Official Answer
Answer
Inconel X-750 (UNS N07750) is a nickel-chromium alloy made precipitation-hardenable by additions of Aluminum and Titanium. In subsea environments, it is chosen for its immunity to chloride-ion stress corrosion cracking and its ability to maintain mechanical properties in sour gas ($H_2S$) environments. The material must be heat treated per NACE MR0175 standards to ensure a maximum hardness of 35 HRC, preventing hydrogen embrittlement. Its modulus of elasticity $E \approx 213$ GPa must be used in all spring rate calculations, which is slightly higher than carbon steel.
