Cyclic constitutive models for G20Mn5QT cast steel at low temperatures

Abstract

Cyclic constitutive model for G20Mn5QT cast steel is essential to simulate the hysteretic behaviour of cast steel joints. In consideration of cast steel joints exposing to low temperature environments, understanding of the effect of the drop of temperature on the cyclic behaviour of the material is preferred. Cyclic loading tests were then conducted on 12 smooth round bar specimens for G20Mn5QT cast steel at 20 °C, −20 °C, −40 °C and −60 °C. Cyclic stress-strain curves were obtained and variations of the peak stress, flow stress and backstress during cyclic loadings were calculated. The cyclic hardening behaviour of G20Mn5QT cast steel was discussed for the four temperature levels. It was found that the isotropic strengthening capacity of G20Mn5QT cast steel decreases with the drop of temperature, while the kinematic hardening behaviour of the material is not sensitive to temperature variations. Parameters in the Voce-Chaboche model were calibrated and validated based on the results of these tests for G20Mn5QT cast steel at the four temperature levels. By specifying the range of values for some parameters, the accuracy of the Voce-Chaboche models was improved in the simulation of the cyclic loading tests.