AISI 321 is an austenitic stainless steel widely used in a variety of industrial applications. This material is highly corrosion resistant, good weldability, and easy to form and process. It is widely used for parts requiring high strength and/or heat resistance, such as aircraft parts and components, industrial furnaces, power generation plant components, and process equipment. This paper discusses the low temperature mechanical properties of AISI 321.
The low temperature mechanical properties of AISI 321 are important in applications where the material may be exposed to temperatures that approach its cryogenic limit. The low temperature mechanical properties of AISI 321 are determined by its behavior at temperatures approaching the absolute zero. At low temperatures, the material shows decreased levels of strength and increased ductility. This is due to three main effects of temperature decrease: cold work hardening, plasticization, and embrittlement.
Cold work hardening of AISI 321 occurs as the temperature is further decreased. This effect causes an increase in work hardening capability, resulting in an increase in yield strength and decrease in ductility. The magnitude of this effect is dependent on the amount of deformation imposed on the material prior to subjection to the low temperature. An increase in applied stress further increases the cold work hardening effect.
Plasticization of AISI 321 occurs at cryogenic temperatures and is due to a decrease in interatomic bonding energies. At temperatures approaching the absolute zero, the material becomes increasingly “soft” and ductile due to decreased interatomic bonding energies, resulting in decreased levels of interfacial strength. As the temperature is increased, these bonding energies increase, resulting in enhanced yield strength.
Finally, embrittlement of AISI 321 occurs as the temperature is decreased. This effect is caused by an increase in dislocation mobility within the material. An increase in dislocation mobility decreases the yield strength of the material and decreases its ductility.
In conclusion, the low temperature mechanical properties of AISI 321 depend on a number of factors, including the amount of cold work hardening, plasticization, and embrittlement. These factors are closely linked to the temperature of the material, and can have a marked effect on the mechanical properties. It is therefore important to consider these effects when evaluating the behavior of AISI 321 at low temperatures.
