Viscoplastic constitutive modelling of the ratchetting behavior of 35CrMo steel under cyclic uniaxial tensile loading with a wide range of stress amplitude

The rate-dependent ratchetting characteristics of 35CrMo alloy under repeated uniaxial tension considering different stress amplitudes were studied at 500 degrees C. It is found that the applied stress rate and stress amplitude influence the accumulated plastic deformation greatly. The existing visco-plastic ratchetting constitutive model can well predict those features considering the effect of stress rate, but not so well when the stress amplitude effect is involved, especially for the cases of relatively low stress amplitude. Accordingly, a modified rate-dependent ratchetting constitutive model has been developed, which can well predict the ratchetting deformations in a wide range of stress amplitude and stress rate. Furthermore, the modified rate-dependent ratchetting constitutive model can be used to assess the ratchet boundary of the alloy with relatively high accuracy.