Explanation

stainless steel containing a considerable amount of chromium, nickel and manganese. The face-centered cubic structure generally has no cold brittle transformation temperature, and is widely used in the low-temperature field. According to the stability of composition and structure, it can be divided into: ① Fe Cr Ni series (AISI300 series stainless steel), 18-8 is the representative steel of Cr Ni austenilic stainless steel; ② Fe Cr Ni Mn and Fe Cr Ni Mn nitrogen systems, manganese can expand the austenite phase area, nitrogen as a interstitial element has a significant solid solution strengthening effect, 21-6-9 low temperature non-magnetic steel is a typical representative, this steel has high strength at 4.2K（ σ 0.2>1300MPa), good plasticity and toughness, used as materials for superconducting magnet frame, superconducting motor rotor, liquid nitrogen dewar and other components; ③ Iron manganese aluminum series is a new type of steel that saves nickel and chromium (Mn: 24% -32%, Al: 4% -8%). Among them, 15Mn26A14 has high low-temperature toughness, stable structure, low low-temperature magnetic permeability, and can be used in various low-temperature engineering projects at 77-4.2K for pipes, plates, and wires; ④ Iron nickel base and nickel base superaalloy series have high strength and toughness at low temperature, and the strength is 2.5-5 times higher than 18-8 stainless steel, which is suitable for cryogenic components in spacecraft.

Classification