With mankind reaching out to the stars, it has become important for the designers to consider suitability for extreme conditions for products.
Therefore it is necessary to know what types or fastener materials are suitable for extreme conditions.
Cryogenic temperatures as low as -70°C exist already on Earth with the coldest recorded temperature being -89.2°C.
Temperatures in Space can be lower than -200°C.
Are there fastening options commonly available for such service conditions?
Fortunately, Austenitic stainless steels such as 304 (1.4301) and 316 (1.4401) are however “tough” at cryogenic temperatures and can be classed as “cryogenic steels”.
They can be considered suitable for sub-zero ambient temperatures sometimes mentioned in service specifications sub-arctic and arctic applications and locations, typically down to -40°C.
This is the result of the ‘fcc’ (face centered cube) atomic structure of the austenite, which is the result of the nickel addition to these steels.
Consider the effect of cryogenic temperatures on the tensile properties of the austenitic stainless steels shown in Table below.
There are a number of petrochemical processes that require operation at low temperature. In ethylene plants, for example, the product is separated by fractional distillation at sub-zero temperature, and towers, drums, piping and heat exchangers may be exposed to temperatures as low as -120°C (-184°F).
The materials most frequently used for operation in sub-zero temperatures are aluminum, carbon steel, 3% or 9% nickel steels and austenitic stainless steels. Austenitic stainless steels are generally employed where the temperatures are below -196°C (-321°F) for the construction of pipes, pumps and valves. Because of their excellent combination of mechanical and physical properties, austenitic stainless steels are being considered for load-bearing structures of large superconducting magnets for plasma containment in magnetic fusion experiments at cryogenic temperatures.