Official Answer
Answer
MP35N is a cobalt-nickel-chromium-molybdenum alloy that provides an extraordinary combination of ultra-high strength (up to 300 ksi), excellent toughness, and superb corrosion resistance. It is specifically selected for the most demanding medical implants (due to biocompatibility) and subsea applications where exposure to hydrogen sulfide ($H_2S$) and high pressures is expected. Its modulus $E$ is approximately $33.5 \times 10^6$ psi. Due to its high cost and specialized processing requirements, it is only used when 17-7PH or Inconel X-750 cannot meet the fatigue life or corrosive environment requirements of the system.
