What is the temperature below which low-temperature steel needs to be used?
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What is the temperature below which low-temperature steel needs to be used?
Stees for low temperature service are alloy steels suitable for use at temperatures below 0°C. Those that can be used at temperatures below -196°C are called cryogenic steel or ultra-low temperature steel. Low-temperature steel should primarily possess the following properties: ① A toughness-to-fracture transition temperature lower than the operating temperature ； ②Strength meeting the design requirements ； ③The tissue structure remains stable at the operating temperature ； ④Good weldability and formability ； ⑤Certain special applications also require extremely low magnetic permeability, cold shrinkage rate, etc. Low-temperature steels can generally be divided into two main categories based on their crystal lattice type: body-centered cubic ferritic low-temperature steels and face-centered cubic austenitic low-temperature steels.
It is specified in GB/T 150.2
Material temperature, material stress state, material properties!
It seems the design temperature is +20°C, below -20℃
The national standard for low-temperature steel generally defines it as temperatures below -20°C, while the American standard defines it as temperatures below -29°C. -Anything below 101 falls into the category of ultra-low temperature. Different steel grades are used at various temperatures; austenitic stainless steels can be used at temperatures close to absolute zero, while martensitic stainless steels are generally not suitable for low temperatures, although some of them can be used in the range of -46°C. Carbon steel is also used at -46°C. The appropriate choice should be made based on the specific circumstances
The logic is reversed here – isn’t it supposed to be that you choose the material based on your processing conditions? Selecting process conditions based on the material – are you a steel salesperson?
The question is too general; there are many types of low-temperature steels, and factors such as temperature, medium, and pressure determine the material you should choose.