Study on Ramberg-Osgood and Chaboche models for 42CrMo4 steel and some approximations

Presented work is focused on experiment-based characterization and modelling of normalized and quenched and tempered low-alloy steel 42CrMo4 subjected to monotonic and cyclic loading and possibility to determine parameters of more complex models from simple ones. The main characteristics of the cyclic Ramberg-Osgood and rate-dependent as well as rate-independent Chaboche's material models, both of which are applicable for this material, have been presented. Similarities in the modelling and simulation of stabilized material behaviour confirmed possibility of such approximation for Ramberg-Osgood and rate-independent Chaboche model. However, due to inadequacy of Ramberg-Osgood for modelling of evolutionary material behaviour throughout loading cycles, separate study of the influence of saturation rate of isotropic hardening of rate-dependent Chaboche's model on modelling and simulation of material behaviour has been performed. The study showed that deviations of simulated material behaviour from the experimentally obtained behaviour are low, and in majority of the materials life negligible and recommendations on the range of values of saturation rate parameters differently heat treated 42CrMo4 steel are provided. In order to make possible further comparisons of analysed models and evaluate applicability of proposed approximations on other materials, further analyses on additional materials would need to be performed.