Modeling of the cyclic deformation behavior of austenitic TRIP-steels

Abstract

The mechanical behavior of TRIP-steels (TRansformation Induced Plasticity) under monotonic loading conditions has been extensively studied both experimentally and by continuum mechanical modeling. The cyclic response received far less attention so far, although the mechanically induced martensitic phase transformation highly affects the cyclic deformation behavior. Especially in high alloy austenitic TRIP-steels a pronounced cyclic hardening is observed in cyclic deformation curves, which evolves proportionally to the volume fraction of deformation-induced martensite. In the present contribution a phenomenological material model is proposed, which is able to capture this effect. A rate independent two-surface plasticity approach is employed. The first surface is of J2-type and describes plastic yielding, whereas the second surface is of Drucker-Prager type and represents the mechanically induced phase transformation. The formulation of the plastic behavior incorporates nonlinear kinematic hardening. The model is calibrated based on a consistent set of uniaxial cyclic deformation experiments with constant strain amplitude under tension-compression. Results of the simulations match the cyclic deformation curves for a large range of strain amplitudes including the transformation induced cyclic hardening well. The qualitative and quantitative agreement between numerical and experimental data as well as the capabilities and limitations of the model are discussed in detail.