An implicit algorithm to verify creep and TRIP behavior of steel using uniaxial experiments

Creep is a complex material feature occurring in mechanical structures under moderate stresses and relatively high temperatures. Transformation-induced plasticity (TRIP) is a macroscopic phenomenon of steel behavior. If phase transformations occur under deviatoric stress, a permanent inelastic strain is obtained even if the yield stress is not reached. Thus, creep and TRIP do not have a yield stress like plasticity and visco-plasticity. Sometimes, during heat treatment of steel, creep and TRIP appear together. In order to determine creep or TRIP behavior it is necessary to verify concrete material laws and to determine corresponding material parameters. For this reason, often uniaxial experiments with small probes are performed in special devices. It is the main purpose of this study, to develop a procedure for the verification of possible laws for creep and TRIP and for determining material parameters, using experimental data. Therefore, an implicit algorithm in two variants will be developed: strain-driven and stress-driven. These algorithms can also be applied to simulations of (spatially homogenous) uniaxial experiments. Based on these algorithms, an optimization scheme will be developed for finding material parameters which realize a best approximation. Finally, the developed procedure will be applied for the investigation of creep and TRIP during heating of the bearing steel 100Cr6 (SAE 52100).