Thermo-mechanical fatigue testing and simulation using a viscoplasticity model for a P91 steel

► An experimental programme of cyclic isothermal testing has been performed. ► Initial material constants for a viscoplasticity model have been derived from experimental data. ► An optimisation procedure has been developed to determine accurate material constants. ► The model has been applied with great accuracy to isothermal conditions. ► Interpolation of the material constant has been used to provide anisothermal predictions.