Constitutive and numerical modeling of coupled dissipative phenomena in 316L stainless steel at cryogenic temperatures

Abstract

A macroscopic material model for simulation of coupled dissipative phenomena taking place in FCC metals and alloys at low temperatures is developed. Three phenomena: plastic flow, plastic strain induced transformation from the parent phase (γ) to the secondary phase (α′) and evolution of micro-damage are studied using a thermodynamically consistent framework. The experimental results indicate a correlation between decreasing damage rate and increasing martensite content. For the micro-damage evolution in the parent austenitic phase a generalization of the classical isotropic ductile damage concept to anisotropic model has been adopted. The kinetics of damage evolution is based on the accumulated plastic strain as a driving force of ductile damage. On the other hand, the deterioration of the brittle secondary phase is described by the damage evolution equation expressed in the form of tensorial function, where the damage tensor depends directly on the stresses applied. This formulation accounts both for the isotropic damage, and for the oriented damage due to different effects of the stress tensor. Total amount of damage in the representative volume element is obtained via the linear rule of mixture. The results obtained in the course of numerical simulations fit well the experimental data.