Answer
Inconel X-750 (UNS N07750) is a nickel-chromium alloy made precipitation-hardenable by additions of Al and Ti. In subsea applications, wave springs are exposed to H2S, CO2, and high chlorides, leading to Stress Corrosion Cracking (SCC). X-750 is chosen for its exceptional resistance to chloride-ion SCC and its ability to withstand extreme pressures. The material is typically processed according to NACE MR0175/ISO 15156 standards. The heat treatment usually involves a solution anneal followed by a double aging process to optimize the trade-off between high yield strength and ductility. Although its modulus $E$ (approx. 213 GPa) is slightly higher than steel, its density and corrosion resistance ensure the integrity of blowout preventer (BOP) seals over a 20-year service life.
