Answer
Inconel X-750 is a nickel-chromium superalloy that is precipitation-hardened using aluminum and titanium. For wave springs in subsea oil and gas or cryogenic aerospace valves, it is selected for its stability across a temperature range of $-400^\circ F$ to $+1300^\circ F$. The processing usually involves a solution treatment followed by one or two stages of aging to optimize the gamma-prime ($\gamma'$) precipitate morphology. In high-temperature creep environments, Inconel X-750 exhibits far superior stress relaxation resistance compared to 17-7PH. The design must account for the lower Modulus of Elasticity ($E \approx 31 \times 10^6$ psi) and higher density ($0.298 lb/in^3$) compared to steel, which affects both the spring rate calculation and the natural frequency.
