicable engine manufacturer material qualification requirements (AMS or proprietary specification) must be satisfied in addition to AMS 5838 base material requirements. Full traceability by heat and lot is maintained per AS9100.