Constitutive model of plastic strain induced phenomena at cryogenic temperatures

FCC metals and alloys are frequently used in cryogenic applications, nearly down to the temperature of absolute zero, because of their excellent physical and mechanical properties, including ductility. These materials, often characterized by the Low Stacking Fault Energy (LSFE), undergo at low temperatures three distinct phenomena: Dynamic Strain Ageing (DSA), plastic strain induced transformation from the parent phase $ \gamma$ to the secondary phase $ \alpha'$ and evolution of micro-damage. As all three phenomena lead to irreversible degradation of lattice and can accelerate the process of material failure, a combined constitutive description appears to be fundamental for the correct analysis of structures applied at very low temperatures. The constitutive model presented in the paper takes into account all the three phenomena as well as the relevant thermodynamic background.