Parameter evolution in a continuous Masing approach for cyclic plasticity and its physical interpretation

Abstract

A continuous Masing model for the description of the elastic–plastic constitutive behaviour of a bainitic low-alloy steel was recently introduced. Its four model parameters can be directly linked to the shape of the stress–strain characteristic and to the microstructure of the material on the basis of the Masing concept. In this study the temperature, strain rate and strain amplitude dependent cyclic evolution of these parameters is presented for a bainitic 2CrMoNiWV steam turbine rotor steel loaded under low-cycle fatigue conditions. It is observed that the parameters develop differently for tensile and compressive loading and that the parameter evolution reflects the observed dislocation density reduction and sub-grain size increase. A statistical correlation analysis indicates that the parameters characterising the element yield strain distribution function significantly correlate with the measured sub-grain size and dislocation density of the material.