Incoloy 909
Incoloy 909 (UNS N19909) is a controlled-thermal-expansion (CTE) superalloy — a precipitation-hardenable nickel-iron-cobalt alloy (38%Ni, 41%Fe, 13%Co, 4.7%Nb, 1.5%Ti) specifically engineered to have a constant, predictable, and very low coefficient of thermal expansion between ambient temperature and 1200°F (649°C). This controlled expansion characteristic is the primary property that distinguishes Incoloy 909 from other nickel superalloys — it enables extremely tight dimensional control in gas turbine engine sealing systems and structural components where differential thermal expansion between dissimilar materials must be minimized.
The alloy achieves high strength through precipitation of gamma-prime (Ni₃Ti) and eta phase (Ni₃Ti) strengthening particles during aging. AMS 5884 covers billet and bar, AMS 5892 covers sheet and strip, and AMS 5893 covers plate — together providing complete product form coverage for gas turbine engine applications.
Product Forms & Size Range of Incoloy 909
Incoloy 909 bar and billet per AMS 5884 is available in round bar from 0.375″ to 10.000″ and as forging billet for gas turbine component blanks, solution-treated. Used for machined engine sealing rings, knife-edge seals, structural retaining rings, and precision structural components in gas turbine engines operating up to 1200°F.
Incoloy 909 sheet and strip per AMS 5892 is available in thicknesses from 0.004″ to 0.187″ and widths up to 48″, solution-treated. Used for formed engine sealing elements, thin-wall structural components, and hot-section structural sheet metal fabrications in aircraft gas turbine engines.
Incoloy 909 plate per AMS 5893 is available in thicknesses from 0.188″ to 3.000″, solution-treated. Used for machined structural components, flanges, and thick-section parts in gas turbine engine hot sections where controlled thermal expansion is essential to system dimensional integrity.
HEAT TREATMENT OF INCOLOY 909
Incoloy 909 is solution treated at 1800°F (982°C) for one hour per inch of thickness, water quenched, then age-hardened at 1400°F (760°C) for 8 hours air cool + 1200°F (649°C) for 8 hours air cool. This two-step aging develops the Ni₃Ti gamma-prime precipitates for maximum strength. Minimum yield strength after aging: 130,000 psi. Minimum tensile strength: 155,000 psi. The alloy shows relatively low thermal expansion (CTE ≈ 7.7 × 10⁻⁶/°F from 70–1200°F) compared to standard superalloys.
Inconel 718
Precipitation-hardenable Ni-Cr-Mo alloy (AMS 5662/5663/5664) — broader use across all gas turbine applications where controlled thermal expansion is not the primary requirement.
Incoloy 800
Standard Fe-Ni-Cr alloy for high-temperature service — simpler, lower-strength alternative where CTE control is not required.
Certified Material for Critical Service
Incoloy 909 is supplied to AMS 5884 (bar and billet), AMS 5892 (sheet and strip), and AMS 5893 (plate). Mill certifications document full chemistry, melt practice, and mechanical properties in the solution-treated condition. Age-hardening is typically performed by the component manufacturer to control final properties and dimensions simultaneously.