INCOLOY 909 is a nickel-iron-cobalt-based superalloy (a type of high-performance alloy) specifically engineered for low thermal expansion combined with excellent high-temperature strength and creep resistance. It belongs to the family of "controlled expansion alloys" and is primarily designed for applications where dimensional stability under fluctuating or elevated temperatures is critical-such as components in gas turbines, aerospace engine parts, and high-precision industrial equipment that operate in thermal cycling environments. Unlike some other INCOLOY grades focused solely on corrosion resistance, INCOLOY 909's core advantage lies in balancing thermal expansion control with mechanical performance at high temperatures.
The composition of INCOLOY 909 is carefully formulated to achieve its low thermal expansion and high-temperature properties. Below is its typical nominal chemical composition (by weight percentage, wt%):
The yield strength of INCOLOY 909 depends on its heat treatment condition (as heat treatment significantly influences the formation of strengthening phases like γ') and the test temperature (since yield strength decreases with increasing temperature). Below are typical yield strength values for the alloy in its most common heat-treated state (solution annealed + precipitation hardened, a standard condition for maximizing strength):
Room temperature (20°C / 68°F): Typical yield strength ranges from 827 MPa to 965 MPa (120,000 psi to 140,000 psi).
Elevated temperatures (relevant for its intended use):
At 650°C (1202°F): Typical yield strength is approximately 655 MPa to 758 MPa (95,000 psi to 110,000 psi).
At 760°C (1400°F): Typical yield strength decreases to around 483 MPa to 586 MPa (70,000 psi to 85,000 psi).
