Official Answer
Answer
A286 is an iron-base superalloy that maintains high strength and, crucially, high toughness at cryogenic temperatures down to -196°C (77K). Unlike standard carbon steels or some martensitic stainless steels which undergo a ductile-to-brittle transition (DBT), A286 remains austenitic. Its coefficient of thermal expansion is also relatively stable. In cryogenic spring design, the increase in Modulus of Elasticity $E$ at low temperatures must be calculated; $E$ can increase by 5-10%, meaning the spring rate $k$ will be higher than at room temperature. A286's precipitation-hardened state (aged at 1300-1400F) ensures it can withstand the high stresses required in compact cryogenic seals.
